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1: Tube DIY Asylum, RE: I tested them before installation (0.00)
Posted by DAK on 2022-06-28, 09:25:01 (172.56.44.7)
I changed them out just to hear if there is a difference with a pair of PIO type by General Instruments. The Spragues both measured .28uf from the .25, but I think that is what they measured initiall .......
2: Tube DIY Asylum, RE: I tested them before installation (0.00)
Posted by DAK on 2022-06-25, 11:27:03 (172.58.27.237)
I tested them with my heathkit cap tester at 400vdc and they showed no leakage. So, i felt they were fit for using. I was wondering if the DC voltages shown with my meter at this time indicates that t .......
3: Tube DIY Asylum, Do I need new coupling caps? (0.00)
Posted by DAK on 2022-06-24, 18:03:26 (172.56.44.35)
I am using some vintage Sprague Black Beauty 160P spec'd at .25uf x 400vdc. They are installed in a SE amp from the driver tube to the output. At idle the measure vdc is from .01 to .04 volts. There i .......
4: Tube DIY Asylum, RE: Make a separate chassis for the power supply (0.00)
Posted by DAK on 2022-05-26, 08:24:03 (172.56.44.241)
Yes you can make a separate shielded cable for the filament supplies that is grounded only on one of the chassis. I also ran a seperate ground cable with the filament wires. Then run the high voltage .......
5: Tube DIY Asylum, Make a separate chassis for the power supply (0.00)
Posted by DAK on 2022-05-26, 06:31:01 (172.56.44.241)
Not only does it cut down the weight for your amp but it would lower the noise floor by putting the AC components further away from the sensitive amplification stage. You can also hide the power suppl .......
6: Tubes Asylum, RE: You can get 2-way LEDs these days that light in both directions. (0.00)
Posted by DAK on 2022-05-23, 14:02:24 (172.56.44.206)
Good to know. Do you know where to get some? cheers. .......
7: Tubes Asylum, RE: Thanks a bunch.......nt (0.00)
Posted by DAK on 2022-05-21, 12:51:54 (172.56.44.202)
. .......
8: Tubes Asylum, To be sure? (0.00)
Posted by DAK on 2022-05-21, 12:03:53 (172.56.44.202)
The pilot light supply is from the heater supply, a yellow and a brown wire. I would just insert the resistor in any of the 2 wires and ground the led, with the unused wire floating? thanks again, Dak .......
9: Tubes Asylum, RE: Replacing a 6.3v indicator light with a LED (0.00)
Posted by DAK on 2022-05-21, 11:44:54 (172.56.44.202)
Thanks TK. Can you go thru the maths so I can do the calculation for other color leds as well. regards. .......
10: Tubes Asylum, Replacing a 6.3v indicator light with a LED (0.00)
Posted by DAK on 2022-05-21, 09:39:49 (172.56.44.43)
Hey all. I want to replace a burnt out on/off indicator light in my Eico 2080 amp with red LED. How does one go about doing that? I have some red leds. Thank you for the suggestions. cheers ::: TOPIC: .......
11: Tubes Asylum, RE: What does CK stand for with. the Raytheon 5687? (0.00)
Posted by DAK on 2022-05-21, 09:35:25 (172.56.44.43)
I think it is just their own designation for "special" or selected tubes. Like Sylvania GB, gold brand, or GE five star, etc. .......
12: Tube DIY Asylum, Watch out for voltage double circuits! (0.00)
Posted by DAK on 2022-05-21, 09:27:27 (172.56.44.43)
I did an overhaul for a Fisher 500 receiver and per usual hooked it up to the variac for the initial power up. I was up to around 80% or so of full power which is when i check the voltage doubler caps .......
13: Tube DIY Asylum, RE: A farmer brought in an old Realistic STA-220 (0.00)
Posted by DAK on 2022-05-21, 09:15:19 (172.56.44.43)
When i was young buck, i used to work in a dairy milking and caring for the dairy cows. But i really don't understand the bit about the on/off switch. .......
14: Tubes Asylum, RE: Bad Rectifier Dyna MKIII? (0.00)
Posted by DAK on 2019-11-05, 10:45:51 (72.130.201.211)
It is better to describe your amp in more detail. Whether it is stock or modded. And also if has been recently rebuilt, etc. Pictures if necessary are also a big help with getting the best advice. ::: .......
15: Tubes Asylum, Check the rectifier heater circuit (0.00)
Posted by DAK on 2019-11-04, 16:19:37 (72.130.201.211)
If the heater voltage went out you would not get any action from the rectifier. .......
16: Tubes Asylum, Are they really made in Holland? (0.00)
Posted by DAK on 2019-11-01, 09:50:36 (72.130.201.211)
I checked out some of the online pics of these Pope 6sn7, and i wonder if they are fakes? AFAIK, and i certainly an not an expert on European tubes, being stateside, Amperex was the major tube maker f .......
17: Tubes Asylum, Install a Current Limiter (0.00)
Posted by DAK on 2019-10-26, 12:44:00 (72.130.201.211)
It is a good idea if your unit does not have one to put in a CL. There are various specs on these devices but i have been using a cl80 from Mouser or Digikey, etc... They take up or adsorb the initial .......
18: Tube DIY Asylum, I think you should keep it PPP EL84 (0.00)
Posted by DAK on 2019-10-09, 11:12:30 (141.239.96.151)
I like the sound of the el84 tube. I prefer it over the 6l6 and definitely over the el34. My el34 amps are mostly in the mothball fleet. I built this PPP EL84 amp about 5 years ago. It sounds very .......
19: Tubes Asylum, They look like CBS 5692 (0.00)
Posted by DAK on 2019-10-04, 19:16:54 (141.239.96.151)
The tan base is typical of the type. They are very good sounding tubes though. I am not aware of any Telefunken 6sn7wgt so that label on these tubes should be a major warning to any tube collector who .......
20: Tube DIY Asylum, Bypassing PS electrolytics is beneficial (0.00)
Posted by DAK on 2019-09-27, 01:42:22 (72.130.201.211)
This procedure can be a real help to make large value electrolytics respond quicker to transients and dynamic sound passages. As others mentioned a large value electrolytic cap has a physical limitati .......
21: Tube DIY Asylum, What do you mean by that? (0.00)
Posted by DAK on 2019-09-16, 12:52:45 (72.130.201.211)
G2 supply is connected to B+ via a 4k 3W resistor, and then there is 3 x 91volt zener diodes connected to ground to achieve "voltage regulation". Also the zener stack is bypassed with a 22uf x 450vdc .......
22: Tubes Asylum, Have you seen the old Mullard propaganda film? (0.00)
Posted by DAK on 2019-09-14, 22:10:07 (72.130.201.211)
It was made right after WW2 when Mullard had lots of tube factories. I believe it showed a technician assembling an el84. Very neat video. .......
23: Tube DIY Asylum, Balance and voltage adjust pots...nt (0.00)
Posted by DAK on 2019-09-14, 22:04:11 (72.130.201.211)
. .......
24: Tubes Asylum, Vintage Mullard is one of the best ever (0.00)
Posted by DAK on 2019-09-13, 23:51:33 (72.130.201.211)
Superior materials, precision assembly, excellent sound quality. Nearly all the originals that were in my collectible 1950s, 60s, tubed audio were still good testing. .......
25: Tube DIY Asylum, This amp uses straight 7189 (0.00)
Posted by DAK on 2019-09-11, 11:23:44 (141.239.96.151)
I think this tube is slightly less powerful than the "A" version. So, you think sticking with 300v G2 is a good operating point? .......
26: Tube DIY Asylum, I can't stray far from the design voltages (0.00)
Posted by DAK on 2019-09-10, 19:40:05 (72.130.201.211)
Since the B+ for the voltage amp/phase splitter tube is set by the Plate voltage. I am trying to stay at 400vdc. With 300v on the G2. This would be close to the GE recommendation. I was wondering how .......
27: Tube DIY Asylum, What should my G2 voltage be? (0.00)
Posted by DAK on 2019-09-10, 11:53:19 (141.239.96.151)
I am just through rebuilding a PP 7189 powered amplifier. The voltages ended up as 410vdc B+ , about 400v at the plate. It has fixed bias which i set at 58ma per pair or 29ma each tube. What should i .......
28: Tubes Asylum, RE: Art Audio Vinyl One owners: which 12ax7 variant as a cathode follower? (0.00)
Posted by DAK on 2019-09-04, 23:32:09 (141.239.96.151)
You can read up on CF from the "Valve Wizard". His articles are mostly geared to guitar amps but the principles are the same. .......
29: Tubes Asylum, you can also use 7581 settings (0.00)
Posted by DAK on 2019-08-29, 11:09:52 (72.130.201.211)
In fact all the 6l6 types settings will work in giving you a reasonable result, especially for gas, shorts. You might have to adjust to get the voltage output ("merit") reading to fall within the mete .......
30: Tubes Asylum, No Not really. (0.00)
Posted by DAK on 2019-08-26, 11:26:45 (72.130.201.211)
Are you will do is check the layout. If the unit is not plugged in and has been sitting for over 24 hours, there is no safety hazard even if you touched something. .......
31: Tubes Asylum, If you open the bottom you should be able to..... (0.00)
Posted by DAK on 2019-08-24, 09:47:32 (141.239.96.151)
Knowing that the cathode bias is a measurement of the current of the kt88 power tube while the amp is "idling". If not already done, you can install a 10 0hm resistor to replace the connection to grou .......
32: Tubes Asylum, PT Barnum explains it well (0.00)
Posted by DAK on 2019-08-22, 09:46:31 (141.239.96.151)
"There is a sucker born every minute." Or something like that. If you don't know any better, and without doing any in depth research, one would think by the advertising content and ebay rating that hi .......
33: Tube DIY Asylum, This looks a lot like like an eico hf87/89 schematic (0.00)
Posted by DAK on 2019-08-20, 20:47:10 (72.130.201.211)
Except that classis LTP uses a conventional bypassed resistor in the 6sn7 cathode. If you did not try a resistor on the cathode, instead of the SS device. That may also help to reduce your gain a litt .......
34: Tube DIY Asylum, What circuit are you following? nt (0.00)
Posted by DAK on 2019-08-20, 10:01:10 (72.130.201.211)
. .......
35: Tubes Asylum, Russian . K40y9 (0.00)
Posted by DAK on 2019-08-17, 12:48:02 (72.130.201.211)
I like the PIO types for their slightly smoother sound . .......
36: Tubes Asylum, I have not seen anyone trying to fake that type (0.00)
Posted by DAK on 2019-08-15, 10:07:28 (72.130.201.211)
Usually not that much money in that particular number. About 20 to 30 bucks for NOS. So, i dunno why anyone would want to fake that one. Still available for a decent price if you know where to look. : .......
37: Tubes Asylum, They look to be genuine. (0.00)
Posted by DAK on 2019-08-14, 11:19:23 (72.130.201.211)
I think that Viva tubes are a pretty respectable outfit. .......
38: Tube DIY Asylum, I like ASC better than Solen (0.00)
Posted by DAK on 2019-08-14, 11:15:22 (72.130.201.211)
Plus the ASC can be top mounted on the chassis. The canned Solen are much more expensive and i don't believe their canned caps have oil inside. I am not sure about that though. They are both metallize .......
39: Tube DIY Asylum, RE: Is there a date code on the older ones like Sprague VitQ? (0.00)
Posted by DAK on 2019-08-11, 20:21:56 (72.130.201.211)
The hook up terminals have a ceramic cap. I actually got these caps from Penn State Univ. I guess they're selling off anything to get money to pay for all of the lawsuits. .......
40: Tube DIY Asylum, Is there a date code on the older ones like Sprague VitQ? (0.00)
Posted by DAK on 2019-08-11, 11:48:40 (72.130.201.211)
Are all Sprague "VitaminQ" filled with PCB oil? I got some marked Western Electric, Sprague VitaminQ. They are pretty huge 30 uf x 800vdc or something close to that. .......
41: Tube DIY Asylum, ASC 386 have no PCBs (0.00)
Posted by DAK on 2019-08-10, 10:19:32 (72.130.201.211)
They are essentially a film cap within an aluminum can cooled by vegetable oil. No health hazard at all. It is the old PIO caps that you should avoid. One benefit to the oil bath is it helps to suppre .......
42: Tube DIY Asylum, All recently made ones are . (0.00)
Posted by DAK on 2019-08-10, 10:14:00 (72.130.201.211)
I don't know when the exact year, maybe in the 80s or even earlier, but they substituted vegetable oil or other non toxic oils. .......
43: Tube DIY Asylum, Wow, talk about persistent! (0.00)
Posted by DAK on 2019-08-08, 22:15:12 (141.239.96.151)
But that is faster work, than the state university i work for. Kudos on the build it looks like a killer amp and sure to start a conversation. .......
