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1: High Efficiency Speaker Asylum, Huge thanks to Steve Schell (0.00)
Posted by jub_jugs on 2009-11-28, 03:27:57 (81.100.55.32)
I'd been hunting for a pair of RCA 1428b for a while. Eventually, I decided to bite the bullet and a while back, I acquired a pair of RCA MI-1428b drivers from eBay. They were in pretty sorry conditio .......
2: Tube DIY Asylum, RE: LCR Phono (0.00)
Posted by jub_jugs on 2009-03-14, 17:18:09 (81.100.55.32)
Tango did do a module with just the inductors... .......
3: Tube DIY Asylum, RE: KPOTD (0.00)
Posted by jub_jugs on 2008-11-22, 12:28:52 (81.100.61.237)
An insurance claim waiting to happen. ;-) .......
4: DIY HiFi Forum, RE: Silk 10k LCR RIAA (0.00)
Posted by jub_jugs on 2008-11-17, 17:27:43 (81.100.61.237)
ah... thanks Brian! .......
5: DIY HiFi Forum, Silk 10k LCR RIAA (0.00)
Posted by jub_jugs on 2008-11-16, 15:27:04 (81.100.61.237)
Hi, I was wondering if the Silk 10k LCR RIAA modules are ok to DC couple? I saw a previous posting that the 600 ones are ok, but I have a couple of questions - if they are, what's the max. voltage all .......
6: Tube DIY Asylum, RE: Might have a point there (0.00)
Posted by jub_jugs on 2008-10-10, 11:36:23 (81.100.61.237)
"I also have a DHT in the input - the 1J6G. I have put the shared cathode resistor to one side of the filaments in this case - pin 7 marked minus. should I put a couple of resistors across the filamen .......
7: Tube DIY Asylum, RE: Separate power supplies for each tube in push pull? (0.00)
Posted by jub_jugs on 2008-10-10, 10:33:08 (81.100.61.237)
I suspect it would be bad for your PSRR. .......
8: Tubes Asylum, RE: Low price KT88s (0.00)
Posted by jub_jugs on 2008-08-13, 05:05:54 (82.108.232.66)
They look exactly like the Teslas a friend and I tried and really didn't like. .......
9: Tube DIY Asylum, RE: If that's good how about 10Y (0.00)
Posted by jub_jugs on 2008-05-19, 03:46:32 (82.108.232.66)
The amp I'm building is 26 into 10Y ;-) .......
10: Tube DIY Asylum, Excellent, thanks John! (nt) (0.00)
Posted by jub_jugs on 2008-05-08, 16:10:09 (81.100.50.204)
. .......
11: Tube DIY Asylum, Output impedance (0.00)
Posted by jub_jugs on 2008-05-07, 12:04:12 (81.100.50.204)
Hi John, What sort of output impedance do you get? Cheers, Pete .......
12: SET Asylum, RE: 10Y - it's psychodelic! (0.00)
Posted by jub_jugs on 2008-04-21, 13:52:17 (81.100.57.51)
Just building the replacement turntable - it will be a Technics SP10 in a custom plinth and I've just bought an SME 312S arm (much better sounding than the V) to hold an Audio Note IO cartridge :-) :: .......
13: SET Asylum, RE: Op point for the 10Y? (0.00)
Posted by jub_jugs on 2008-04-21, 13:50:42 (81.100.57.51)
That's the one. :-) .......
14: Tube DIY Asylum, RE: Inverted Interstage transformers and Class A2 (0.00)
Posted by jub_jugs on 2008-04-15, 07:18:43 (12.144.49.15)
I think you're right about it being a case of every little bit helps. The driving impedance goes down from ~750 Ohms to about ~400 which I guess will make a bit of difference. I think current offset i .......
15: Tube DIY Asylum, RE: Inverted Interstage transformers and Class A2 (0.00)
Posted by jub_jugs on 2008-04-15, 07:12:56 (81.100.57.51)
A couple of 10672 (the ones I have) went on eBay a few weeks ago for about 160 Euros. I don't think anyone knew what they were.... .......
16: Tube DIY Asylum, RE: Inverted Interstage transformers and Class A2 (0.00)
Posted by jub_jugs on 2008-04-15, 07:11:56 (12.144.49.15)
I think you're right about it being a case of every little bit helps. The driving impedance goes down from ~750 Ohms to about ~400 which I guess will make a bit of difference. I think current offset i .......
17: Tube DIY Asylum, RE: Inverted Interstage transformers and Class A2 (0.00)
Posted by jub_jugs on 2008-04-15, 06:21:12 (12.144.49.15)
Mine are 1:0.8 I suspect it's simply to get a lower drive impedance, while keeping as much voltage swing as possible. At 1:0.8 the voltage swing is just about enough to clip the driver (6EM7 into 801A .......
18: Tube DIY Asylum, RE: Inverted Interstage transformers and Class A2 (0.00)
Posted by jub_jugs on 2008-04-15, 03:05:17 (12.144.49.15)
I tried this with Lundahls and all I got was a very rolled off sound. Depending on the wirng geometry, some transformers don't like being connected inverted. .......
19: SET Asylum, RE: 10Y - it's psychodelic! (0.00)
Posted by jub_jugs on 2008-04-11, 10:01:03 (81.100.57.51)
Hi Brian, it's the Shishido cct. - 6EM7 into 0.8:1 step down. .......
20: SET Asylum, RE: 10Y - it's psychodelic! (0.00)
Posted by jub_jugs on 2008-04-10, 15:26:41 (81.100.57.51)
I find the 801 is very nice in class A2. .......
21: Tube DIY Asylum, RE: The 5676 - no Lifetime Achievement Award! (0.00)
Posted by jub_jugs on 2007-11-26, 08:19:25 (82.108.232.66)
Indeed. Bugger :-( Back to the drawing board! .......
22: Tube DIY Asylum, RE: OPT for push-pull 10y tubes (0.00)
Posted by jub_jugs on 2007-11-26, 03:30:49 (12.144.49.15)
Yep, 801A in A2 SE works *very* nicely :-) .......
23: SET Asylum, RE: Is ANYTHING as good as a 45? (0.00)
Posted by jub_jugs on 2007-10-02, 11:00:44 (81.100.57.51)
I concur. 183/483 are a step up. Must be the bug filament power. .......
24: Tube DIY Asylum, RE: Choke values (0.00)
Posted by jub_jugs on 2007-08-12, 10:14:15 (81.100.57.51)
Hi Andy, Chokes *would* be the best way to go - that's the direction I'm heading in. As "." has suggested - can you fit an outboard choke input supply? If it has to fit on the chassis, then yeah, you .......
25: Tube DIY Asylum, RE: Choke values (0.00)
Posted by jub_jugs on 2007-08-12, 03:59:08 (81.100.57.51)
You mean connect the two connections of the CM chokes in series? No, that won't work. You need a regular choke. Cheers, Pete .......
26: Tube DIY Asylum, RE: Reversing the polarity of a dc filament supply for 300B anyone else have problems? (0.00)
Posted by jub_jugs on 2007-06-19, 10:21:33 (82.108.232.66)
It seems that Svetlanas are prone to this (noisy on startup). A friend has some and they do it. They're not known for their reliability. .......
27: SET Asylum, Re: Yep, love the 46... (0.00)
Posted by jub_jugs on 2007-04-04, 05:15:15 (82.108.232.66)
Usually I run at 25mA/250V or so. For heaters, I would definitely go with DC filaments for use as a driver. Some sort of CCS type supply, e.g. Tentlabs/Ronan-reg., etc. is best. Preferrably, choke loa .......
28: SET Asylum, Yep, love the 46... (0.00)
Posted by jub_jugs on 2007-04-02, 09:56:55 (62.252.0.6)
...what can I say, I think it's great! .......
