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1: MagneQuest/Peerless Forum, RE: Baby Ongaku (0.00)
Posted by keto on 2015-05-11, 10:14:53 (187.237.239.4)
Hey Xavier, congrats for the new amps -- they look great. Congrats too for the project itself. Very cool, on many levels! -- Tom .......
2: SET Asylum, RE: Sure, it is approximate, but the main message is tweeters crossed high don't need that much power... (0.00)
Posted by keto on 2012-04-06, 06:39:48 (189.228.120.108)
I totally agree. I've got 2 of 3 Bottlehead S.E.X. amps built, as handy experimental platforms for a tri-amped system. 2W and a continuous volume control. Mids are 106dB between 300 and 1200hz and the .......
3: SET Asylum, RE: Acoustic output of tweeter is 10 percent of total acoustic output above 5 khz... (0.00)
Posted by keto on 2012-04-05, 22:53:19 (189.228.120.108)
I read of a similar power distribution WRT frequency years ago, over at the Lambdacoustics Forum. Lets see if I can remember it correctly :-) ...... that the Chicago Symphony was measured producing 65 .......
4: MagneQuest/Peerless Forum, RE: check these guys out.... (0.00)
Posted by keto on 2012-03-02, 15:57:27 (189.139.141.149)
Hey Mike, Jorge's horns are awesome! -- Tom .......
5: MagneQuest/Peerless Forum, RE: check these guys out.... (0.00)
Posted by keto on 2012-03-02, 15:56:16 (189.139.141.149)
Hey Jorge, I didn't know you were "Saturntube". Your cover is now blown, hahahaha! --Tom .......
6: High Efficiency Speaker Asylum, RE: a few questions about shelf filters (0.00)
Posted by keto on 2012-01-19, 09:47:59 (189.228.119.114)
Thanks a lot for the help, Paul. Tonight I'll be taking some measurements, to see how the 4550 and the mids really behave on a 60 x 60 CD horn. I now understand the line-level, step-filter's relation .......
7: High Efficiency Speaker Asylum, RE: a few questions about shelf filters (0.00)
Posted by keto on 2012-01-17, 11:52:20 (189.228.119.114)
At 10khz its more like 105dB. The idea is to flatten the response from 1.5khz to 10khz to a uniform 105dB. I'm curious if its possible to design a passive line-level filter with a shelf at 1.5khz and .......
8: High Efficiency Speaker Asylum, RE: a few questions about shelf filters (0.00)
Posted by keto on 2012-01-17, 10:39:19 (189.228.119.114)
Thanks. Would it be possible to do such a slope in the passive realm, either at speaker- or line-level? .......
9: High Efficiency Speaker Asylum, a few questions about shelf filters (0.00)
Posted by keto on 2012-01-17, 08:28:22 (189.228.119.114)
Hey all, I've been looking for tutorials on shelf filters and found this one at the Linkwitz Labs site http://www.linkwitzlab.com/filters.htm#6 I haven't yet figured out what "s" is in the formula, bu .......
10: High Efficiency Speaker Asylum, ping Tom Danley re suggestions for how to protect a BMS 4550 (0.00)
Posted by keto on 2012-01-16, 07:15:36 (189.228.119.114)
Hi Tom, I've got individual (stereo) SET amps (with volume controls) for the Unity mids and tweeters, and would like to move from the B&C driver to the BMS 4550. Would you be able to recommend a prote .......
11: MagneQuest/Peerless Forum, RE: 801-300B amplifier with FSO-30 (0.00)
Posted by keto on 2012-01-14, 16:26:25 (189.228.119.114)
Congrats. They look awesome! .......
12: MagneQuest/Peerless Forum, RE: changed URL ... (0.00)
Posted by keto on 2011-12-18, 22:16:48 (187.193.247.241)
Great stuff, gluca! Looks like a wolf on sheep's clothing, hahaha... sorry, couldn't help myself. .......
13: MagneQuest/Peerless Forum, hang on (0.00)
Posted by keto on 2011-12-13, 21:08:12 (187.193.247.241)
Mike, did you say a 50K:10K? If so, that would be really handy between the Seduction or Eros and the P&G 10K.... .......
14: MagneQuest/Peerless Forum, 8K:4,2 autoformer? (0.00)
Posted by keto on 2011-11-16, 21:40:25 (189.228.121.86)
Hey Mike, how's it going? I'm building a Bottlehead S.E.X. amp which will operate in a 1st-order, 300hz-1200hz bandpass: four 8-ohm mids wired in parallel, which present a 2-ohm load to the amp. For s .......
15: MagneQuest/Peerless Forum, RE: build ideas for 2A3 or 45 parallel feed (0.00)
Posted by keto on 2011-11-05, 21:20:17 (187.193.249.199)
Mmmmmmmmmm, cobalt. Maybe a 300B @ 200Vp-k 50mA -37Vg and the 2.5K load for 2.5W. With such a low voltage you could direct-couple. Sorry, you mentioned the 45 and 2A3 and I got distracted by visions o .......
16: MagneQuest/Peerless Forum, RE: the plot thickens (0.00)
Posted by keto on 2011-10-27, 05:57:21 (189.139.139.188)
Thanks. The rectangular thing is an IEC with a big RFI filter. .......
17: MagneQuest/Peerless Forum, the plot thickens (0.00)
Posted by keto on 2011-10-24, 22:33:53 (189.228.113.13)
Hmmm, using a shelf-annealed BCM-8 for choke-input duty has yielded promising results. Time to make some stand-offs and show-horn that guy in there. .......
18: MagneQuest/Peerless Forum, The mighty PGP8.1 rides again (0.00)
Posted by keto on 2011-10-23, 20:11:32 (189.228.113.13)
Here's the first step of an active crossover platform. I just got the high voltages up and running and regulated with OC3s. .......
19: High Efficiency Speaker Asylum, trompe l'oeil (0.00)
Posted by keto on 2011-10-22, 10:03:03 (187.193.249.207)
They are large BR enclosures .......
20: High Efficiency Speaker Asylum, RE: Hey Guys check this adjustable tapped horn plan. (0.00)
Posted by keto on 2011-10-21, 21:56:14 (187.193.249.207)
Cool videos. No headphones around, so I listened to them one these... I'd really like to hear those Jerichos sometime. .......
21: High Efficiency Speaker Asylum, power ratings on HF drivers, with lower-order XO filters (0.00)
Posted by keto on 2011-10-05, 17:44:28 (189.139.57.253)
Hey all, how do I calculate a minimum crossover frequency for 3rd, 2nd and 1st order filters, using the GPA-390 as an example and assuming full-power? 300 Hz - 7 kHz at rated power. 120 watts continuo .......
22: MagneQuest/Peerless Forum, RE: take this schematic with a grain of salt (0.00)
Posted by keto on 2011-09-20, 06:15:49 (189.139.138.109)
Thanks a lot -- thats good to know. Not sure yet if I'll pre-drill or maybe make an adapter. The S-240-A's are 2.5" x 2.5" .......
23: MagneQuest/Peerless Forum, take this schematic with a grain of salt (0.00)
Posted by keto on 2011-09-17, 10:37:46 (189.139.138.109)
Okay, that's good advice with all of my schematics :-), but in this case, there are two major factors. 1. I got a welcome message from Brian Sowter about the 2:1+1 input transformer model 1125 and DC .......
24: Tube DIY Asylum, RE: Question about Bourns multi-turn pot's (0.00)
Posted by keto on 2011-09-16, 15:32:58 (189.139.138.109)
Thanks. I'll use the "3590" for the "total bias" (1K) as well, instead of the larger "3500". That way, with the same sized chassis holes, I can try different values. .......
25: Tube DIY Asylum, RE: The schematic looks awesome (0.00)
Posted by keto on 2011-09-15, 06:48:54 (189.139.138.109)
Thanks. I'm still missing the... Sowter 1125 input transformer, 115V:5Vct@2.5A filament transformer (300B pair), 115V:6.3V@3A heater transformer (6CJ3 pair), and 115V:6.3V@3A heater transformer (6SN7G .......
26: Tube DIY Asylum, RE: Question about Bourns multi-turn pot's (0.00)
Posted by keto on 2011-09-14, 17:30:09 (189.139.138.109)
I just edited the schematic, and included a few more target voltages. .......
27: Tube DIY Asylum, RE: Question about Bourns multi-turn pot's (0.00)
Posted by keto on 2011-09-14, 17:28:58 (189.139.138.109)
Thanks. I just checked out the prices, and wow, that's outside the budget. But its good to know about the technology. In this case the 10-turns will provide a very fine adjustment to the bias and bala .......
28: Tube DIY Asylum, RE: I see a couple problems with the schematic (0.00)
Posted by keto on 2011-09-14, 17:26:42 (189.139.138.109)
Thanks, I just edited the schematic. I'd forgotten to ground the CT. How's that look? .......
29: MagneQuest/Peerless Forum, improved schematic for PP300B (0.00)
Posted by keto on 2011-09-14, 13:06:12 (189.139.138.109)
Thanks for all the great suggestions. This is the new schematic. Sorry for posting such a bizarre schematic, before. .......
30: Tube DIY Asylum, Question about Bourns multi-turn pot's (0.00)
Posted by keto on 2011-09-14, 13:00:50 (189.139.138.109)
Hi all, pictured are 3590 (500R) and 3500 (1K) style Bourns 2W, 10-turn pot's, that I'm planning on using in a PP300B (see "work-in-progress" schematic), as balance and bias adjusters. I just s .......
31: MagneQuest/Peerless Forum, RE: help requested for a negative bias supply (0.00)
Posted by keto on 2011-09-13, 21:28:44 (189.139.138.109)
Super! Would it look like this? I guess the 540Vct would be best, for starters -- so as not to go over +/- 360vdc. There will be shrink tubing on all the unused taps! Thanks! .......
32: MagneQuest/Peerless Forum, parafeed a la UTC (0.00)
Posted by keto on 2011-09-13, 11:55:35 (189.139.138.109)
I just picked up a pair of UTC bias transformers (115V:254-960Vct @250mA), and in the original box was a brochure that included instructions for how to parafeed a 6J5 driver, with the ground leg re .......
33: MagneQuest/Peerless Forum, RE: Would a high voltage delay help? (0.00)
Posted by keto on 2011-09-12, 21:30:47 (189.139.138.109)
I will keep the delay in mind. Many thanks! .......
34: MagneQuest/Peerless Forum, RE: help requested for a negative bias supply (0.00)
Posted by keto on 2011-09-12, 21:28:17 (189.139.138.109)
I hadn't thought of referencing the heaters. 6SN7GTA will (only) take a difference of "100V DC or 200V total DC + peak". Thanks a lot. .......
35: MagneQuest/Peerless Forum, RE: negative bias supply (0.00)
Posted by keto on 2011-09-07, 22:45:54 (189.228.116.173)
Thanks for all the help, V2nd. I'll check with Sowter to see if the two windings can handle the voltage difference. And, I'll move the 100H choke. Here's a mock up for Front Panel Express with the .......
36: MagneQuest/Peerless Forum, RE: What is it doing that you do not like? (0.00)
Posted by keto on 2011-09-07, 21:07:23 (189.228.116.173)
Its just a schematic, at this stage. Maybe the more appropriate question from me would be: "Will this negative voltage supply work?" .......
37: MagneQuest/Peerless Forum, help requested for a negative bias supply (0.00)
Posted by keto on 2011-09-07, 00:35:38 (189.228.116.173)
Hey all, I'm pretty sure there's something wrong with the negative bias supply as described, and would appreciate any suggestions as to how to fix it and/or for further reading. The psu choke shoul .......
38: Tube DIY Asylum, RE: How do I shunt-regulate a PP300B output stage? (0.00)
Posted by keto on 2011-09-04, 08:28:41 (189.228.116.173)
Sorry, my drawing is an approximation of the surrounding circuit. PSUD2 predicts 3uF and 220uF would work well, and in a similar circuit I found that 4uF and 30uF worked well -- thus the range of valu .......
39: Tube DIY Asylum, 300B SR (0.00)
Posted by keto on 2011-09-04, 06:30:19 (189.228.116.173)
okay, just found this... .......
40: Tube DIY Asylum, RE: How do I shunt-regulate a PP300B output stage? (0.00)
Posted by keto on 2011-09-04, 06:17:11 (189.228.116.173)
Thanks, DanL. This may sound strange, but I'd rather not make the PP300B itself "constant current". Above is my (erroneous?) approximation of what a PP6EM7 output would look like if its current dra .......
41: Tube DIY Asylum, How do I shunt-regulate a PP300B output stage? (0.00)
Posted by keto on 2011-09-03, 22:55:24 (189.228.116.173)
Hey all, given a PP300B output stage that swings from 170mA (quiescent) to 200mA (full 20W output) with a 4Kp-p load (350Vp-k), I've been tinkering with PSUD and come up with a high-voltage supply .......
42: MagneQuest/Peerless Forum, PP 6EM7 output operating points (0.00)
Posted by keto on 2011-08-23, 17:48:43 (189.139.141.55)
Here's the intended quiescent operating point for the output halves of the 6EM7's. Racing down a slippery slope here (!), if the load-line holds as drawn, current draw will vary between 72mA and 10 .......
43: MagneQuest/Peerless Forum, PP 6EM7 schematic (0.00)
Posted by keto on 2011-08-23, 17:37:47 (189.139.141.55)
Here's the latest schematic, with predicted operating points. Between the two Vishay pots on the input, overall current draw and balance will be set to 36mA for each output triode. Each driver shou .......
44: MagneQuest/Peerless Forum, PP 6EM7 top plate (0.00)
Posted by keto on 2011-08-23, 16:26:44 (189.139.141.55)
Here's a kind of lo-rez pic of a Front Panel Express file, for a PP6EM7 top-plate. Circuit (which will include a PGP8.1, BCM-8 PS filter choke and S-240-A OPT) to follow... .......
45: MagneQuest/Peerless Forum, RE: hate to bee the party pooper... (0.00)
Posted by keto on 2011-07-05, 18:08:25 (189.139.60.182)
What, no free lunch? :-) So, maybe an EXO-46 type coil could be used for a super-tweeter @ 10Khz? Okay, that's pretty loco. Thanks for all the cool info. --keto .......
46: MagneQuest/Peerless Forum, RE: really interesting idea from kurt s (0.00)
Posted by keto on 2011-07-05, 05:20:00 (189.139.60.182)
Oh no. I was hoping to direct interest over to the thread, and now its not there. .......
47: MagneQuest/Peerless Forum, really interesting idea from kurt s (0.00)
Posted by keto on 2011-07-04, 08:48:44 (189.139.60.182)
How low would an air-core, parafeed OPT go? .......
48: Tube DIY Asylum, RE: What's the formula for maximum system detail? (0.00)
Posted by keto on 2011-04-12, 10:53:23 (189.139.239.212)
Here's a list, pretty much from a system I heard recently... R-T-R source tube tape EQ, a la Bottlehead Eros 40% efficient horns, multi-amped, with for each, a... SET (could be DHT) parafeed output, w .......
49: Tube DIY Asylum, RE: Autoformer Phase Splitters (0.00)
Posted by keto on 2011-04-10, 20:52:14 (189.139.239.212)
I never considered Rp. Thanks! .......
50: Tube DIY Asylum, RE: Autoformer Phase Splitters (0.00)
Posted by keto on 2011-04-10, 19:12:55 (189.139.239.212)
It could be done that way, but isn't necessary. As described, the autoformer sees, in AC terms, SE "signal+noise" in one direction and just "noise" going in the other, resulting in the EXO-173 doing i .......
51: Tube DIY Asylum, RE: Autoformer Phase Splitters (0.00)
Posted by keto on 2011-04-10, 16:45:17 (189.228.108.9)
In the picture, the SE signal would be applied to the upper 6C45's grid, only, and the second 6C45's grid would be grounded; the intention being to also send the noise floor of the driver/input stage .......
52: Tube DIY Asylum, RE: Allen Wright passes (0.00)
Posted by keto on 2011-03-01, 19:42:14 (189.139.239.3)
RIP. Such a generous contributor on this great forum. .......
53: MagneQuest/Peerless Forum, DPA 300B -- RIP Allen Wright (0.00)
Posted by keto on 2011-03-01, 05:43:07 (189.139.239.3)
Sadly, Allen Wright just passed away. His DPA (I assume "differential power amplifier") used a high P-P impedance. .......
54: MagneQuest/Peerless Forum, RE: more ... (0.00)
Posted by keto on 2011-02-24, 21:19:06 (189.139.239.3)
I may be confusing AC and DC current (or worse!), but when I look at plate curves and PPDHT, I don't see symmetric "current swing". For example, in the 20W PP300B circuit published by Western Electric .......
55: MagneQuest/Peerless Forum, RE: do you ... (0.00)
Posted by keto on 2011-02-24, 17:00:18 (189.139.239.3)
I'd suggest this as a point of departure, for a PP2a3. The C4S is from Bottlehead and has a connection to ground that I forgot to include; the OPT..... from MQ of course! The output operating point .......
56: MagneQuest/Peerless Forum, RE: Ping Keto (0.00)
Posted by keto on 2011-02-24, 06:40:45 (189.139.239.3)
The last version sourced the C4S drivers' currents from the output cathode. I'm not sure what happens at start-up, to be honest. But afterwards the sound was transparent and the circuit, quiet as a mo .......
57: Tube DIY Asylum, RE: New Amp (0.00)
Posted by keto on 2011-01-23, 12:06:12 (189.139.144.87)
Great-looking amp. Congrats! .......
58: MagneQuest/Peerless Forum, RE: New amp project (0.00)
Posted by keto on 2011-01-14, 07:57:35 (189.139.139.161)
Thats a great-looking project. What are your operating points for the 6GK5? .......
59: High Efficiency Speaker Asylum, RE: work in progress -- comments welcome! (0.00)
Posted by keto on 2010-12-20, 06:04:57 (189.228.115.121)
tempting.... but maybe its time to really measure the horns and mid-basses and go from there? .......
60: High Efficiency Speaker Asylum, work in progress -- comments welcome! (0.00)
Posted by keto on 2010-12-18, 18:56:25 (189.228.115.121)
Here's a pic of the latest enclosure for a project I've been monkeying around with forever :-). 14 cu ft enclosure tuned to about 20hz with 15" x 8" diameter vent for Lambda TDX15, 2 cu ft enclosur .......
61: MagneQuest/Peerless Forum, RE: Happy Thanksgiving across all of tube land!!! {no further text} (0.00)
Posted by keto on 2010-11-25, 22:07:56 (189.139.239.76)
Happy Thanksgiving to you, also! .......
62: MagneQuest/Peerless Forum, RE: Peerless 50K:10K? (0.00)
Posted by keto on 2010-11-25, 22:06:36 (189.139.239.76)
Hey Mike, the transformer would go between a Bottlehead phono stage of 4K output impedance and a 10K P&G attenuator. Max signal on the primary would be 1.5V -- the 300B Paramounts would reach full vol .......
63: MagneQuest/Peerless Forum, Peerless 50K:10K? (0.00)
Posted by keto on 2010-11-24, 13:43:51 (189.139.239.76)
Hi all, did Peerless or someone else ever make a 50K:10K or similar small-signal transformer? Thanks .......
64: MagneQuest/Peerless Forum, RE: A good transformer works magic. (0.00)
Posted by keto on 2010-11-19, 06:00:12 (189.139.239.76)
Wow, that's some AMAZING work. Does the circuit include a low-gain bypass of the active stage, in the form of input transformer direct to output transformer? .......
65: High Efficiency Speaker Asylum, 1/4 wavelength rule -- new idea (photo) (0.00)
Posted by keto on 2010-10-19, 15:43:04 (189.139.239.76)
Thanks for all the great input. Here's a new idea for spacing. 18" CTC between horn and midbass means there may be trouble above 180hz in that pass-band, unless the midbass is also somewhat directi .......
66: High Efficiency Speaker Asylum, RE: (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-18, 08:29:30 (189.139.239.76)
I have the 16-ohm B&C DE-25's 28-1202 SPL mids and the time-alligned passive crossover, and will upgrade to the BMS4550 if those would work better. At the moment I'm focused on the "heavy lifting" .......