44: Tube DIY Asylum, Very Nice! can you post a schematic? (0.00)
Posted by DAK on 2019-08-05, 09:53:42 (72.130.201.211)
I would be very interested in your take on a SE 6550 amp. cheers .......
45: Tube DIY Asylum, How hot do the Zs get? (0.00)
Posted by DAK on 2019-08-03, 13:50:31 (72.130.201.211)
I was wondering if you checked the temperature of those parts during operation. .......
46: Tube DIY Asylum, If i needed 290v for G2 (0.00)
Posted by DAK on 2019-08-01, 09:31:12 (72.130.201.211)
in a PP fixed bias 7189 amp, do i need 2 strings of zeners for each channel. And what value of bypass cap do you recommend? Thanks for the help. Dak .......
47: Tube DIY Asylum, So what is the verdict? (0.00)
Posted by DAK on 2019-07-31, 15:34:13 (72.130.201.211)
Hey DT, i am thinking about using zeners in a PP 7189 amp with fixed bias to set the G2 voltage at 290vdc. So, wondering if this method worked for you. Any anomalies such as ear fatigue using the zene .......
48: Tubes Asylum, I don't know about that but.... (0.00)
Posted by DAK on 2019-07-26, 10:23:57 (72.130.201.211)
For the more collectible tubes that test good and have good markings, proper box, etc.. The prices are still higher than i would ever pay. .......
49: Tubes Asylum, RE: Interesting.... (0.00)
Posted by DAK on 2019-07-23, 09:39:28 (72.130.201.211)
I bought an octal socket, with pretty gold plated pins and contacts, that allowed the tube to be inserted more than half way down even though the alignment slot was off. This allowed the tube pins to .......
50: Tubes Asylum, I don't like the Chinese made tube sockets. (0.00)
Posted by DAK on 2019-07-22, 10:12:20 (72.130.201.211)
Very poor manufacturing tolerances. I bought some Cinch awhile ago that are well made. Hopefully i have enough for my projects. .......
51: Tubes Asylum, The problem with Loctals (0.00)
Posted by DAK on 2019-07-20, 09:46:48 (141.239.96.151)
Is finding some good sockets. I am not sure if they are currently made .......
52: Tubes Asylum, The box doesn't matter.... (0.00)
Posted by DAK on 2019-07-17, 15:20:20 (72.130.201.211)
People put all kinds of tubes into boxes. That is why you should never buy a tube with just a picture of the box. You should always insist on a pic of the tube as well. Anyway, the printing on the tu .......
53: Tube DIY Asylum, RE:I am hoping to find an OEM OPT for a Fisher 800 (0.00)
Posted by DAK on 2019-07-17, 15:15:29 (72.130.201.211)
Thank you for the link. I have actually contacted them and may send the original OPT and from that they will reuse the core and end bells to rewind a replacement. Price is not bad just a C note. ::: T .......
54: Tube DIY Asylum, Anyone know where i can get a single OPT for a Fisher 800c? (0.00)
Posted by DAK on 2019-07-16, 19:29:20 (72.130.201.211)
Please LMK if you know where i can buy a single output trans for the Fisher 800c receiver. tyvm .......
55: Tubes Asylum, RE: Sylvania Gold Brand (0.00)
Posted by DAK on 2019-07-16, 09:38:16 (72.130.201.211)
Sylvania GB tubes are a line of selected tubes that presumably meant to compete with the likes of Amperex "PQ" or RCA Command Series. Like FL says the 5963 is a military/industrial type of the 12au7 p .......
56: Tubes Asylum, Nothing shady about gold pins on Sylvania GB tubes (0.00)
Posted by DAK on 2019-07-09, 14:29:49 (72.130.201.211)
The Sylvania "Gold Brand" was their PQ or premium quality tubes. I am not sure who started the "Special" or Select line of tubes, but other manufacturers soon started copying. Maybe the Bendix "Red Ba .......
57: Tubes Asylum, If your unit requires 12ax7/5751 a 6eu7 is not helping (0.00)
Posted by DAK on 2019-07-08, 10:36:18 (72.130.201.211)
Sure you can use do a socket rewire but if you have a vintage piece rewiring the sockets is not an option if you want to keep its value. .......
58: Tubes Asylum, I have a few NOS triple micas (0.00)
Posted by DAK on 2019-07-08, 10:26:07 (72.130.201.211)
I bought them a long time ago when i first started collecting tubes. .......
59: Tubes Asylum, They look like the real thing. (0.00)
Posted by DAK on 2019-07-06, 23:10:33 (141.239.96.151)
Not as desirable as the 3 mica ones. The boxes look like they have been fondled too much so probably not NOS. .......
60: Tube DIY Asylum, RE: Those distortion numbers are decent for SE (0.00)
Posted by DAK on 2019-07-01, 10:45:50 (141.239.96.151)
I would think that your changes are more subtle than heavy handed. But, AK, doesn't like people to riff off of his circuits. There is some kind of cultural differences between the usa and his native a .......
61: Tube DIY Asylum, Those distortion numbers are decent for SE (0.00)
Posted by DAK on 2019-06-30, 09:49:46 (72.130.201.211)
What were the changes made to the rh circuit? .......
62: SET Asylum, I always thought the Dec amps were pricey (0.00)
Posted by DAK on 2019-06-29, 10:46:19 (72.130.201.211)
But, since they are made in the USA i guess that would be a reasonable cost for an established company with recognized products. For their SE amp if you DIY, your cost would be less than a 1/2 for jus .......
63: Tube DIY Asylum, Why not just use the zeners from Plate to G2? (0.00)
Posted by DAK on 2019-06-29, 10:40:24 (72.130.201.211)
I have used that method several times and that works well. I usually string 3 or 4 7 to 12 volt Z together to get the proper G2 voltage. .......
64: Tubes Asylum, Remember to drain the power supply! (0.00)
Posted by DAK on 2019-06-27, 12:14:02 (72.130.201.211)
For continued happiness and lower health costs. .......
65: Tube DIY Asylum, RE: 1958 Hafler Article (0.00)
Posted by DAK on 2019-06-26, 10:02:08 (72.130.201.211)
I dunno, but they chose ceramic for cost not sound quality. .......
66: Tube DIY Asylum, Trolls and Haters... (0.00)
Posted by DAK on 2019-06-26, 09:55:31 (72.130.201.211)
There are always people who believe that their opinion is THE correct point. But, if you can determine the speed difference between electrons going across the elements in a tube vs a transistor throug .......
67: Tube DIY Asylum, Looks like a real amp to me. (0.00)
Posted by DAK on 2019-06-21, 21:14:21 (141.239.96.151)
Components laid out to achieve a fairly straight line from input to output in the amp section with the power supply at the far side. It looks like it is purposely built where sonics are the most impor .......
68: Tubes Asylum, Don't quit your day job (0.00)
Posted by DAK on 2019-06-20, 17:24:43 (141.239.96.151)
None of those tubes are really worth a lot. Only the 5881 is worth maybe 20 bucks? .......
69: Tubes Asylum, Not so precious, precious. (0.00)
Posted by DAK on 2019-06-15, 09:26:48 (72.130.201.211)
Rca 6sn7 are certainly capable tubes. But collector value is usually reserved for the older black glass GT type sn7. Not many GTB types are considered collectible or command a high price. 1940s rca vt .......
70: Tube DIY Asylum, Pardon my ignorance but....what? (0.00)
Posted by DAK on 2019-06-15, 09:13:04 (72.130.201.211)
Obviously a reference to a college football game .......
71: Tubes Asylum, Does anyone know what the guberment paid for any of the Bendix tubes? (0.00)
Posted by DAK on 2019-06-14, 22:13:09 (72.130.201.211)
They are a tube engineer's wet dream. I wonder what the unit cost for any of the red bank tubes was back then???? .......
72: Tubes Asylum, I got some (0.00)
Posted by DAK on 2019-06-14, 08:53:10 (72.130.201.211)
They are much more impressive in person! although, i have not tried them. Sometimes you can get them for cheap. I just wanted to have some for my "Bendix" tube collection. .......
73: Tubes Asylum, Thanks for the correction! nt (0.00)
Posted by DAK on 2019-06-13, 08:34:37 (72.130.201.211)
. .......
74: Tubes Asylum, RE: Mecury model 1000 tester and Bendix tubes?? (0.00)
Posted by DAK on 2019-06-12, 02:11:50 (141.239.96.151)
5992 is 6v6 and 6094 is 6x4? i am not sure about that as i am going by memory. .......
75: Tubes Asylum, Is there really an adapter from 12ax7 to 6sn7? (0.00)
Posted by DAK on 2019-06-10, 10:43:47 (141.239.96.151)
For one thing the amplification factor is like 12 to 100. It seems that difference would be a problem in most circuits. .......
76: Tube DIY Asylum, Where would society be without a spoon to stir the pot? (0.00)
Posted by DAK on 2019-06-10, 10:39:29 (141.239.96.151)
I am not one of JM's followers but I do know that without those that explore the boundaries of what is considered the norm there would be very little innovation. There are many inventions that were "a .......
77: Tubes Asylum, Thanx for the correction Eli! (0.00)
Posted by DAK on 2019-06-04, 22:25:38 (72.130.201.211)
I was going by obviously, faulty memory! That tube is very good and worth the wait from Russia. .......
78: Tubes Asylum, Russian 6p3c-e (0.00)
Posted by DAK on 2019-06-04, 10:21:12 (72.130.201.211)
I believe that is the correct appellation. It is probably the coin based "5881" that is sold. .......
79: Tubes Asylum, 803S are not the same as 5751 (0.00)
Posted by DAK on 2019-06-02, 13:05:58 (141.239.96.151)
Not to be picky but the 803 is a 12ax7 type. Also Mullard and Amperex never really made a 5751 type tube AFAIK. .......
80: Tube DIY Asylum, Hi frequency ringing sounds like a microphonic tube...nt (0.00)
Posted by DAK on 2019-05-30, 01:59:55 (72.130.201.211)
. .......
81: Vintage Asylum, Tube equipment from that era is still relevant (0.00)
Posted by DAK on 2019-05-29, 09:15:27 (72.130.201.211)
Almost any brand of tube equipment will still have some value. Of course the famous ones are more desirable and hence cost more to buy. I have noticed that the high power Japanese SS receivers and amp .......
82: Vintage Asylum, I did not know 5.1 amps are considered vintage (0.00)
Posted by DAK on 2019-05-29, 08:50:23 (72.130.201.211)
I guess it depends on how many years back people would consider vintage means. .......
83: Tube DIY Asylum, RE: What is the bias supply voltage (0.00)
Posted by DAK on 2019-05-22, 17:17:43 (72.130.201.211)
I have not actually run it up to full voltage. The last time i did that i blew up a bias cap. But, that was my bad as i had wired the caps in backwards. I will be doing a full voltage test today to se .......
84: Tube DIY Asylum, After pulling the 4 ax7s the bias voltage came up.. (0.00)
Posted by DAK on 2019-05-22, 13:08:47 (72.130.201.211)
That was a relief to see it at over -2 volts with no load. But, the cold start on the tubes must keep the bias voltage down for the 7591s for a few seconds. I think i will see how long it takes for th .......
85: Tube DIY Asylum, I am not sure about my Fisher 800c bias circuit results (0.00)
Posted by DAK on 2019-05-21, 13:50:21 (141.239.96.151)
Well, i put all the parts in according to the schematic and when i powered it up my voltage results seem low. According to the schematic i should get -22vdc at full power, going to the 4 preamp tube h .......
86: Tube DIY Asylum, No not yet (0.00)
Posted by DAK on 2019-05-18, 10:46:37 (72.130.201.211)
I have been busy with "chores". I have had no trouble with other bias supplies before. This one seems a little backwards imo. Originally, Fisher used a dual can cap which has only 1 negative lead. And .......
87: Tube DIY Asylum, Not a big deal (0.00)
Posted by DAK on 2019-05-15, 09:05:15 (72.130.201.211)
Just gotta replace the bad cap. .......
88: Tube DIY Asylum, I need to recheck the original schematic. (0.00)
Posted by DAK on 2019-05-14, 10:54:58 (72.130.201.211)
I may have copied the symbols wrong. .......
89: Tube DIY Asylum, Why is my first cap blowing up? (0.00)
Posted by DAK on 2019-05-14, 09:18:54 (72.130.201.211)
Working on that bias supply, CRC configuration, for the Fisher 800C and powered it up the 2nd time and my first cap, a new one, blew up at 50vac. It is hooked up correctly, with the negative terminal .......