29: Tube DIY Asylum, Re: How do I lower the gain of a 6SN7-based SET? Is there a family tube with lower gain... (0.00)
Posted by jub_jugs on 2007-03-12, 02:16:28 (62.252.0.6)
The problem with throwing away gain, is that it increases noise. It's best to have a sensible gain-structure in place to start with. This of course requires significant changes to the amp. If this isn .......
30: Tube DIY Asylum, Re: Catch 22 with a 45 tube (0.00)
Posted by jub_jugs on 2007-03-10, 08:31:12 (62.252.0.6)
Use two 0.047, one either side. Cheers, Pete .......
31: Tube DIY Asylum, Re: Kurt must know (0.00)
Posted by jub_jugs on 2007-03-10, 04:41:38 (62.252.0.6)
I built a PP KT-88 amp using 1J6G as input and driver. Mu is indeed *about* 14, but it' hard to be accurate as there's no class-A data about. I just extrapolated the class-B data. Cheers, Pete ::: TOP .......
32: ANK AudioKits Forum, Re: Black Gate in kit1 - help me choose which (0.00)
Posted by jub_jugs on 2007-02-15, 02:39:32 (82.108.232.66)
No, it's not correct. That's the purpose of the cathode bypass cap - to STOP the cathode voltage changing with swing. Cheers, Pete .......
33: Tube DIY Asylum, Whatever... (0.00)
Posted by jub_jugs on 2007-02-06, 12:02:23 (62.252.0.6)
. .......
34: Tube DIY Asylum, sadly, it seesm you don't. (0.00)
Posted by jub_jugs on 2007-02-06, 09:44:50 (82.108.232.66)
Now stop posting crap before someone tries one of your ideas and gets hurt. .......
35: Tubes Asylum, Re: Take the 12AU7s... (0.00)
Posted by jub_jugs on 2006-11-30, 08:20:40 (217.171.96.222)
The vice sounds like a nice idea ;-) Give time to savour the punishment. I'm afraid I can offer no advice on 12AU7s as I gave up on the a long time ago. I was just trying to be a smartarse! Cheers. :: .......
36: Tubes Asylum, Take the 12AU7s... (0.00)
Posted by jub_jugs on 2006-11-30, 07:50:55 (217.171.96.222)
...smash them with a big hammer and start using a decent tube.... ;-) .......
37: Tube DIY Asylum, Re: So what's the current choice of TVCs? (0.00)
Posted by jub_jugs on 2006-11-18, 01:40:10 (62.252.0.6)
Agree 100%. It was one one of the biggest upgrades I ever made to my system. .......
38: Tube DIY Asylum, ssssh ;-) (nt) (0.00)
Posted by jub_jugs on 2006-11-14, 09:28:19 (82.108.232.66)
. .......
39: Tube DIY Asylum, Re: SE DHT monoblock questions (0.00)
Posted by jub_jugs on 2006-11-03, 05:21:04 (82.108.232.66)
Hi, You can't connect 6SN7 up so that you use opposite sections - there is only one heater connection and so both sides will be heated. If you only connect one half of so that it draws current, you ri .......
40: Tube DIY Asylum, Re: What do you use as an OT? /n (0.00)
Posted by jub_jugs on 2006-10-30, 12:12:29 (62.252.0.6)
Hi Fred, You're welcome. Are you planning a project using the 801A? What do you have in mind? Cheers, Pete .......
41: Tube DIY Asylum, Re: What do you use as an OT? /n (0.00)
Posted by jub_jugs on 2006-10-29, 16:48:36 (62.252.0.6)
Hi Fred, Not sue how to describe the 801s really, :-/ I find it pretty well balanced to be honest. I originally had Russian teflon caps and they sounded very clean, so I put Jupiters in, which complet .......
42: Tube DIY Asylum, Re: What do you use as an OT? /n (0.00)
Posted by jub_jugs on 2006-10-29, 00:56:51 (81.155.215.192)
They're a custom Tango model, #10634 which are 1.5K. They also have a cathode feedback winding, which is used to lower the output impedance in A2. They also use a custom wound interstage (#10672) whic .......
43: Tube DIY Asylum, No, but I use it in class A2. (0.00)
Posted by jub_jugs on 2006-10-28, 08:29:39 (81.155.215.192)
Ia=90mA, Va=220V, Vg=+24V. That will get you about 7W. See Nobu Shishido's work. .......
44: Tubes Asylum, Well they sure weren't factory sealed by the time he took the photos. (nt) (0.00)
Posted by jub_jugs on 2006-10-21, 02:08:51 (62.252.0.6)
, .......
45: Tubes Asylum, hehe... and paint it black ;-) (nt) (0.00)
Posted by jub_jugs on 2006-10-20, 13:34:55 (62.252.0.6)
. .......
46: Tubes Asylum, Re: Damn! (0.00)
Posted by jub_jugs on 2006-10-20, 06:33:32 (162.13.51.24)
But of course when you try to sell 'em , they'll go for $12.99, and the buyer will whine about the shipping cost. ;-) .......
47: Tubes Asylum, Re: Are people completely stupid?!! (0.00)
Posted by jub_jugs on 2006-10-20, 06:19:59 (162.13.51.24)
ePay :-( .......
48: Tube DIY Asylum, Re: ECC99 (0.00)
Posted by jub_jugs on 2006-09-28, 02:14:44 (162.13.51.24)
You make that sound like a bad thing? ;-) .......
49: Tube DIY Asylum, BTW (0.00)
Posted by jub_jugs on 2006-09-20, 09:25:03 (162.13.51.24)
I checked against a Mk 4 and it's exactly the same. .......
50: Tube DIY Asylum, My AVO Mk 3 is the same... (0.00)
Posted by jub_jugs on 2006-09-20, 09:24:21 (162.13.51.24)
Things like 2A3s (and generally DHTs) always test very low. However, the data book usually publishes alternative settings for Vg=0V, Va=100V, (or Va=90V for smaller tubes) and when I test using these .......
51: Tubes Asylum, Re: Eimac 304TL (0.00)
Posted by jub_jugs on 2006-09-16, 14:12:32 (81.154.19.166)
Thoriated tugsten filaments are notoriously brittle, I've had several tubes with such filaments arrive with them rattling around in the bottom of the tube :-( In addition, they work-harden with use, s .......
52: Tube DIY Asylum, I wouldn't call C3M rare... (0.00)
Posted by jub_jugs on 2006-09-15, 09:04:56 (162.13.51.24)
...they're commonly available on eBay and in Europe. Jacmusic has 90 or so listed, BTW. Cheers, Pete .......
53: Tube DIY Asylum, Yes they do degrade. (0.00)
Posted by jub_jugs on 2006-09-15, 09:00:47 (162.13.51.24)
At the very least, they will need re-forming as the dielectric layer only forms and is maintained in the presence of a polarising voltage. In addition, because no seal is perfect, the electrolyte tend .......
54: Tube DIY Asylum, Re: Why a pre-amp makes a difference (0.00)
Posted by jub_jugs on 2006-09-15, 08:56:13 (162.13.51.24)
Hi, that was exactly my point. The implication of you comment: "But 10 watts driving a pair of 89 db speakers in room gives 99 db. And that is with *no preamp." was that you could somehow by adding a .......
55: Tube DIY Asylum, Whay would a pre-amp make a difference? (0.00)
Posted by jub_jugs on 2006-09-15, 04:29:01 (162.13.51.24)
10 Watts is 10 Watts. .......
56: Tube DIY Asylum, Sae think, but much cheaper. (0.00)
Posted by jub_jugs on 2006-09-09, 15:22:41 (62.252.0.6)
ok, so it's a different value, but the other one's a rip-off. .......
57: Tubes Asylum, Do you mean 1633? (0.00)
Posted by jub_jugs on 2006-09-08, 02:43:40 (162.13.51.24)
If so, then no, they are NOT a direct substitute. Electrically, they look quite similar except for the filament voltage (25V for 1633, 6.3V for 6SN7), so you could use them as long as you change the f .......