67: High Efficiency Speaker Asylum, RE: (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-18, 06:40:01 (189.139.239.76)
Thanks, that's an interesting looking design. For the moment, though, I'm happy with my current bass-bins. They are now rotated 90°, with an 8" space between the TD15X and the Unity Horn -- which m .......
68: High Efficiency Speaker Asylum, RE: (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-17, 22:56:25 (189.139.239.76)
Thanks, and especially for the reference to the "upper end of the pass-band". Very helpful. .......
69: High Efficiency Speaker Asylum, RE: (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-17, 22:55:01 (189.139.239.76)
Thanks a lot for the detailed response. To what does "1/8 wl from a boundary" refer? Not "edge-to edge" is it? Also, what I'm still trying to figure out (and enjoying the process) is how to complement .......
70: High Efficiency Speaker Asylum, RE: (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-17, 22:39:24 (189.139.239.76)
Thanks for the great explanation, of another piece of the puzzle! .......
71: High Efficiency Speaker Asylum, (1/4 wavelength rule? (0.00)
Posted by keto on 2010-10-16, 10:06:28 (189.139.239.76)
To get good integration between two drivers, is the 1/4 wavelength measured from their edges, or from their centers? Thanks! .......
72: Vinyl Asylum, RE: cart for ATP12T + TD124? (0.00)
Posted by keto on 2010-10-09, 07:11:58 (189.228.110.145)
Thanks, but I need to steer clear of the the MC's since the the TT has a heavy, iron, magnetic platter. Reports are that an MC cartridge would be drawn toward such a platter. .......
73: Vinyl Asylum, cart for ATP12T + TD124? (0.00)
Posted by keto on 2010-10-07, 12:02:38 (189.228.110.145)
Hello, What would be your cartridge recommendation be for an Audio Technica ATP-12T arm, with an effective mass of 18-20g, and a TD124 with the iron-platter? The Nagaoka line-up looks great, but there .......
74: High Efficiency Speaker Asylum, RE: I always found it to be kinda funny at shows (0.00)
Posted by keto on 2010-09-30, 07:33:41 (189.228.117.6)
Bernstein, in the Harvard Lecture series "the unanswered question" said something similar, but about the 9th symphony, that it was Mahler predicting the dark century to come. .......
75: Vinyl Asylum, SL-1200MK2 and anti-skate (0.00)
Posted by keto on 2010-09-29, 06:29:03 (189.247.74.155)
I recently got a technics table rebuilt, and it seems to be working really well, except that at the end of the record when I lift the needle, it pulls slightly "outward" as if there's too much anti-sk .......
76: High Efficiency Speaker Asylum, RE: Best commercially available horn system (0.00)
Posted by keto on 2010-09-25, 07:47:23 (189.247.74.155)
I totally agree, having heard a few of the Danley's inventions at Servodrive a few years ago and having set-up a pair of his 300hz Lambda Horns in my own system. In terms of design, the SM60F looks es .......
77: MagneQuest/Peerless Forum, RE: MQ565 & AS250 (0.00)
Posted by keto on 2010-09-16, 20:14:45 (189.139.59.88)
Wow! Amazing-looking amps! With which speakers do you listen to them? .......
78: MagneQuest/Peerless Forum, RE: Panasonic (0.00)
Posted by keto on 2010-08-27, 07:52:58 (189.139.63.251)
I also use a Panasonic with an extension. Very handy. If possible, check the ring tone! .......
79: SET Asylum, RE: JBL Pro speaker for SET use? (0.00)
Posted by keto on 2010-08-26, 19:56:58 (189.139.63.251)
I listen to the JBL two-way, the 4320, with Bottlehead 300B Paramounts. Seems to work really well. The passive2nd/2nd order XO is at 800hz with the tweeter polarity reversed, so I'm hoping to try b .......
80: High Efficiency Speaker Asylum, pic of new 413L/20.5hz bass bin (0.00)
Posted by keto on 2010-08-24, 07:15:06 (189.139.63.251)
Here's everything just tossed together. The bass bin will be horizontal, eventually. XO is sort of 2nd/2nd order at 300hz, with reversed polarity on the Unity horn. .......
81: High Efficiency Speaker Asylum, RE: This all sounds quite desirable but where does one audition (0.00)
Posted by keto on 2010-07-31, 11:09:22 (189.228.123.192)
Thanks, that's what I was trying to describe, what's in figure#7 :-). Great design! .......
82: High Efficiency Speaker Asylum, RE: This all sounds quite desirable but where does one audition (0.00)
Posted by keto on 2010-07-31, 10:23:00 (189.228.123.192)
The SM60 CLF looks really interesting. So, with a coaxial driver you divert the mids a little, down the horn wall? Great idea! .......
83: High Efficiency Speaker Asylum, RE: Choose your poison (0.00)
Posted by keto on 2010-07-31, 07:24:31 (189.228.123.192)
How do you deal with phase at and around the crossover frequency? The horns I've been modeling with the McBean horn response program seem to have phase shifts that are slightly or much greater than a .......
84: MagneQuest/Peerless Forum, here's to a speedy recovery, Mike (0.00)
Posted by keto on 2010-07-29, 06:51:48 (189.228.121.210)
all the best, del sur --Tom .......
85: High Efficiency Speaker Asylum, RE: can AE build a lower Qts version of TD15M? (0.00)
Posted by keto on 2010-07-09, 14:13:44 (189.139.58.189)
There are also the TDX, TDH and TDS, AV15H and AV15X. Maybe one of those would fit the bill. I tried a TD15M in a K-15 cabinet and got very little if any LF extension. .......
86: High Efficiency Speaker Asylum, RE: midrange choices (0.00)
Posted by keto on 2010-06-16, 15:02:18 (189.247.78.122)
maybe this one would work... http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=2493 .......
87: High Efficiency Speaker Asylum, RE: The most respected coaxials (0.00)
Posted by keto on 2010-06-15, 17:13:43 (189.247.78.122)
Is that the famous 550hz horn? .......
88: SET Asylum, RE: the power transformer (0.00)
Posted by keto on 2010-06-11, 17:58:14 (189.247.78.122)
Thats a really nice-loking amp! .......
89: SET Asylum, MQ 5504? (0.00)
Posted by keto on 2010-06-09, 21:54:43 (189.247.78.122)
It might be the MQ 5504..... .......
90: MagneQuest/Peerless Forum, RE: Balanced Seth opinions (0.00)
Posted by keto on 2010-05-29, 08:06:30 (189.247.79.145)
Hey Mike, assuming the image uploads... the "lower" 6C45 would be in addition to the SETH circuit front end. The 2 6C45 grids could be "fed" with signal and ground, respectively, and no LTP, which .......
91: MagneQuest/Peerless Forum, RE: Balanced Seth opinions (0.00)
Posted by keto on 2010-05-28, 22:58:41 (189.247.76.23)
I think you could leave the EXO-173 in, as a balancing grid choke for the 2A3 outputs .......
92: High Efficiency Speaker Asylum, just changed that setting... (nt) (0.00)
Posted by keto on 2010-05-23, 14:49:29 (189.228.124.62)
. .......
93: High Efficiency Speaker Asylum, RE: Unity Horn w/ B&C DE25-16, BMS 4550 o TAD2001? (0.00)
Posted by keto on 2010-05-21, 22:44:44 (189.228.124.62)
yeah, sure .......
94: High Efficiency Speaker Asylum, RE: Unity Horn w/ B&C DE25-16, BMS 4550 o TAD2001? (0.00)
Posted by keto on 2010-05-21, 06:12:23 (189.228.124.62)
Thanks for the schematic. While I'm now leaning away from the TAD because of cost and availability, its interesting to see that there is again basically a 1st order bandpass for the mids, in addition .......
95: High Efficiency Speaker Asylum, RE: Unity Horn w/ B&C DE25-16, BMS 4550 o TAD2001? (0.00)
Posted by keto on 2010-05-20, 22:21:33 (189.228.124.62)
Thanks a lot for all the helpful info. I do like the effect of the (Unity) sound remaining pretty much the same in the "sweet spot" as everywhere else in the room. I visited Servodrive in Chicago abou .......
96: High Efficiency Speaker Asylum, Unity Horn w/ B&C DE25-16, BMS 4550 o TAD2001? (0.00)
Posted by keto on 2010-05-20, 06:57:34 (189.228.124.62)
Hey all, I'd like to upgrade my Unity Horns, and since every path seems to branch out into other paths, I'm wondering if someone out there has done something similar, or might otherwise help me narrow .......
97: MagneQuest/Peerless Forum, RAAL 140-15D Ribbon Tweeter, maybe OT... (0.00)
Posted by keto on 2010-05-19, 16:38:08 (189.228.124.62)
Hey all, the specs for the RAAL 140-15D Ribbon Tweeter say... "Recently, we finished development of Amorphous C-cores transformer application in our ribbons. We are the first to use AMCC's in ribbons .......
98: Tube DIY Asylum, RE: 45 schematic (0.00)
Posted by keto on 2010-05-11, 21:11:52 (189.228.124.62)
I think the 1K voltage dropping resistor should be 10K .......
99: Tube DIY Asylum, RE: Here I go again ... (0.00)
Posted by keto on 2010-04-15, 18:57:35 (189.247.75.85)
I like the fail safe direct-coupling voltage. Maybe accomodate for a pair of VR tube sockets. 2 0B3's in series would give you about 180V, which would allow you to experiment with more driver headroom .......
100: MagneQuest/Peerless Forum, RE: power resistor vs CCS in tail.... (0.00)
Posted by keto on 2010-04-10, 22:51:21 (189.247.75.77)
I don't know anything about feedback or UL chokes, but the "active" and "passive" first stages should have the same loads. The 6EM7 looks good for this circuit, because it has a lot of gain (mu=68, .......
101: MagneQuest/Peerless Forum, RE: Drive stage suggestions please (0.00)
Posted by keto on 2010-04-10, 09:28:23 (189.247.75.77)
Nice thing about a direct-coupled "compact" is that it can probably be breadboarded with less parts than other PP options (you'd have a pair of grid chokes left over, assuming there was one on each 'a .......
102: MagneQuest/Peerless Forum, RE: 811A - A2 - Parafeed Amp (0.00)
Posted by keto on 2010-03-29, 13:40:47 (189.228.126.160)
Here's a schematic for something that might work. V1 and V2 could be from a double triode. Here are three of the many such possibilites -- for 6BX7 as V2 at 20Vk: 235Vpk/20mA, 245Vpk/25mA, 252Vpk/3 .......
103: MagneQuest/Peerless Forum, RE: 811A - A2 - Parafeed Amp (0.00)
Posted by keto on 2010-03-27, 19:54:43 (189.228.126.160)
Maybe you could drive the SE 811A with a choke-loaded cathode-follower, which would bias the 811A at about +20V .......
104: MagneQuest/Peerless Forum, RE: wow! (0.00)
Posted by keto on 2010-03-20, 12:10:38 (189.228.124.110)
and a zillion variants, which might make for interesting tube-rolling .......
105: MagneQuest/Peerless Forum, wow! (0.00)
Posted by keto on 2010-03-20, 07:33:41 (189.228.124.110)
Thats some amazing-looking work. And the 6GK5 input/driver is very interesting. Congrats! .......
106: High Efficiency Speaker Asylum, RE: North Creek's noble 8 gauge inductors (0.00)
Posted by keto on 2010-01-31, 14:07:20 (189.228.117.10)
Really interesting post. Maybe there were some strange interactions just from having the inductances of the OPT secondary, the choke and the speakers all in series, that disappeared or were minimized .......
107: MagneQuest/Peerless Forum, RE: A headphone amp. mk2 (0.00)
Posted by keto on 2010-01-30, 20:19:16 (189.228.117.10)
Bravo! Thats a cool looking circuit! .......
108: Tube DIY Asylum, RE: Changing screws in transformer and choke (0.00)
Posted by keto on 2010-01-22, 08:46:26 (189.228.117.10)
Stainless becomes magnetic once its torqued; brass is non-magnetic. .......
109: MagneQuest/Peerless Forum, RE: 10K P&G's? (0.00)
Posted by keto on 2009-12-16, 14:20:35 (189.228.123.38)
Let me know how many paypal shekels to send you for one, when you get the chance.... Thanks! .......
110: MagneQuest/Peerless Forum, RE: 10K P&G's? (0.00)
Posted by keto on 2009-12-16, 05:10:25 (189.228.123.38)
I'll be in Seattle from the 20th of Dec thru the 3rd of Jan and am thinking of the P&G, since it offers continuous rather than stepped attenuation (right?) -- along the lines of..... a fancy 2P4T sele .......
111: MagneQuest/Peerless Forum, 10K P&G's? (0.00)
Posted by keto on 2009-12-15, 19:58:50 (189.228.123.38)
Hey Mike, would you have one of those 10K stereo P&G's still around?? --keto .......
112: MagneQuest/Peerless Forum, you've got mail ;-) and hey.... (0.00)
Posted by keto on 2009-11-30, 08:46:33 (189.228.121.250)
Whats the ballpark MOL on those critters? Maybe run a cathode follower into them and step up the signal in a Sakuma or Il Monstro kinda way??? Or just as an input transformer, driven of course with th .......
113: High Efficiency Speaker Asylum, RE: Sub Woofer? (0.00)
Posted by keto on 2009-11-14, 08:22:45 (189.139.142.45)
I bet that's a great sounding system! Check out the link below. For me such LF extension adds an interesting illusion of large spaces (my configuration is one of their TDX15's and two 1400g 15" passiv .......
114: MagneQuest/Peerless Forum, RE: Here's Where It's Going... (0.00)
Posted by keto on 2009-11-04, 22:32:45 (189.139.142.45)
Wow, that's some amazing work!!! .......
115: High Efficiency Speaker Asylum, RE: Karlson Army Surge and Kall to Kount-in (0.00)
Posted by keto on 2009-10-23, 16:14:24 (189.247.78.187)
would this driver do well in a K15... http://www.aespeakers.com/drivers.php?driver_id=12 ? .......
116: High Efficiency Speaker Asylum, RE: Karlson Army Surge and Kall to Kount-in (0.00)
Posted by keto on 2009-10-23, 12:47:30 (189.247.78.187)
above 300hz are the lambda unity horns, which with their time-alligned XO's are a little more efficient than the TDM15's. In the Karlson's there's a little more bloom and volume to the sound, when com .......
117: High Efficiency Speaker Asylum, RE: Karlson Army Surge and Kall to Kount-in (0.00)
Posted by keto on 2009-10-23, 12:26:42 (189.247.78.187)
K15 copies here in Toluca, Mexico, with Lambda Apollo TDM15's, being used with a 1st order low pass at 300hz. .......
118: High Efficiency Speaker Asylum, RE: Could I upgrade my Midrange Horns ?............................ (0.00)
Posted by keto on 2009-10-21, 12:35:17 (189.139.142.19)
Maybe. I use the 60 x 60 300hz unity's and like them, and I remember at one point there was a design for another 300hz one that had a little more horizontal and less vertical dispersion (?), maybe 40x .......
119: High Efficiency Speaker Asylum, RE: Could I upgrade my Midrange Horns ?............................ (0.00)
Posted by keto on 2009-10-21, 06:39:35 (189.139.142.19)
How about a 2-way Danley 300hz unity horn? So far on his website, I only see the synergy model, a 3-way horn that extends to 80hz. Maybe he has a new 300hz model that's not listed? .......
120: Bottlehead Forum, "la vaquita negra" (the little black cow)... (0.00)
Posted by keto on 2009-10-05, 16:18:34 (189.195.7.156)
...is a deli here in Toluca, Mexico that serves good chesses, chorizos, jamon serrano etc., and as xcortes aptly pointed out, I'm always looking for an excuse to buy more stuff there. .......
121: Bottlehead Forum, problem solved! (0.00)
Posted by keto on 2009-10-05, 16:15:00 (189.195.7.156)
Thanks for the tip, I swapped in the two new output RCA pairs and paid attention to getting them snug but not wrench-to-wrench tight. .......
122: Bottlehead Forum, RE: I think I figured it out (0.00)
Posted by keto on 2009-10-05, 12:06:04 (189.195.7.156)
Hehe, maybe, or maybe I just need to stop working out. Now, I'm pretty well convinced it was the overheating. Great thing is that my RCA source is right across the street from the ol' vaquita negra. W .......
123: Bottlehead Forum, I think I figured it out (0.00)
Posted by keto on 2009-10-05, 11:17:04 (189.195.7.156)
I think through over-tightening and or overheating, I've damaged a few of the RCA's, since there's a little bit of play to their signal posts underneath. Luckily it should be simple to switch them out .......
124: Bottlehead Forum, FP3 trouble-shooting... (0.00)
Posted by keto on 2009-10-04, 23:29:23 (189.195.66.103)
Hey all, I just finished a FP3. Resistances and Voltages are good, and I'm getting perfect sound out of the right channel.... but none out of the left. At idle there's the same very low background win .......
125: High Efficiency Speaker Asylum, RE: K15 midbass pair up and running (0.00)
Posted by keto on 2009-09-14, 09:37:23 (189.195.1.213)
What's your favorite 1" driver? Any chance one could get away with a 1st/1st passive XO, say, around 1K5hz? .......
126: High Efficiency Speaker Asylum, K15 midbass pair up and running (0.00)
Posted by keto on 2009-09-13, 22:56:06 (189.194.252.51)
I now have a boomin' bloomin' pair of K15 copies up and running. The sound is growing on me. Drivers are Lambda TDM15 Apollo's. .......
127: Tube DIY Asylum, RE: Anyone carry panel metters like this in 100ma or 150ma in US? (0.00)
Posted by keto on 2009-09-09, 06:49:58 (189.195.137.134)
Maybe here... http://www.simpsonelectric.com/main/index.asp?p=Products&id=18 .......
128: Bottlehead Forum, RE: Keto from Toluka set me up! (0.00)
Posted by keto on 2009-08-16, 19:23:03 (24.17.14.62)
Nothing like inmates enabling one another! There was a thread a while back at high efficiency speakers, about the benefits of increasing amplifier output impedances driving horn-loaded speakers, also .......
129: Vinyl Asylum, thanks for all the great responses (0.00)
Posted by keto on 2009-08-14, 09:23:52 (24.17.14.62)
The new twist is that I've now been told the ATP12T is a high mass arm, and so will work best with a low compliance cart. So, I've got to sort through specs, and try to get a handle on "static" vs "dy .......
130: Vinyl Asylum, MM cart recommendations? (0.00)
Posted by keto on 2009-08-12, 10:27:20 (24.17.14.62)
I'm looking for a nice MM cart to go along with a Thorens 124 table, ATP 12T arm and Bottlehead Seduction phono stage. I've come up with a list of possiblilities and would really appreciate recommenda .......
131: High Efficiency Speaker Asylum, RE: model (0.00)
Posted by keto on 2009-06-16, 19:51:06 (201.161.27.254)
This is really helpful, since I'm adding internal damping and will now also try reducing the internal volume using styrofoam blocks, like an 8.5" x 12" x 15" one between the PRs (which will get me dow .......
132: Bottlehead Forum, how about FINESSE? (0.00)
Posted by keto on 2009-06-14, 20:10:35 (201.161.27.254)
(a magician's) sleight of hand that arcs complex curves from a cartesian grid (pool), instantaneously sublimating digital info (from hard drive) to something intelligible to Foreplay, etc. ::: TOPIC:: .......
133: High Efficiency Speaker Asylum, RE: model (0.00)
Posted by keto on 2009-06-13, 08:04:35 (201.161.27.254)
I just re-measured my enclosures and they are 3.86 cu ft minus the cone and plate amp, so probably a real 3.5 cu ft. This, with one TDX15 and 2 PR1400-15 per enclosure. Any chance you might run these .......