90: Tube DIY Asylum, It has the same values but i need to check my serial number... (0.00)
Posted by DAK on 2019-05-12, 22:55:52 (141.239.96.151)
Thanks for the kind offer Jim. I will let you know if i need the schematic. Cheers, Dak .......
91: Tube DIY Asylum, I will be using stock values....nt (0.00)
Posted by DAK on 2019-05-11, 10:20:08 (141.239.96.151)
. .......
92: Tube DIY Asylum, Good point! (0.00)
Posted by DAK on 2019-05-10, 20:06:16 (141.239.96.151)
I was trying to figure out a way to put a pot in the line for the output tube bias voltage adjustment, but maybe it is ok with the slightly higher bias voltage. For the bias filter caps i was going to .......
93: Tube DIY Asylum, Thanks for the schematic! (0.00)
Posted by DAK on 2019-05-09, 18:44:24 (141.239.96.151)
It is funny that the schematic posted in the original Fisher Manual has the same parts but drawn in a little different way. I like this schematic better . Since i am using a modern FWBR, i will no dou .......
94: Tube DIY Asylum, Negative bias voltage supply for Fisher 800C (0.00)
Posted by DAK on 2019-05-09, 16:25:19 (141.239.96.151)
I am rebuilding this power supply and it is kinda odd the way fisher decided to implement. Originally it uses a Selenium FWBR, although working it is prudent to change out and a cardboard covered can .......
95: SET Asylum, RE: Fixed Bias and runaway tubes not an issue i"ve encountered (0.00)
Posted by DAK on 2019-05-06, 15:02:33 (72.130.201.211)
I have made quite a few fixed bias amps and i have not personally encountered any failure of the circuit or the adjustment pot which caused tube runaway because of lack of negative voltage. The only i .......
96: SET Asylum, Ideally, you want the safety resistor to give a voltage... (0.00)
Posted by DAK on 2019-05-06, 02:05:59 (141.239.96.151)
... that puts the valve in "shut off" if the pot wiper loses contact. So, the resistor value will also need to be in parallel with the pot value and those 2 values when paralleled will need to fall ab .......
97: SET Asylum, You just add an appropriate resistor across the pot (0.00)
Posted by DAK on 2019-05-05, 09:28:09 (72.130.201.211)
The resistor goes from the negative voltage input to the output of the pot. Therefore, when and if the pot's wiper loses contact, which will result in no bias voltage the resistor will always be suppl .......
98: SET Asylum, I love the understated appearance. (0.00)
Posted by DAK on 2019-05-04, 19:59:35 (141.239.96.151)
Especially the wine bottle cork vibration control! No seriously, a perfect use for an otherwise disposable item under all that glass, steel and copper. Totally feng shui! I wonder is it possible you c .......
99: Tubes Asylum, IDH rectifiers power up slowly is a + over SSR (0.00)
Posted by DAK on 2019-05-03, 08:47:35 (141.239.96.151)
Sometimes this makes them a preference over a Solid state rectifier. I know this is off topic but it is a consideration if you were worried about PS voltages, especially surge voltage. And since diffe .......
100: Tube DIY Asylum, Used tubes are an unknown (0.00)
Posted by DAK on 2019-05-01, 10:57:42 (72.130.201.211)
You can never know if they are noisy, weak, mismatched sections....until you test then listen. It could be a long process. .......
101: Tube DIY Asylum, You have to admire his passion. (0.00)
Posted by DAK on 2019-04-30, 08:52:39 (72.130.201.211)
While i don't subscribe to some of his ideas, I think there are some that are worth pursuing. If we all followed the same ways, we would all end up in the same place. How boring and crowded that would .......
102: Tubes Asylum, Is that just speculation? (0.00)
Posted by DAK on 2019-04-29, 13:26:05 (72.130.201.211)
Unless it is in the tube notes. It is just guesswork .......
103: Tubes Asylum, But they're awfully purdy! nt. (0.00)
Posted by DAK on 2019-04-28, 11:58:07 (72.130.201.211)
. .......
104: SET Asylum, Yes, i have read that. (0.00)
Posted by DAK on 2019-04-28, 11:55:46 (72.130.201.211)
I would like to get something that is more ready to use. .......
105: Tube DIY Asylum, That maybe the death howl of a power tube. (0.00)
Posted by DAK on 2019-04-28, 11:46:45 (72.130.201.211)
If the power tube started to go Fukushima (previously referred to as "Chernobyl"), it will make a very loud hum and other hair raising noises. Also an instability or oscillation in your amp will also .......
106: SET Asylum, Looking for a 10v x 5.0A DC supply (0.00)
Posted by DAK on 2019-04-26, 19:17:56 (72.130.201.211)
I am going to use it for a SE amp. I hear one can also use High Frequency ACV supply. I am not wanting to get anything from a far east supplier and dealing with communication (or lack of) problems. So .......
107: Tube DIY Asylum, RE: I saw made in china on some specs. (0.00)
Posted by DAK on 2019-04-26, 09:42:26 (72.130.201.211)
IIRC, it was on the lower priced PT. I did not check many just one. .......
108: Tube DIY Asylum, I saw made in china on some specs. (0.00)
Posted by DAK on 2019-04-25, 20:16:59 (72.130.201.211)
It was on the low cost unit. I was wondering about the rest of their line. .......
109: Tube DIY Asylum, Are all their trannys made in China? nt. (0.00)
Posted by DAK on 2019-04-25, 08:43:13 (72.130.201.211)
. .......
110: Tube DIY Asylum, Enclosed transformers are usually potted (0.00)
Posted by DAK on 2019-04-21, 13:50:23 (72.130.201.211)
The potting material serves to dampen vibration and also helps to conduct heat to the metal cover to be dissipated. Lots of chifi with enclosed trannys are usually of just the cover type not potted. : .......
111: SET Asylum, RE: Tube ot SS Rectification for 813?? (0.00)
Posted by DAK on 2019-04-13, 09:56:49 (72.130.201.211)
Part of the decision process is determined by your PT. If your PT high tension secondary is a little low say 1000v, a FWBR will bump up the voltage to a level that is close to your needs. If on the oh .......
112: Tubes Asylum, RE: ECC35, They don't make it stateside very often (0.00)
Posted by DAK on 2019-04-08, 10:57:10 (72.130.201.211)
What with the plethora of USA made gty, vt 229, wgt, 5691, etc, etc. Most of the US users would get any of these types which still priced well below the Euro tubes. .......
113: Tubes Asylum, Really, They are just 9 pin minis (0.00)
Posted by DAK on 2019-04-07, 11:23:54 (72.130.201.211)
While i agree with what you believe in a general way. That is, those particular tubes are made with precision and craftsmanship sometimes incorporating special design that is not duplicated by the rea .......
114: Tubes Asylum, Those tubes are so rare are comparisons even possible? (0.00)
Posted by DAK on 2019-04-06, 22:59:29 (72.130.201.211)
It would be one lucky or deep pocketed collected to have all of the variants that you are describing. .......
115: Tubes Asylum, How a tube sounds in a particular piece is highly subjective (0.00)
Posted by DAK on 2019-04-02, 10:42:56 (72.130.201.211)
And due to the interaction between your equipment to the speakers and to the room all the flowery descriptive terms given by NOS tube sellers are just advertising embellishments. That being said, i be .......
116: Tube DIY Asylum, Can you check your scheme with Schade type FB? (0.00)
Posted by DAK on 2019-03-28, 12:01:10 (72.130.201.211)
It would be informative to see what effect plate to plate fb between the kt88 and 12bz7. Most builders use around 200k maybe a little more for the fb resistor. I have built such an amp with 6sl7 and 6 .......
117: Tubes Asylum, Wow! Who knew Kenrad tubes could get you chicks! (0.00)
Posted by DAK on 2019-03-24, 00:36:08 (72.130.201.211)
Obviously, not an ad from "Scouting America". .......
118: Tubes Asylum, Unless the tube is defective, not likely. (0.00)
Posted by DAK on 2019-03-23, 13:12:53 (141.239.96.151)
Maybe a short within the tube elements could cause an huge AC event to manifest at the speaker, but i have not actually seen such a thing. Testing the tubes would verify if there is a bad tube. I wou .......
119: Tube DIY Asylum, RE: SE 6sl7 to 6v6 is a classic circuit.....nt (0.00)
Posted by DAK on 2019-03-16, 22:45:41 (141.239.96.151)
, .......
120: Tube DIY Asylum, I installed VitaminQ 118P (0.00)
Posted by DAK on 2019-03-14, 03:13:50 (72.130.201.211)
They seem to be mostly neutral in their effect on sound. .......
121: Tubes Asylum, If they are NOS what happened to the original boxes? (0.00)
Posted by DAK on 2019-03-11, 18:30:28 (72.130.201.211)
They certainly did not come in white boxes. It seems the seller is not giving you the whole story. .......
122: Tubes Asylum, Yeah, but how long will it sound good??????????? (0.00)
Posted by DAK on 2019-03-11, 17:43:36 (72.130.201.211)
IME, chinese 12ax7 can sound good for a month or 2 and then they start to sound kind of tired. Like a sprinter they can start strong but start to fade after putting in some distance. .......
123: Tubes Asylum, I think those are GE 5751. (0.00)
Posted by DAK on 2019-03-11, 17:36:56 (72.130.201.211)
Did the tube seller mention that those tubes have gold pins? The picture doesn't look like they have gold plated pins. Sometimes you can manipulate the colors of the digital pics to enhance yellows gi .......
124: Tubes Asylum, Your issue may not be tubes (0.00)
Posted by DAK on 2019-03-10, 17:13:38 (72.130.201.211)
those odd noises are more like bad electrolytic caps. .......
125: Tubes Asylum, RE: Is there such a thing as a "slow" tube? (0.00)
Posted by DAK on 2019-03-08, 10:41:25 (72.130.201.211)
I won't say testers cant' be trusted but they are only a guide to a tube's health. Only in circuit will you be able to know for sure how good a tube is. Also like vintage tube audio, they need to be r .......
126: Tubes Asylum, RE: Is there such a thing as a "slow" tube? (0.00)
Posted by DAK on 2019-03-07, 08:10:26 (72.130.201.211)
IME, weak tubes can conduct more after warming up. The cathode needs to get hot before releasing electrons. In some testers the "short" indicator light needs to be steady on to indicate a defect. Not .......
127: Tubes Asylum, I am glad that there is support (0.00)
Posted by DAK on 2019-03-06, 08:28:11 (72.130.201.211)
Although i dont use that tube it is my hope that they can have a successful company. And ever since they announced the release of made in usa Western Electric tubes the internet has been full of gossi .......
128: Tubes Asylum, OTK is russian military designation (0.00)
Posted by DAK on 2019-03-04, 08:29:38 (72.130.201.211)
It is a Russian tube, OTK means that it was accepted for military use. .......
129: Tubes Asylum, They are Russkie tubes (0.00)
Posted by DAK on 2019-03-03, 08:33:27 (72.130.201.211)
The ufo shaped getters are a dead giveaway. Although the etched glass marking is what a GE tube would look like. The GE logo is not correct, that should be painted on. Reporting this kind of counterfe .......
130: Tubes Asylum, Maybe an RFT ecc83? (0.00)
Posted by DAK on 2019-03-02, 20:48:51 (72.130.201.211)
You know the short plate ones. Some of their tubes were branded Tfunk. but, if no diamond stamp it is not made by Tele. .......
131: Tubes Asylum, RE: I have done some pin resoldering making octal umbilicals (0.00)
Posted by DAK on 2019-03-01, 21:21:27 (141.239.96.151)
The important thing is to have a very hot iron and hopefully a piece of the tube element wire poking thru the hollow pin. Heating up the pin and the wire makes the solder wick right into the cavity. A .......
132: Tube DIY Asylum, Especially if the kit is from China.... nt (0.00)
Posted by DAK on 2019-03-01, 21:15:01 (141.239.96.151)
. .......
133: Tubes Asylum, Oh yeah, tube porn! nt (0.00)
Posted by DAK on 2019-02-27, 12:39:23 (72.130.201.211)
. .......
134: Tubes Asylum, That is normal (0.00)
Posted by DAK on 2019-02-27, 12:32:26 (72.130.201.211)
As the amp warms usually the initial bias voltage decreases a little. You are only talking .06 volts which is not much. But you should see the number stabilize and not drift lower. If the number doesn .......
135: Tube DIY Asylum, I turned a Harman Kardon A500 into an amp (0.00)
Posted by DAK on 2019-02-26, 23:04:25 (141.239.96.151)
It was because of a problem in the preamp section that was just to hard to pin down. I cut off the mounting tabs for the faceplate and just used the amp section. It sounded really good that way ::: TO .......
136: Tubes Asylum, Most bias pots are 25 to 50k (0.00)
Posted by DAK on 2019-02-20, 08:05:47 (72.130.201.211)
In order to have an adequate adjustment range. .......