58: Tubes Asylum, Yes... (0.00)
Posted by jub_jugs on 2006-09-07, 07:20:38 (162.13.51.24)
... I have some AWV 6SN7 and they're all pretty good. Cheers, Pete .......
59: Tube DIY Asylum, Re: What about DHTs in first 2 stages? (0.00)
Posted by jub_jugs on 2006-09-01, 14:54:24 (62.252.0.6)
Hey Andy, DHT or IDHT makes no difference to direct coupling. you can just use a larger plate resitor on the first stage or use a dropping resistor. To drive a 300B or 2A3 properly, you need at least .......
60: Tube DIY Asylum, Another disadvantage... (0.00)
Posted by jub_jugs on 2006-09-01, 07:26:05 (62.252.0.6)
...is that if the tube in the first stage fails, the next stage loses bias and stands a good chance of destroying that tube also. Cheers, Pete .......
61: Tube DIY Asylum, Eagle. (0.00)
Posted by jub_jugs on 2006-08-25, 03:45:53 (162.13.51.24)
Excellent & free. You need to download the tube libraries. .......
62: SET Asylum, Re: 26 tube (0.00)
Posted by jub_jugs on 2006-08-22, 06:46:04 (162.13.51.24)
I can imagine the clarity with a dc filament supply and I know that the 26 really is a hummer that needs to be worked with. But ac breathes life into the sound, and true substance is suspect without i .......
63: Critic's Corner, Case insensitive (0.00)
Posted by jub_jugs on 2006-08-21, 08:52:45 (162.13.51.24)
SMTP is not case-sensitive, FWIW. Cheers, Pete .......
64: Tube DIY Asylum, Re: They've only had 1 valve change.. {nt} (0.00)
Posted by jub_jugs on 2006-08-17, 04:28:38 (162.13.51.24)
Could be dirty pins on the tubes, as mentioned above. If the sockets are not the best, it could be that the contacts have lost their tension. Cheers, Pete .......
65: Tube DIY Asylum, It depends how good the original sockets were... (0.00)
Posted by jub_jugs on 2006-08-17, 01:51:13 (162.13.51.24)
...and how much wear & tear they've had. Cheers, Pete .......
66: Tubes Asylum, Re: What kind of noise? (0.00)
Posted by jub_jugs on 2006-08-16, 12:28:54 (62.252.0.6)
I just looked up the power amp spec. and it says 700mV is required for full output. As most CD players have a peak output of 2V plus, I would say that there is no need for a pre-amp and a good passive .......
67: Tubes Asylum, Re: What kind of noise? (0.00)
Posted by jub_jugs on 2006-08-16, 10:40:52 (162.13.51.24)
It's really hard to say, tubes can produce noise, but it shouldn't be excessive. Are your speaker very sensitive? Do you have a schematic for the pre-amp? It could be that you have too much gain in th .......
68: Tubes Asylum, What kind of noise? (0.00)
Posted by jub_jugs on 2006-08-16, 10:31:07 (162.13.51.24)
Hum? Hiss? The causes will vary depeding on the type of noise. Cheers, Pete .......
69: Tube DIY Asylum, Re: Dumb question...bear with me (0.00)
Posted by jub_jugs on 2006-08-16, 05:26:03 (162.13.51.24)
Hi Russ, By "CCS heating" I meant current regulation in the heater supply, of course this only applies for DC heating, but for a pre-amp/line-stage I think AC is too noisy anyway. We've tried (so far) .......
70: SET Asylum, As long as the filamnet supply can handle it. (0.00)
Posted by jub_jugs on 2006-08-16, 04:41:23 (162.13.51.24)
They have nearly twice the current draw. .......
71: SET Asylum, Do you have access to a tube tester? (0.00)
Posted by jub_jugs on 2006-08-16, 01:56:11 (162.13.51.24)
you should get them tested to make sure they're really dead, it would be a shame to write them off just yet. Sadly, there doesn't seem to be such a thing as cheap 45s these days. :-( Although I guess .......
72: Tubes Asylum, This is normal... (0.00)
Posted by jub_jugs on 2006-08-16, 01:50:47 (162.13.51.24)
...cold heaters have a much lower resistance than hot, so will initially draw a high current. I shouldn't hurt tube life. If you are worried, you can use some sort of soft-start mechanism, or current- .......
73: SET Asylum, Or russian teflons? (0.00)
Posted by jub_jugs on 2006-08-15, 13:41:45 (62.252.0.6)
if you haven't heard them, you should. They are very good. And very cheap. Cheers, pete .......
74: SET Asylum, Re: Did I kill my tubes? (0.00)
Posted by jub_jugs on 2006-08-15, 13:27:57 (62.252.0.6)
Are you 100% sure the connection is correct now? If it is, it sounds like you've destroyed the grids :-( I suspect that with the grid connected as plate, it probably drew a lot of current and melted t .......
75: Tube DIY Asylum, DHT (0.00)
Posted by jub_jugs on 2006-08-15, 09:28:04 (162.13.51.24)
DHTs do something very special, not sure how to describe it, it just sounds more real. I went away from it after trying it a while back, but hearing Andy's stuff has inspired me to go back to it and d .......
76: Tubes Asylum, 5692 == 6SN7 (0.00)
Posted by jub_jugs on 2006-08-12, 05:42:53 (62.252.0.6)
5692 & 6SN7 have the same characteristics as 6SN7, except that the 5692 is specified for industrial applications where long lifetime & reliability is required. They cheated a bit to do this by specify .......
77: Tubes Asylum, You can delete a post... (0.00)
Posted by jub_jugs on 2006-08-10, 01:57:43 (162.13.51.24)
...as long as no-one has replied to it. Just click the "delete" button. .......
78: Tube DIY Asylum, Yup, my watch says "316L" on the back. (nt) (0.00)
Posted by jub_jugs on 2006-08-08, 07:09:25 (162.13.51.24)
.......
79: Tubes Asylum, Re: with dht rectifiers such as 5U4G, does it mean it doesn't provide "soft start" feature? (0.00)
Posted by jub_jugs on 2006-08-08, 07:05:43 (162.13.51.24)
Yes, directly heated rectifiers warm up much more quickly than indirectly heated types, but they still take a few seconds to warm up, so it's not instant, just quicker. Whether to use them or not depe .......
80: General Asylum, When I first bought a tube amp (0.00)
Posted by jub_jugs on 2006-08-08, 04:46:40 (162.13.51.24)
I stopped fiddling and enjoyed the music for about 5 yrs. .......
81: Tubes Asylum, Haha..that's nothing (0.00)
Posted by jub_jugs on 2006-08-06, 10:12:48 (86.128.223.91)
.. .......
82: General Asylum, Quite possibly, but I choose to remain a sceptic.... (0.00)
Posted by jub_jugs on 2006-08-02, 06:11:03 (162.13.51.24)
...based on my current understanding of physics. It's my loss, I guess! 8-) .......
83: General Asylum, you could try facts... (0.00)
Posted by jub_jugs on 2006-08-02, 05:40:47 (162.13.51.24)
...but I guess that way people wouldn't buy it. After all, saying that it's actually just a bit of metal which does nothing lacks the sexiness of quantum dots. .......
84: General Asylum, My bullshit detector just snapped its needle... (0.00)
Posted by jub_jugs on 2006-08-02, 02:15:32 (162.13.51.24)
I've never read such cobblers. (And yes I do know something about quantum physics). .......
85: Inmate Systems, jub_jugs's Main (0.00)
Posted by jub_jugs on 2006-07-28, 08:50:39 (162.13.51.24)
To add your system, you must register .">
Audio Asylum Inmate jub_jugs's Main System
Home
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.......
86: Tube DIY Asylum, Re: Use a current inrush limiter. (0.00)
Posted by jub_jugs on 2006-07-27, 06:10:39 (162.13.51.24)
Ah yes, sorry, missed that. So the filter caps are after the plugpack? You could put it before the rectifier (maybe one in each leg). Maybe a small series resistor (say 1 Ohm) would even be ok as long .......