134: High Efficiency Speaker Asylum, RE: Would AE's TD15X work in a scoop? (0.00)
Posted by keto on 2009-06-07, 20:44:18 (201.161.26.135)
I use a TDX15 per side, with 2 opposing 1400g 15" PR's per TDX15, in 5 cu ft boxes. This is the old Lambdacoustics "God of thunder" design, with response down into the teens. I've got an M&K plate amp .......
135: Bottlehead Forum, RE: Thanks for your help, again! (0.00)
Posted by keto on 2009-06-07, 20:26:15 (201.161.26.135)
I agree with getting the "masking" tape off ASAP .......
136: Bottlehead Forum, RE: Seduction in Glossy Black Atire (0.00)
Posted by keto on 2009-06-07, 05:40:17 (201.161.26.135)
Might be a good idea to let the paint really dry out, maybe set in the sun for a couple weeks, or maybe it could be speeded up in an oven? I finished some transformers similarly and found the paint su .......
137: Bottlehead Forum, Thanks.... (0.00)
Posted by keto on 2009-04-30, 09:38:25 (201.161.25.147)
..to PJ and CB for the advice. Good thing I asked, because I was headed in a wrong direction. Just about to start on the build, but can't say I've decided exactly what to do. The FP3 is such a cool, h .......
138: MagneQuest/Peerless Forum, RE: Are you wedded to the 76? (0.00)
Posted by keto on 2009-04-29, 13:29:49 (201.161.25.147)
Sounds really interesting. What did you do for the 5V 250mA filaments? .......
139: MagneQuest/Peerless Forum, RE: Hey Mike, how about this idea? (0.00)
Posted by keto on 2009-04-29, 09:56:40 (201.161.25.147)
Hey DanL, thanks a lot for the ideas. I've gone back and looked at the 76 plate curves and done a lot of rethinking, keeping in mind the "toughest load" situations of either 15K or 20K, even though fr .......
140: MagneQuest/Peerless Forum, Hey Mike, how about this idea? (0.00)
Posted by keto on 2009-04-27, 16:50:05 (201.161.25.147)
I'm just about to jump into my Bottlehead FP3 kit, and have once again come up against the circuit I've kind of always wanted to build. I'd like to run it past you, to see what you think, and see if y .......
141: Bottlehead Forum, RE: Did you feel the quake? (0.00)
Posted by keto on 2009-04-27, 16:16:20 (201.161.25.147)
Yeah, but I just thought my cat was messing with my sub settings, again. Everything okay over there in Polanco and up there in the hills? .......
142: Bottlehead Forum, B7 placement in FP3? (0.00)
Posted by keto on 2009-04-27, 11:25:25 (201.161.25.147)
Being a homebrewer, but not a clever one, I'm still wondering where a pair of B7 OPT's would fit in the extended FP3 layout. The mounting screws are 2" on center. I'm thinking the safest would be out .......
143: MagneQuest/Peerless Forum, compact (0.00)
Posted by keto on 2009-04-26, 12:05:55 (201.161.25.147)
Hey all, since I just strapped a pair of Bottlehead 15K SW's to my Cobalt 15K B7's, and so am finally listening to tunes via MQ goodies (a la "sex kitten" or "pseudo ingot"), and figure I can only NOW .......
144: MagneQuest/Peerless Forum, RE: Seth current draw (0.00)
Posted by keto on 2009-02-25, 16:17:39 (201.161.27.254)
here's an option for PP300B for 20W and a 4K plate to plate load, looks like the current would swing from 170mA to 200mA, in A1. I don't know what A1 means ;-) .......
145: MagneQuest/Peerless Forum, get well soon (0.00)
Posted by keto on 2009-02-04, 00:11:43 (189.195.18.135)
Man, sorry to hear about the injuries. Hope you find all that necessary R and R and TLC, and that you're feeling better soon. .......
146: Bottlehead Forum, RE: Advice and critique wanted (0.00)
Posted by keto on 2009-01-25, 09:35:56 (200.56.121.148)
I don't understand the output voltage regulation. What about adding a very small first cap to the power supply, in the realm of 1uF or 2uF, to raise the B+ to around 600vdc and then use a dropping res .......
147: Bottlehead Forum, RE: SEX amp: problem with octal socket and its bracket (0.00)
Posted by keto on 2008-12-17, 19:19:42 (189.195.7.254)
The nut fits snugly into the slot of the bracket and you just tighten the slot-head of the screw. I needed a helping hand to do that stage of the build, to hold the bracket in place and the get the fa .......
148: MagneQuest/Peerless Forum, out of curiosity...... (0.00)
Posted by keto on 2008-12-17, 09:21:00 (189.195.6.64)
What do you like to do with a 15K B7 in cobalt? I have a pair here, that I've only used a little, years ago now, with 76's and 26's. And, I've finally got a Bottlehead Forplay 3 kit, which I've yet to .......
149: Bottlehead Forum, RE: New to DIY audio (0.00)
Posted by keto on 2008-10-25, 18:48:30 (189.139.55.140)
I just built a nice system with the S.E.X. amp and a pair of Altec Boleros. There's a pair on ebay at the moment... .......
150: Bottlehead Forum, wow! (0.00)
Posted by keto on 2008-10-14, 05:48:33 (189.139.62.65)
Hey, congratulations. Looks great! .......
151: Bottlehead Forum, clarinetist (0.00)
Posted by keto on 2008-10-11, 23:05:29 (189.139.55.248)
I play clarinet in the Orquesta Sinfonica del Estado de Mexico and had never weilded a soldering iron before discovering the Bottlehead .......
152: High Efficiency Speaker Asylum, Thanks a million! (nt) (0.00)
Posted by keto on 2008-10-05, 01:10:19 (200.94.154.100)
. .......
153: Bottlehead Forum, Thanks (0.00)
Posted by keto on 2008-10-03, 14:35:33 (189.139.56.48)
I look forward to taking you up on that offer! I'll be in touch! .......
154: Bottlehead Forum, S.E.X. review and FP3 musings (0.00)
Posted by keto on 2008-10-03, 14:16:01 (189.139.56.48)
Hey, all. I'd been on hiatus from tube stuff for about 3 years, because of a job change and a move and another job change, and was happy to sneak back into it a couple weeks ago while visting the Stat .......
155: MagneQuest/Peerless Forum, Re: Mikey's next 2 wheeler (0.00)
Posted by keto on 2007-04-27, 22:13:17 (189.166.74.54)
Hope you get well soon, Mike... --keto .......
156: MagneQuest/Peerless Forum, Re: A question for Mqracing (0.00)
Posted by keto on 2007-02-19, 06:56:02 (189.166.61.164)
Steve, Really interesting-looking project, there. Maybe you could work from the OPT, backwards, that is, define your OP pair(s) and the tranny they'll need, first; triode3's ideas here sound interesti .......
157: MagneQuest/Peerless Forum, Re: New project with MQ RS-500 (0.00)
Posted by keto on 2006-12-10, 18:37:03 (189.166.66.36)
SE, really great looking construction. For a -42Vg on the 845, do you need the step-up? If not, maybe try the whole winding of the EXO-173 (cobalt???) as a straight grid choke (which will provide an e .......
158: MagneQuest/Peerless Forum, nice, as usual... (0.00)
Posted by keto on 2006-11-30, 20:25:06 (189.166.66.36)
I bet Mike can't wait to wind your 50th anniversary model, with the gold wire and all... --keto .......
159: MagneQuest/Peerless Forum, wow! (0.00)
Posted by keto on 2006-11-25, 18:14:25 (189.166.66.36)
A knockout! Will the beatings stop now? --keto .......
160: MagneQuest/Peerless Forum, Re: EXO-173 - Sum Phases of Differential VA? (0.00)
Posted by keto on 2006-11-03, 14:27:06 (75.34.227.1)
It would function as the grid choke for the output, though you might also experiment with adding a grid resistor, or even a resistor across each half winding. You'd want a low Rp triode, like a pair o .......
161: MagneQuest/Peerless Forum, Re: on siren calls and "simple" amps (0.00)
Posted by keto on 2006-10-25, 22:10:07 (189.166.74.157)
Cool, I'll keep that in mind; likewise if you come through the Bajio, desde luego... --keto .......
162: MagneQuest/Peerless Forum, a day at the lab (0.00)
Posted by keto on 2006-10-25, 22:07:58 (189.166.74.157)
A great local technician had my 76 preamp in the lab last week, and came up with a few observations that might be of interest here. First, a C4S plate loaded 76, cap coupled to a B7 15K:500 seems to r .......
163: MagneQuest/Peerless Forum, Re: Tell me more about the XM46 (0.00)
Posted by keto on 2006-10-24, 22:38:42 (189.166.74.157)
So far it looks like the XM46 is happy with a 50 ohm source, or 1/20 the the input load value. Maybe 10 ohms would be even better! I like the looks of a simple 1st/1st XO right after the B7 output, wh .......
164: MagneQuest/Peerless Forum, Re: Do I need this pre? And what transformer? (0.00)
Posted by keto on 2006-10-24, 06:33:18 (189.166.74.157)
ciao gluca, I'm using an XO from Marchand (link), passive but with an active stage before, so its not really passive, right? Easy to drive with an op amp pre that a local technician put together, whic .......
165: MagneQuest/Peerless Forum, Re: 300b... hmm.. (0.00)
Posted by keto on 2006-10-20, 06:26:28 (189.166.58.56)
I was thinking within the context of the Parabee, a 3K OPT, going from grid leak Rs to grid chokes, etc... --keto .......
166: MagneQuest/Peerless Forum, Re: 300b... hmm.. (0.00)
Posted by keto on 2006-10-20, 05:47:26 (189.166.58.56)
I was thinking a lower power OP, with a 250Vp-k and about 40madc, like the WE ones Mike mentions in the link. Too much current for a 45, but perfect for both 2A3 and 300B, and a relatively simple mod .......
167: MagneQuest/Peerless Forum, a simple 300B? (0.00)
Posted by keto on 2006-10-19, 20:56:14 (189.166.58.56)
Xavier, what about converting the amp to a lower-powered, direct-coupled 300B? Operating points similar to a 2A3? ...maybe see how much of the sound is the topology and how much is the 45, sort of... .......
168: MagneQuest/Peerless Forum, Re: Help with EXO-173 P-P amp (0.00)
Posted by keto on 2006-10-09, 19:10:28 (189.166.163.105)
In addition to the larger cap, per MQ, you might try a 270K load across each half winding. I'm not sure why, but this may help. Check Randy Carter's Il Monstro circuit, which similarly loads the EXO-1 .......
169: MagneQuest/Peerless Forum, 76 linestage update (thanks, Gordon Rankin) (0.00)
Posted by keto on 2006-09-26, 14:13:40 (189.166.69.42)
Hey all, below is a link to an installation, in Morelia, Mexico. With a ground lift and shield lift (2 little switches, belowdecks), installation was easy. The little Mackie powered monitors shown don .......
170: MagneQuest/Peerless Forum, Re: EXO-01 phono output (0.00)
Posted by keto on 2006-09-26, 06:38:04 (189.166.69.42)
fred, yep, that's what I was thinking, and if the simple R isolating the choke from its immediate environment (plate) is a good thing, maybe doing 5K5-choke-5K5 would do the same WRT the PSU. Among ot .......
171: MagneQuest/Peerless Forum, Re: EXO-01 phono output (0.00)
Posted by keto on 2006-09-25, 15:01:34 (189.166.69.42)
Someone mentioned here that a resistor between choke and plate will somewhat isolate the capacitive element of the former from the latter. Add an 11K there and the loadline will also be more horizonta .......
172: MagneQuest/Peerless Forum, the 15K:500 cobalt B7 and day in the lab... (0.00)
Posted by keto on 2006-09-18, 22:21:17 (189.166.75.149)
Hey Mike et al... today the 76-based parafeed preamp went up on the bench, revealing all kinds of cool stuff that's probably pretty obvious for the inventor of the B7. 1. ...the schematic went up on .......
173: MagneQuest/Peerless Forum, Re: B7 15K:500 Parafeed questions (0.00)
Posted by keto on 2006-09-18, 06:22:49 (189.166.75.149)
There's a pic at the link below, which will give you an idea. Plan for about a 2" cube, but don't do any building until they're in hand, since the required space will depend on orientation, standoffs, .......
174: MagneQuest/Peerless Forum, cap bypass (0.00)
Posted by keto on 2006-09-14, 05:47:01 (189.166.65.169)
Maybe its because I use two stacked in series, but I've yet to hear a difference with or without a .1uF or .047uF. The preamp is now at a tech's lab, so there ought to be an opportunity to install and .......
175: MagneQuest/Peerless Forum, Re: details please. . . (0.00)
Posted by keto on 2006-09-12, 19:35:20 (189.166.65.169)
hey soulcargo, the circuit's at the link below (there's a 1A fuse in there, too). The .47uF cap (too small value) is all I have on hand, but I expect to try up to about 4uF caps -- the output Z of the .......
176: MagneQuest/Peerless Forum, MQ-stuffed linestage (link to pics) (0.00)
Posted by keto on 2006-09-11, 18:14:44 (189.166.65.169)
Hey all, check out the link for pics of a project of mine that's actually working, in both channels, no less. There are actually only three MQ items: a PGP8.1 and a pair of cobalt 15K B7's. Much exper .......
177: MagneQuest/Peerless Forum, Re: OK: here I go (0.00)
Posted by keto on 2006-09-07, 23:00:13 (189.166.64.48)
Hey Xavier, with the C4S sourced from the output cathode you lose a little bit of the output, since about 5V of the 40.5V bias is "occupied" by the C4S -- but there are other advantages, that to my ea .......
178: MagneQuest/Peerless Forum, Re: Finally: My TL-404 71A amp schematic (0.00)
Posted by keto on 2006-09-06, 23:30:01 (189.166.58.64)
hey xavier, Interesting circuit, there. On startup, there may be extra stress on the 71A conducting current before heating up completely and maybe drawing grid current if conducting before the driver. .......
179: MagneQuest/Peerless Forum, Re: Seeking advice .. DC coupled phase split choke (0.00)
Posted by keto on 2006-08-22, 06:25:34 (189.166.55.233)
CY, I'm starting to see how it would work, and that there's no DC current flowing across the autoformer. But don't you have to make sure the insulation of the autoformer is designed with "an isolated .......
180: MagneQuest/Peerless Forum, Re: Seeking advice .. DC coupled phase split choke (0.00)
Posted by keto on 2006-08-21, 15:02:52 (189.166.55.233)
If there's no DC current flowing to the other output grid, how does the tube maintain its quiescent bias? With no time for building, I've managed to get half of one monoblock wired. If you get a direc .......
181: MagneQuest/Peerless Forum, Re: Seeking advice .. DC coupled phase split choke (0.00)
Posted by keto on 2006-08-19, 10:02:49 (189.166.55.233)
CY, Interesting topology, though it requires that the autoformer handle DC current and high voltage; also there will be a voltage drop across the winding, which might mess up the output bias... --keto .......
182: High Efficiency Speaker Asylum, Re: Loud noises at night (0.00)
Posted by keto on 2006-07-28, 09:35:42 (200.95.124.81)
Tom, Cool recording. For a composer's recreation of a non-explosive, chemical interaction (bubbles in a gaseous mixture), check out Xenakis's "Pithoprakta" (sp?). I just sent a message to your "info" .......
183: MagneQuest/Peerless Forum, Re: 845s? (0.00)
Posted by keto on 2006-07-21, 13:05:49 (200.95.124.81)
Hey Mike, 4K is also what WE recommends for both 10W and 20W PP300B's, in class A, with a substantial current swing. I hope to be posting soon on "PP2A3 v2.0", but just wanted to mention that my direc .......
184: MagneQuest/Peerless Forum, Re: Kudos for the EXO173 (0.00)
Posted by keto on 2006-07-11, 17:59:24 (200.95.124.217)
How are you running the 417A? And what drives its grid? At the moment I have a 6C45 (okay, totally different valve) at 185Vp / -3Vg / 6mA, with a C4S plate load, into .47uF(RTX), EXO-173 and PP2A3. I .......
185: MagneQuest/Peerless Forum, Re: err.. (update) (0.00)
Posted by keto on 2006-07-11, 16:30:29 (200.95.124.217)
hey boatshed, thanks a lot for reading the updates; my posts takes a lot of sifting, because there are a lot of blind alleys and other dead ends, within. Even now, I'm completely split between... 1) ( .......
186: MagneQuest/Peerless Forum, err.. (update) (0.00)
Posted by keto on 2006-07-07, 10:22:45 (201.124.122.22)
Hey all, after scrawling some more composite load lines, I see (now) that a PP2A3 at 295Vp-k, 120mA (shared) and -45Vg (375R shared cathode bias), with a 5K p-p load is really very linear. My mistake .......
187: MagneQuest/Peerless Forum, Re: 9 Watt Transconductance Amp (0.00)
Posted by keto on 2006-07-06, 07:04:32 (201.124.122.22)
John, Great design and execution, especially targeting the single driver speaker load. 9W basically from one stage, too. Amazing. Has this been done in differential, with a PP output? --keto ::: TOPIC .......
188: MagneQuest/Peerless Forum, pp2a3 as "constant current" (correction) (0.00)
Posted by keto on 2006-07-03, 09:39:55 (201.124.122.22)
Hey all, the class A pp300b stats of "100mA at zero signal and 150mA at 10W output" (and also "170mA to 200mA at 20W"), into a 4K p-p load have had me stumped for a long time, until I (just) figured o .......
189: Bottlehead Forum, Re: Parafeed cap calcs for 76 Preamp? Suggestions? (0.00)
Posted by keto on 2006-06-30, 14:52:28 (201.124.122.22)
Garland, Cool to hear that it sounds good. What's the rest of the circuit? Power supply, volume control, possibility for dc heaters, etc? And which 5-pin socket are you using? I'm looking for one with .......
190: MagneQuest/Peerless Forum, Re: Nubie question re Bugle 45 Amp (0.00)
Posted by keto on 2006-06-26, 18:14:34 (201.124.122.22)
If your filament secondary can handle 2.5A, you could also power up with an old 2A3... keto .......
191: MagneQuest/Peerless Forum, Re: Nubie question re Bugle 45 Amp (0.00)
Posted by keto on 2006-06-25, 13:03:54 (201.124.122.22)
Kurt, Since 36V/260R=138mA, maybe the 45 cathode is shorted to ground? Maybe the cathode in the "A" channel is not connected to its cathode bias resistor? Just a hunch... --keto .......
192: MagneQuest/Peerless Forum, Re: Nubie question re Bugle 45 Amp (0.00)
Posted by keto on 2006-06-24, 22:13:07 (201.124.122.22)
In one case your B+ voltage is equal to the 45 anode and in the other, its 36v lower. Maybe in the first case, there is zero current being drawn by the 45? Powered down, what is the DCR of the OPT pri .......
193: MagneQuest/Peerless Forum, "no R no C pp" (0.00)
Posted by keto on 2006-06-24, 00:30:46 (201.124.122.22)
C.Y, I'd like to see that. Closest I came was a 6SN7 pair as long-tail pair input, with resistive loads and direct-coupled to the output 2A3's, resulting in a clear sound, but no voltage headroom in t .......
194: MagneQuest/Peerless Forum, Re: Somewhat off topic, but..... (0.00)
Posted by keto on 2006-06-23, 07:30:51 (201.133.185.172)
Cal, I'm looking forward to experimenting with the 6AL5 biasing a 6C45, and my only experience so far with diode bias in general is putting together and listening to a great-sounding Bottlehead kit th .......
195: MagneQuest/Peerless Forum, 6AL5 tube diode bias (0.00)
Posted by keto on 2006-06-22, 06:38:30 (201.133.185.172)
C.Y, thanks for mentioning the 6AL5; I'm plotting out a new platform for a PP2A3, and will add (to the 9 sockets so far) a 7-pin socket for that doble diode, right near the input. How's that 6AL5 soun .......
196: MagneQuest/Peerless Forum, Re: Seeking advice .. Resistor loaded parafeed SE (0.00)
Posted by keto on 2006-06-21, 19:24:27 (201.133.185.172)
Interesting 5K+5K load. I can't help with the voltage doubler, but, what about putting the two filter chokes in a single output PSU filter, and then use a larger value resistive load for the 5842? I k .......