137: Tubes Asylum, A lot of pots have its value as part of the part number (0.00)
Posted by DAK on 2019-02-19, 19:36:50 (72.130.201.211)
But it is easy to measure the resistance like CB says. You might have to lift the wire that connect to the bias cap/s to get a stable reading. .......
138: Tubes Asylum, For me i am more concerned with how it performs (0.00)
Posted by DAK on 2019-02-18, 10:59:35 (72.130.201.211)
A tube tester is not going to give you the whole story. I found tubes that test good but not sound good. Also tubes that test mediocre but sound fine. But initially, a tube tester at least gives you s .......
139: Tube DIY Asylum, Thanx Buffy, you da man! nt. (0.00)
Posted by DAK on 2019-02-13, 21:57:07 (141.239.96.151)
. .......
140: Tube DIY Asylum, The RCA tube manual gives no info on triode mode (0.00)
Posted by DAK on 2019-02-13, 09:48:05 (72.130.201.211)
But in pentode the manual says, "Because of its high power sensitivity, the 813 requires very little driving power to give full power output." Although, i recall running across somebody drew load line .......
141: Tube DIY Asylum, Big difference on input sensitivity (0.00)
Posted by DAK on 2019-02-12, 18:44:28 (72.130.201.211)
The amount of drive you need for the 845 is way more than for an 813. .......
142: Tube DIY Asylum, Aren't the 813 load lines non linear at the voltage? nt (0.00)
Posted by DAK on 2019-02-10, 23:08:13 (141.239.96.151)
. .......
143: Tubes Asylum, Is that true for other tubes as well? (0.00)
Posted by DAK on 2019-02-05, 09:08:21 (72.130.201.211)
I know that there are some vintage triodes that have a mesh around the tube. Are these tubes also using a screen? If yes doesn't that screen need to be grounded? .......
144: Tubes Asylum, Amperex ef86 mesh plate, Telefunken solid plate, Why? (0.00)
Posted by DAK on 2019-02-04, 23:54:29 (141.239.96.151)
Like in the EF86/6267, i believe Amperex used mesh plate and most other brands were solid plate. There must have been some reason for the choice by Amperex for mesh plate. .......
145: Tubes Asylum, Mesh plate tubes, what is the difference.. (0.00)
Posted by DAK on 2019-02-03, 09:26:31 (72.130.201.211)
.. between that and regular metal plate tubes. I mean, why the difference in construction. Is there an advantage or a disadvantage? Thanks for your comments. .......
146: Tube DIY Asylum, Thank you for sharing! (0.00)
Posted by DAK on 2019-02-01, 15:10:52 (141.239.96.151)
I am going to copy it in my book of schematics. It looks very much like some of the SE amps i make with beam pentodes, but using anode to anode feedback resistor. .......
147: Tubes Asylum, I meant the vintage ones. (0.00)
Posted by DAK on 2019-02-01, 08:46:51 (72.130.201.211)
They sound better than any other types in my SE amp. .......
148: Tube DIY Asylum, I like checking out different schematics (0.00)
Posted by DAK on 2019-02-01, 08:31:08 (72.130.201.211)
It maybe something i would like to try. And it gives me ideas about building that i have not tried. For me looking at different schematics is like a book of classic cars. Anyway, if you could i would .......
149: Tube DIY Asylum, Is it possible to post the schematic? (0.00)
Posted by DAK on 2019-01-31, 19:25:13 (72.130.201.211)
I was thinking of using a paralleled 6sl7 as a driver tube in a SE application. cheers, Dak .......
150: Tube DIY Asylum, RE: Plate resistance is halved and transconductance is doubled (0.00)
Posted by DAK on 2019-01-31, 16:24:16 (72.130.201.211)
Good to know. thank you. .......
151: Tubes Asylum, RE: I wish you could find good Tesla and Siemens of this era. (0.00)
Posted by DAK on 2019-01-31, 16:12:13 (72.130.201.211)
The vintage Tesla, seems to be almost used up and getting super rare. Siemens/RFT can be found NOS but the price is ridonkulous. The "dimple top" was one of my faves so i stashed a bunch. Someone sell .......
152: Tube DIY Asylum, Are there not other considerations? (0.00)
Posted by DAK on 2019-01-31, 15:34:03 (72.130.201.211)
Besides the rewiring of the pins. For example, since the plate resistance is halved, should the plate resistors be changed? Also the grid to ground resistor/s? .......
153: Tube DIY Asylum, I removed it (0.00)
Posted by DAK on 2019-01-30, 09:27:31 (72.130.201.211)
It did not work well there so i put the CL80 on the primary. BTW, what is TN-S? .......
154: Tubes Asylum, When i was into EL34 i did extensive listening tests (0.00)
Posted by DAK on 2019-01-29, 08:57:11 (72.130.201.211)
with my completely rebuilt EICO HF89. I found the prewar Tesla el34 to be very close to original Mullard welded plates. And the Siemens to be just a tad behind that. But, the Siemens/RFT were very rob .......
155: Tubes Asylum, You need to at least let the amp break in. (0.00)
Posted by DAK on 2019-01-29, 08:47:19 (72.130.201.211)
In a new amp if you change out the tubes too soon you won't get a chance to get a sense of what your amp sounds like with your reference recordings. It seems logical to use the original tubes for brea .......
156: Tubes Asylum, Overall i like the 6l6 and 6l6g (0.00)
Posted by DAK on 2019-01-29, 08:37:46 (72.130.201.211)
But, those tubes can not be used in amps with plate voltages over 400v. For high voltage amps, what FL says is my experience as well. But if you have the money you might also check out KT66 and EL37. .......
157: Tube DIY Asylum, DBK, is right, chuck that pentode (0.00)
Posted by DAK on 2019-01-28, 08:45:11 (72.130.201.211)
To achieve even more triode goodness, lose that extra grid which is just getting in the way, and go to a real triode. .......
158: Tubes Asylum, Bill, everytime you touch this tube, something blows up! (0.00)
Posted by DAK on 2019-01-21, 08:13:44 (141.239.96.151)
nt. .......
159: Tubes Asylum, Thanks for the info (0.00)
Posted by DAK on 2019-01-15, 17:41:02 (141.239.96.151)
I was wondering if there was any difference to justify the different designation but it seems to make sense that if they did not want to make a different jig for the 5v4 that they would just redesigna .......
160: Tubes Asylum, Sylvania 5V4GA big plates (0.00)
Posted by DAK on 2019-01-15, 16:21:37 (72.130.201.211)
This tube seems to be similar in design to the 5ar4 version. Does anyone know if they are built to different specs like most 5v4ga vs 5ar4 ? .......
161: Tubes Asylum, It is a private sale. (0.00)
Posted by DAK on 2019-01-10, 07:30:04 (72.130.201.211)
So the seller can charge whatever he wants. but AR would put an extra step or 2 when selling their product over the regular item. Whether that is worth the extra money , i can't say. .......
162: Tube DIY Asylum, So, 1 or 2 units? (0.00)
Posted by DAK on 2019-01-09, 18:22:17 (141.239.96.151)
Should i put 1 on each leg or ? I measured the voltage rise on another amp and it was about 4 or 5 seconds to reach full voltage with a little bit of an overshoot. This was with the cl on the primary .......
163: Tube DIY Asylum, Putting a CL or 2 on the high voltage secondary? (0.00)
Posted by DAK on 2019-01-09, 12:19:14 (72.130.201.211)
I read that some people do this. I usually put the CL on the AC primary one on each leg. Putting it on the secondary has the advantage of allowing the heaters to come up unimpeded while the high volta .......
164: Tube DIY Asylum, Thanks Paul. (0.00)
Posted by DAK on 2019-01-08, 20:57:45 (72.130.201.211)
that seems like an easy enough thing to do. I will try to get them installed and report back. regards, Dak .......
165: Tube DIY Asylum, How would you implement them? (0.00)
Posted by DAK on 2019-01-08, 07:36:45 (72.130.201.211)
do you know of any circuits that show their use? thanks for the help .......
166: Tube DIY Asylum, RE: What about as a cathode load for a 6sl7? (0.00)
Posted by DAK on 2019-01-06, 18:08:48 (72.130.201.211)
Or similar tube requirement. I have not tried something like that. .......
167: Tube DIY Asylum, What were these little trannies made for? (0.00)
Posted by DAK on 2019-01-06, 14:27:49 (72.130.201.211)
An audio buddy gave me a pair of these UTC O 13 ouncer inductors. They have specs of 300/50hys 0/3ma . I believe DCR is 6000 ohms. Thanks for sharing. .......
168: Tube DIY Asylum, Very nice! (0.00)
Posted by DAK on 2019-01-06, 12:13:01 (72.130.201.211)
What are the eyelets made of, and how did you set them? I have made my own with terminal posts mounted similar to your design. .......
169: Tubes Asylum, I am not so sure (0.00)
Posted by DAK on 2019-01-03, 10:03:13 (72.130.201.211)
" For practical purposes though. Vacuum tubes were no longer employed after 1967. But I assume I have no way to prove that officially as the government would want to know, why, I want to know." I am p .......
170: Tubes Asylum, Thanks, i will check and see. nt. (0.00)
Posted by DAK on 2019-01-01, 17:47:39 (72.130.201.211)
. .......
171: Tubes Asylum, RE: What is the primary impedance for SE OPT for 6ar6 (0.00)
Posted by DAK on 2019-01-01, 16:55:18 (72.130.201.211)
I have a 3k 15watt tranny that i was hoping to use, but that doesn't seem like a good fit. .......
172: Tubes Asylum, RE: What is the primary impedance for SE OPT for 6ar6 (0.00)
Posted by DAK on 2019-01-01, 15:47:45 (141.239.96.151)
Yeah, that is my fall back position. I wanted to find some manufacturer information. I would appreciate a citing if you know of one. cheers, Dak .......
173: Tubes Asylum, What is the primary impedance for SE OPT for 6ar6 (0.00)
Posted by DAK on 2019-01-01, 13:56:24 (141.239.96.151)
I was thinking of building an amp using 6384 Bendix output tube. Thanks for the help and a happy new year to all. cheers, Dak .......
174: Tube DIY Asylum, RE: UL or Pentode? (0.00)
Posted by DAK on 2019-01-01, 02:01:06 (141.239.96.151)
To me Pentode mode seems to be more visceral and dynamic. If i have an UL OPT, i hook it up first as an easy way to do testing and then make the G2 supply and try that. .......
175: Tube DIY Asylum, RE: "inexpensive" is relative (0.00)
Posted by DAK on 2018-12-31, 10:46:34 (72.130.201.211)
I mostly prefer pentode mode. While UL is simpler i prefer the sound from a pentode stage. Are you considering implementing this circuit. It would be interesting to see it and what it sounds like vs a .......
176: Tube DIY Asylum, "inexpensive" is relative (0.00)
Posted by DAK on 2018-12-31, 10:24:21 (72.130.201.211)
Noting the date of printing, i guess UL OPT must have been way more expensive than normal PP OPT back then. That is a lot more circuitry to add on to a normal output stage just to enjoy some "UL" expe .......
177: Tube DIY Asylum, It was a very large chassis. (0.00)
Posted by DAK on 2018-12-29, 11:22:07 (72.130.201.211)
Much larger than the SCA35 which the circuit was made for. The B+ is from dual 5v4gb rectifiers so a slow startup would help the high voltage spike. So its a mystery. Maybe, soldering damaged the unit .......
178: Tube DIY Asylum, I tried that circuit but the SS device failed. (0.00)
Posted by DAK on 2018-12-29, 09:15:57 (72.130.201.211)
I followed the recipe and had the lm337 mounted on the chassis with an insulator and after a couple of weeks it failed. Dunno why. Maybe a voltage spike. It was an amp that i built for an audio buddy .......
179: Tubes Asylum, Can you post your circuit of this SE amp? (0.00)
Posted by DAK on 2018-12-28, 11:15:59 (72.130.201.211)
I have a handful of these tubes and was wanting to give them a chance at some amp duty. I would appreciate a chance to look your circuit over. .......
180: Tubes Asylum, The tubes in your preamp are rather generic (0.00)
Posted by DAK on 2018-12-25, 15:51:18 (72.130.201.211)
There is nothing wrong with that! Obviously, the equipment designers had to deal with what was available as far as tubes were concerned. Since the stock tubes are mil spec type, they were ordered by t .......
181: Tubes Asylum, Many , many, direct substitutes (0.00)
Posted by DAK on 2018-12-25, 11:20:10 (72.130.201.211)
The 6189 is an industrial 12au7. You have lots of different choices. I feel that the European types are the best sounding. Of the USA brands if you can find some NOS 5814 enjoy a good reputation. Ther .......