87: Tube DIY Asylum, Use a current inrush limiter. (0.00)
Posted by jub_jugs on 2006-07-27, 03:49:33 (162.13.51.24)
You could use an NTC thermistor between the mains inlet & transformer primary to limit inrush current. When cold it has a nigh resistance, limiting current and as it heats up, resistance drops to a ne .......
88: Tube DIY Asylum, Re: Bear in mind LM317 is safe for load less than 1.5A. (0.00)
Posted by jub_jugs on 2006-07-27, 01:44:46 (162.13.51.24)
Exactly. If you're using indirectly heated tubes and you're getting hum, then you are doing something wrong. Cheers, Pete .......
89: Tube DIY Asylum, Re: Tube schematic recommandation (0.00)
Posted by jub_jugs on 2006-07-26, 01:37:02 (162.13.51.24)
The son-of-heffa works very well, serveral friends are using them. KT-88 based, but 6550 works just as well. I built a variant with DHTs. Cheers, Pete .......
90: Tube DIY Asylum, True enough, not had a problem myself though... (nt) (0.00)
Posted by jub_jugs on 2006-07-21, 01:48:49 (162.13.51.24)
. .......
91: Tube DIY Asylum, Re: How to measure DCR of my power transformer or choke. (0.00)
Posted by jub_jugs on 2006-07-19, 07:32:44 (162.13.51.24)
You can just measure it with a DMM. Cheers, Pete .......
92: SET Asylum, Re: The major differences/advantages/disadvantages between 6J5 and the 6SN7? (0.00)
Posted by jub_jugs on 2006-07-14, 02:18:43 (162.13.51.24)
6J5 & 6SN7 have the same characteristics except that 6J5 is a single element in one envelope and 6SN7 has to. Apart from that they are electrically identical. There are many, many different types of b .......
93: Tubes Asylum, No... (0.00)
Posted by jub_jugs on 2006-07-12, 02:22:47 (162.13.51.24)
0B3 needs to have at least 5mA running through it to keep it lit, 5651 has a max. current of 3.5mA. If the circuit is designed to use 5651, it's unlikely to be putting enough current through the tube .......
94: Tube DIY Asylum, Thanks! )nT) (0.00)
Posted by jub_jugs on 2006-07-10, 15:04:11 (62.252.0.6)
. .......
95: Tube DIY Asylum, Re: info (0.00)
Posted by jub_jugs on 2006-07-10, 09:01:52 (162.13.51.24)
Hi Ed, Any comments on the sound of the TentLabs filament supplies? Cheers, Pete .......
96: Tube DIY Asylum, Re: pls help - cathode bypass cap (0.00)
Posted by jub_jugs on 2006-07-09, 02:48:45 (62.252.0.6)
Yeah, it will, which means it may not work too well if you remove the one on the output stage. In driver/input stages, I agree with the others who say that no cap. usually sounds better. Cheers, Pete .......
97: Tube DIY Asylum, This one looks good too. (0.00)
Posted by jub_jugs on 2006-07-09, 02:34:45 (62.252.0.6)
Not built it, but a version is on my list to try. Cheers, Pete .......
98: Tube DIY Asylum, Re: Hey T, how about 01A-10Y-300B? (0.00)
Posted by jub_jugs on 2006-07-09, 02:32:40 (62.252.0.6)
That would be pretty similar to 26-10Y-300B. I built such an amp as a breadboard a couple of years ago. All things being equal, at the time, I preferred a high-gM input stage - more dynamic as you say .......
99: Tube DIY Asylum, Here's a nice design which fits wiht my prejudices. (0.00)
Posted by jub_jugs on 2006-07-09, 02:28:05 (62.252.0.6)
All DHT. .......
100: Tube DIY Asylum, There is no best. (0.00)
Posted by jub_jugs on 2006-07-08, 15:23:21 (62.252.0.6)
Build a breadboard, expermiment. Find out what you like and dislike. Cheers, Pete .......
101: Tube DIY Asylum, Fixed bias is perfectly fine for 2A3 (0.00)
Posted by jub_jugs on 2006-07-07, 06:48:49 (162.13.51.24)
In fact the data sheets give suggested operating points for it. It's just that the grid resistor cannot be too large (50K max.) To avoid grid-current & runaway problems. Cheers, Pete .......
102: Tube DIY Asylum, Just to confuse things... (0.00)
Posted by jub_jugs on 2006-07-07, 01:41:47 (162.13.51.24)
...some 10s have oxide filaments. Cheers, pete .......
103: Tubes Asylum, Do you have a photo? (nt) (0.00)
Posted by jub_jugs on 2006-07-04, 02:29:09 (162.13.51.24)
. .......
104: Tube DIY Asylum, Re: Question on website reference (0.00)
Posted by jub_jugs on 2006-07-03, 07:06:45 (162.13.51.24)
>So for a diff pair with CCS using the above values and 16mA load (not >100mA), then the series resistor is 1.3k. yes. >Does anything happen if you don't put tubes in the sockets and the >regulator se .......
105: Tube DIY Asylum, Re: Question on website reference (0.00)
Posted by jub_jugs on 2006-07-03, 05:24:49 (162.13.51.24)
Hi Andy, For this example 400 Ohms is correct. Total current is 122.5mA, so 50V drop divided by 122.5mA is 408 Ohms. In this case, 100mA goes to the load, 22.5mA down the VR tube. This only works for .......
106: Tube DIY Asylum, Farnell? (0.00)
Posted by jub_jugs on 2006-06-29, 01:55:11 (162.13.51.24)
The big ones seem to be quite pricey though.... .......
107: Tubes Asylum, Re: Type 19 usuage (0.00)
Posted by jub_jugs on 2006-06-25, 13:23:10 (62.252.0.6)
I use 1J6G (the octal equivalent) in a PP amp I built. They are a DHT with a common cathode. They're designed as class-B oputput tubes, but yhey work very nicely as a differential / long-tailed pair i .......
108: Tube DIY Asylum, Re: Negative feedback for Jeff (0.00)
Posted by jub_jugs on 2006-06-22, 08:49:45 (162.13.51.24)
Hi, I thought that these propagation delays due to dielectric only applied (at least significantly) to waveguides, such as co-ax? Are you sure that this is significant for bare wire? Of course, circui .......
109: Tube DIY Asylum, Er...I don't think so. (0.00)
Posted by jub_jugs on 2006-06-22, 02:10:20 (162.13.51.24)
Electrons do not travel at 2/3 of the speed of light. Electrons drift velocity in a conductor is in the order of a few m/sec. Electricity in a conductor moves more like a wave. Nearby electrons push o .......
110: Tubes Asylum, Re: You really have to get those tube manufacturing manuals (0.00)
Posted by jub_jugs on 2006-06-22, 01:53:45 (162.13.51.24)
"But as tube aficionados will tell you, the black plates generally sound better" Black plates don't necessarily sound better & not for the reasons you've stated. If they sound better it's a coindciden .......
111: Tube DIY Asylum, Re: What do the textbooks tell you? (0.00)
Posted by jub_jugs on 2006-06-21, 14:35:22 (62.252.0.6)
C2 doesn't "couple" anything. C2 wil shunt any signal at that grid to ground at AC. There won't be any signal there. As for the choke in the tail, the 595R is only the DC resistance. For AC you need t .......
112: Tube DIY Asylum, Re: How are you so sure? (0.00)
Posted by jub_jugs on 2006-06-21, 09:24:50 (162.13.51.24)
The LTP phase splitter stage (i.e. the part with the 6SN7, forget the rest of the schematic, which is outside this discussion) is pretty much textbook example of a long-tailed pair. Apart from the tai .......
113: Tube DIY Asylum, There is no "downside". (0.00)
Posted by jub_jugs on 2006-06-21, 07:51:39 (162.13.51.24)
It's simple. If the grid is at 0V DC, it can be connected directly to ground. If it is not at 0V DC, it cannot be directly connected to ground, so it is connected to ground via a capacitor to put it a .......