197: MagneQuest/Peerless Forum, and in the other corner... (0.00)
Posted by keto on 2006-06-18, 20:00:42 (201.135.109.13)
Hey all, I'm now trying a pair of OD3 shunt regulators for the PP2A3 output AND the C4S-loaded 6C45 driver (I would have tried a 6BX7, but ran out of octal openings). The 6C45 draws 5.5mA + 2mA for th .......
198: MagneQuest/Peerless Forum, PP300B and the S-240-A (0.00)
Posted by keto on 2006-06-18, 10:41:34 (201.135.109.13)
Hey all, This PP amp platform I've been working with is pretty big and heavy, so I'm building a fleet of 9" x 15" boxes: one for a pre-amp, 2 for se45's (finally!) and 2 for the continuing PP adventur .......
199: MagneQuest/Peerless Forum, Re: Hey Keto (0.00)
Posted by keto on 2006-06-09, 21:25:18 (201.145.217.63)
Xavier, I play the clarinet. Last time I was in Toluca was about a year ago. They play every Friday night at 8:00, for most of the season. Also, their conductor is now here most of the time. I'll chec .......
200: MagneQuest/Peerless Forum, Re: the pp2a3 adventure continues... (0.00)
Posted by keto on 2006-06-09, 11:03:32 (201.121.232.107)
Hey Xavier, yep, I'm in Guanajuato. I've been to Toluca to play with the OSEM, but never stopped off in Lerma. If its in those hills I remember, it must be nice and green. Saludos, tambien... --keto : .......
201: MagneQuest/Peerless Forum, the pp2a3 adventure continues... (0.00)
Posted by keto on 2006-06-08, 22:01:37 (201.135.109.49)
Hey all, I've been looking at new ways of connecting a direct-coupled 6n1p-pp2a3 (link, below). Last week, I removed the VR tubes and sourced the C4S plate loads instead from the shared output cathode .......
202: MagneQuest/Peerless Forum, system? (0.00)
Posted by keto on 2006-06-03, 08:55:01 (201.135.109.49)
What else is in the system? If its for horns, you might get away with two DHT stages, start to finish. .......
203: MagneQuest/Peerless Forum, new idea (0.00)
Posted by keto on 2006-06-03, 08:40:05 (201.135.109.49)
gluca, Thanks to your warning; as a result, I've come across a new scheme, or a way to consider 2 distinct options. Option one is to continue with a 2K or 2K5 resistor in the common cathode of the out .......
204: MagneQuest/Peerless Forum, Re: 6H30 --- warning --- (0.00)
Posted by keto on 2006-06-02, 23:06:15 (201.135.109.49)
Thanks a lot for that warning; I'm now taking a step back, and to the drawing board... --keto .......
205: MagneQuest/Peerless Forum, Re: 45 preamp? (0.00)
Posted by keto on 2006-06-02, 09:03:18 (201.135.109.49)
What about a 45 into a 2:1 autoformer, like the EXO-173? Rp of less than 2K would mean a Zout of less than 500. I think this was mentioned here before. Or for less than unity gain, the 5K:500ct B7 wou .......
206: MagneQuest/Peerless Forum, dcr/Lcrit/perm (0.00)
Posted by keto on 2006-05-31, 23:36:01 (201.135.109.49)
Hey Mike, It seems like one complication is that the specs are somewhat "universal". At the link is yet another gem from Paul Joppa, relating critical inductance and peak current. "If the inductor is .......
207: MagneQuest/Peerless Forum, input transformer (0.00)
Posted by keto on 2006-05-31, 19:10:07 (201.135.109.49)
Rodney, thanks for all the good suggestions. Soon, I will be trying a 6H30 front end, the idea being 100mA through the 2A3 pair, choke-loaded 40mA through each 6H30 half, and 20mA through two series O .......
208: MagneQuest/Peerless Forum, Re: I think that schematic looks great (0.00)
Posted by keto on 2006-05-30, 21:54:26 (201.135.109.49)
Thanks, I'm not sure what the circuit was doing before I put the EXO-173, mostly SE, I guess. The attenuator in parallel with the autoformer is an interesting combo. 15K is too low, and the EXO-173 is .......
209: MagneQuest/Peerless Forum, oops (0.00)
Posted by keto on 2006-05-29, 12:32:00 (201.135.109.49)
gluca, sorry for the confusion; and its comforting to know now that its not just one person doing all that work. Is the 813 is a 10W amp, more or less?.. --keto .......
210: MagneQuest/Peerless Forum, Re: new PP2A3 wrinkle (0.00)
Posted by keto on 2006-05-29, 08:39:48 (201.135.109.49)
gluca, yes, I got the idea of direct-coupled PP from Gary Pimm's PP47. I also used one of his current sinks in the output cathode, which sounded really, really nice, until I shorted it, somehow. I thi .......
211: MagneQuest/Peerless Forum, new PP2A3 wrinkle (0.00)
Posted by keto on 2006-05-28, 20:09:19 (201.135.109.49)
hey all, ages ago, "jsn" of "boozhoundlabs" fame posted my schematic for a future PP2A3, which is at the link below. Until today the amps were like the schematic, but without the EXO-173 autoformer. T .......
212: MagneQuest/Peerless Forum, what a thread... (0.00)
Posted by keto on 2006-05-25, 15:50:09 (201.135.109.49)
Hey Mike, The more I read here, the more I realize that by working out my PP2A3's (signal and PSU) almost strictly by sound, I've ended up with a pretty weird circuit. Inspired by all these posts, I'v .......
213: MagneQuest/Peerless Forum, Re: is low dcr the holy grail in choosing a choke? (0.00)
Posted by keto on 2006-05-23, 06:44:05 (201.135.109.49)
Hey Mike, I'd say the 52 ohm plan B, since the 5 ohm plan A seems pretty extreme, since I'm happy with the compromise 18 ohms, which weighs, err, a lot. The BFFC jujitsus the ripple and drops just a c .......
214: MagneQuest/Peerless Forum, Re: Solid Gold, I mean silver (0.00)
Posted by keto on 2006-02-04, 06:49:53 (201.135.104.69)
Gordon, thanks for the fascinating post. Maybe I shouldn't ask, maybe I should let it drift in the imagination, but, well, whats a "BAC (Big Ass Chokes) (BCP16-AG) 450H"? The AG must mean silver wire, .......
215: MagneQuest/Peerless Forum, Re: a musical Ben.... (0.00)
Posted by keto on 2006-01-16, 06:09:44 (200.95.87.87)
I saw the music to Mozart's quartet for "glass armonica" and strings this summer, which from reports the world over is devilishly difficult. Note in the article the musical example chosen was, rather, .......
216: MagneQuest/Peerless Forum, Re: Why is a monkey amp called "monkey"? (0.00)
Posted by keto on 2006-01-07, 15:47:48 (201.137.233.95)
Well, the "monkey" driver plate has two hands: one grips the output grid and the other pulls bananas from the output cathode; its a circuit that would never have existed without opposable thumbs. Not .......
217: MagneQuest/Peerless Forum, Re: fully loaded question (0.00)
Posted by keto on 2006-01-02, 00:10:31 (201.137.233.95)
Paul, thanks a lot for the safety check (and all the little details, too) -- much appreciated! --keto .......
218: MagneQuest/Peerless Forum, you've got mail (nt) (0.00)
Posted by keto on 2006-01-01, 19:30:55 (201.137.233.95)
. .......
219: MagneQuest/Peerless Forum, thanks (0.00)
Posted by keto on 2006-01-01, 19:22:14 (201.137.233.95)
Your "technically you want a transformer than can sink more current in that setup" is what I'm after, and so far using the power formulas, I come up with 54mA for choke-input full-wave bridge being eq .......
220: MagneQuest/Peerless Forum, Re: fully loaded question (0.00)
Posted by keto on 2006-01-01, 17:18:11 (201.137.233.95)
Hey Mike, I picked up a hint from one of the sages, that this might be a normal option on a power transformer, that is, to use the center tap and a pair of diodes as "full wave", or, ignore the center .......
221: MagneQuest/Peerless Forum, fully loaded question (0.00)
Posted by keto on 2006-01-01, 14:56:52 (201.137.233.95)
Hey all, since I've "resolved" to press my stash of unused MQ inductors into service, I've got this design question thats all about safety checks and MOL's. Here goes. I've been using the PGP8.1 (and .......
222: MagneQuest/Peerless Forum, amen, and an inductive nuevo año (nt) (0.00)
Posted by keto on 2005-12-31, 18:02:13 (201.137.233.95)
. .......
223: MagneQuest/Peerless Forum, here's one option (0.00)
Posted by keto on 2005-12-24, 12:56:52 (201.153.205.184)
Jim, the Bottlehead C4S is a very handy "CCS". It can be ordered and configured for either "constant current source" for the first half of your 6SL7 or "constant current sink" for the second half. Or .......
224: MagneQuest/Peerless Forum, Re: Glass Collage (0.00)
Posted by keto on 2005-12-22, 23:40:28 (201.153.205.184)
how about this? .......
225: MagneQuest/Peerless Forum, Re: Gander at my new amps, MQ filled (0.00)
Posted by keto on 2005-12-22, 05:19:30 (201.153.205.184)
How'd you get 3 or 4 inductors and all the other stuff in there? Looks great... --keto .......
226: MagneQuest/Peerless Forum, Re: core geometries and materials (0.00)
Posted by keto on 2005-12-22, 05:16:55 (201.153.205.184)
Hey Mike, Sounds like an interesting idea, since streamlining a corner of your production would free up more time and energy for new projects. If the iron doesn't have covers, it goes below-decks -- n .......
227: MagneQuest/Peerless Forum, Re: Did you get my email? (0.00)
Posted by keto on 2005-12-18, 06:19:10 (201.153.205.184)
Hi Jim, I just tried sending the schematic again. I hope it gets throught this time... --keto .......
228: MagneQuest/Peerless Forum, Re: Convert Single Ended 6L6 To Parafeed (0.00)
Posted by keto on 2005-12-16, 22:17:03 (201.153.205.184)
Would you be into simplifying the circuit a little? From the threads below it looks like you're maybe heading towards a "parafeed pentode" with some feedback. For a triode 6L6 the Tung-Sol data sheets .......
229: MagneQuest/Peerless Forum, Re: PGP 8.1 (newbie) question (0.00)
Posted by keto on 2005-12-11, 13:47:16 (201.153.205.184)
Jabber-- The 6X5GT heater can be as much as 450V below its cathode, and the 6DN7's as much as 100V (DC component) above. So, if you create a centertap with two resistors, and reference it to, say 75VD .......
230: MagneQuest/Peerless Forum, Re: Looking for Ideas... (0.00)
Posted by keto on 2005-12-10, 12:15:15 (201.153.205.184)
My mistake on the 47, unless you want to experiment with unity coupling, that is a Rp of 3K5 into a 5K reflected load (see link). I understand about the Paramour chassis. Frankenstein's monster is alr .......
231: MagneQuest/Peerless Forum, electronic concerts using PP2A3 amps (0.00)
Posted by keto on 2005-12-09, 12:54:21 (201.153.205.184)
Hi all, Last week my not-quite-ready-for-primetime amps debuted to rave critical acclaim, here in the town of Guanajuato (Mexico). My back is still aching from hauling the beasts around, but I feel li .......
232: MagneQuest/Peerless Forum, Re: Looking for Ideas... (0.00)
Posted by keto on 2005-12-09, 06:01:10 (201.153.205.184)
It would seem like the Paramour platform would be a good one for experimentation. The RH's 5K load is only a little higher than its 4K operating point, for the 2A3, and then converting to 45 wouldn't .......
233: MagneQuest/Peerless Forum, Re: Help with power supply (0.00)
Posted by keto on 2005-11-30, 16:48:50 (201.153.205.184)
fitz, I've had success using the 6BY5 damper diode as rectifier and the MQ "PGP8.1" in a number of different circuits, mostly power amps, so I can recommend similar paths, of the zillion possibilities .......
234: MagneQuest/Peerless Forum, Re: ping Mike, about that Altec 1570B amp (0.00)
Posted by keto on 2005-11-24, 05:43:34 (201.153.205.184)
Ciao Gluca, How about a voltage amp stage before the 807's and drop the last stage? The 811A probably draws a little grid current all the time (this I get from staring at the data sheets, only), and a .......
235: MagneQuest/Peerless Forum, Re: ping Mike, about that Altec 1570B amp (0.00)
Posted by keto on 2005-11-23, 20:58:29 (201.153.205.184)
That 17173 looks to swing about 0/50-50/0mA. So you could instead put an EXO-173 before the driver (at 750Vp, the date sheet requests just that EXO-173's 150vrms swing, from grid to grid), and put sep .......
236: MagneQuest/Peerless Forum, Re: ping Mike, about that Altec 1570B amp (0.00)
Posted by keto on 2005-11-23, 20:28:44 (201.153.205.184)
Not of the shirt-pocket variety? .......
237: MagneQuest/Peerless Forum, ping Mike, about that Altec 1570B amp (0.00)
Posted by keto on 2005-11-23, 10:44:06 (200.95.87.170)
Hey Mike, I was scribbling away at PP811A ideas, inspired by Jim Doyle's (?) post a while back, trying to shoehorn the whole thing into a 3-stage direct coupled compact (6SN7-6A5Gcf-811A), and then I .......
238: MagneQuest/Peerless Forum, really good advice, all around (0.00)
Posted by keto on 2005-11-23, 06:22:18 (201.153.205.184)
Thanks a lot VS! --keto .......
239: MagneQuest/Peerless Forum, Re: Ideas (0.00)
Posted by keto on 2005-11-20, 16:58:01 (201.153.205.184)
Thanks, VS; first, for your safety checks (a good while back) keeping me out of trouble, and now, for the fine tuning. In the near short term, I'm out of the woods, since I got 25:1 ratios between pri .......
240: MagneQuest/Peerless Forum, well (0.00)
Posted by keto on 2005-11-19, 10:13:46 (201.153.205.184)
These plate to plate readings, trash my "simple null" idea. 50/70ma 26mvac 55/65ma 30mvac 60/60ma 27mvac 65/55ma 25mvac 70/50ma 33mvac 56/64ma 7mvac And because the primary to secondary noise floor r .......
241: MagneQuest/Peerless Forum, update (0.00)
Posted by keto on 2005-11-18, 16:50:59 (201.153.205.184)
Hi, all These measurements are with a DVM, so I assume they're peak to peak readings. New Sovtek 2A3's. Tried a new pair both ways, with the balance at 60/60madc. Stuck with the quieter, of about 16mv .......
242: MagneQuest/Peerless Forum, haven't had the chance (nt) (0.00)
Posted by keto on 2005-11-18, 16:15:38 (201.153.205.184)
. .......
243: MagneQuest/Peerless Forum, further PP2A3 musings (0.00)
Posted by keto on 2005-11-17, 21:23:28 (201.153.205.184)
Hi all, I've got a new pair of Sovtek 2A3's in the finished amp, and they're balanced up and burning in nicely. My first impression, after hearing Valve Art's, TJ's (the 2.5V300B's), and now the Sovte .......
244: MagneQuest/Peerless Forum, one more thing (0.00)
Posted by keto on 2005-11-14, 15:32:01 (201.153.205.184)
gluca, I removed the splitter on the input, so the attenuator feeds one 6N1P grid and the other is grounded. This is the circuit I keep wandering back to. I put the TJ300B(2.5V) pair back in, and bala .......
245: MagneQuest/Peerless Forum, Re: new PP2A3 pics, courtesy of jsn... (0.00)
Posted by keto on 2005-11-13, 10:30:16 (201.153.205.184)
Hey Mike, "...and "what's that monster trans"?" Its the EXO-173; it just looks larger because its in the foreground. Or were you asking about the BFFC-150? In my partial rebuild, I've finally got 1/4" .......
246: MagneQuest/Peerless Forum, Re: a source for inspiration ... sweet chassis ... great schem (0.00)
Posted by keto on 2005-11-11, 23:54:38 (201.153.205.184)
Gianluca, because of the direct-coupling, I use the balance pot on the input cathode and measure the DC voltage difference between the two output plates; this just to set things up. When I've gone bac .......
247: MagneQuest/Peerless Forum, Re: BFFC ? (0.00)
Posted by keto on 2005-11-11, 11:53:42 (201.153.205.184)
Rodney, at the link you'll find some info on that MQ "rather large" filter choke (to get a pair, just dial the MQ hotline and say "supersize me, Mike"). And yes, the EXO-173 is one of the early ones. .......
248: MagneQuest/Peerless Forum, new PP2A3 pics, courtesy of jsn... (0.00)
Posted by keto on 2005-11-10, 15:56:35 (201.128.236.57)
Thanks to jsn, I've now got a niche at the very cool Boozhoundlabs site (see link). As you will see, I've abandoned the direct-coupled "compact" (a lowish-resolution long-tailed-pair) and taken a step .......
249: MagneQuest/Peerless Forum, Re: SETH voltages (0.00)
Posted by keto on 2005-11-09, 14:50:17 (201.128.236.57)
Blair, with the amps off and unplugged, check the high voltage DC caps, to make sure they're drained. Measure DC resistance (ohms) from ground to the cathode pin of the 6C45, to make sure that connect .......
250: MagneQuest/Peerless Forum, Re: Inspiration is what I need ... and a little help. (0.00)
Posted by keto on 2005-11-01, 16:09:32 (200.78.116.75)
What is the maximum signal the 102TX's can safely handle? Maybe you could design a low-mu, parafeed stage, cap-coupled to the 102TX? Maybe using a 71A, exactly as described in the sage link? Something .......
251: MagneQuest/Peerless Forum, thanks a lot... (0.00)
Posted by keto on 2005-10-29, 10:24:34 (201.153.208.199)
whoa, wool felt washers. As impressive as all their inventories, their search engines. The PGP8.1 machine screws are 8-32, right? Looks like McM has longer than 2" lengths in these. Or, how about thes .......
252: MagneQuest/Peerless Forum, fastener source? (0.00)
Posted by keto on 2005-10-28, 07:01:55 (201.153.208.199)
I'm looking to isolate the PGP8.1's and other MQ hardware, and some of my chassis work is 1/4" thick, so I'll need longer brass bolts. The site below looks good, but I'm wondering if anyone here has o .......
253: MagneQuest/Peerless Forum, parafeed preamp w/ 15K B7s and now, 6DN7 (0.00)
Posted by keto on 2005-10-26, 11:33:00 (201.153.208.199)
Hi all, I think I have a good match here, using the 6DN7, with the low mu half as shunt regulator (1st paragraph of link) and the high mu half as parafeed voltage amp. From a B+ voltage of 442vdc, a 2 .......
254: MagneQuest/Peerless Forum, maybe I'm easily amused... (0.00)
Posted by keto on 2005-10-24, 06:35:47 (201.153.208.199)
Early in the a.m. I finished up a parafeed preamp, using the cobalt 15K:500 B7 OPTs -- all, as a kind of experimental platform. Signal circuit is 100K pot, 12SN7 (170Vp-k, 5mA, -5Vg), 30K plate load a .......
255: MagneQuest/Peerless Forum, Re: any cap mounting ideas? (0.00)
Posted by keto on 2005-10-22, 13:33:49 (201.153.208.199)
Hey Mike, if they indeed have a lip, as it appears, and if you want that Russian text topside, try this (scrolling down and right)... http://www.surplussales.com/Capacitors/capclmp.html looks like jus .......
256: Tube DIY Asylum, Re: 2A3 pp OT (0.00)
Posted by keto on 2005-10-22, 10:12:46 (201.153.208.199)
I've used a single NOS Stancor A-3307 for PP2A3 experimenting, and see at the link below there's a single unit there, with the same specs, but a different model number. The A-3307 (5Kct) told me all I .......