182: Tube DIY Asylum, 6c4 are plentiful ...nt (0.00)
Posted by DAK on 2018-12-24, 09:58:44 (72.130.201.211)
. .......
183: Tube DIY Asylum, RE: 6EM7 . it has 2 separate grids (0.00)
Posted by DAK on 2018-12-19, 10:00:04 (72.130.201.211)
Pin 1 grid 2 , pin 4 grid 1. .......
184: Tubes Asylum, Checkout the Schematic. (0.00)
Posted by DAK on 2018-12-16, 19:57:11 (72.130.201.211)
If i am not mistaken the DC for the filament is parallel series. So the boards are in parallel while the 2 tubes are in series. .......
185: Tube DIY Asylum, RE: Airbus is multi-national company (0.00)
Posted by DAK on 2018-12-10, 22:42:03 (72.130.201.211)
Unless Airbus got a variance for using leaded solder then ISO 9001 requires lead free solder. Seems like keeping an jet airliner flying would be an important consideration if the solder was subject to .......
186: Tube DIY Asylum, I wonder if it was no lead solder. (0.00)
Posted by DAK on 2018-12-10, 20:38:03 (72.130.201.211)
If i am correct NASA and the military still require leaded solder in electronics because of leaded solder being more "pliable" and not as brittle as unleaded solder among other reasons. .......
187: Tubes Asylum, The 12AX7 print looks suspicious (0.00)
Posted by DAK on 2018-12-09, 11:57:11 (141.239.96.151)
Reminds me of the rebranded tubes which appeared in the 70s and 80s when real stock ran out and tube sellers marked compatible tubes as a certain type because they would "work" in the same circuit. Li .......
188: Tubes Asylum, They look like RCA 5965 (0.00)
Posted by DAK on 2018-12-09, 08:48:17 (72.130.201.211)
They have the same folded plate with 2 staples. Mine do not have the top mica spacer but it could be that earlier models of that tube had them. Who did you get the tubes from? .......
189: Tube DIY Asylum, Outgassing is not necessarily a vacuum problem (0.00)
Posted by DAK on 2018-12-08, 20:35:16 (141.239.96.151)
The 2 tubes in the photo are Bendix 5992, probably the most expensive 6v6 type you can buy. Anyway, outgassing can occur when the tube elements are heated and some gases are released by the tube eleme .......
190: Tubes Asylum, Maybe discontinued? (0.00)
Posted by DAK on 2018-12-05, 09:45:25 (72.130.201.211)
Sometimes the run of a certain color glass is limited. But i would think the internal structure would be the same. .......
191: Tubes Asylum, The Bell 6060 is a rare bird (0.00)
Posted by DAK on 2018-12-04, 13:34:35 (72.130.201.211)
On mine the original tubes were Siemens/RFT. I have one in my storage that i bought over 20 years ago and have not used it. I don't even remember if i have rebuilt it. The one thing i know i did not l .......
192: Tubes Asylum, I am just saying that could be a factor (0.00)
Posted by DAK on 2018-12-04, 13:20:33 (72.130.201.211)
The clear top 12au7 does have a reputation that has been promoted by some. The structure of the rca au7 is typical of the brand with long ladder type gray plates except the getter on the side. I used .......
193: Tube DIY Asylum, Look at this pic, it appears more localized (0.00)
Posted by DAK on 2018-12-04, 12:43:38 (72.130.201.211)
5992 tubes .......
194: Tube DIY Asylum, RE: Blue glow (0.00)
Posted by DAK on 2018-12-04, 11:53:17 (72.130.201.211)
Is that the reason my 5992 have that blue glow? .......
195: Tubes Asylum, Bendix tubes have a lot more mass (0.00)
Posted by DAK on 2018-12-04, 10:08:58 (72.130.201.211)
They used ceramic spacers to hold the plate structure, like the 6384. This added a lot of mass. A Bendix tube from the aerospace line, weighs at least twice as much as a normal mica spacered tube. .......
196: Tubes Asylum, RE: Interesting about added mass to the anode plates. (0.00)
Posted by DAK on 2018-12-04, 08:42:12 (72.130.201.211)
Well, the physics is undeniable but i have not come across any studies. In comparing the various forms of military 6sn7 and 6sl7 types you can see various ideas which were acceptable. Sylvania 6sl7wgt .......
197: Tubes Asylum, RE: FYI on an RCA clear top the getter is attached to the plate! (0.00)
Posted by DAK on 2018-12-04, 07:33:37 (72.130.201.211)
It is not only the rca 12au7, many other tubes with side getters use that spot weld method to attach the getter. As for the mass loading i was just spit balling ideas, so i have not read anything abou .......
198: Tubes Asylum, FYI on an RCA clear top the getter is attached to the plate! (0.00)
Posted by DAK on 2018-12-03, 14:17:37 (72.130.201.211)
I have one in front of me as i write this and FL photo clearly shows the getter ring spot welded to the plate. i also know that GE clear top 6sn7 uses this method as well. Tungsol 6550 with side gette .......
199: Tubes Asylum, There could be a reason why a cleartop has a "different" sound (0.00)
Posted by DAK on 2018-12-03, 10:02:52 (72.130.201.211)
Mounting the getter or getters on the plates would have an effect on the resonance of the plate. This is a well known fact and may have a sonic impact. There is also the mass loading effect the additi .......
200: Tubes Asylum, RE: Which 6CA7 or EL34? (0.00)
Posted by DAK on 2018-12-01, 07:54:02 (72.130.201.211)
I always like the Siemens dimple top. Which is also sold under other brands as well, like RFT. Downside is they are kinda pricey. But by all accounts most of the currently available brands are perfect .......
201: SET Asylum, Get some efficient speakers. (0.00)
Posted by DAK on 2018-11-28, 10:52:43 (141.239.96.151)
Unless you are going to get into vinyl a preamp is mostly for switching sources and to help bring your signal to the amp up to a level that yields full output and to drive long interconnects. So, depe .......
202: Tube DIY Asylum, Nice! (0.00)
Posted by DAK on 2018-11-27, 10:40:33 (141.239.96.151)
Does the motor have the same torque as the corded type? .......
203: SET Asylum, Don't neglect custom made amps. (0.00)
Posted by DAK on 2018-11-23, 11:44:16 (141.239.96.151)
An amp made by a custom builder can be a diamond in the rough. Custom builders have many advantages over the commercial guys and will usually give you more amp for your dollar. It is hard to find the .......
204: SET Asylum, RE: Advise on SET + single driver setup (0.00)
Posted by DAK on 2018-11-17, 10:37:49 (72.130.201.211)
You know almost everyone started like you, with simple push pull amps and moderately efficient speakers. And woe to you if you subscribed to mags like Stereophile where the flavor of the month can lea .......
205: Tubes Asylum, Cary Audio uses them , lots of them (0.00)
Posted by DAK on 2018-11-17, 00:14:41 (141.239.96.151)
In a lot of their equipment both amps and preamps. I use an AE3 and AE1 preamp. The only bad thing is that the tubes are probably chinese or russian in origin. .......
206: Tubes Asylum, RE: tube damper for EL34/KT77, maybe not necessary. (0.00)
Posted by DAK on 2018-11-17, 00:06:05 (141.239.96.151)
If your power tube has microphonic problems, then probably they should be replaced. There are large military tube shield/dampers that are somewhat rare but are more scientifically designed than an O r .......
207: Tubes Asylum, Pre mid 1950s it was the signal tube of choice. (0.00)
Posted by DAK on 2018-11-15, 12:12:34 (72.130.201.211)
When home audio started to take off, most manufacturers went to 9 pin noval tubes which cost less and the sockets were cheaper. Also one could brag about having the "latest technology", which were 9 p .......
208: Tubes Asylum, Just referring to the brand.....nt (0.00)
Posted by DAK on 2018-11-13, 16:44:55 (72.130.201.211)
. .......
209: Tube DIY Asylum, You can use a dremel tool and file (0.00)
Posted by DAK on 2018-11-13, 10:24:10 (72.130.201.211)
That is what i do. I have a socket that i removed the metal solder tabs so i can trace the outline of the socket onto the chassis. Then i use a cutoff blade on my Dremel. There are some corners that a .......
210: Tubes Asylum, RE: Mullard xf4 info (0.00)
Posted by DAK on 2018-11-12, 18:20:27 (72.130.201.211)
The later made mullard el34 have stapled plates. These are considered less desirable than the earlier versions. I have lots of early version Mull el34 and a few of the later ones and i don't know if t .......
211: Tube DIY Asylum, RE: Plate load resistors and B+ voltage (0.00)
Posted by DAK on 2018-11-04, 15:06:42 (72.130.201.211)
The difference between the 2 values are only 2%!!! that number for tube circuits is a non issue as most values are specified to be far more than that. .......
212: Tubes Asylum, That is why i specified pre war KT90. (0.00)
Posted by DAK on 2018-11-01, 14:01:02 (72.130.201.211)
It is somewhat difficult to find these tubes. But, prices are not as bad as original UK made KT88. I use the KT120 in my SE amps and they are very good too, and certainly more available than the origi .......
213: Tubes Asylum, KT90 (0.00)
Posted by DAK on 2018-10-31, 12:23:07 (72.130.201.211)
Original KT90 pre Balkan war, are one of the best power tubes of that group. In power amps that usually eat 6550 or KT88 they loaf along. Sound quality is right there with vintage 88s. KT120 are good .......
214: Tube DIY Asylum, Why the large cap in the fb loop? (0.00)
Posted by DAK on 2018-10-30, 09:15:14 (72.130.201.211)
I thought maybe it was a typo or should be grounded instead of in line. Also the 6sl7 would be just a test as you would not need to change anything in the circuit to make it work, although not optimal .......
215: Tube DIY Asylum, Try a 6sl7 instead of a 6sn7 (0.00)
Posted by DAK on 2018-10-29, 20:45:32 (72.130.201.211)
The feedback resistor of 220K goes well with the 6sl7 in a 6l6 SE amp that i built a while back. It is roughly the same design as yours. Also for more gain, i also made an amp with LED biased 6sl7. th .......
216: Tube DIY Asylum, As the song says, the things you do for love....nt (0.00)
Posted by DAK on 2018-10-27, 23:15:58 (72.130.201.211)
. .......
217: Tube DIY Asylum, RE: Chassis choice.... (0.00)
Posted by DAK on 2018-10-27, 09:02:22 (72.130.201.211)
Steel can support much more weight per given thickness. And it is easy enough to work with a hole punch or step drill. Also easier to paint than aluminium. .......
218: Tube DIY Asylum, Hum cancelling tap? (0.00)
Posted by DAK on 2018-10-25, 22:32:14 (72.130.201.211)
How does that work? In terms of resistance between the 3 primary taps. Since the #1 tap was connected to a 2W 1.2K resistor which seems like a voltage dropping resistor for the screen grid. So, i thou .......
219: Tube DIY Asylum, RE: There is still tons of audio tube stuff here , stateside. (0.00)
Posted by DAK on 2018-10-24, 18:44:28 (72.130.201.211)
I feel that vacuum tubes are a pretty good investment. The value is always appreciating as long as one tries to sell during good economic times. They are fairly easy to lug around. Unlike lps and equi .......
220: Tube DIY Asylum, That price is not representative of sale price (0.00)
Posted by DAK on 2018-10-24, 12:18:09 (72.130.201.211)
If you go "advanced search" and check completed listings you can have a better idea of the range of sale prices. .......
221: Tube DIY Asylum, That seller is in Japan! (0.00)
Posted by DAK on 2018-10-24, 12:15:39 (72.130.201.211)
Maybe a "regular" price for them. Anyway, not the place to buy USA made tubes. .......
222: Tube DIY Asylum, For a Mac, why would you not want some USA tubes? (0.00)
Posted by DAK on 2018-10-23, 11:35:09 (72.130.201.211)
Just to keep it looking original GE or RCA 6l6gc, 7581 or 7027 would be the original choices. .......
223: Tube DIY Asylum, Nice to hear from you and nice amp. nt. (0.00)
Posted by DAK on 2018-10-20, 12:39:36 (72.130.201.211)
. .......
224: Tube DIY Asylum, They are weak (0.00)
Posted by DAK on 2018-10-16, 10:32:41 (72.130.201.211)
Tubes also get noisy when they are weak and ready to be replaced. .......
225: Tube DIY Asylum, RE: It could be a screen grid tap. (0.00)
Posted by DAK on 2018-10-16, 02:15:40 (72.130.201.211)
The 1.2K resistor connected the tap at 1 to an unused solder lug which had a wire that connected to ????? That is how i received the trannys. They were both hooked up that way. .......