114: Tubes Asylum, Re: guide in choosing an octal rectifier tube (0.00)
Posted by jub_jugs on 2006-06-21, 06:27:48 (162.13.51.24)
1) Directly heated or indirectly heated? DH tubes warm up pretty quickly. Indirectly heated tubes have a longer delay before applying B+ to your expensive signal tubes. 2) Current rating (average and .......
115: SET Asylum, Re: wow, this helps a great deal, thanks. After.... (0.00)
Posted by jub_jugs on 2006-06-15, 14:17:11 (62.252.0.6)
801A works very nicely in A2 as well. 7W vs the 2 or 3 available in A2. .......
116: Tube DIY Asylum, best we stock up on DMSA then... (0.00)
Posted by jub_jugs on 2006-06-15, 14:12:16 (62.252.0.6)
. .......
117: Tube DIY Asylum, Re: Tube 49 (0.00)
Posted by jub_jugs on 2006-06-08, 23:54:52 (62.252.0.6)
It sounds good, quite a bold, dynamic sound, a bit like a 12A from what I remember. And yes, tehy're cheap compared to the more commonly used DHTs. Cheers, Pete .......
118: Tube DIY Asylum, Re: Opt question (0.00)
Posted by jub_jugs on 2006-06-08, 01:50:18 (162.13.51.24)
If you're using an ordinary 5K:8 transforer, it is almost certain to have inadeqaute inductance to support a 60K load at LF. The tube sees the transformer's primary inductance in parallel with the ref .......
119: Tube DIY Asylum, 26 circuits (0.00)
Posted by jub_jugs on 2006-06-03, 11:09:48 (62.252.0.6)
You can find some here: http://www.positive-feedback.com/Issue16/kennedy.htm http://www.vt52.com/ (Navigate to DIY). http://www.vinyl.and.triodes.net/diy/26_preamp/26pre.htm http://home.pacifier.com/~ .......
120: Tube DIY Asylum, Re: substitute for a DN2540 that's not from Supertex? (0.00)
Posted by jub_jugs on 2006-06-03, 06:55:41 (62.252.0.6)
I got some from Mouser in the US - they shipped to the UK no-problem. Cheers, Pete .......
121: Tube DIY Asylum, Re: linestage OPT coupled output with 6J5 or 6SN7 any one ? (0.00)
Posted by jub_jugs on 2006-06-03, 06:55:07 (62.252.0.6)
Why don't you build it & decide for yourself? Shouldn't be too hard to fiddle with, e.g. change to conventional cathode bypass rather than untrapath. Alternatively, 20K is good for a 26, so you could .......
122: DIY HiFi Forum, You need a hotter soldering iron (nt). (0.00)
Posted by jub_jugs on 2006-06-02, 03:21:46 (162.13.51.24)
. .......
123: Tube DIY Asylum, Re: URL (0.00)
Posted by jub_jugs on 2006-06-01, 09:43:31 (162.13.51.24)
Also look at: www.vt52.com for 26 schematics. Cheers, Pete .......
124: Tubes Asylum, Re: Many KT88 ?'s (0.00)
Posted by jub_jugs on 2006-05-28, 01:53:51 (62.252.0.6)
The GEC/Genelex are the standard by which all others are judged. Most people would say they sound best. I would agree with that, having tried a few. Whether they're worth the money is another question .......
125: SET Asylum, Magnetostriction (0.00)
Posted by jub_jugs on 2006-05-25, 01:47:06 (162.13.51.24)
Magnetostriction causes a (magnetic) material to deform under a magentic field. The magnetic fields in an OPT are quite strong, and so the effect may just be strong enough to be audible. .......
126: Tube DIY Asylum, Re: resistors & voltage rating (0.00)
Posted by jub_jugs on 2006-05-08, 09:28:25 (162.13.51.24)
Resistors can indeed have a voltage limit due to the way some of them are manufactured - a helical cut in a film of resistive (metal) film deposited on a ceramic cylinder. The voltage limit is determi .......
127: Tube DIY Asylum, Sounds good... (0.00)
Posted by jub_jugs on 2006-05-04, 17:04:57 (62.252.0.6)
I guess there's always something to learn. Cheers, Pete .......
128: Tube DIY Asylum, Has anyone read his other book "Building Valve Amplifiers"? (0.00)
Posted by jub_jugs on 2006-05-04, 15:27:58 (62.252.0.6)
I believe in concentrates more on the practical side? Any good? Cheers, Pete .......
129: Tube DIY Asylum, Make that LT1086CT5 for a fixed 5V (nt) (0.00)
Posted by jub_jugs on 2006-04-29, 08:31:01 (62.252.0.6)
. .......
130: Tube DIY Asylum, Re: 78S05 replacement for heater ? (0.00)
Posted by jub_jugs on 2006-04-29, 07:30:50 (62.252.0.6)
Use LT1086 adjustable regs. They have Cheers, Pete .......
131: Tube DIY Asylum, Re: cutting chassis (0.00)
Posted by jub_jugs on 2006-04-23, 11:27:57 (62.252.0.6)
I just did some square holes in a copper chassis. Used a dremel with a cutting wheel & then tidied it up by filing. Turned out pretty good really. Cheers, pete .......
132: Tube DIY Asylum, Re: 6A3? (0.00)
Posted by jub_jugs on 2006-04-19, 09:09:33 (162.13.51.24)
It's difficult to say, it depends on how sensitive your speakers are, and I suspect it will vary with brand. You may be able to get it quiet enough with a hum-pot. Personally, I would use DC, using a .......
133: SET Asylum, Who cares when it looks that nice! (0.00)
Posted by jub_jugs on 2006-04-19, 07:37:46 (162.13.51.24)
But I guess it depends on operating conditions... I'm guessing 2-ish Watts? Or...? Cheers, Pete .......
134: Tube DIY Asylum, 6A3? (0.00)
Posted by jub_jugs on 2006-04-19, 05:58:41 (162.13.51.24)
Alternatively, NOS 6A3s (or 6B4G) are cheap as chips, but require a 6.3V filament supply. Cheers, Pete .......
135: SET Asylum, Looks like the TJ 45? (nt) (0.00)
Posted by jub_jugs on 2006-04-19, 03:43:03 (162.13.51.24)
. .......
136: Tube DIY Asylum, Re: The 50 can be infuriating. (0.00)
Posted by jub_jugs on 2006-04-17, 05:26:14 (86.128.128.127)
Hello, Yeah, the ones I used first were the old globes with oxide filaments, but they sounded pretty similar to 10Ys etc. I guess something was obviously not right. I will probably re-visit the 10 som .......
137: Tube DIY Asylum, The 50 can be infuriating. (0.00)
Posted by jub_jugs on 2006-04-14, 09:28:59 (62.252.0.6)
I agree 100% that the driver sets the sound of the amp. I initially started with a 6S45 transformer coupled to the 50, but was never satisfied (nice, but a bit bland). Things got much better when I in .......
138: Tube DIY Asylum, Re: Small signal DHT mu 15-20 ? (0.00)
Posted by jub_jugs on 2006-04-13, 09:02:51 (162.13.51.24)
Looks like a nice tube - reminds me I have some RE084s to try sometime.... Cheers, Pete .......
139: Tube DIY Asylum, Re: Small signal DHT mu 15-20 ? (0.00)
Posted by jub_jugs on 2006-04-13, 07:27:27 (162.13.51.24)
What's an SD2? Can't find any info.... Cheers, Pete .......
140: Tubes Asylum, Re: I just got 2 GE and 2 Audio Arts 211 tubes, all with loose wires. (0.00)
Posted by jub_jugs on 2006-04-13, 04:07:35 (162.13.51.24)
Sounds like you're taking about the filament support springs. If they're rattling around in the tube, the tube is dead. You'll probably have the remains of the filaments in the bottom of the tubes too .......