257: MagneQuest/Peerless Forum, I really like the looks of the MQA-18 (0.00)
Posted by keto on 2005-10-20, 10:08:20 (201.153.208.201)
...since I'm FINALLY building a parafeed 12SN7GTA + big blue B7 (15K:500) linestage, and as described, the MQA-18 would be a perfect, drop-in PP sub for the B7, with 40 + 40 vrms from the SN7GTA, step .......
258: MagneQuest/Peerless Forum, PP47 experiment (0.00)
Posted by keto on 2005-10-10, 21:29:51 (201.145.236.140)
Hi all, I built a mono PP47, sort of like Gary Pimm's, with direct-coupling between stages -- but the first stage is a SE5842 and a grounded-grid 5842 to set the grid potential of the "other 47" of th .......
259: MagneQuest/Peerless Forum, At what time do you go riding every morning? (nt) (0.00)
Posted by keto on 2005-10-10, 06:54:53 (201.145.236.140)
. .......
260: MagneQuest/Peerless Forum, sorry, that was just thinking aloud... (0.00)
Posted by keto on 2005-09-22, 08:30:21 (201.145.236.140)
Hey how's your PP circuit coming along? What is it you're building? I'm happily playing so many concerts this year that I've only squeezed in minor changes to the PP2A3 circuit. Can you imagine having .......
261: MagneQuest/Peerless Forum, min parts... (0.00)
Posted by keto on 2005-09-18, 07:21:05 (201.129.142.20)
ciao gluca, The original circuit there would seem to cause a variation of "+" 50% or "-" 100% of the output current as the shared cathode voltage potential swings from 2X quiescent to 0V; adding an EX .......
262: MagneQuest/Peerless Forum, Re: And the winner is.... 6W6GT (0.00)
Posted by keto on 2005-09-17, 07:42:40 (201.129.142.20)
Jim, Sounds like a really interesting project, and already off to the best start with those OPTs. If in the breadboarding stages you have a higher B+ source, high enough for direct-coupling between tw .......
263: MagneQuest/Peerless Forum, Re: a sucessful move.... (0.00)
Posted by keto on 2005-09-14, 21:58:42 (201.129.142.20)
Congrats, Mike. Sounds like a big step for y'all and MQ. Da best, del sur... --keto .......
264: Tube DIY Asylum, Re: Getting started with PP designs... (0.00)
Posted by keto on 2005-09-02, 11:10:23 (200.95.87.154)
I'd suggest a direct-coupled, 2-stage amp -- which is what I listen to, with a 6N1P and a pair of 2A3s. There's a hand-drawn schematic here http://diyparadise.com/ultracompact.html if you scroll down .......
265: Tube DIY Asylum, it wasn't the electrolytics... (0.00)
Posted by keto on 2005-08-30, 18:38:33 (201.128.226.31)
...but the oboe and english horn reeds being dried out. 7 years? C'mon ;-) And the bassists themselves had been equally dried out, which is definitely not a normal state of affairs. .......
266: High Efficiency Speaker Asylum, wishing you the very best... (nt) (0.00)
Posted by keto on 2005-08-29, 13:01:29 (201.128.226.31)
. .......
267: Bottlehead Forum, thanks a lot (nt) (0.00)
Posted by keto on 2005-08-23, 14:54:19 (201.128.226.31)
. .......
268: Bottlehead Forum, Thanks all, and one more question for Paul... (0.00)
Posted by keto on 2005-08-22, 18:56:49 (201.128.226.31)
Would the "bias chain" set the (output) C4S sink parameters? Thanks... --keto .......
269: Bottlehead Forum, A question about C4S current sinks, for PP6DN7 (0.00)
Posted by keto on 2005-08-21, 09:16:47 (201.128.226.31)
Hi all, I've got the parts for eXperimenting a mono PP6DN7, and am wondering why not use a C4S current sink on BOTH stages, in the first to establish the two differential halves of the signal (straigh .......
270: MagneQuest/Peerless Forum, Re: next to Cobalt SE Parafeed . . (0.00)
Posted by keto on 2005-08-20, 09:22:24 (201.128.226.31)
For your first question, let's hope Kurt responds. For the second, I have a pair of nickel EXO-045's, of an "XXL" variant, which is a slightly higher lamination stack than the standard one, and a pair .......
271: MagneQuest/Peerless Forum, check out this thread... (0.00)
Posted by keto on 2005-08-20, 07:30:36 (201.128.226.31)
. .......
272: MagneQuest/Peerless Forum, what's the world coming to? (0.00)
Posted by keto on 2005-08-19, 22:53:27 (201.128.226.31)
Boozlabhounds eschewing Single Malts for a "blended solution"? Hey jsn, now that you've gone over to the "dark side", check out the genius link below, for a truly mind-boggling journey for two triodes .......
273: MagneQuest/Peerless Forum, hadn't thought of that...here's the link, for the photo and schematic... (0.00)
Posted by keto on 2005-08-17, 05:44:14 (201.128.226.31)
...which shows a big step-up input transformer. Thanks for your comment... --keto .......
274: MagneQuest/Peerless Forum, PP845 booster amp idea (0.00)
Posted by keto on 2005-08-15, 06:49:58 (201.128.226.31)
Hi all, on the Sakuma site, he's got a one-stage PP845 booster amp that got me thinking. Maybe my direct-coupled 6N1P (signal+mute) to PP2A3 (compact) could be wired with an alternate out, bypassing t .......
275: MagneQuest/Peerless Forum, a clue, maybe... (0.00)
Posted by keto on 2005-08-13, 19:52:30 (201.128.226.31)
From Mike's post below, EXO-173 driver of Rp less than 5K for M6 and greater than 5K for nickel. Comparing that to the B7 trannies, that would mean an impedance of a little less than 15K for M6 and mo .......
276: Tube DIY Asylum, correction (0.00)
Posted by keto on 2005-08-06, 12:50:49 (201.145.218.165)
The forum is still active and the archives still accessible. Here´s one post about passive radiators... .......
277: Bottlehead Forum, two strikes (0.00)
Posted by keto on 2005-08-06, 09:41:05 (201.145.218.165)
Not only did I misuse the term, but I even missed its spelling. The "vagaries" were all my own, really, in trying to deal with a DC filament supply and a battery bias for the 26. The sound was great, .......
278: Bottlehead Forum, Re: Help! really dumb DHT question (0.00)
Posted by keto on 2005-08-04, 20:43:13 (201.145.218.165)
The 82 ohm resistors provide the center tap for the 1.5V/1.05A filament source. Maybe you've got your cathode resistor attached to the positve node of the filament winding, and that yields a smaller c .......
279: Tube DIY Asylum, passive radiators? (0.00)
Posted by keto on 2005-08-04, 19:14:09 (201.145.218.165)
Lambda 15" TDX's with a pair of 1400g pr's each tune to about 20hz in a 5 cu ft box (PR's fire on opposite sides, so the box doesn't move). In earlier experiments in the now disappeared Lambda Forum s .......
280: High Efficiency Speaker Asylum, when you're not keeping small objects from bouncing around... (0.00)
Posted by keto on 2005-08-04, 17:08:47 (201.128.226.63)
walls falling over, etc., can you hear that there's much of a delay with the LabSub, or does it just not matter? I admire the idea of the all 1st order XO's. Bravo! --keto .......
281: MagneQuest/Peerless Forum, report on input "grid chokes" in a PP2A3 direct-coupled "compact" (0.00)
Posted by keto on 2005-08-04, 16:53:44 (201.128.226.63)
Hi all, I've come back to one of my favorite PP2A3 circuits, which appears in the link, if you scroll down a little. The shared cathode of the output is now a power resisistor, since I did something b .......
282: K&K Audio / Lundahl Transformers, Re: Straw Poll (0.00)
Posted by keto on 2005-08-04, 14:12:19 (201.128.226.63)
Thanks for the response. I checked out the Digital archives and now see that the USB is totally different from the typical CD/DVD outs. And yes, that was a SE parafeed output for the RAKK DAC. --keto .......
283: K&K Audio / Lundahl Transformers, Re: Straw Poll (0.00)
Posted by keto on 2005-08-03, 06:41:52 (201.128.226.63)
Is there a post somewhere that covers possible inputs for the RAKK DAC? My CD DVD player has a coax digital out and an optical one. A project I'm working on for 2006 would require using a computer as .......
284: MagneQuest/Peerless Forum, Re: actually.... (0.00)
Posted by keto on 2005-07-20, 22:22:53 (200.95.87.190)
Hi Mike, I've had little time to experiment, but continue to be captivated by the sound of grid-choked SE6N1P direct-coupled to PP2A3, though its not much of a design on paper, since the input clips a .......
285: High Efficiency Speaker Asylum, ping...Nick McKinney (0.00)
Posted by keto on 2005-07-20, 17:55:17 (200.95.87.190)
Drop me a line, if you get the chance. Thanks... --keto .......
286: MagneQuest/Peerless Forum, "ground isolation", of course...thanks (nt) (0.00)
Posted by keto on 2005-07-20, 13:51:20 (200.95.87.190)
. .......
287: MagneQuest/Peerless Forum, second that idea (0.00)
Posted by keto on 2005-07-20, 10:27:29 (200.95.87.190)
Tanker, The EXO173 is your ticket, since among other things its rated for 100vrms, which is 50vrms per 300B grid -- just what you need. --keto .......
288: MagneQuest/Peerless Forum, about that 173jr (0.00)
Posted by keto on 2005-07-19, 19:31:52 (200.95.87.190)
I was thinking that a 2vrms (6C45 pair) or 3vrms (6N1P) or 5vrms (6GC7) mol CT autoformer, combined with a C4S shared-cathode current-sink would make a great driver for a direct-coupled PP2A3 output. .......
289: MagneQuest/Peerless Forum, maybe a 3 stage circuit? (0.00)
Posted by keto on 2005-07-18, 08:36:12 (201.129.142.142)
If you have the B7 on hand, how about a 3-stage circuit, SE-PP-PP: 12AU7 or other parafed to the B7 primary, center-tapped secondary to a 6SN7 long-tailed pair (C4S current sink?), RC coupled to your .......
290: MagneQuest/Peerless Forum, it works (0.00)
Posted by keto on 2005-07-17, 22:00:55 (201.129.142.142)
A 6SN7 direct coupled to a parafed 300B. Hmmm. Can words describe how it sounds? .......
291: Propeller Head Plaza, thanks for the great link (nt) (0.00)
Posted by keto on 2005-07-14, 12:29:57 (201.133.169.148)
. .......
292: Bottlehead Forum, What about at low levels, or is the amp quiet with the input grounded? (nt) (0.00)
Posted by keto on 2005-07-14, 07:37:36 (201.137.233.59)
. .......
293: Propeller Head Plaza, looking for spectrum analysis for mac OS9 or OSX (0.00)
Posted by keto on 2005-07-14, 06:52:42 (201.137.233.59)
I'm looking for a simple program, to visualize and investigate spectra from acoustic sources, to be able to see their real harmonic composition. Any ideas for such an item, that will work with my iBoo .......
294: MagneQuest/Peerless Forum, Re: ping MQ.....input autoformer? (0.00)
Posted by keto on 2005-06-12, 18:41:38 (201.133.185.154)
Hey Mike, I guess that such a 2vrms item would involve sub-microscopic work, and that scaling up to the refined EXO-173 might be the best design bet. I thought I'd toss out the idea, though, in case t .......
295: MagneQuest/Peerless Forum, ping MQ.....input autoformer? (0.00)
Posted by keto on 2005-06-10, 12:31:54 (201.128.225.119)
Hey Mike, how's it going? Since you're winding angel-hair on tiny bobbin GCs these days, I thought I'd chime in again with an interest in an input autoformer. Something of the 1:1+1 variety (like the .......
296: MagneQuest/Peerless Forum, operating points? (0.00)
Posted by keto on 2005-05-31, 11:35:17 (201.137.233.167)
Hey Jeff, let me know if you adjust that 20W-output operating point to fit the S-240-A (for slightly less than 20W, I suppose?). Also, getting ahead of myself, probably, but last night I set up the PP .......
297: MagneQuest/Peerless Forum, "...the driver has more effect than any output tube..." (0.00)
Posted by keto on 2005-05-28, 19:09:39 (201.129.128.9)
Well put. Careful though, if you keep going toward a Sakuma-style circuit, the next step will be your 10-PP2A3 as a driver for PP845. For driving a 300B there's a clean 6dB of headroom to be had from .......
298: MagneQuest/Peerless Forum, bravo (0.00)
Posted by keto on 2005-05-26, 13:09:38 (200.78.116.126)
Thanks for posting that schematic! --keto .......
299: MagneQuest/Peerless Forum, exo-173, S-240-A, et al.... (0.00)
Posted by keto on 2005-05-25, 19:45:06 (201.129.128.12)
Joe-- Its good to know your calculations were on target. In this case, I chose the 8.2uF's because I had a pair of them handy, and in my next experiment -- PP6SN7 longtail pair, parafed to "top" and " .......
300: MagneQuest/Peerless Forum, parafeed PP2A3 experiments (0.00)
Posted by keto on 2005-05-23, 09:56:24 (201.128.245.174)
Hi all, I've now parafed the S-240-A output of one of my PP2A3 amps, in a mostly-differential amp. The input is the EXO-173, to both grids of a 6N1P, with a 3.5mA (about -3.5Vg) C4S current sink on th .......
301: MagneQuest/Peerless Forum, a little progress... (0.00)
Posted by keto on 2005-05-15, 10:46:09 (201.135.109.187)
Hi Mike, ...between Morgan Jones and the asylum archives, I see that a 1K8 resistor from the top of the plate choke will set the 47's screen at 250V/6mA. Staring at the data sheets, I get a gain of a .......
302: MagneQuest/Peerless Forum, how about parafeeding a 47? (0.00)
Posted by keto on 2005-05-11, 19:05:35 (201.133.185.139)
Hi all ... A while back I did a little experimenting with the Dowdy Choke, EXO-045ni and 45, monkeyed, with a pair of OB3s on the 45 cathode, and a C4S on the driver plate. Now I'm wondering if I coul .......
303: MagneQuest/Peerless Forum, greetings (this one works, I think) (0.00)
Posted by keto on 2005-04-02, 09:11:22 (201.128.225.183)
Hey Mike, don't you know we're deep in margarita season down here? I've been happily busy with concerts, and so nearly off-line. I did check in this week at the MQ forum, so I caught your message, and .......
304: Bottlehead Forum, singe (0.00)
Posted by keto on 2004-11-24, 16:36:12 (148.243.92.196)
I had the same reaction, running the TJ300B's at 2A3 operating points, in the Paramour and other circuits. However, in a PP300B circuit, they sound great. I don't know if this is because they're opera .......
305: Bottlehead Forum, Valve CD's are a great reference (0.00)
Posted by keto on 2004-11-22, 06:11:49 (148.243.92.164)
Brad, Good to hear that VALVE might be making a return. Maybe someone could tackle a big Buddha text? His stuff in VALVE and the C4S manual is really fascinating, and I'd pay top peso/shekel for anoth .......
306: MagneQuest/Peerless Forum, Re: b7 grid choke Vs the real thing (0.00)
Posted by keto on 2004-11-18, 15:09:40 (148.240.220.110)
SLM-- I'll take a shot at part of your Q. If the B7's primary has an L of several hundred and the GC of a few thousand, than that would translate into a couple octaves of difference. But then, the B7 .......
307: Tube DIY Asylum, 300B's (0.00)
Posted by keto on 2004-11-17, 07:04:36 (148.240.220.110)
If you go to the Western Electric site, they've got many OP's for the 300B, like... 300Vp-k, -58Vg, 80mA, 1700K, 7.5W, -26dB(2nd), -37dB(3rd) --keto .......
308: MagneQuest/Peerless Forum, bravo (0.00)
Posted by keto on 2004-11-15, 16:59:20 (148.240.100.50)
eelind, That's a very cool circuit. I didn't know you could parallel feed a pentode. That is what the 6V6 is doing, right? Any idea if I could do this with a "47" (see link), into a 15K:500 transforme .......
309: MagneQuest/Peerless Forum, progress and an SOS for driver suggestions... (0.00)
Posted by keto on 2004-11-13, 16:02:52 (148.240.220.73)
Hi all, My circuit now is EXO-173, PP6N1P, caps, EXO-173, PP300B, OPT. What I would like to do is take the 425V B+ node, and select some drivers that will have good voltage swings, given the 300Bs' ap .......
310: MagneQuest/Peerless Forum, design (0.00)
Posted by keto on 2004-11-13, 15:23:22 (148.240.220.73)
You've got to run into problems when the end use of something gets too far from its designers' intentions, and even moreso if the marketing department insists that it be so, and then starts influencin .......
311: MagneQuest/Peerless Forum, 15K:500ct - PP6SN7 - EXO-173 - PP300B (0.00)
Posted by keto on 2004-11-12, 13:34:41 (148.240.220.73)
I read somewhere that the EXO-173 might be used as a correcting center-tapped grid-choke, so I've given it a try with the circuit in the title. My direct-coupled PP2A3 experiments have been interestin .......
312: Tube DIY Asylum, Re: 45/2A3 PP amp or is it 2A3/45 PP amp (0.00)
Posted by keto on 2004-11-11, 20:30:24 (148.240.220.73)
Ah, its a stereo amp...for hunting vampires. Thanks... --keto .......
313: Tube DIY Asylum, Re: 45/2A3 PP amp or is it 2A3/45 PP amp (0.00)
Posted by keto on 2004-11-11, 18:24:02 (148.240.220.73)
Now, why did you have to do that? Here I am, figuring and refiguring my PP2A3 (it was a PP300B earlier this week), and I've got the final fixings for a 45 SE amp on the way... Is this a PP45-PP2A3 cir .......
314: High Efficiency Speaker Asylum, 120dB (0.00)
Posted by keto on 2004-11-10, 14:56:52 (148.240.220.73)
I'd say 16W into "100dB" above 300hz is good, or the ability to produce 112dB, there. Fudging in the LF, and both channels, that would be about 120dB system-capable, which might include 12dB of headro .......
315: MagneQuest/Peerless Forum, hey, Mike... (0.00)
Posted by keto on 2004-11-10, 06:04:05 (148.240.220.73)
Thanks a lot for sending along the stuff, and for the new ideas about the PP2A3 experimentations. I see now that I'd overlooked a couple cool things that I could add to my present circuit, the EXO-173 .......
316: Tube DIY Asylum, Re: 6SN7 operating voltage too low? (0.00)
Posted by keto on 2004-11-10, 05:18:57 (148.240.220.73)
Looks like a classic trade off between direct-coupling and a B+ of less than 1000VDC! At 170Vp-k, 4mA, -6Vg, and 33K load, it looks like you'll have enough driver voltage swing for an EL34. I bet it w .......
317: High Efficiency Speaker Asylum, Re: Need help with Lambda TD15M Apollo basshorn (0.00)
Posted by keto on 2004-11-09, 20:38:06 (148.240.220.73)
Thanks for posting this. I've got a pair of the same drivers, which I hope to load, somehow and someday, and am always interested in constructions designed around them. John Sheerin has built a 50hz h .......
318: MagneQuest/Peerless Forum, PJ's specal plate choke as cathode load? (0.00)
Posted by keto on 2004-11-08, 21:21:40 (148.240.220.73)
This afternoon I was scheming about a negative high voltage source, so as to connect an EXO-173 to a PP6BX7 or PP12B4 cathode follower, and that directly-coupled to the PP2A3 grids. What about, instea .......
319: MagneQuest/Peerless Forum, pong (0.00)
Posted by keto on 2004-11-07, 19:58:24 (148.240.220.73)
Thanks; you've got mail. Watch your toes on the punt...--keto .......
320: Tube DIY Asylum, Re: a few questions about negative "bias" supplies (0.00)
Posted by keto on 2004-11-07, 19:42:53 (148.240.220.73)
Good call. Looks like I'll stick with a dedicated negative supply, for the two cathode loads, and use the output supply for the (CF) driver plates voltage potential. I see that more study is definitel .......