226: Tube DIY Asylum, It could be a screen grid tap. (0.00)
Posted by DAK on 2018-10-15, 22:47:05 (72.130.201.211)
There originally was a 1.2K 2w resistor from this tap to an open tap which could have been to the screen. But i also read that this was for ccathode feedback too. .......
227: Tube DIY Asylum, It is not a center tap for a PP pair. (0.00)
Posted by DAK on 2018-10-15, 17:04:21 (72.130.201.211)
If it were a PP output trans the resistance between the 2 output tube taps would be very close, almost the same. As my measurement shows this is not the case. .......
228: Tube DIY Asylum, What is this output trans tap for? (0.00)
Posted by DAK on 2018-10-15, 14:43:20 (72.130.201.211)
I got some Norelco Transformers many years ago. They are single ended with solder lug connections, supposedly for el84 outputs. I bought the units off of someone so just taking the sellers word. I did .......
229: Tubes Asylum, Call that one a classic tube is marketing hype. nt (0.00)
Posted by DAK on 2018-10-14, 16:33:18 (72.130.201.211)
/ .......
230: Tube DIY Asylum, Right, further discussions would have been through PM. nt (0.00)
Posted by DAK on 2018-10-14, 16:26:38 (72.130.201.211)
. .......
231: Tube DIY Asylum, Ok, thought you were trying to make a pair...nt. (0.00)
Posted by DAK on 2018-10-14, 12:06:11 (72.130.201.211)
; .......
232: Tube DIY Asylum, I think i might have one. (0.00)
Posted by DAK on 2018-10-14, 00:47:59 (72.130.201.211)
would you be interested in buying it if i can find it. I may have sold it but i may have not. .......
233: Tubes Asylum, RE: Siemens frame grid e83cc original Siemens made not TFK made (ecc803s) (0.00)
Posted by DAK on 2018-10-13, 10:31:33 (72.130.201.211)
Do they have the SH markings? They should be superior to standard wound grid type ecc83. I think i have some Tele and Tesla frame grid e83cc but i don't use that type in my equipment now. I prefer 6sn .......
234: Tubes Asylum, I have not heard of that tube before (0.00)
Posted by DAK on 2018-10-13, 10:27:30 (72.130.201.211)
If they are going to call it a "classic" then it has to be a tube that was well regarded in the past. I am no expert but i am a tube collector and it seems that one has avoided my radar. .......
235: Tube DIY Asylum, I like Sanyo Oscon (0.00)
Posted by DAK on 2018-10-11, 22:22:14 (72.130.201.211)
But seriously, Nichicon Muse, Elna Cerafine, Phillips LL, etc. They all are very good and really not that expensive. But it would be worthwhile to experiment with trying the LED biasing, also bypassin .......
236: Tubes Asylum, I think it was just a marketing thing for Amperex (0.00)
Posted by DAK on 2018-10-11, 09:42:59 (72.130.201.211)
Probably just to distinguish their audio tubes. I don't think it was a special line of tubes from their audio types. Did someone buy the rights to that "brand name"? .......
237: Tube DIY Asylum, You might be able to loosen the tension on the shaft (0.00)
Posted by DAK on 2018-10-07, 10:16:40 (72.130.201.211)
Probably if you put a drop of machine oil on the shaft and rotate them thru its rotation a bunch of times it will get a lot looser. .......
238: Tubes Asylum, I meant the Ericson 12by7 nt (0.00)
Posted by DAK on 2018-10-06, 09:31:53 (141.239.96.151)
The 33S30B is like the RCA red base 5692. But not red base. .......
239: Tubes Asylum, RE: Any chance getting a pic? nt (0.00)
Posted by DAK on 2018-10-05, 09:10:01 (72.130.201.211)
. .......
240: Tube DIY Asylum, RE: Amp Project (0.00)
Posted by DAK on 2018-10-04, 09:30:41 (72.130.201.211)
What kind of amp, tube line up, are you thinking of building? Do you have a particular circuit and transformers you wish to use? .......
241: Tubes Asylum, Yours might be a rebrand. (0.00)
Posted by DAK on 2018-10-02, 21:23:09 (72.130.201.211)
They did not make too many, afaik. I think they specialized in communication type tubes. .......
242: High Efficiency Speaker Asylum, I usually have the opposite problem with my Altec 19 (0.00)
Posted by DAK on 2018-10-02, 09:44:34 (72.130.201.211)
I make my own Single Ended amps. And i am usually facing too much high frequency energy. I have turned down the high frequency control too. I installed a pf cap across the feedback resistor in the amp .......
243: SET Asylum, RE: Speaking of KVs...building a HV power supply. (0.00)
Posted by DAK on 2018-10-01, 09:13:16 (72.130.201.211)
I have very efficient speakers but I just want to build something that is challenging and will be more of a legacy type of amp. Something the grand kids will look at and say, gramps was off the hook, .......
244: SET Asylum, Holy crap those 833s look like Coleman Lanterns! (0.00)
Posted by DAK on 2018-10-01, 09:03:39 (72.130.201.211)
I did not realize those tubes were so big. Unless you see them in reference to other everyday objects. .......
245: SET Asylum, That is what the scheme calls for. nt. (0.00)
Posted by DAK on 2018-09-29, 11:24:44 (72.130.201.211)
. .......
246: SET Asylum, Thanks Max! (0.00)
Posted by DAK on 2018-09-29, 09:32:28 (72.130.201.211)
First had info is always the best. cheers .......
247: SET Asylum, Speaking of KVs...building a HV power supply. (0.00)
Posted by DAK on 2018-09-28, 18:49:26 (72.130.201.211)
I am researching to build a 1000VDC PS and wanted to know if there are any references that may help me along. Obviously #1 is to prepare a will and a note on where to look for me if i don't turn up fo .......
248: Tube DIY Asylum, I have not tried the chifi teflon sockets. (0.00)
Posted by DAK on 2018-09-28, 08:47:54 (72.130.201.211)
They seem to be much more carefully made than the cheap ceramic ones. .......
249: Tube DIY Asylum, Thanks for the tip. (0.00)
Posted by DAK on 2018-09-27, 19:04:23 (72.130.201.211)
Have you ever tried one of those phenolic ones? Are they supposed to mount on the top or bottom of the chassis? Too bad about the missing pins though. Pin 2 is for the heater of most pentode power tub .......
250: Tube DIY Asylum, Yeah, those are really dodgy (0.00)
Posted by DAK on 2018-09-27, 10:37:15 (72.130.201.211)
I put one of those in to replace a rectifier tube socket. The tolerance on the socket was so poor that you could insert an octal tube in any way and the tube would go more than 3/4 way down into the s .......
251: Tube DIY Asylum, I don't have enough space for anything bigger (0.00)
Posted by DAK on 2018-09-26, 18:53:39 (72.130.201.211)
This is a retro or refit of an existing amp and not being far sighted i put myself in this position where i can only just fit the 1" socket. .......
252: Tube DIY Asylum, RE: Try the huge tube selling company down in Florida.... (0.00)
Posted by DAK on 2018-09-26, 18:43:43 (72.130.201.211)
Howzit Ivan, what is the outfit called? .......
253: Tube DIY Asylum, Looking to buy some NOS USA octal sockets (0.00)
Posted by DAK on 2018-09-26, 11:26:30 (72.130.201.211)
If anyone knows where to get some or perhaps willing to sell? I am looking for the smaller diameter ones, that fit in a 1" diameter hole. Cheers, Dak .......
254: SET Asylum, if triodes are so good why doesn't audio only use them? (0.00)
Posted by DAK on 2018-09-25, 19:33:00 (72.130.201.211)
Obviously, there are other considerations. The vast majority of amps use pentodes and beam tubes. Certainly, not as linear but could be as good sounding as some triode amps, could be worse sounding th .......
255: Tubes Asylum, You could do a test. (0.00)
Posted by DAK on 2018-09-23, 10:12:28 (72.130.201.211)
Like put them in an oven on some tin foil. BTW, you should not use them on power tubes. The contact on the glass can cause a temperature difference which might weaken it. .......
256: SET Asylum, That should pay for the coupling caps. nt (0.00)
Posted by DAK on 2018-09-21, 09:18:50 (72.130.201.211)
. .......
257: SET Asylum, What is your budget? (0.00)
Posted by DAK on 2018-09-20, 22:00:21 (72.130.201.211)
Did i miss your alocated funds for this purchase. It is the bottomline for any audio purchase. Knowing that a more representative recommendation can be given. But really, the DHT tubes are way overpri .......
258: Tubes Asylum, In that amp the 6l6 is a voltage regulator? (0.00)
Posted by DAK on 2018-09-17, 00:01:23 (72.130.201.211)
I remember modding a similar ASL 845 for a buddy and i thought the 6l6 was not in the "signal path". Be that as it may you still need to observe the max voltage requirements. With your rare Brimar tub .......
259: Tube DIY Asylum, Could be a tube (0.00)
Posted by DAK on 2018-09-14, 08:58:59 (72.130.201.211)
Also a poor connection in the tube socket and maybe a cold solder joiont .......
260: Tubes Asylum, You would need to convert to individual bias resistors (0.00)
Posted by DAK on 2018-09-08, 12:03:19 (72.130.201.211)
It is not hard to do. Just double the value of the resistor for each tube. Each resistor will also need its own bypass cap. Then you can match current for better performance. .......
261: Tubes Asylum, RE: One bad tube in a quad, what to do? (0.00)
Posted by DAK on 2018-09-08, 09:52:06 (72.130.201.211)
If your amp has cathode bias resistor for each individual tube you can measure the voltage drop across the resistor and match up the tubes that have the same voltage drop. It would be matched current .......
262: Tube DIY Asylum, RE: KT150 subsisute KT88 (0.00)
Posted by DAK on 2018-09-08, 09:47:08 (72.130.201.211)
that would be one issue,,The primary for the output transformer but you can use the 2x tap to get around that. .......
263: Digital Drive, What about from my Oppo to the walkman? (0.00)
Posted by DAK on 2018-09-02, 13:05:08 (66.91.168.87)
My problem is that my disc player on this computer is not working. So, either i get another cd drive or maybe rig something else. thanks for the suggestions. cheers, Dak .......
264: Digital Drive, Yes, i am thinking of doing that. (0.00)
Posted by DAK on 2018-09-01, 08:51:26 (141.239.96.151)
Can the cd be copied directly into the walkman? .......
265: Digital Drive, model nw 393 nt (0.00)
Posted by DAK on 2018-08-31, 11:22:05 (66.91.168.87)
Oops forget the nt.... it is just NW 393 She got it by trading in some airline miles, so no real money spent. The only thing is i have to find some place to download music. .......
266: Tubes Asylum, Who told you that? (0.00)
Posted by DAK on 2018-08-31, 11:12:02 (66.91.168.87)
Or what made you think that? It is really off base and may have potentially catastrophic results to your amp. .......
267: Digital Drive, Wife bought a digital walkman, now what? (0.00)
Posted by DAK on 2018-08-30, 17:25:29 (66.91.168.87)
I presume that there is NO music on this thing? So, where do i go to upload tunes? This thing is smaller than a pack of cards. It does not look very rugged. And what about sound quality? Will it be be .......
268: Tubes Asylum, Test your tubes with music you are most familiar with (0.00)
Posted by DAK on 2018-08-30, 10:57:33 (66.91.168.87)
If you use unfamiliar recordings you will not have a base to compare the differences. Since tube rolling yields more subtle changes, new music might not reveal as much as playing something that is int .......
269: Tubes Asylum, I am not sure about pursuing the 6gm5 (0.00)
Posted by DAK on 2018-08-29, 07:55:49 (141.239.96.151)
I was going to use the OPT from this amp that i am repurposing. But, i think the primary impedance of about 5K into 4 ohm is too high for the 6gm5 and not a good match for my speakers, which are 8 ohm .......
270: Tube DIY Asylum, I found hammered paint to be really good at covering problem areas (0.00)
Posted by DAK on 2018-08-28, 14:26:05 (66.91.168.87)
I use it all the time on recycled chasses or is it chassises???? Anyway, I read that to get the "wrinkled" paint to correctly "wrinkle" is more time consuming in that you have to actually bake the pai .......
271: Tubes Asylum, RE: Raytheon EL84 Mullard? Not Mullard? (0.00)
Posted by DAK on 2018-08-28, 10:54:29 (66.91.168.87)
I don't believe these were actually made in US. It was not unusual for manufacturers to brand country of origin the same as where it was sourced. Mullard or IEC is most guilty of this. They would labe .......
272: Tubes Asylum, That's right! (0.00)
Posted by DAK on 2018-08-27, 18:17:41 (66.91.168.87)
My brain finally delivered that one tube. Damn, too much data in RAM. It took nearly a half an hour to finally get that info into the processors. http://www.mif.pg.gda.pl/homepages/frank/sheets/084/6/ .......