141: Tube DIY Asylum, Re: Small signal DHT mu 15-20 ? (0.00)
Posted by jub_jugs on 2006-04-12, 18:31:26 (62.252.0.6)
Western Electric 102L? Cheers, Pete .......
142: Tubes Asylum, Re: What about mercury rectifiers? (0.00)
Posted by jub_jugs on 2006-04-12, 02:24:20 (162.13.51.24)
Probably because noise etc. is just one aspect which affects sound quality. Hg rectifiers also have a much lower internal impedance, which is usually beneficial in power supplies. They also lose one o .......
143: Tubes Asylum, Re: Are these matched pairs? (0.00)
Posted by jub_jugs on 2006-04-12, 02:17:56 (162.13.51.24)
Pairs 4 & 5 do certainly seem less well matched than the others, but still not so bad - they're within 10%. How much this affects the amp really depends on the circuit. Tube testers aren't really that .......
144: Tube DIY Asylum, Single plate 6A3 (0.00)
Posted by jub_jugs on 2006-04-10, 01:39:33 (162.13.51.24)
I have one. It's labelled "6A3" but it's actually a VT-52. It tests poorly as a 6A3, but good as a VT-52. Looks exactly like the other VT-52s I have, including the filament. I don't think a *real* sin .......
145: Tubes Asylum, Re: Western Electric 448A, 448B, or 454A tubes (0.00)
Posted by jub_jugs on 2006-03-31, 01:06:36 (162.13.51.24)
I got some on eBay a while back. But yes, they're incredibly rare. oldtube.com has some listed: .......
146: Tube DIY Asylum, Re: Dual tube rectifiers and reservoir capacitors? (0.00)
Posted by jub_jugs on 2006-03-27, 04:50:57 (162.13.51.24)
Yes, you'll increase the current rating (and therefore the allowed capacitance) using rectifiers in parallel. However, because the tubes may not share current equally, I would not assume double. ::: T .......
147: Tube DIY Asylum, Look like the glass fluorescing... (0.00)
Posted by jub_jugs on 2006-03-27, 04:46:24 (162.13.51.24)
I have tubes that do this. It's fine. Glow in a gassy tube is more pinkish and the glow tends to surround the plate struture rather than being on the glass. .......
148: Tube DIY Asylum, Yes... (0.00)
Posted by jub_jugs on 2006-03-17, 01:47:22 (162.13.51.24)
...but i much preferred the 46 as driver. Had a bit more bite than the 45. Input was WE448A as triode. .......
149: Tubes Asylum, Just think of the microphonics! (0.00)
Posted by jub_jugs on 2006-03-07, 03:01:08 (162.13.51.24)
I'm surprised it doesn't just howl itself to death. .......
150: Tubes Asylum, Re: 6SN8 Tubes, Are they really 6SN7? (0.00)
Posted by jub_jugs on 2006-02-22, 04:07:18 (162.13.51.24)
6H8C (cyrillic alphabet) = 6N8S which is the Russian 6SN7 equivalent. .......
151: Tube DIY Asylum, 'Event Horizon'? (0.00)
Posted by jub_jugs on 2006-02-20, 06:25:23 (162.13.51.24)
feel the gravity.... .......
152: High Efficiency Speaker Asylum, Re: Onken W Plans - I have them!!! (0.00)
Posted by jub_jugs on 2006-02-17, 02:17:38 (162.13.51.24)
yes please: real_i_should_coco@hotmail.com .......
153: Tube DIY Asylum, Re: Tube diode bias 2A3 circuit and picture (0.00)
Posted by jub_jugs on 2006-02-16, 07:50:38 (162.13.51.24)
Nice work with the caps. The only slight qualm I have is that some data-sheets list max. capacitance for 5AR4 as 60uF. This may shorten the life of the rectifer as you're about 50% over that for your .......
154: SET Asylum, Completely different, yes. (nt) (0.00)
Posted by jub_jugs on 2006-02-01, 03:41:57 (162.13.51.24)
. .......
155: Tubes Asylum, A circuit digram would help.... (0.00)
Posted by jub_jugs on 2006-01-20, 06:10:16 (162.13.51.24)
.......
156: Tube DIY Asylum, Re: Help: Connecting Lundahl 1623 90ma (0.00)
Posted by jub_jugs on 2006-01-14, 06:35:56 (62.252.0.6)
For 3K:8R use Alt. "C" in the datasheet and yes, V+ means B+. Cheers/ Pete .......
157: Tube DIY Asylum, Re: Red LED for cathode bias (0.00)
Posted by jub_jugs on 2006-01-12, 11:57:16 (62.252.0.6)
I've used blue LEDs in the past, they drop a bit more voltage. Seemed to work OK. (Blue LEDs have a higher Vf - in the region of 3-4V or so) You could try bypassing them to see what difference you get .......
158: Tube DIY Asylum, Re: Very interesting!! (0.00)
Posted by jub_jugs on 2006-01-09, 05:50:56 (162.13.51.24)
Hi Andy, in practice I've found that tubes do vary quite a bit in terms of filament surrent drawn for a given voltage. I've used CCS regs. in the past with good results, but found that some provision .......
159: SET Asylum, Re: new 300B's for Kit One (0.00)
Posted by jub_jugs on 2005-10-22, 11:06:21 (62.252.0.6)
Surprisingly, I liked the orginal chinese pretty well when I had mine, even though the bass was a bit overblown in my system. I also tried JJ - a bit brighter & tighter, but not as sweet sounding. TJ .......
160: Tubes Asylum, Re: 6SN7- Burnt mark and tester readings (0.00)
Posted by jub_jugs on 2005-10-13, 11:53:12 (62.252.0.6)
Some tubes are burned in, yes. Not sure what you mean by "burn" marks though. I was talking about the silver deposits that tend to form over the ends of the heaters on tubes such as 6SN7. No experienc .......
161: Tubes Asylum, Re: 6SN7- Burnt mark and tester readings (0.00)
Posted by jub_jugs on 2005-10-13, 06:29:01 (162.13.51.24)
The silver marks over the filaments are caused by the getter material migrating to this position as the tube is used. These marks can form in a fairly short time and I have seen them on new in box tub .......
162: SET Asylum, Re: 2A3 change to 45 (0.00)
Posted by jub_jugs on 2005-10-12, 03:01:04 (162.13.51.24)
I would expect most schematics to use self (cathode) bias, so the 300V on the plate of most schematics is plate to ground and includes ~50V bias for a 45 thus giving ~250V plate to cathode. 300V B+ is .......
163: Tube DIY Asylum, 6J5 (nt) (0.00)
Posted by jub_jugs on 2005-09-22, 04:56:31 (162.13.51.24)
. .......
164: SET Asylum, Re: PX 25 (0.00)
Posted by jub_jugs on 2005-09-19, 01:09:55 (162.13.51.24)
See link for data sheet (TDSL is your friend). Rp ~1.3k which means a 4K transformer is good using the 3xRp rule of thumb. I expect anything from 3K (more power) to 5K (less distortion) would be good. .......
165: Tube DIY Asylum, Re: Anyone heard/built a VT-50 amp? (0.00)
Posted by jub_jugs on 2005-09-19, 00:57:12 (162.13.51.24)
50s can be great, but they're difficult to use. I'm still trying to get it right after 3 years! If you use one of the originals (not new TJ production), you need to keep the resistance in the grid cir .......
166: Tubes Asylum, Re: Tube tester settings for 183/483 tubes on Hickok 539A? (0.00)
Posted by jub_jugs on 2005-09-16, 07:54:52 (162.13.51.24)
They are the same as a 45, but with a 5V filament rather than 2.5V .......
167: SET Asylum, Re: 300B two designs....... (0.00)
Posted by jub_jugs on 2005-05-27, 05:53:31 (62.252.0.6)
Ok, a bit different to my amp then, which was fixed bias for the output and transformer coupled. How are you planning to load the 46? Choke? Resistor? Are you going to breadboard this? Might be a good .......