321: Tube DIY Asylum, a few questions about negative "bias" supplies (0.00)
Posted by keto on 2004-11-07, 14:32:03 (148.240.220.73)
I'm working on configuring a PP cathode follower direct-coupled to a PP triode output, having in mind the 6SN7 and 2A3. Using the quiescent OP of 250Vp-k, -8Vg and 9mA for the first stage, with the in .......
322: Bottlehead Forum, Re: 0D3 in foreplay (bend width question) (0.00)
Posted by keto on 2004-11-06, 05:54:50 (148.240.108.253)
Be careful with only regulating 20% of the B+ voltage. Or maybe you have significant series resistance upstream, in the PS chokes? The OD3 sheet recommends 50% regulation. If less than that, it might .......
323: Tube DIY Asylum, CCS at OPT center tap (0.00)
Posted by keto on 2004-11-06, 05:27:58 (148.240.108.253)
A CCS at the OPT centertap, and a resistor in the shared cathode would provide a very hermetic AC circuit. A CCS in the shared cathode (as I have it, with PP2A3) allows for a lower impedance "exit" fr .......
324: MagneQuest/Peerless Forum, EXO173-PP6SN7-PP6BX7(CF)-PP2A3 (0.00)
Posted by keto on 2004-11-04, 18:23:30 (148.240.220.90)
Hi all, After not so good results with just the 6SN7 or 6BX7, I cobbled together the above circuit (subject), which sounds pretty fine. The 6BX7 as a cathode follower seems like a really good driver f .......
325: MagneQuest/Peerless Forum, PP2A3"Jr." (0.00)
Posted by keto on 2004-11-03, 16:15:36 (148.240.220.90)
Having toasted my last C4S board, on the zillionth re-figure, I've now removed the VR tubes from the circuit, and come up with the following. EXO-173, PP6SN7 direct-coupled to PP2A3. The 6SN7 halves a .......
326: MagneQuest/Peerless Forum, Re: Line Preamp Tube Poll (0.00)
Posted by keto on 2004-11-02, 11:22:07 (148.240.220.90)
Before the DC filaments drove me bananas, it was the 26, to which I will return if I again need a preamp... --keto .......
327: MagneQuest/Peerless Forum, 6N1P-6SN7-2A3 (0.00)
Posted by keto on 2004-11-02, 06:00:42 (148.240.100.72)
DanL The phase-splitting iron on hand is the MQ "B7"15K:500ct parafeed linestage, and really needs a preamp before it. Thanks for the C4S idea; I'll have to try that. This topology opens up a big fiel .......
328: MagneQuest/Peerless Forum, ever further afield... (0.00)
Posted by keto on 2004-11-01, 16:32:02 (148.240.100.72)
I've now added a CF to my direct-coupled PP2A3, to create the world's heaviest, most ridiculously complex 5W amp: Cobalt 7.75:1+1 input 6N1P 138Vp-k, 5.5mA, -2Vg, C4S plate loads 6SN7 150Vp-k, 5.4mA, .......
329: MagneQuest/Peerless Forum, fun stuff (0.00)
Posted by keto on 2004-11-01, 06:40:55 (148.240.100.72)
My SE6N1P direct-coupled to PP2A3 sounds good, but would require a B+ of about 550VDC (!) to work well. 300V for the 2A3 and OPT, and 250Vp for the driver. This is because the voltage swing from stage .......
330: MagneQuest/Peerless Forum, EXO-173 + 6SN7 cathode follower (0.00)
Posted by keto on 2004-10-31, 18:49:10 (148.240.100.72)
I'm trying two 6SN7 halves as cathode followers between the EXO-173 and the PP2A3 grids, to adjust (for kicks) the individual 2A3 biases, with fixed (6SN7) 1K8 cathode bias resistors connected to a 25 .......
331: SET Asylum, Re: New JE Labs 2A3 is born... (long) (0.00)
Posted by keto on 2004-10-30, 09:39:04 (148.240.220.241)
In Mexico City, I went to the section downtown that deals in industrial water pumps, and found "motor run" capacitors, both new and "semi-nuevo". The largest are a pair of Sprague 30uF 660VAC oil caps .......
332: MagneQuest/Peerless Forum, Re: Need Help With Readings on PGP8.1 Transformer (0.00)
Posted by keto on 2004-10-30, 07:41:00 (148.240.220.241)
Just a wild guess, here. Are the paralleled 4 and 5 secondaries well-connected? If just one was working (really connected), it would have to handle twice its spec'ed current, its voltage might be lowe .......
333: MagneQuest/Peerless Forum, example of DC balance and (maybe) AC balance (0.00)
Posted by keto on 2004-10-28, 18:36:09 (148.240.220.241)
Well, in a year's experimenting, I've tried a few things. I hope that my comments are of some help. Out of curiousity, I changed my second amp into a nearest-possible-facsimile of the SETH circuit (!) .......
334: MagneQuest/Peerless Forum, on balance and other reflections (0.00)
Posted by keto on 2004-10-27, 13:43:54 (148.240.111.15)
Hey Jeff and mrclassicman, Here are a couple notes you might find of interest. All is in the realm of "...what seems to be going on..." The S-240-A primary has fantastic AC balance, and will sustain t .......
335: MagneQuest/Peerless Forum, from the bench, chapter 1 (0.00)
Posted by keto on 2004-10-25, 22:38:56 (148.240.111.15)
The link below is for the circuit in question, but with a simple 15K grid leak on the 6N1P, 5mA per half and a S-240-A OPT. There was a clean 1kHz sine wave with the driven 6N1P plate swinging up to 1 .......
336: MagneQuest/Peerless Forum, direct-coupled 6N1P-PP2A3 progress (0.00)
Posted by keto on 2004-10-24, 11:32:42 (148.240.108.89)
I've finally managed to shoe-horn in pretty normal OP's for drivers and outputs: 125Vp / 5mA / 1.9Vk and 420Vp / 62mA / 172Vk. Measurements with my DMM lead me to believe that the output AC loop is co .......
337: MagneQuest/Peerless Forum, world's largest inductor? (0.00)
Posted by keto on 2004-10-22, 00:47:15 (148.240.220.30)
Or, world as largest inductor? Move aside BFFC, and this one is spherical! .......
338: MagneQuest/Peerless Forum, They're all... (0.00)
Posted by keto on 2004-10-21, 17:12:02 (148.240.100.208)
...in their labs, building the SETH amps, of course. Nice work on the site, great info, and major clues as to how it all works. Makes me wonder what a (C)LCLC filter must sound like, for PP2A3. Much a .......
339: Bottlehead Forum, ahem...please disregard (nt) (0.00)
Posted by keto on 2004-10-21, 00:10:14 (148.240.220.14)
. .......
340: Bottlehead Forum, Re: balanced foreplay (0.00)
Posted by keto on 2004-10-20, 23:00:32 (148.240.220.14)
How about long-tailed-pair cathode-followers, with the first grid for signal (volume pot) and the second grid grounded? 170Vp-k, 2.5mA and -8.5Vg, with a 5mA C4S sink in each shared cathode? 5V compli .......
341: Tube DIY Asylum, good call (0.00)
Posted by keto on 2004-10-20, 19:52:41 (148.240.220.14)
You mean the 8.2uF and 4uF? Good idea. I've been scheming about strapping the huge 30uF 660VAC motor run cap to the inside of the chassis box, and overlooked your simpler solution. Thanks! --keto ::: .......
342: Tube DIY Asylum, I just can't resist... (0.00)
Posted by keto on 2004-10-20, 18:48:18 (148.240.220.14)
I've asked a lot of questions about power supplies, and a lot of folks would tell me to check PSUD at "duncan amps", which I wouldn't do, because I have a mac, and no virtual PC program. Well, I final .......
343: Bottlehead Forum, Re: Uh, Well . . . (0.00)
Posted by keto on 2004-10-20, 12:14:04 (148.240.220.14)
My answers were pretty short, and based only on the 2A3 pinout, not on the Paraglow circuit. Is there a 90K resistor on the C4S board? Or anywhere else in the circuit? Either of the shorts could be ch .......
344: Bottlehead Forum, Re: HELP!! One Paraglow II is too HOT!! (0.00)
Posted by keto on 2004-10-20, 00:22:25 (148.240.220.14)
Continue with resistance readings and visual inspections, given the symptoms. "...A3 reading on the left (bad) amp of 432VDC..." a short between output grid and plate? "...A4 ...[of]... 148.8VDC on t .......
345: MagneQuest/Peerless Forum, 6BY5 and 76 heaters on same 6.3V secondary? (0.00)
Posted by keto on 2004-10-18, 18:40:10 (148.240.100.253)
The 6BY5 heater draws 1.6A and the 76's, 0.3A. The 6BY5 has 450V max heater negative WRT to cathode. So, I could reference a 6.3v CT at about +50vdc, right? Would power supply noise creep into the 76 .......
346: MagneQuest/Peerless Forum, correction (0.00)
Posted by keto on 2004-10-05, 19:01:04 (148.240.100.158)
If using a power resistor below such a Pimm (BB)CCS, one should allow for FULL bias swing (45V) plus CCS compliance (20V). In this case I will use a 1K 50W resistor, and make sure the output Vk is abo .......
347: MagneQuest/Peerless Forum, a shoehorn and an achilles heel (0.00)
Posted by keto on 2004-10-05, 06:23:29 (148.240.100.158)
I got a couple great tips from Gary Pimm yesterday. First, an explanation of the shared cathode voltage swing in the circuit below, that its 1/2 the voltage gain of the driver. Second, that his batter .......
348: Bottlehead Forum, Re: 6N1P foreplay PT and C4S (0.00)
Posted by keto on 2004-10-04, 22:01:08 (148.240.100.158)
Sounds like a really interesting idea. R1 sets the plate current, and would be .95V/.0068A or 139.7R. I think the C4S has a 300V limit, and R2 sets the current for the LED's, which shunts to ground. H .......
349: MagneQuest/Peerless Forum, ...and I thought I was wasting heat... (0.00)
Posted by keto on 2004-10-03, 16:32:39 (148.240.100.158)
Since the coupling cap value is inversely proportional (I think) to the source impedance, you'll be looking at a pretty big one. See posts for extremely low Z-out parafeed problems, like Gary Pimm's r .......
350: Hi-Rez Highway, Anyone heard of this new "Edirol" unit? (0.00)
Posted by keto on 2004-09-28, 22:04:33 (148.240.100.79)
I realize this may not be truly "high resolution", but was wondering if anyone here knows of this recorder, or of Edirol. Thanks a lot... --keto .......
351: MagneQuest/Peerless Forum, Re: new driver idea for PP2A3 (0.00)
Posted by keto on 2004-09-27, 20:52:38 (148.240.100.79)
The EXO-173 is now installed, as a double-duty monkey choke. 250 + 250 ohm and 125 ohm shared 6N1P cathodes sounded the same, so I took advantage of the pot to null a .05mA imbalance (!) to 8.32mA + 8 .......
352: MagneQuest/Peerless Forum, Re: new driver idea for PP2A3 (0.00)
Posted by keto on 2004-09-26, 21:24:53 (148.240.100.127)
Thanks a million for the comments, PJ. Especially, well, every one of 'em. I think the "monkey on a stick" idea is great in SE, tapping the silenced output filament node. In such a simple PP as mine, .......
353: MagneQuest/Peerless Forum, Re: ah... ha.... (0.00)
Posted by keto on 2004-09-24, 09:23:43 (148.240.100.127)
Thanks for the kind words, Mike, and the bandwidth. The idea to use the VR in the output cathode comes from a post of Doc B's. To get this particular type of circuit really quiet, I think the locking- .......
354: SET Asylum, back to the 845... (0.00)
Posted by keto on 2004-09-23, 07:35:48 (148.240.100.127)
The other thing is, the state of NM has great surplus yards, like the Black Hole in Los Alamos, which might mean relatively inexpensive parts sourcing for such a beast as a really nice 845 amp. --keto .......
355: MagneQuest/Peerless Forum, well, it works... (0.00)
Posted by keto on 2004-09-22, 22:52:44 (148.240.100.127)
The circuit as drawn in the previous post works, with a pair of Dowdy Chokes, each drawing ... 6mA. Ahem. In dialing in this new version, the Vp of each 6N1P half (and 2A3 grid) is 117V minus the volt .......
356: Bottlehead Forum, Re: Update on Foreplay w/ B7-15K output transformers (0.00)
Posted by keto on 2004-09-22, 06:13:46 (148.243.92.123)
The paralleled sections will cause a lower Z source for the parafeed output (cap + B7). I think that means that it will require a larger cap than would a single section, to get the same LF extension. .......
357: SET Asylum, excuse me for butting in... (0.00)
Posted by keto on 2004-09-21, 17:12:31 (148.243.92.123)
...butt, there's a meeting announced here: http://www.audioasylum.com/forums/bottlehead/messages/85808.html which will likely include at least one very cool 2A3 amp. I thought that might be of interes .......
358: MagneQuest/Peerless Forum, new driver idea for PP2A3 (0.00)
Posted by keto on 2004-09-21, 14:36:55 (201.129.128.236)
Hey all, I've been thinkin' about what to do next, and came up with this nearly-parts-on-hand solution. The output is PP2A3 and the CCS is 120mA. The VR would be either two or three OD3's in parallel, .......
359: MagneQuest/Peerless Forum, hang on... (0.00)
Posted by keto on 2004-09-21, 05:30:07 (148.240.220.196)
A 1300 ohm source and a 15K load should be okay, right? .......
360: MagneQuest/Peerless Forum, might be alright (0.00)
Posted by keto on 2004-09-20, 12:35:43 (148.240.220.217)
Thanks for the link. Always comforting to know others have blazed the trail, or maybe simply know who the others are who've done so. Why would you want to run your 2A3's "lower and hotter"? Maybe you' .......
361: MagneQuest/Peerless Forum, Re: so what about parafeed? (0.00)
Posted by keto on 2004-09-20, 06:54:30 (148.240.100.227)
On VS's graph curves, for a parafeed output, I think the ovalness is the choke's inductance, and the nominal angle is the reflected load of the OPT. I think its typically the plate choke that determin .......
362: MagneQuest/Peerless Forum, Jeff Lessard's 2A3 PP (0.00)
Posted by keto on 2004-09-19, 22:36:40 (148.243.92.117)
Nicely done, Jeff! --keto .......
363: Bottlehead Forum, Re: RFII / EMI-FILTERS (0.00)
Posted by keto on 2004-09-17, 09:09:18 (148.243.92.201)
I have a 5 amp version with just the IEC connection (and a 3 amp version with a power switch -- which I haven't used yet). It seems like a really bad idea not to have a fuse between the line in and th .......
364: MagneQuest/Peerless Forum, Re: about that 6c45 (0.00)
Posted by keto on 2004-09-17, 08:33:12 (148.243.92.201)
My experience with the 6C45 is pretty sketchy, and impressions of "edge" in the sound may have been the result of oscillations, RFI, lack of DC heaters, etc. That said, when I built the 6C45 spud, wit .......
365: MagneQuest/Peerless Forum, about that 6c45 (0.00)
Posted by keto on 2004-09-16, 23:23:49 (148.243.92.201)
You're right about the current source reducing driver headroom a little (from site), a reason maybe not to go in that direction. With those adjustable power resistors, have you tried a higher current .......
366: MagneQuest/Peerless Forum, Re: tap jumping - good or evil? (0.00)
Posted by keto on 2004-09-16, 16:12:11 (148.240.108.63)
Hold the phone. Maybe the lack of bass isn't in the output stage. Maybe the 6C45 is a little shrill. For $35 you could try a C4S pair, and set 'em at 5 to 10mA, in place of the plate choke. Or you cou .......
367: SET Asylum, Re: 2a3 vs 45 vs 300b (0.00)
Posted by keto on 2004-09-16, 08:18:25 (148.240.220.101)
Could you modify to a direct-coupled 2A3? I've found that a great circuit sounds stunning with even the least-expensive 2A3's... --keto .......
368: Tube DIY Asylum, Re: GZ34 vs 6BY5 (damper diode)? (0.00)
Posted by keto on 2004-09-15, 12:52:53 (148.240.220.101)
Thats interesting, and not the first time a larger input C has been recommended. I will try this. Thanks! --keto .......
369: Tube DIY Asylum, GZ34 vs 6BY5 (damper diode)? (0.00)
Posted by keto on 2004-09-15, 08:11:52 (148.240.220.101)
Any opinions on using a GZ34 in a full wave, 12uF cap input, 150mA, 350-0-350 supply? I'm using a 6BY5 and a 4uF cap input, and figure I'm pushing its limit, and with a GZ34 could probably end up wit .......
370: MagneQuest/Peerless Forum, VR draw (0.00)
Posted by keto on 2004-09-15, 05:44:04 (148.240.220.101)
Maybe you could try a 3K 10W resistor in place of the choke. The total calculated draw would be 35mA at 195V and 40mA at 180V. With the ECC99 drawing 15mA, that would leave the VR's at 20mA and 25mA. .......
371: MagneQuest/Peerless Forum, Re: Sudden bargains forced my hand... (0.00)
Posted by keto on 2004-09-14, 22:26:41 (148.240.220.101)
Nice graphic, there. If that 60H choke can handle 38mA of DC current, you might try replacing the 3.3uF cap with a pair of OB3's (180V), or 33mA and OB3+OC3 (195V), for Vp's of 147V and 162V (at 15mA) .......
372: Tube DIY Asylum, Re: Pre-RDH, Langford-Smith PP 2A3 designs (0.00)
Posted by keto on 2004-09-13, 19:27:07 (148.240.220.101)
Thanks a million for all the references. I see in the pic above that my operating points are okay. So I guess the AB1 OP's from the 2A3 data sheet are maximized for that class, and wouldn't be for cla .......
373: Tube DIY Asylum, Re: Looking For 45PP Schematics - Help Appreciated (0.00)
Posted by keto on 2004-09-13, 07:15:51 (148.240.220.101)
If you decide on PP45 and get your output transformers first, you might want to try -- or have the builder try -- a version of the direct coupled 27-2A3PP that appears in my "inmate photos". A 2K5 res .......
374: Tube DIY Asylum, for those with RDH, operating points for PP2A3? (0.00)
Posted by keto on 2004-09-12, 21:52:57 (148.240.220.101)
I've noticed on the 2A3 data sheets a recommendation for PP2A3 operating points of 300Vp, -62Vg, 40mA. That's for 10W in AB, with a 5Kct OPT. I understand that in RDH, there is a reference to OP's for .......
375: MagneQuest/Peerless Forum, Re: With the loss of Black Gate what now? (0.00)
Posted by keto on 2004-09-10, 14:18:16 (148.240.220.101)
How about the UNLYTIC brand? --keto .......
376: MagneQuest/Peerless Forum, Re: Plate choke, grid choke and coupling cap (0.00)
Posted by keto on 2004-09-09, 15:47:38 (148.240.220.101)
Have you checked the many reports about parafeed B7 linestage coupling caps, over at the Bottlehead forum? The range for an active loaded triode of Rp about 7K was from 1uF to 20uF, with several votes .......
377: High Efficiency Speaker Asylum, Re: Lambda Acoustics Apollo 15-M? (0.00)
Posted by keto on 2004-09-06, 21:48:04 (148.240.108.57)
The 15M was designed for a 2 cu ft sealed box, with an F3 of 80hz. You might check the archives of the lambdadrivers yahoo forum, for an early post about using the TDM in a much larger box, and possib .......
378: Tube DIY Asylum, Re: Pinging keto............... (0.00)
Posted by keto on 2004-09-05, 23:03:07 (148.240.100.112)
Better ask MQ, since I don't remember exactly what the pair cost.... ---keto .......
379: MagneQuest/Peerless Forum, monkey: CCS+OD3+choke? (0.00)
Posted by keto on 2004-09-05, 06:53:19 (148.240.100.51)
How about this, for a (direct-coupled) "monkeyed" 45? From the filament balance pot, a 36mA CCS and an OD3 shunt to ground. Then, the driver's plate choke load drawing from the OD3's 150V node, and ad .......