273: Tubes Asylum, Is there a high output pentode that fits Noval base? (0.00)
Posted by DAK on 2018-08-27, 17:45:07 (66.91.168.87)
I am looking for a tube with characteristics like a 7591 but using the small or mini tube 9 pin noval socket. If there is such a thing. Thanx for the suggestions. .......
274: Tubes Asylum, Polam or Telam? (0.00)
Posted by DAK on 2018-08-27, 09:55:52 (66.91.168.87)
One of those guys also made an el84 that had a circle or hole in the plate. .......
275: Tubes Asylum, I have seen other Raytheon that look like Mullard (0.00)
Posted by DAK on 2018-08-27, 09:48:33 (66.91.168.87)
Some ax and au 7. I thought they Japanese made but they did not have any marking of made in Japan or other indication of foreign made. .......
276: Tubes Asylum, RE: I eliminated the preamp on a EICO ST70 also better than original (0.00)
Posted by DAK on 2018-08-23, 06:27:58 (66.91.168.87)
I made a clone of the EICO HF86 which is PP EL84 and pretty much just the amp section of the 81. It was very nice. Everyone liked the sound of that amp. .......
277: Tubes Asylum, RE: I eliminated the preamp on a EICO ST70 also better than original (0.00)
Posted by DAK on 2018-08-22, 13:12:09 (66.91.168.87)
Sure, these units are getting harder to find, so making them a better performer is a big plus. I dunno if you are familiar with the EICO ST70 but it has MASSIVE output trannys. Seriously, they are hug .......
278: Tubes Asylum, I eliminated the preamp on a EICO ST70 also better than original (0.00)
Posted by DAK on 2018-08-22, 11:22:13 (66.91.168.87)
I hardwired the Selector switch bypassing the tone controls directly to the balance-volume controls for a big improvement. While this might be considered bad for the resale value of the unit, doing th .......
279: Tubes Asylum, There are many grounds in the unit (0.00)
Posted by DAK on 2018-08-20, 08:40:15 (66.91.168.87)
The preamp section has many areas that require a ground. Each of those connections can be a fault. .......
280: Tube DIY Asylum, RE: AC and DC heating from same secondary winding (0.00)
Posted by DAK on 2018-08-19, 09:21:58 (66.91.168.87)
I have done this on a couple of amps with seemingly no issues. But, it is better if you can get a small 6.3v or 12.6v filament trans and rectify that for less stress on you PT. .......
281: Tubes Asylum, What da heck is that thing? nt (0.00)
Posted by DAK on 2018-08-18, 09:09:57 (66.91.168.87)
. .......
282: Tubes Asylum, Most likely you need new power tubes. (0.00)
Posted by DAK on 2018-08-15, 23:03:42 (66.91.168.87)
Try getting a new quad and see if that is your problem. At the least get your power tubes tested. .......
283: SET Asylum, Is this amp SS rectified? (0.00)
Posted by DAK on 2018-08-14, 13:00:34 (66.91.168.87)
I see there is a FWBR, but it probably is for rectifying the heaters. Anyway you might get some relief by changing that to Schottky rectifiers. Also the same applies if there main rectifier is also SS .......
284: Tubes Asylum, RE: That is a nice sounding amp (0.00)
Posted by DAK on 2018-08-12, 21:52:20 (66.91.168.87)
Sorry to hear of your ailments. I know in my twilight years living with a lot of aches and pains is almost a daily thing, so i thank god i am not dealing with disability. So bypassing the electrolytic .......
285: SET Asylum, RE: Cary 2A3 SE Amps - Want to upgrade coupling caps (0.00)
Posted by DAK on 2018-08-12, 21:28:21 (66.91.168.87)
My experience points to a better power supply to achieve what you want. Euphonic, pleasing to the ear, is related to more second harmonics in the distortion spectrum. So, in terms of blacker backgroun .......
286: SET Asylum, RE: Cary 2A3 SE Amps - Want to upgrade coupling caps (0.00)
Posted by DAK on 2018-08-12, 09:58:31 (66.91.168.87)
The VitaQ is coupled to the output tube and the Solen maybe a coupler too. Bypassing any of these is problematic because of the space involved. Solen's are not known for their sound quality so dependi .......
287: Tubes Asylum, That is a nice sounding amp (0.00)
Posted by DAK on 2018-08-11, 09:11:52 (66.91.168.87)
I worked on the amp version of that unit. I had to change out some PS caps. I also bypassed them with some film caps which helped in the amp dynamics. I think i have seen the schematic for that amp on .......
288: Tubes Asylum, RE: Anybody try the 5690 rectifier? (0.00)
Posted by DAK on 2018-08-09, 20:01:02 (66.91.168.87)
Hi, thanks for replying. I am interested to know what voltage you input and what voltage and current you achieved. Or what was the tube line up you used. .......
289: Tubes Asylum, Anybody try the 5690 rectifier? (0.00)
Posted by DAK on 2018-08-09, 16:07:19 (66.91.168.87)
I got some of these and wonder what kind of voltages you obtained and how it performed. Also a description of your PS circuit would be nice. cheers, Dak .......
290: Tubes Asylum, It is normal for some tubes (0.00)
Posted by DAK on 2018-08-09, 02:00:22 (66.91.168.87)
I believe some russian tubes do that. I have some Bendix 5992 that emit that blue glow. Here is a photo .......
291: Tube DIY Asylum, I found a tube bias table at the Weber site (0.00)
Posted by DAK on 2018-08-06, 09:56:39 (66.91.168.87)
He has a table of recommended bias currents based on various common power tubes based on 3 levels, hot, average, and cool. For 6l6gc based on 425v the 3 values are 49ma, 42ma, and a cool of 35ma. ::: .......
292: Tube DIY Asylum, AB (n/t) (0.00)
Posted by DAK on 2018-08-05, 21:29:02 (66.91.168.87)
. .......
293: Tube DIY Asylum, What current should i run fixed bias 6l6GC? (0.00)
Posted by DAK on 2018-08-05, 18:44:47 (66.91.168.87)
I got 430vdc for Av, 380v G2v, I set the tubes at .44vdc with 10 ohm resistors to ground. This sounds pretty good but i am not sure how "hot or cold" that is for biasing that tube. Thanks , Dak ::: TO .......
294: Tubes Asylum, To be fair, you don't know what kind of operation the cb provider is. (0.00)
Posted by DAK on 2018-08-04, 21:53:26 (66.91.168.87)
There are a lot of guys that do "one off" cb. And they get to their orders as life allows. .......
295: Tube DIY Asylum, RE: and I suppose not responding at all is out of the guestion? (nt) (0.00)
Posted by DAK on 2018-08-04, 09:35:19 (66.91.168.87)
You need to know both answers when taking a poll. If you don't have enough responses you statistical base is too small to make a meaningful determination. So for the record i did not have any problems .......
296: Tube DIY Asylum, Just saying no is not as entertaining to read (nt) (0.00)
Posted by DAK on 2018-08-04, 03:54:38 (66.91.168.87)
. .......
297: Tube DIY Asylum, It is the time when Russian hackers are at work (0.00)
Posted by DAK on 2018-08-03, 13:51:47 (66.91.168.87)
According to the CIA and Homeland Security, this is entirely possible. This site is a known haven for the movers and shakers of the Washington elite. .......
298: Tube DIY Asylum, It is the time when the BB is backing up its data (0.00)
Posted by DAK on 2018-08-03, 08:37:14 (66.91.168.87)
So, at that time Big Brother is stealing all your bandwidth. Hence you can't get through. I would complain to your Congressman. PS, leave the aluminum hat at home when you go to see him. .......
299: Tubes Asylum, RE: To get the most of what the 845 provides use high sensitivity speakers (0.00)
Posted by DAK on 2018-07-31, 15:27:35 (66.91.168.87)
Is it universal, that when you get older, it is the details that start to matter more? But i am a firm believer that a custom made amp can be built to a much higher level than any commercial made amp, .......
300: Tubes Asylum, To get the most of what the 845 provides use high sensitivity speakers (0.00)
Posted by DAK on 2018-07-31, 09:39:22 (141.239.96.151)
IMO, when i got my Altec 19 the amount of detail retrieval was unexpected. All the low level info was brought out . I can't say that huge horn speakers like the 19 will be your cup of tea but somethin .......
301: Tube DIY Asylum, You were right, (0.00)
Posted by DAK on 2018-07-25, 13:41:02 (66.91.168.87)
Is it likely to get any worse? I can't really do anything about it. .......
302: Tube DIY Asylum, How do i test your theory? NT. (0.00)
Posted by DAK on 2018-07-25, 09:33:19 (66.91.168.87)
. .......
303: Tube DIY Asylum, RE: Pyranol capacitors---risk of leakage in tube amp power supply? (0.00)
Posted by DAK on 2018-07-24, 13:11:22 (66.91.168.87)
I agree that if you are conservative with its use, and physically the cap is in good shape, then there should be no problem. They were pretty much designed to last a lifetime, or two. .......
304: Tubes Asylum, Just because it is a Milspec tube doesn't mean it sounds good. (0.00)
Posted by DAK on 2018-07-24, 11:25:20 (66.91.168.87)
Or sound better than an ordinary tube. The milspec is for various reasons, mostly to do with ability to survive more abuse in terms of shock, vibration, humidity, etc. While being able to fulfill its .......
305: Tube DIY Asylum, don't you want to know why? (0.00)
Posted by DAK on 2018-07-24, 09:25:52 (66.91.168.87)
In my amp i think it might be an electrolytic cap but i have not gotten around to changing it out yet. Thanks for sharing. .......
306: Tube DIY Asylum, RE: Amp hums on start up (0.00)
Posted by DAK on 2018-07-23, 17:03:29 (66.91.168.87)
If it were magnetic coupling, wouldn't it , the hum , always be there? .......
307: Tube DIY Asylum, The amp has new tube sockets (0.00)
Posted by DAK on 2018-07-23, 13:59:18 (66.91.168.87)
Yeah, this is a "new build" not a refurbish. But, i always clean and tension the tube socket pins when i rebuild a unit. .......
308: Tube DIY Asylum, RE: Amp hums on start up (0.00)
Posted by DAK on 2018-07-23, 12:19:00 (66.91.168.87)
Actually one of them is recycled. It is i suppose a likely culprit. I was wondering if others had experienced this issue before with an electrolytic? Why do you suppose the hum backs off as the voltag .......
309: Tube DIY Asylum, Amp hums on start up (0.00)
Posted by DAK on 2018-07-23, 10:58:36 (66.91.168.87)
My SE el84 amp hums at start up. It is using a 5v4 rectifier. After 30s the hum is hardly noticeable. My speakers are Altec 19 so at power on it is distracting. Other than the initial humminess the am .......
310: Tubes Asylum, If you really want to hear the sonic contribution of each tube.... (0.00)
Posted by DAK on 2018-07-22, 21:34:20 (66.91.168.87)
build yourself a single ended amp with your favorite tubes. SE amps are usually 2 stage, driver tube coupled to a power tube. If you are just talking a head phone amp that is a low powered affair and .......
311: Tube DIY Asylum, Check out michael percy.com (0.00)
Posted by DAK on 2018-07-19, 09:35:46 (66.91.168.87)
Also there is an outfit in Germany that is the only real Alps dealer that i know of. .......
312: Tube DIY Asylum, Why is C1 on the 5881 cathode? (0.00)
Posted by DAK on 2018-07-16, 14:09:07 (66.91.168.87)
I have seen that before, esp. in tube cad journal, but what is the advantage of doing that? .......
313: Tubes Asylum, That would indicate a tube or tube socket problem. nt. (0.00)
Posted by DAK on 2018-07-16, 11:09:22 (66.91.168.87)
. .......
314: Tube DIY Asylum, Don't be too hasty! (0.00)
Posted by DAK on 2018-07-16, 11:03:52 (66.91.168.87)
I am thinking like Ray, that you may regret your decision to divest yourself, unless you need to thin out the herd. I have sold stuff and made many decisions i later regretted so i tend to temper radi .......
315: Tubes Asylum, RE: What part of the circuit would cause a low "whistle" (0.00)
Posted by DAK on 2018-07-16, 09:39:39 (66.91.168.87)
That type of noise is usually an oscillation. If removing that tube from the circuit makes it go away then it is the tube or something in that socket. .......
316: Tube DIY Asylum, That is attention to detail nt. (0.00)
Posted by DAK on 2018-07-15, 17:53:23 (141.239.96.151)
. .......
317: Tube DIY Asylum, PSE 211? That would be a real nut buster! (0.00)
Posted by DAK on 2018-07-13, 18:47:58 (66.91.168.87)
The amount of iron that would take would be very weighty. Maybe a 3 chassis unit would not require Arnold Schwarzenegger's assistance. .......