168: SET Asylum, Re: 300B two designs....... (0.00)
Posted by jub_jugs on 2005-05-27, 02:12:04 (62.252.0.6)
I've not tried EL34 driving 300B, but have tried various other tubes, all transformer coupled: 10/10Y/801A, 843, WE101L, 45, 46 & 112A. The 45 was very nice, but I wanted a little more bite. The 101L .......
169: SET Asylum, Yep. triode connected. (0.00)
Posted by jub_jugs on 2005-05-20, 00:35:48 (62.252.0.6)
G2 to Plate. Cheers/ Pete .......
170: SET Asylum, 46 is my fave... (0.00)
Posted by jub_jugs on 2005-05-19, 10:44:35 (62.252.0.6)
...I use it transformer coupled. .......
171: Tube DIY Asylum, Have you tried Gerry at Crowthorne tubes? (nt) (0.00)
Posted by jub_jugs on 2005-04-06, 04:09:39 (62.252.0.6)
. .......
172: Tube DIY Asylum, You could try the 49 (0.00)
Posted by jub_jugs on 2004-03-12, 06:57:37 (62.252.0.5)
It's a baby brother battery version of the 46 2V@120mA fil. Triode strapped it has mu of 4.9 and 4K Rp. Cheap too. Haven't tried it yet though, so can't comment on the sound. Cheers/ Pete .......
173: Tube DIY Asylum, Re: Big DH multigrids (0.00)
Posted by jub_jugs on 2004-02-20, 04:55:25 (62.252.0.5)
In your photo it seems to be sitting on a bench, when I saw it it was on a trolley, with the PSU below...had to be wheeled around! A real boat-anchor! Cheers/ Pete .......
174: Tube DIY Asylum, Re: Big DH multigrids (0.00)
Posted by jub_jugs on 2004-02-20, 03:16:03 (62.252.0.5)
Ah yes...I seem to recall that's where we got the idea from.... It's a bit of a monster that one! Cheers/ Pete .......
175: Tube DIY Asylum, thoriated (0.00)
Posted by jub_jugs on 2004-02-20, 02:34:56 (62.252.0.5)
Hi Douglas, Filament was white/orange, it looks just like any other thoriated jobby. The data sheet below shows it as carbonized/thoriated.... http://www.tubes.ru/techinfo/TransmittingTubes/gu-81m.htm .......
176: Tube DIY Asylum, Re: Big DH multigrids (0.00)
Posted by jub_jugs on 2004-02-19, 15:48:16 (62.252.0.5)
A friend has some...we plotted some triode curves a while back, I think we only got to about 500V. It certainly likes to draw current! filaments were powered by a car battery! Actually, that may be th .......
177: Tubes Asylum, Re: gassy mesh 50 (0.00)
Posted by jub_jugs on 2004-02-04, 07:40:22 (62.252.0.5)
Am using an interstage transformer with a -ve bias supply. Cheers/ Pete .......
178: Tubes Asylum, Re: gassy mesh 50 (0.00)
Posted by jub_jugs on 2004-02-04, 05:01:17 (62.252.0.5)
Hi Ed, I will try cooking it on filament power for a while. I tried putting it in the oven for an hour, but no luck :-( Guess I will just have to hope for the best.... Cheers/ Pete .......
179: Tubes Asylum, Re: gassy mesh 50 (0.00)
Posted by jub_jugs on 2004-02-04, 02:39:06 (62.252.0.5)
Thanks for your reply! In fact I tried cooking it in the oven aswell (80 deg. C) for an hour and a half, but it made no difference. I will try your suggestion regarding filament voltage, it's not as i .......
180: Tubes Asylum, gassy mesh 50 (0.00)
Posted by jub_jugs on 2004-02-03, 12:27:09 (62.252.0.5)
I have a mesh 50 tube which was fine for a while, but soon developed a purple glow. was listening to it and within the space of a few minutes I noticed it. It seems to have gotten worse and now glows .......
181: Tube DIY Asylum, more on dBm.... (0.00)
Posted by jub_jugs on 2004-01-22, 03:20:07 (62.252.0.5)
Seems that 0dBm is only equivalent to 0dBU into 600R. I have no idea how to convert for different impedances. Cheers/ Pete .......
182: Tube DIY Asylum, more on dBm.... (0.00)
Posted by jub_jugs on 2004-01-22, 03:20:07 (62.252.0.5)
Seems that 0dBm is only equivalent to 0dBU into 600R. I have no idea how to convert for different impedances. Cheers/ Pete .......
183: Tube DIY Asylum, Re: Clip leads and SE power stages are agianst my religion... (0.00)
Posted by jub_jugs on 2004-01-22, 01:49:55 (62.252.0.5)
Hi Douglas, I think you should give it a go with the UTCs it could well work great! Cheers/ Pete .......
184: Tube DIY Asylum, Re: Clip leads and SE power stages are agianst my religion... (0.00)
Posted by jub_jugs on 2004-01-22, 01:49:55 (62.252.0.5)
Hi Douglas, I think you should give it a go with the UTCs it could well work great! Cheers/ Pete .......
185: Tube DIY Asylum, Re: Clip leads and SE power stages are agianst my religion... (0.00)
Posted by jub_jugs on 2004-01-22, 01:48:36 (62.252.0.5)
Hi Douglas, I think you should give it a go with the UTCs it could well work great! Cheers/ Pete .......
186: Tube DIY Asylum, Re: Clip leads and SE power stages are agianst my religion... (0.00)
Posted by jub_jugs on 2004-01-22, 01:48:36 (62.252.0.5)
Hi Douglas, I think you should give it a go with the UTCs it could well work great! Cheers/ Pete .......
187: Tube DIY Asylum, Re: that doesn't look good to me... (0.00)
Posted by jub_jugs on 2004-01-21, 13:26:59 (62.252.0.5)
Well, if the tx is 5k:80k that's a 2.3:1 step-up so you should be able to get ~8v out, but that's presumably across the whole primary. So not enough I think... I guess it all depends on how that 15dBm .......
188: Tube DIY Asylum, Re: that doesn't look good to me... (0.00)
Posted by jub_jugs on 2004-01-21, 13:26:59 (62.252.0.5)
Well, if the tx is 5k:80k that's a 2.3:1 step-up so you should be able to get ~8v out, but that's presumably across the whole primary. So not enough I think... I guess it all depends on how that 15dBm .......
189: Tube DIY Asylum, Re: Douglas, have you gone completely differential? (0.00)
Posted by jub_jugs on 2004-01-21, 12:33:26 (62.252.0.5)
Here's some info in dBm, dBU etc.... .......
190: Tube DIY Asylum, Re: Douglas, have you gone completely differential? (0.00)
Posted by jub_jugs on 2004-01-21, 12:33:26 (62.252.0.5)
Here's some info in dBm, dBU etc.... .......
191: Tube DIY Asylum, Re: mind the higher capacitance at one end too (0.00)
Posted by jub_jugs on 2004-01-15, 14:16:31 (62.252.0.5)
That brings up a good point, what would be the recommended orientation? High or low capacitance end to ground? Is there a general rule for this or just listening? Cheers/ Pete .......
192: Tube DIY Asylum, Re: Should DCR ALWAYS be a minimum? (0.00)
Posted by jub_jugs on 2004-01-15, 11:35:20 (62.252.0.5)
Was using a 45K resistor to -180V mainly because the -180V was handy with the transformer I was using. I'm using a 1J6G whose cathode resistance is ~5k, so I kind of guessed that a min. of 5x the cath .......
193: Tube DIY Asylum, Re: Should DCR ALWAYS be a minimum? (0.00)
Posted by jub_jugs on 2004-01-15, 09:56:51 (62.252.0.5)
Hi Dave, At the moment it's a resistor to a -ve supply. I was interested in how this would sound in comparison to using the resistor or a transformer phase splitter. I like the idea because it allows .......