380: MagneQuest/Peerless Forum, Thanks, Kurt. (nt) (0.00)
Posted by keto on 2004-09-04, 14:22:02 (148.240.100.51)
. .......
381: MagneQuest/Peerless Forum, Re: How do I stretch a 45 into A2? (0.00)
Posted by keto on 2004-09-02, 15:58:05 (148.240.220.126)
Now that was pretty much right under my nose, wasn't it? Are you still using the 6H30 as a driver? Thanks... --keto .......
382: MagneQuest/Peerless Forum, Re: Cathode follower (0.00)
Posted by keto on 2004-08-31, 15:59:17 (148.243.92.189)
Nice. Trade in 15V of peak to peak driver voltage swing (given 450V PSU cap rating) for 15V of C4S compliance. I could add a 12B4A to the 6N1P driver, or switch to the two halves of a 6DN7. Thanks for .......
383: Tube DIY Asylum, Re: Around 100 ohms (0.00)
Posted by keto on 2004-08-30, 21:36:13 (148.243.92.237)
Thanks for that info. Dropping that figure into the calculation "C = 2L / R-squared" tells me the 470uF cap can stay. Thanks... --keto .......
384: Tube DIY Asylum, Re: Where do you find a 15H 18 ohm choke? (0.00)
Posted by keto on 2004-08-30, 21:31:17 (148.243.92.237)
From Magnequest, the 150mA / 15H model from the BFFC line... --keto .......
385: Tube DIY Asylum, Re: ESR of 6BY5 or similar damper diode? (0.00)
Posted by keto on 2004-08-29, 15:10:55 (148.240.100.204)
I agree. In this case though, I'm using a single LC filter, since I was using a CLC filter at 150mA / 400VDC, first cap of 4uF to 8uF, and this managed to burn out the 6BY5. So, I've backed down to 32 .......
386: Tube DIY Asylum, ESR of 6BY5 or similar damper diode? (0.00)
Posted by keto on 2004-08-29, 11:33:42 (148.240.100.204)
Using the formula C = 2 x L / R-squared, for the appropriate cap value for a choke-input PSU filter, I have the secondary winding of the power xfrmr secondary (155 ohms) and the DCR of the choke (18 o .......
387: Tube DIY Asylum, wow (0.00)
Posted by keto on 2004-08-29, 08:42:12 (148.240.100.24)
That's a cool-looking piece of work. Are the maple plates glued to the sides, and then the component plates screwed-in from below? --keto .......
388: MagneQuest/Peerless Forum, Re: Monkey amps and A2 (0.00)
Posted by keto on 2004-08-28, 09:53:10 (148.240.100.232)
Thanks, DL, and thanks for specifying the 40mA choke. I was thinking that a high-L grid choke dropping the full 56V 45 bias would have the stored energy for A2. But, maybe separate supplies are requir .......
389: MagneQuest/Peerless Forum, forgot to mention... (0.00)
Posted by keto on 2004-08-27, 10:57:30 (148.240.100.232)
The advantage to the bypassed cap in the cathode is that variations in line voltage and individual tube's operating point variations are more forgivingly distributed, so one could probably end up with .......
390: MagneQuest/Peerless Forum, bypassed R vs VR "monkey" cathode (0.00)
Posted by keto on 2004-08-27, 09:58:26 (148.240.100.232)
Since its just a question of time before MQ pulls the plug on my bandwidth (heh, heh), I can't resist quickly mentioning... The VR "monkey" cathode locks in that voltage reference and seems to keep th .......
391: K&K Audio / Lundahl Transformers, good advice (0.00)
Posted by keto on 2004-08-27, 08:25:16 (148.240.100.232)
The strapping together of a breadboard can be an afternoon project, and a funky looking breadboard sounds a lot better than a drawing of the "perfectly resolved" schematic does. Very good advice, ther .......
392: MagneQuest/Peerless Forum, "fringe-science-ey" (0.00)
Posted by keto on 2004-08-26, 22:41:35 (148.240.108.204)
Yep, yep, yep. Been bit by the 45 bug. Roll a pair into that shiny new monster of yours and you'll understand. This is my totally uninformed take on the grid choke. First, I'm ordering a pair of the B .......
393: MagneQuest/Peerless Forum, How do I stretch a 45 into A2? (0.00)
Posted by keto on 2004-08-26, 15:25:19 (148.240.108.204)
I read somewhere that an A2-capable amp might be direct-coupled between stages, so that when the output grid swings positive it has a source of extra current and doesn't shut off at Vg-k = 0. I have a .......
394: Bottlehead Forum, Re: Thanks Keto (0.00)
Posted by keto on 2004-08-24, 20:49:27 (148.240.100.109)
Here's the deal. With a nice 500R Vishay cermet resistor in the cathode of the 6C45 plus a 100R "cathode stopper", I put in a pair of VR diodes and adjusted the 6C45 operating point (7mA C4S) until th .......
395: MagneQuest/Peerless Forum, inspired by your post and pics... (0.00)
Posted by keto on 2004-08-24, 16:53:23 (148.240.220.51)
...I put together a monkeyed 6C45-45. 115Vp / 7mA / -1.5Vg 6C45 driver with C4S load drawing from 172V "45" cathode (and OB3 pair), and 430Vp on the "45". I used the 172V node to keep it all under the .......
396: Bottlehead Forum, works with a 45! (0.00)
Posted by keto on 2004-08-24, 15:58:22 (148.240.220.51)
That posting you mentioned is a real classic. Just this afternoon I got a similar circuit up and running, with a pair of OB3's drawing about 32mA at about 172V, this for the cathode of a directly coup .......
397: MagneQuest/Peerless Forum, Re: monkey amp with MQ and surplus iron (0.00)
Posted by keto on 2004-08-24, 06:21:51 (148.240.100.134)
Very cool work, there. Does the 6C45 draw most of the 2A3's current? I've been scribbling on a schematic for a similar amp, but with 45 outputs, trying to decide between resistor, choke and CCS loadin .......
398: MagneQuest/Peerless Forum, PSU filter from pencil and paper (0.00)
Posted by keto on 2004-08-22, 12:25:29 (148.240.220.140)
With PSUD out of my mac's reach, I've taken the L = R(load) / 1130 and C = 2L / RxR formulas, a "225Vp, -3Vg, 25mA" operating point for the 6C45, and a 12H / 246ohm / 75mA (MQ BCM-8) choke, and come u .......
399: Tube DIY Asylum, Re: Replace 300b grid resistor with choke good idea or.. (0.00)
Posted by keto on 2004-08-22, 00:17:23 (148.240.220.140)
I've used the Magnequest EXO-173 as a simple grid choke, as a 2:1 step-down and as a 1:1+1 phase "splitter". As a simple grid choke, like what you're describing, I think it has an inductance of less t .......
400: MagneQuest/Peerless Forum, PP300B + 6C45 spud... (0.00)
Posted by keto on 2004-08-21, 23:42:50 (148.240.220.140)
Still lost in the world of bi-amping, swapping output amps above and below 300hz. The latest combo adds in a PP300B, recycled from the direct-coupled PP2A3. 15W less dissipation from the shared cathod .......
401: High Efficiency Speaker Asylum, Re: Bravo Magnetar! (monderately long) (0.00)
Posted by keto on 2004-08-18, 06:28:48 (148.240.100.207)
The series idea centers the image with MTM (in theory); in MMT, I think its not such a good idea... --keto .......
402: High Efficiency Speaker Asylum, Re: Bravo Magnetar! (monderately long) (0.00)
Posted by keto on 2004-08-17, 19:52:29 (148.240.100.207)
If you're already tri-amping, you might try the MTM with the two M's in series. This may open a path for the HF, simulating a sharper roll-off of the mids. It may sound lousy, who knows? --keto ::: TO .......
403: MagneQuest/Peerless Forum, update on shunt-reg PSU (0.00)
Posted by keto on 2004-08-16, 12:32:31 (148.240.100.207)
The lower noise floor was just a fluke, but the voltage reference idea does work. Just need another CCS now... --keto .......
404: Tube DIY Asylum, Wirewound (nt) (0.00)
Posted by keto on 2004-08-16, 07:06:06 (148.240.100.207)
. .......
405: Tube DIY Asylum, Re: Cathode Balance Pot- What Type? (0.00)
Posted by keto on 2004-08-16, 05:55:19 (148.240.100.207)
I'm using a 500 ohm Spectrol to balance 6N1P cathodes, balance in the sense that they control the operating points of the directly-coupled PP2A3 output. Only one of the 6N1P halves carries the audio s .......
406: High Efficiency Speaker Asylum, Re: Does anyone have experience with the Marchand XM46 passive line-level filter? (0.00)
Posted by keto on 2004-08-15, 20:34:26 (148.240.100.207)
Yep. It is without noise. I use a pair of 300hz ones, with 1st/2nd order slopes, because that's what my speakers require. The input Z is about 1K, and a CD player seems to drive this with no problem. .......
407: MagneQuest/Peerless Forum, Re: a blocking cap on the hot lead (0.00)
Posted by keto on 2004-08-14, 20:33:59 (148.240.100.207)
Looks like a cool circuit. Only thing I'd recommend is for the input/driver, to take the output from the plate rather than from the "mu" output, since I've read about resonance problems otherwise. Som .......
408: MagneQuest/Peerless Forum, Re: a blocking cap on the hot lead (0.00)
Posted by keto on 2004-08-14, 20:24:23 (148.240.100.207)
Yes, yes ... very cool graphs. And that .47uF was okay for bi-amping the mids and highs, but for full range something between 2uF and 5uF was better, just like those graphs predict. I've been switchin .......
409: MagneQuest/Peerless Forum, Re: one more question (0.00)
Posted by keto on 2004-08-13, 21:35:37 (148.240.100.219)
I'm probably going to get this all wrong..., but the EXO-173 is designed for zero DC current, so I think you'll want a blocking cap between that battery and the EXO-173 and one between the plate of th .......
410: MagneQuest/Peerless Forum, Re: it does work, sort of... (0.00)
Posted by keto on 2004-08-12, 05:52:44 (148.240.220.212)
So far, adding OD3 regulators has sounded better and measured quieter, though I've only used them to regulate single-ended circuits. In this case its a PP output stage (+ the input stage), so I'm look .......
411: MagneQuest/Peerless Forum, both, sort of (0.00)
Posted by keto on 2004-08-11, 20:46:38 (148.240.220.212)
I can't post a new schematic, but in the real amp, its all one power supply... --keto .......
412: Bottlehead Forum, possible new twist on OD3 pair + C4S-loaded driver (0.00)
Posted by keto on 2004-08-11, 20:44:59 (148.240.220.212)
I've just changed something in a direct-coupled PP amp, with a 120mA constant current sink in the output cathode, that might apply to "parafeed" SET's as well, depending on how much of a current draw .......
413: MagneQuest/Peerless Forum, it does work, sort of... (0.00)
Posted by keto on 2004-08-11, 18:51:20 (148.240.220.212)
There's direct-coupling between stages, which is probably unclear in the schematic. This is what I tried. I removed the 5K dropping resistor BEFORE the VR tubes and installed a 10K/10W resistor BETWEE .......
414: High Efficiency Speaker Asylum, Re: Hum (0.00)
Posted by keto on 2004-08-11, 04:14:46 (148.240.220.212)
Jim... How'd you manage that??? Green with envy, --keto .......
415: MagneQuest/Peerless Forum, shunt-regulated PSU idea (0.00)
Posted by keto on 2004-08-10, 22:11:38 (148.240.220.212)
Hi all... Looking for an ever-quieter amp, and reluctant to punch even one more octal hole in the chassis; assuming that a 30mA VR shunt would be enough for a 120mA PP output supply; but worried that .......
416: High Efficiency Speaker Asylum, Re: Tips for commercial tube amp with Oris system? (0.00)
Posted by keto on 2004-08-10, 16:16:56 (148.240.100.141)
It might be worth scouring the archives to find where others have run into solutions the work or don't work, to define what paths you might want to pursue, and then post them here. That way you can na .......
417: Bottlehead Forum, new SW's and grid chokes question (0.00)
Posted by keto on 2004-08-10, 06:04:53 (148.240.100.141)
Hi all... I'm still a little lost at sea WRT understanding "load" and "source". That upcoming SW passive pre seems like a good fit for my system, with a grid choke as "load" for the pre and "source" f .......
418: Bottlehead Forum, Re: Kugelis/Soul Sister PS dropping resistor for 0D3? (0.00)
Posted by keto on 2004-08-09, 06:43:44 (148.240.100.141)
The 350-0-350vac secondary is a 700V winding with a center-tap. For the circuit you've described, the center tap is grounded and a full-wave rectifier (diode pair) converts the AC to DC. If followed b .......
419: Bottlehead Forum, Re: Kugelis/Soul Sister PS dropping resistor for 0D3? (0.00)
Posted by keto on 2004-08-08, 23:24:45 (148.240.220.59)
Subtract 300V from your B+ supply, and divide the difference by .035A (for 25mA OD3-pair draw) or .03A (20mA); for a B+ voltage of about 450V, a 5K 10W resistor will get you close. Hope this helps. -- .......
420: Bottlehead Forum, Re: ...now I'm confused (0.00)
Posted by keto on 2004-08-05, 12:14:08 (148.240.100.202)
The LEDs always draw 2mA. In this case, 275V/2mA=137500 ohms. A 135K 2W or 3 x 45K 1/2W resistors in series. --keto .......
421: Bottlehead Forum, Re: Took B+ up to 265V... (0.00)
Posted by keto on 2004-08-05, 11:17:24 (148.240.100.202)
The R2 ought to be about 135K, and to get a 6mA plate current, try a slightly higher value R1, say 200 ohms. --keto .......
422: Bottlehead Forum, Re: Futzing around with C4S and marginal(?) tubes. (0.00)
Posted by keto on 2004-08-04, 21:39:42 (148.240.100.202)
270V B+ would seem like a good fit for a Vp of 150V to 170V, since you'd be near the middle of the + and - voltage swing. If you stick with the 220V B+, maybe try a 5mA current draw. So, how does it s .......
423: MagneQuest/Peerless Forum, power xfrmrs and other animals... (0.00)
Posted by keto on 2004-08-01, 11:21:28 (148.240.108.59)
Hey, all... ...in the complex soup of my 2A3PP amp circuit, I just substituted back in the EXO-173, as a step-down grid choke, in the place of my trusty "sweet whispers" 100K attenuator -- this, on th .......
424: K&K Audio / Lundahl Transformers, Re: OT... analog to digital? (0.00)
Posted by keto on 2004-07-08, 09:54:44 (148.240.100.207)
Thanks for the tip... --keto .......
425: K&K Audio / Lundahl Transformers, Re: OT... analog to digital? (0.00)
Posted by keto on 2004-07-08, 06:56:09 (148.243.92.128)
Thanks, please keep us informed (musician, brandishing a large fistful of Pesos).... --keto .......
426: MagneQuest/Peerless Forum, Re: new power supply schematic for PP2A3 (0.00)
Posted by keto on 2004-07-07, 17:31:21 (148.243.92.128)
Comparing the 6N1P and 6C45 (both at 8-10mA/150-175Vp) I found the latter added a nice "zing" to the sound, both with the EXO-173 "phase-splitting" and with direct-coupling. My other attempts to use t .......
427: K&K Audio / Lundahl Transformers, OT... analog to digital? (0.00)
Posted by keto on 2004-07-07, 13:24:30 (148.243.92.128)
Hey all, an archive of reel-to-reel tapes here needs to be converted to digital (CD) for easier-access. Any suggestions for a RAKK-level "ADC", in kit or ready-made? Thanks... --keto .......
428: K&K Audio / Lundahl Transformers, basic questions (0.00)
Posted by keto on 2004-07-06, 22:25:17 (148.243.92.128)
My Sony DVD/CD player has a coaxial digital out; would your DAC have a coaxial digital in? Would the digital out of a DAT or a minidisc player also connect to the input of your DAC? Any reason not to .......
429: K&K Audio / Lundahl Transformers, Re: RAKK dac webpage up!! (0.00)
Posted by keto on 2004-07-05, 17:55:00 (148.243.92.128)
Cool, very cool. I think I even understand the options! Can the passve OPT be wired for 1:1, for those of us (hey, where'd everyone go?) with 0.5V input sensitivity? For an output Z of 450R, correcto? .......
430: MagneQuest/Peerless Forum, new power supply schematic for PP2A3 (0.00)
Posted by keto on 2004-07-05, 08:28:24 (148.243.92.128)
Hi all, My direct-coupling to a PP output stage is too hot, so, I think its time to use a pentode based 120mA CCS in the cathode. In re-configuring (two more holes in the chassis ... new power trans a .......
431: Bottlehead Forum, Re: Help Needed on 2A3 DC Heaters (0.00)
Posted by keto on 2004-07-03, 06:21:37 (148.243.92.204)
I just looked for a post by Phil Sieg, for the formulas to fill in the blanks, a la Ronan, and though I didn't find that post (its got to be there...), I came across lots of posts on DC heaters for a .......
432: MagneQuest/Peerless Forum, spud update (0.00)
Posted by keto on 2004-07-02, 10:03:01 (148.243.92.204)
Removing the cathode bypass cap took much of the "edge" off the sound, and the OPT is now a true 5K:8 and sounds good. The Parafeed cap is in the ground leg of the OPT primary, connected to the 6C45 c .......
433: MagneQuest/Peerless Forum, Re: ? about the TFA-204 (0.00)
Posted by keto on 2004-07-01, 20:46:04 (148.243.92.204)
Thanks, Paul. The series feed OPT needing that low impedance, "B+ side to cathode" path, was what I was wondering about. I like this spud idea, but so far I'm not too crazy about the sound. The 5842 i .......
434: MagneQuest/Peerless Forum, ? about the TFA-204 (0.00)
Posted by keto on 2004-07-01, 06:49:48 (148.243.92.204)
After the improvement to the sound from adding a 5R6 across the outputs of the 5K:8 OPT, I'd like to try a real 2K5 plate load for the 6C45 spud, and was wondering about the TFA-204. What about using .......
435: MagneQuest/Peerless Forum, brilliant (0.00)
Posted by keto on 2004-06-30, 18:33:22 (148.243.92.204)
Thanks Docor Spud; I put a 5R6 resistor across the output and like the sound much better. Thanks... --keto .......
436: K&K Audio / Lundahl Transformers, Re: sneak preview of the RAKK dac (0.00)
Posted by keto on 2004-06-30, 08:31:23 (148.243.92.204)
If this board were installed in a stereo preamp chassis, with RCA (or digital?) inputs hard-wired to a selector switch, and supplied with your 12.6V module, would it still require your output transfor .......
437: MagneQuest/Peerless Forum, Thats got to hurt.... (0.00)
Posted by keto on 2004-06-29, 06:17:40 (148.243.92.204)
You've probably got great treatment; here in the south, Aloe Vera is good for burns. Take it easy... --keto .......
438: MagneQuest/Peerless Forum, Re: new-spud (schem) (0.00)
Posted by keto on 2004-06-29, 06:08:25 (148.243.92.204)
Thanks VS.... I forgot to mention the voltage regulator as a power source for this breadboarding, so that otherwise 50mA to 100mA swing is greatly reduced. And, that I am bi-amping at 300Hz, taking an .......
439: MagneQuest/Peerless Forum, new-spud (schem) (0.00)
Posted by keto on 2004-06-28, 14:29:58 (148.243.92.204)
I think it was somewhere in the VALVE CD (which my iMac swallowed and refuses to return or read) where I read that a single LC doesn't really constitute a choke input filter. So I just changed an LCRC .......
440: MagneQuest/Peerless Forum, 6C45 OP's (0.00)
Posted by keto on 2004-06-28, 10:20:57 (148.240.100.122)
Hi Anand. The 6C45 was at 200Vp-k, -1.9Vg-k and 37mA, with OC3+OC3=215V. After reading your question, I installed OB3+OD3= 237V, which resulted in 219Vp-k, -2Vg-k and 43mA. So, pretty close to the pla .......