194: Tube DIY Asylum, Re: Should DCR ALWAYS be a minimum? (0.00)
Posted by jub_jugs on 2004-01-15, 06:28:36 (62.252.0.5)
Thanks! Yes, I now see copper has a tempco. of .393% per deg. C. Your comment about heating from the tubes is well taken - I suspect that will be the main factor in my application.... Food for thought .......
195: Tube DIY Asylum, Re: Should DCR ALWAYS be a minimum? (0.00)
Posted by jub_jugs on 2004-01-15, 03:07:56 (62.252.0.5)
Hi Dave, What sort of ambient temperature change do you need for a 5% change in DCR? I'm just about to try a cathode choke in my PP KT-88 amp, but I'll be using the choke in the phase splitter section .......
196: Tube DIY Asylum, Please let us know how it turns out... (0.00)
Posted by jub_jugs on 2004-01-13, 13:52:07 (62.252.0.5)
Hi Allen, I would be very interested in how you get on with, please keep us posted.... Cheers/ Pete .......
197: Tube DIY Asylum, Re: EL509/519 (0.00)
Posted by jub_jugs on 2004-01-12, 09:12:26 (62.252.0.5)
Hi FB, Thanks for the info! Yeah, they look like they would be a much better bet for driving such a nasty load. With two of those in parallel it looks much more sensible while keeping the turns ratio .......
198: Tube DIY Asylum, Re: Good luck with that one! (0.00)
Posted by jub_jugs on 2004-01-12, 04:18:26 (62.252.0.5)
Hi Allen, Unfortunately he's away at the minute so I can't get the details and it was quite a while ago since we attempted this, but I remember we expected about 60 Watts or so - probably not enough f .......
199: Tube DIY Asylum, Hmmm...apogees! (0.00)
Posted by jub_jugs on 2004-01-11, 14:32:34 (62.252.0.5)
A friend of mine has a pair of these and so far they have defeated all efforts to drive them to a sensible volume with a valve amp.... The last attempt was a parallel push-pull 813 monster.... Good lu .......
200: Tubes Asylum, Re: Need help about rectifier tube of Quad II (0.00)
Posted by jub_jugs on 2004-01-09, 13:58:06 (62.252.0.5)
Yes, but won't this affect the heater voltage also...something you don't want to change.... /Pete .......
201: Tube DIY Asylum, Re: PP advantages for a preamp. (0.00)
Posted by jub_jugs on 2004-01-09, 13:43:26 (62.252.0.5)
Hmmm...what about 3rd harmonic and other odd order stuff which doesn't get cancelled? Personally I believe that the harmonic spectrum is also important. /Pete .......
202: Tubes Asylum, Re: tube ID (0.00)
Posted by jub_jugs on 2004-01-09, 13:36:42 (62.252.0.5)
According to Ludwell Sibley's Tube Lore, it's a UV-201A Cheers/ Pete .......
203: Tubes Asylum, cool, thanks! <nt> (0.00)
Posted by jub_jugs on 2003-12-17, 01:09:00 (62.252.0.5)
. .......
204: Tubes Asylum, Anyone have triode data for 2E24? thanks...<nt> (0.00)
Posted by jub_jugs on 2003-12-16, 12:13:12 (62.252.0.5)
. .......
205: Tube DIY Asylum, Re: Anybody used an 834 (or similar) in A2? (0.00)
Posted by jub_jugs on 2003-12-12, 05:39:18 (62.252.0.5)
Funnily enough, just built an A2 amp using 801A - basically Shishido's 6EM7-801A amp. Sound is promising, but am still fiddling with it. Seems to be good for about 4-5W. That runs +ve grid bias rather .......
206: Tube DIY Asylum, coolamundo! <nt> (0.00)
Posted by jub_jugs on 2003-12-06, 15:49:44 (62.252.0.5)
. .......
207: Tubes Asylum, Re: Brimar 6SN7GT (0.00)
Posted by jub_jugs on 2003-12-05, 10:27:50 (62.252.0.5)
I have pair of theses and yup, they're very good. Mind you I like all the Brimar 6SN7s, though there seem to be many variations in construction (though all the ones I've seen have oval plates). They a .......
208: K&K Audio / Lundahl Transformers, Thanks Kevin! <nt> (0.00)
Posted by jub_jugs on 2003-12-02, 14:14:04 (62.252.0.5)
. .......
209: K&K Audio / Lundahl Transformers, Lundahl PSU chokes suitable for choke input? <nt> (0.00)
Posted by jub_jugs on 2003-12-02, 14:06:27 (62.252.0.5)
. .......
210: Tubes Asylum, 1/2 6sL7=6K5G (nt) (0.00)
Posted by jub_jugs on 2003-12-02, 07:40:18 (213.38.170.72)
. .......
211: SET Asylum, Ah, ok, thanks! (nt) (0.00)
Posted by jub_jugs on 2003-11-21, 05:26:41 (213.38.170.72)
. .......
212: SET Asylum, power output (0.00)
Posted by jub_jugs on 2003-11-21, 01:45:49 (213.38.170.72)
I had a play with the curves last night and calculated output power for loads 5K - 8K at 425V/35mA. This seems to come out at 1.1-1.4W, at least when staying in A1. I've heard folks talk about 3W max. .......
213: SET Asylum, What sort of load would you use at that OP? <nt> (0.00)
Posted by jub_jugs on 2003-11-20, 05:01:09 (213.38.170.72)
. .......
214: Tubes Asylum, Re: Brimar - Oval Plates (0.00)
Posted by jub_jugs on 2003-07-14, 14:35:11 (62.252.0.6)
Never heard 5692s unfortunately. The Brimars I just happened upon and fortunately I liked them! Having said that everyone's tastes vary so I guess the only way to know for certain is to try it! Are yo .......
215: Tubes Asylum, Re: Brimar - Oval Plates (0.00)
Posted by jub_jugs on 2003-07-14, 07:26:58 (213.38.170.71)
Hi Derick, Yes, those look like some of the ones I have. I've used them in a 300B amp as the first stage, rather than a driver and I find them to be very good sounding - very sweet, maybe not as detai .......
216: Tubes Asylum, Re: Those don't look like oval plates (0.00)
Posted by jub_jugs on 2003-07-08, 06:38:58 (213.38.170.71)
Hmmm...they do indeed look like Russian ones. I've not heard those. The Brimars I have come in several varieties - All have oval plates, some dark gray, some a shade lighter. Most have orange letterin .......
217: Tubes Asylum, Re: Forget about them VT-2131's (0.00)
Posted by jub_jugs on 2003-07-08, 01:19:29 (62.252.0.6)
I'm also a fan of the Brimars, I take it you mean the ones with orange printing on the base and the oval plates? I've been told that there are russian ones branded Brimar out there ( the plates look c .......
218: K&K Audio / Lundahl Transformers, Thanks Kevin! <nt> (0.00)
Posted by jub_jugs on 2003-06-26, 02:51:47 (213.38.170.71)
.......
219: K&K Audio / Lundahl Transformers, 1660 PP Q for Kevin (0.00)
Posted by jub_jugs on 2003-06-25, 06:20:15 (213.38.170.71)
Hi, Just wondering what the max. DC imbalance allowed for is in 1660-PP? I understand it has a small gap to allow some... Thanks/ pete .......
220: Tube DIY Asylum, Re: High(ish) voltage -ve supply (0.00)
Posted by jub_jugs on 2003-06-15, 08:48:30 (62.252.0.6)
Whoops! forgot to say, looking for 60-90V Cheers/ Pete .......
221: Tube DIY Asylum, High(ish) voltage -ve supply (0.00)
Posted by jub_jugs on 2003-06-15, 08:43:30 (62.252.0.6)
Hi, Just wondering if anyone has any info on building a high voltage (at least higher than most regs allow) -ve supply for bias. I was going to try and use a regualator and I see info on stacking them .......
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