441: MagneQuest/Peerless Forum, 6N1P parafeed driver (link to schem) (0.00)
Posted by keto on 2004-06-28, 07:34:16 (148.240.100.122)
After reading the cool "blue sky" entries below, I drew up a 6N1P parafeed driver stage (link), using the elements with which I'm familiar. It includes PJ's plate choke and my guess at his operating p .......
442: MagneQuest/Peerless Forum, 6C45 spud amp (pic) (0.00)
Posted by keto on 2004-06-26, 15:10:19 (148.240.108.221)
Curious to hear a "spud class" amp, I put this one together. Parallel PGP8.1s, 6BY5GA, BFFC150, 470uF, 15R, 470uF, 1K8; this then feeds a VR stack of OB3+OC3=195VDC with 0.047uF bypasses and the Dowdy .......
443: MagneQuest/Peerless Forum, Re: Amazing! (0.00)
Posted by keto on 2004-06-26, 06:43:32 (148.240.108.221)
If you send me a jpg, I can add it to my inmate photos and post it here. thomasbaileyjones-at-yahoo-dot-com thanks... --keto .......
444: Tube DIY Asylum, Re: PP topology: Compact vs fi-primer PP (0.00)
Posted by keto on 2004-06-13, 17:55:07 (148.243.92.117)
I've experimented a little with the "compact" idea, with good results. The one you've drawn either lacks CR or CL coupling between stages, or needs to have the second output triode's grid raised to th .......
445: Tube DIY Asylum, 8.2uF/630V, now (0.00)
Posted by keto on 2004-06-12, 20:06:51 (148.240.108.215)
Good to hear 10uF is tolerable. .......
446: Tube DIY Asylum, 2.2uF/630V AXON now in; so far, so good (nt) (0.00)
Posted by keto on 2004-06-12, 15:47:37 (148.240.108.215)
. .......
447: Tube DIY Asylum, excellent, excellent, excellent... (0.00)
Posted by keto on 2004-06-12, 15:04:39 (148.240.108.215)
Thanks. The data sheet I have doesn't mention the possibility. Ahhh, back to soft-start. --keto .......
448: Tube DIY Asylum, damper diodes + cap input filter? (0.00)
Posted by keto on 2004-06-12, 11:41:50 (148.240.108.215)
I had some problems a while back with 6BY5s burning up when I went from choke input to cap input. Anyone have any luck using damper diodes and cap input? Thanks... --keto .......
449: K&K Audio / Lundahl Transformers, confirmed... (0.00)
Posted by keto on 2004-06-11, 12:19:47 (148.240.108.215)
Thanks Lynn, for re-publishing such re-discoveries. Since I'm still trying to get the big picture with my direct-coupled, 6N1P-PP2A3 amps (see "inmate photos", especially the last circuit), and my too .......
450: Tube DIY Asylum, Thanks to all, for the many great suggestions (nt) (0.00)
Posted by keto on 2004-06-10, 23:47:43 (148.240.108.215)
. .......
451: Tube DIY Asylum, Re: Normally ... (0.00)
Posted by keto on 2004-06-09, 20:25:00 (148.240.108.185)
"500 ohms-100uF-15H@30mA(890 ohms)-100uF; you will get 302v with 0.5vRMS of ripple, at 23mA current draw; the choke DCR was measured on an actual Hammond 155J" Sorry...thanks for the suggestion! I got .......
452: Tube DIY Asylum, Re: Normally ... (0.00)
Posted by keto on 2004-06-09, 15:22:32 (148.240.108.185)
Thanks. The circuit will be 15K pot -- 6N1P (5mA/120Vpk/-2.5Vg) -- C4S with approx 250V at "top" (and shunting 2mA) -- 3uF cap -- 15K:500 line output transformer. So, the current draw would be 14mA si .......
453: K&K Audio / Lundahl Transformers, Re: RAKK question... (0.00)
Posted by keto on 2004-06-09, 15:06:52 (148.240.108.185)
Thanks, Dave. I'll look forward to the upcoming presentations, since there's very little I understand about DACs. One thing I do see though, is that my SE-PP amps (see "inmate photos") might be reconf .......
454: K&K Audio / Lundahl Transformers, RAKK question... (0.00)
Posted by keto on 2004-06-09, 06:13:08 (148.240.108.185)
This sounds like a very interesting kit. In my existing system, I have about 0.25Vrms input sensitivity and an input impedance of 15K. Would there be a RAKK configuration appropriate to such an input? .......
455: K&K Audio / Lundahl Transformers, Harmonic Equalizer (0.00)
Posted by keto on 2004-06-09, 06:00:31 (148.240.108.185)
Wow, what a twist. For PP2A3, would it be: output transformer CT -- 20uF -- about 50R -- shared filament CT? Thanks for mentioning all this. --keto .......
456: Tube DIY Asylum, help requested for low current PSU (less than 20mA) (0.00)
Posted by keto on 2004-06-08, 12:46:55 (148.240.108.185)
Without the PSUD2 available (no PC), and not finding the answer yet in Morgan Jones, I find myself still wondering, given a 270-0-270 20mA power transformer, with UF4007 or Cree Full Wave CT rectifier .......
457: Bottlehead Forum, Re: C4S upgrade problems (0.00)
Posted by keto on 2004-06-07, 06:15:06 (148.240.108.185)
I've happily experimented with the C4S kits and found that the calculation for R1 can yield a little more current than predicted, say 11.5mA instead of 9.5mA or 10mA for a 100 ohm R1. I bet installing .......
458: Bottlehead Forum, Re: C4S upgrade problems (0.00)
Posted by keto on 2004-06-06, 22:00:44 (148.240.108.185)
My guess is that the the 238VDC reading is your problem, because it means that the 12AT7 starts swinging voltage and quickly runs into the limit of the C4S. Does the other amp have the same voltages? .......
459: Tube DIY Asylum, difference in making a choke input to cap input choke... (0.00)
Posted by keto on 2004-06-05, 15:25:23 (148.243.92.144)
You might want to check this link... .......
460: Tube DIY Asylum, Re: PP Triodes (0.00)
Posted by keto on 2004-06-04, 15:45:50 (148.240.100.33)
Since there are almost as many recommendations as builders, it'll be enlightening to read about what you come up with. My recommendation would be that you stockpile only the bare essentials, first. If .......
461: MagneQuest/Peerless Forum, speaking of the 15K:500 cobalt B7... (0.00)
Posted by keto on 2004-06-04, 06:40:44 (148.240.100.33)
I've beeen using the primary (alone) of a Magnequest B7 linestage transformer, as a simple grid choke for a low-mu input/driver (27), and liked the sound very much, but am now back with a 100K attenua .......
462: MagneQuest/Peerless Forum, that makes sense, even to me... (0.00)
Posted by keto on 2004-06-03, 21:32:49 (148.240.100.33)
Thanks, D. Taking a step back from the edge, I've taken the "27" pair away and re-installed a single 6N1P, and a 100K attenuator. Almost looks like a normal amp now, without all the stuff topside. Now .......
463: Tube DIY Asylum, Re: PP300B vs SE845 (0.00)
Posted by keto on 2004-06-03, 07:16:16 (148.240.100.33)
The pic shows the "scaffold" 6C45, used to set the grid potential of the second output triode (2A3 or 300B), just like in the lower, dark portion of the "27" circuit at the link below. The grid of the .......
464: Tube DIY Asylum, Re: PP300B vs SE845 (0.00)
Posted by keto on 2004-06-02, 23:19:48 (148.240.100.33)
Your S&B-6C45-PP300B is very close to what I've been happily messing around with lately, posted here and at the new Magnequest site. Would "monkey" refer to a direct coupling? .......
465: Bottlehead Forum, Re: Could Paramour be rebuilt into a poor man's eXcite using BCP-15 and MQs new RH-PF 5K OT? (0.00)
Posted by keto on 2004-06-02, 23:09:18 (148.240.100.33)
How about a 12AU7 at 95Vp-k, 2.5mA, -3Vg, and a 4K/10W cathode resistor and derated cathode bypass cap for the DHT? Might be good for one full watt... .......
466: Bottlehead Forum, Re: Can we discuss these proposed Foreplay lay-outs??? (0.00)
Posted by keto on 2004-06-02, 16:54:24 (148.240.100.33)
If I understand the new version, the toggles switch between sources? If they were placed on the back panel, you'd have shorter connections. An extension on the volume pot would also help, in the same .......
467: MagneQuest/Peerless Forum, grid chokes, again (ping...MQ) (0.00)
Posted by keto on 2004-06-02, 08:04:31 (148.240.100.33)
Hey Mike, Thanks for those grid choke hints (over and over) a while back. I now have one amp set up EXO173 (floating center tap) 27SE (+ 27 "scaffold"), direct-coupled to PP2A3/S-240; and the other as .......
468: Tube DIY Asylum, Re: Spec and operating points (0.00)
Posted by keto on 2004-05-31, 06:47:12 (148.240.220.238)
I've used the Bottlehead "C4S" kit (three pairs of them), over and over again, adjusting for a B+ of 200-300V and current of 2-10mA, and it's always sounded good to my ears. That would be a relatively .......
469: Tube DIY Asylum, Re: heater current and HV current... (0.00)
Posted by keto on 2004-05-30, 20:53:58 (148.240.220.238)
See Paul Joppa's post, above! And, what type is your (driver) plate load? Resistor, Inductor, CCS? Available B+ voltage? --keto .......
470: Tube DIY Asylum, Re: 845 Hum pot connections (0.00)
Posted by keto on 2004-05-30, 20:15:40 (148.240.220.238)
Hey, Douglas. Not saying this wont work, but in my experience, trying to null the filament noise in a PP output hasn't done the job. Okay, so my attempt only amounted to a 100-ohm pot connecting pairs .......
471: Tube DIY Asylum, heater current and HV current... (0.00)
Posted by keto on 2004-05-30, 12:51:53 (148.240.220.238)
Careful, there. All of the tubes mentioned will draw more 6.3V heater current. The stock transformer might not be specified for such a change, or the increased B+ current draw. --keto .......
472: Tube DIY Asylum, Re: sweet working spot for 12AU7 and 6CG7 (0.00)
Posted by keto on 2004-05-30, 09:52:59 (148.240.100.218)
Brief 6cg7 and 6sn7 experience: as an input/driver (for PP2A3) the 6cg7 sounded better at 10mA than at 5mA, and the 6sn7 sounded warmer than the 6cg7, at the same OPs. The 6cg7 shares the same pinout .......
473: Tube DIY Asylum, Re: mu-under-9 double-triode 9-pin suggestions? (0.00)
Posted by keto on 2004-05-30, 08:17:41 (148.240.100.218)
Thanks for the 2C50 lead. 10mA signal + 10mA "shadow" + 20mA VR shunt is the max for my PSU. With the 27s, 4.5mA + 4.5mA + 20mA works well. The 6N1P and 6C45 both sounded great within this limit, but .......
474: MagneQuest/Peerless Forum, update... (0.00)
Posted by keto on 2004-05-29, 19:11:46 (148.240.100.218)
In this circuit, my tired but trusty Valve Art 2A3 pair are better than the 45s or TJ300Bs. Using a pair of the 20uF/600V sprague/atom electrolytic caps (from Ned's triode electronics), I've raised B+ .......
475: Tube DIY Asylum, mu-under-9 double-triode 9-pin suggestions? (0.00)
Posted by keto on 2004-05-29, 17:56:45 (148.240.100.218)
Wondering if there might be something like a lower-current (10mA) variant of the 12B4A, but with two identical sections and a similar amplication factor. Something like a 12AU7, but with half the gain .......
476: High Efficiency Speaker Asylum, Re: Help with passive crossover from 300hz edgar horn to 15" direct radiator? (0.00)
Posted by keto on 2004-05-27, 16:54:11 (148.240.108.224)
I use an 8mH choke in series and a 47uF cap in parallel with the TDM, a 2nd order 300hz low pass that sounds pretty good. --keto .......
477: MagneQuest/Peerless Forum, Re: volt-sec weights in on the ultra-compact (0.00)
Posted by keto on 2004-05-25, 21:28:02 (148.240.108.162)
Thanks VS, for weighing in, and Mike for the posting. My favorite chart is the CCS and resistive cathode bias in the 2A3 pair. I think it indicates the asymmetry of the compact when the phase inversio .......
478: Tube DIY Asylum, TFE? (0.00)
Posted by keto on 2004-05-22, 22:34:28 (148.240.108.141)
No answer here; just more questions. What's a TFE coax (a length of shielded cable?) and in what form would it produce a 2A3's input capacitance? So, you've heard results with the "neutralizing stuff" .......
479: MagneQuest/Peerless Forum, grid choke input (0.00)
Posted by keto on 2004-05-22, 08:50:26 (148.240.108.141)
Thats exactly what I was wondering. Thanks. Nice lead material on the EXO173, Dowdy and BFFC, BTW. --keto .......
480: Tube DIY Asylum, Re: Phase Inversion for P-P 2A3's (0.00)
Posted by keto on 2004-05-20, 11:53:08 (148.240.100.38)
I've got one amp set up like this schematic (except now with a more appropriate grid choke) and one using a 6C45, 12uF Auricap and the Magnequest EXO-173 for phase inversion. They're both great and qu .......
481: Tube DIY Asylum, Re: Got an idea for a interstage tranny-coupled 2A3, read & comment? (long) (0.00)
Posted by keto on 2004-05-19, 21:36:26 (148.240.100.38)
I would agree with rethinking the IT and overall gain, and say if you can't direct-couple between stages, maybe think of a cap and grid choke coupling between stages. I'm listening to a 27 (no attenua .......
482: MagneQuest/Peerless Forum, Re: My parafeed 300B prototype and questions (0.00)
Posted by keto on 2004-05-19, 18:55:50 (148.240.100.38)
Its my understanding that parallel caps provide the sum of the two capacitances and half the voltage rating. If so, those 4 20uF caps will be equivalent to a single 80uF/165VAC cap. Maybe stack them s .......
483: MagneQuest/Peerless Forum, ? about grid chokes (0.00)
Posted by keto on 2004-05-19, 17:43:39 (148.240.100.38)
Hey Mike and all, my experiments with lower and lower mu drivers has lead to a new circuit inevitability. The mu=9 27 (+PP2A3) is still just a little hot for most CDs, but has opened the door to liste .......
484: MagneQuest/Peerless Forum, the Harry F. Olson book... (0.00)
Posted by keto on 2004-05-19, 17:07:49 (148.240.100.38)
... and others of similar interest have been re-released by Dover Publications (good and inexpensive). Applying his 1952 analysis to Orpheus' lyre, you might find that the gut strung to that tortoise .......
485: MagneQuest/Peerless Forum, "three magic building blocks" (0.00)
Posted by keto on 2004-05-18, 20:14:21 (148.240.100.38)
I like that concept, maybe translated as energy "stored" (capacitance), "expended" (resistance) or "channeled" (inductance). In his "Musical Engineering" (1952), Harry Olson compares acoustical and el .......
486: Bottlehead Forum, Re: String players? (ears perk up here...) (0.00)
Posted by keto on 2004-05-18, 15:35:23 (148.240.100.38)
Yeah, you're right; Heifetz was Heifetz. BTW, do you know the "Miracle Makers" CD, with Elmar Oliveira playing Strads and Guarneris? It was produced by Bein and Fushi of Chicago. Its a great disc that .......
487: Bottlehead Forum, Re: String players? (ears perk up here...) (0.00)
Posted by keto on 2004-05-18, 13:02:34 (148.240.100.38)
The first vinyl I listened to throught Seduction kit I built in December were the Guarneri's first recordings of the Late Beethoven Quartets. Even on a modest Dual/Ortofon set up, it was many times be .......
488: MagneQuest/Peerless Forum, 27-PP45 (0.00)
Posted by keto on 2004-05-17, 21:11:42 (148.240.100.38)
Interested in trying cooler than 60mA operating points, like the ones on the WE 300B info page (see link), I installed a 2.5K unbypassed resistor in the direct-coupled circuit, pictured in the previou .......
489: MagneQuest/Peerless Forum, Re: I have some 5842's and 6c45...but am afraid (0.00)
Posted by keto on 2004-05-16, 17:17:20 (148.240.100.153)
I'm using the 6C45-12uF-EXO173 right now, (10mA, 150Vp, -2Vg) and its my favorite sounding driver to date, having tried just a 12B4A 6BZ7, 6CG7 and 6N1P, besides. If you're using the EXO173, I think t .......
490: MagneQuest/Peerless Forum, yet another comment on filament windings (0.00)
Posted by keto on 2004-05-15, 22:16:05 (148.240.100.153)
While I can't completely separate all the factors involved, its pretty clear that with a CCS or bypassed resistor in the output cathode, a common filament winding sounds and measures best. I also thin .......
491: MagneQuest/Peerless Forum, 27-PP2A3-S245 (pic) (0.00)
Posted by keto on 2004-05-15, 08:10:11 (148.240.108.213)
While direct-coupling a PP output has to be one of the worst things for global warming, it does produce a couple watts of interesting sound. The above is my shopworn circuit, now with a SE 27 directly .......
492: MagneQuest/Peerless Forum, Re: 14-05-2004 version (0.00)
Posted by keto on 2004-05-14, 15:02:46 (148.243.92.99)
I think you'll want to connect the bottom of the CCS (rather than its top) to the ECC99 cathode, and I agree with the comment about maybe doing away with the 40uF-position cap. In some of Lynn Olson's .......
493: MagneQuest/Peerless Forum, Re: The 100k is going !! ;-) (0.00)
Posted by keto on 2004-05-14, 08:32:45 (148.240.108.108)
I'm using the 6SN7 (mu=20) at the moment, with just the "grid-choke-lite" and find that almost all CD recordings will drive the amps into clipping, so my next experiment will be with the 27 (mu=9). If .......
494: MagneQuest/Peerless Forum, general loud applause.... (0.00)
Posted by keto on 2004-05-13, 15:06:18 (148.240.220.49)
Looks great! Just a couple suggestions. The 100K may be a little large. You might try a lower value, say above 10K. Allen Wright suggested to me 1K, and he builds a lot of amps. You want that R to be .......
495: Tube DIY Asylum, hmmm... (0.00)
Posted by keto on 2004-05-12, 14:34:52 (148.243.92.164)
I've been staring at the LTP and trying to understand its function. In terms of the input capacitance, I was looking at C g1-k1 and C g1-k2 and seeing them as equal and in series, and as such, half of .......
496: Tube DIY Asylum, Sorry...LTP = long-tailed pair (nt) (0.00)
Posted by keto on 2004-05-12, 07:01:45 (148.243.92.164)
Shared cathode and second grid grounded. At least thats how I understand it. Like the output in this link... .......
497: Tube DIY Asylum, Question about input capacitance(s) in an LTP circuit... (0.00)
Posted by keto on 2004-05-12, 06:16:06 (148.243.92.164)
In an LTP, would the input capacitance of the first and second tube be equal and in series with one another, presenting half of the original value? I find it an interesting sounding circuit and am try .......
498: MagneQuest/Peerless Forum, Re: EXO-173 progress (0.00)
Posted by keto on 2004-05-11, 15:53:44 (148.243.92.164)
Hey, Douglas. The 6.8uFs ground to the output cathode? and the 50K ct to earth? Revisiting my own EXO-173, the WW pot in the shared, PP2A3 cathode is a very bad idea, methinks. At least it sounded tha .......
499: MagneQuest/Peerless Forum, another 6SN7 variant (0.00)
Posted by keto on 2004-05-11, 14:18:43 (148.243.92.164)
Buenas tardes, all... The idea above generated some sort of resonating humm, which I couldn't figure out, so I changed things around to a single-ended 6SN7 direct-coupled to the "compact" PP2A3, a sim .......
500: MagneQuest/Peerless Forum, compact Dowdy/6SN7 direct-coupled to PP2A3 (0.00)
Posted by keto on 2004-05-08, 19:46:26 (148.240.100.162)
What's that venerable name doing in the title?? V2nd was kind enough to safety-check my direct-coupled PP2A3 amp schematic and also included a suggestion for a PP input instead of the SE one I'd been .......
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