318: Tubes Asylum, Essentially the same (0.00)
Posted by DAK on 2018-07-12, 16:25:03 (66.91.168.87)
But the vintage KT66 is a very well made tube. If you compared the two you will observe that the kt66 is a little more robustly constructed. The original kt66s are also supposed to have a 10K hour lif .......
319: Tubes Asylum, My point exactly. (0.00)
Posted by DAK on 2018-07-09, 14:03:53 (66.91.168.87)
Don't put expensive tubes in there. But, even el cheapo tubes are mostly spec'd to last 2000 hours. A few hundred hours is a sign of a developing issue. And think how much better your preamp would sou .......
320: Tubes Asylum, A signal tube should last at least 3K hours. (0.00)
Posted by DAK on 2018-07-09, 11:56:52 (66.91.168.87)
A tube that gets noisy is a sign that it is wearing out. So, why is it wearing out so quickly? That definitely points to an issue with the preamp. If you are not savvy with tube circuits find somebody .......
321: Tubes Asylum, You need to check voltages. nt. (0.00)
Posted by DAK on 2018-07-09, 10:39:39 (66.91.168.87)
. .......
322: Tubes Asylum, Are you sure it is the tube? (0.00)
Posted by DAK on 2018-07-09, 10:06:06 (66.91.168.87)
It maybe your circuit. Maybe B+ is too high? Or cathode to heater voltage differential if the circuit is cathode follower. .......
323: Tube DIY Asylum, RE: 100 power amplifiers to lift your hat (0.00)
Posted by DAK on 2018-07-07, 15:46:42 (66.91.168.87)
This list has been up for awhile now, at least a year. Anyway, it is a highly subjective process that an amp makes his list but, interesting reading nonetheless. So, it is great that he has all these .......
324: Tube DIY Asylum, Thanks for the tip (0.00)
Posted by DAK on 2018-07-05, 14:05:37 (141.239.96.151)
I already changed out the 7591 coupling caps with some PIO type. The amp is a little better sounding with them in. I will also change out the caps in the preamp and the phono stage tubes. .......
325: Tube DIY Asylum, RE: Wax caps? (n/t) (0.00)
Posted by DAK on 2018-07-05, 08:38:00 (66.91.168.87)
No, the chocolate drops are probably mylar type although i have not broken one open. I suppose it could be plastic insulation. .......
326: Tube DIY Asylum, Fisher caps are usually Ero. (0.00)
Posted by DAK on 2018-07-04, 20:59:20 (141.239.96.151)
Maybe this unit had some new coupling caps put in? Or later on they switched to a different brand? The caps look original based on how they were installed. Fisher layout being very neat and tidy, as w .......
327: Tube DIY Asylum, They are branded "Dumont" nt (0.00)
Posted by DAK on 2018-07-04, 20:50:40 (141.239.96.151)
. .......
328: Tube DIY Asylum, I got some of those. (0.00)
Posted by DAK on 2018-07-04, 16:43:36 (66.91.168.87)
But I think the ones in the 500 are CD. I will check later if there is still printing left. .......
329: Digital Drive, what with the proliferation of streaming audio i thought (0.00)
Posted by DAK on 2018-07-04, 15:12:46 (66.91.168.87)
the price of cd players would also decline. But this doesn't seem to be happening much. .......
330: Tube DIY Asylum, It wasn't really broken... (0.00)
Posted by DAK on 2018-07-04, 14:18:00 (66.91.168.87)
I just did not notice the behavior of that circuit when starting with a variac and incrementally advancing the ACV. Although, i am seriously thinking about replacing the "chocolate" drops with somethi .......
331: Tube DIY Asylum, RE: That's good news! (0.00)
Posted by DAK on 2018-07-04, 10:59:19 (66.91.168.87)
Well, the amp was working and sounding good with everything original, and i mean everything. The problem was a bad on/off switch. So bypassing that made the amp work. I replaced that and am thinking o .......
332: Tube DIY Asylum, What did i do wrong? Nothing (0.00)
Posted by DAK on 2018-07-04, 09:37:24 (66.91.168.87)
I just thought i would post a follow on my "problem" . I switched out the original FWBR on a Fisher 500B, and during power up on a variac after installation, i noticed that at 20vac my negative voltag .......
333: Tube DIY Asylum, Is it possible to measure the FWBR in circuit? (0.00)
Posted by DAK on 2018-06-30, 13:14:41 (66.91.168.87)
I hate to desolder my wires. In which case it would probably be easier to just cut it out and solder a new one in. .......
334: Tube DIY Asylum, RE: That is a long time to apply heat to ..... (0.00)
Posted by DAK on 2018-06-30, 09:13:59 (66.91.168.87)
In retrospect, i probably did not apply heat to the joint for more than 10seconds to only 1 lug. But i will check the unit to see if it has developed a fault. It is the only component that could have .......
335: Tube DIY Asylum, RE: 10 to 20 seconds (0.00)
Posted by DAK on 2018-06-29, 19:56:58 (66.91.168.87)
the rectifier legs are attached to a 4 place solder lug. So, i soldered it without any heat sinks. .......
336: Tube DIY Asylum, What did i do wrong, bad part or ? (0.00)
Posted by DAK on 2018-06-29, 19:22:01 (66.91.168.87)
I replace a vintage Siemens FWB rectifier in a Fisher 500B receiver for the heater and negative voltage of the fixed bias operation. It was replaced with a modern unit of roughly 3A x 400v. I wired it .......
337: Digital Drive, I have seen a lot of Schiit lately (0.00)
Posted by DAK on 2018-06-29, 13:01:26 (66.91.168.87)
Yeah, all kidding aside, I don't think i can in buy something which is named that. .......
338: Tubes Asylum, RE: 5687 in CF instead of a 12AU7 in CF mode? For a pre-amp's output valve!? (0.00)
Posted by DAK on 2018-06-26, 09:31:13 (66.91.168.87)
I have experience with the 5687 as a phase splitter in the MFA M75 amp. In that use it works great but i found that the 7119 sounded better. You might also consider the 7044 tube. The 7119 had a more .......
339: Tube DIY Asylum, Why would one use a 1/2 watt resistor? (0.00)
Posted by DAK on 2018-06-19, 14:03:41 (66.91.168.87)
In that location, in my own builds i would use minimum rn65 or preferably rn70. As you mentioned previously, It is also known that a larger resistor is less noisy than a smaller one, all things being .......
340: Digital Drive, If that is the way they feel about cd, what about lps? (0.00)
Posted by DAK on 2018-06-18, 23:55:06 (66.91.168.87)
Lps are at least twice as much sometimes way more effort than cds. .......
341: Tubes Asylum, W3 is a 2 chassis design with the Acro 300 OPT (0.00)
Posted by DAK on 2018-06-18, 11:14:25 (66.91.168.87)
It is one of their earliest kits in home audio. I passed on picking up a set because it is so hard to get a pair that had been together. Most people who stumbled across them separated the 2 units. Wha .......
342: Tube DIY Asylum, what are the advantages? (0.00)
Posted by DAK on 2018-06-18, 11:05:48 (66.91.168.87)
Halving the impedance? .......
343: Tube DIY Asylum, You only need 2 binding posts per channel (0.00)
Posted by DAK on 2018-06-17, 10:46:10 (66.91.168.87)
IMO if the amp is just for your own use then only 1 pair per channel is needed. But, if planning for other types of speakers then speaker selector switching can be problematic. I am not sure if any of .......
344: Tube DIY Asylum, Individual binding posts (0.00)
Posted by DAK on 2018-06-17, 08:10:48 (66.91.168.87)
I just mount the requied number of individual binding posts that the output trans needs. This can be expensive if you use 'audiophile' type like Cardas or Neotech. I usually choose only 2 impedances 4 .......
345: Tube DIY Asylum, And to top it off Dale is a bi-gender name! (0.00)
Posted by DAK on 2018-06-15, 14:13:43 (66.91.168.87)
All kidding aside. I like to fool with resistors too. But, trying to track down the ones i want vs getting the job done with what i have in stock, i will usually stick with getting the job done initia .......
346: Tubes Asylum, dV/dI ???? on no, that is calculus! (0.00)
Posted by DAK on 2018-06-15, 14:08:21 (66.91.168.87)
Inspite of Brother Plieman's best efforts and dodging numerous "fast ball chalkboard eraser's" I never got the hang of that. .......
347: Tubes Asylum, How do you determine primary impedance of output transformer (0.00)
Posted by DAK on 2018-06-15, 13:59:23 (66.91.168.87)
from the power tube requirements? Is this derived from the plate curves? I have not delved deeply into a scratch build. thanks for the help. .......
348: Tubes Asylum, will this Hammond 1638SEA be a fit for 813 tube (0.00)
Posted by DAK on 2018-06-15, 08:54:58 (66.91.168.87)
I am still looking for an output tranny for my 813 single ended amp. I know the criteria for an output trans is depending on the operating conditions too. But, i have not found much data on the 813 tu .......
349: Tube DIY Asylum, sorry not meaning to disrespect any male nurses. nt (0.00)
Posted by DAK on 2018-06-15, 08:29:21 (66.91.168.87)
. .......
350: Tube DIY Asylum, I hope she was 55, not 60 , or 65 or worse! nt (0.00)
Posted by DAK on 2018-06-14, 21:04:20 (66.91.168.87)
. .......
351: Tube DIY Asylum, I don't know what you mean. nt (0.00)
Posted by DAK on 2018-06-14, 13:22:57 (66.91.168.87)
. .......
352: Tube DIY Asylum, 2 people are not a very large sample size (0.00)
Posted by DAK on 2018-06-14, 11:16:48 (66.91.168.87)
I use Dale rn type resistors all the time and who wants to spend the time deciding whether the t25c is better than the tc50 ? .......
353: Tube DIY Asylum, I ran into a noisy cathode resistor (0.00)
Posted by DAK on 2018-06-12, 09:54:04 (66.91.168.87)
In my SEP KT120 amp it was annoyingly noisy, with a buzzing sound. After pursuing various methods to remove the noise i found that half of the noise was contributed by 1 watt carbon comp cathode resis .......
354: Tube DIY Asylum, My bad guys, i must have had a senior moment (0.00)
Posted by DAK on 2018-06-11, 01:25:14 (66.91.168.87)
It is funny how you sometimes think you solved an important problem only to realize you were totally off base. Must have been an acid flashback. .......
355: Tube DIY Asylum, 2.5vct filament tranny query (0.00)
Posted by DAK on 2018-06-10, 12:27:30 (66.91.168.87)
I actually need a 5v fil trans. Is there any issues that i am not aware of using this 3A 2.5vct trans without the ct as a 5v trans. The current rating would be halved right. I am considering of adding .......
356: Digital Drive, what model DAC is that? nt (0.00)
Posted by DAK on 2018-06-10, 09:40:48 (141.239.96.151)
. .......
357: Tubes Asylum, What's wrong with framice? (0.00)
Posted by DAK on 2018-06-08, 22:19:00 (66.91.168.87)
Tinnerman nut is so blase. .......
358: Tubes Asylum, RE: What spec screws hold the bottom plate for an Eico HF87? (0.00)
Posted by DAK on 2018-06-08, 10:02:21 (66.91.168.87)
screws are frequently adapted to the owner's needs. Sometimes they are not stock anymore. You might have to get different types like machined and sheet metal to have the right ones. Most of the eico e .......
359: Digital Drive, Recommended CD player (0.00)
Posted by DAK on 2018-06-07, 10:31:53 (66.91.168.87)
Hi, i mostly play cds and i am still hunting for a player that is worth spending the extra money. Currently i am using a Rega Jupiter, the one with the Star Trek Enterprise loading door. It sounds goo .......
360: Tubes Asylum, I can see that from the tube description (0.00)
Posted by DAK on 2018-06-02, 20:52:54 (141.239.96.151)
But why did GE put the G2 on pin3 and p8 which is close to the filament connections? .......
361: Tubes Asylum, Anybody using the 6350 twin triode? (0.00)
Posted by DAK on 2018-06-02, 12:45:37 (66.91.168.87)
It is i guess a 'computer tube' but the pinout is rather odd in the grid is on p3 and cathode is on p2. Which opposite to most mini noval triodes. Thanks for the comments, Dak .......
362: Tubes Asylum, Anybody using the 6350 twin triode? (0.00)
Posted by DAK on 2018-06-02, 12:41:09 (66.91.168.87)
It is i guess a 'computer tube' but the pinout is rather odd in the grid 2 is on p3 and cathode is on p2. Which opposite to most mini noval triodes. .......
363: Tubes Asylum, RE: So the Made in Great Britain is false then? (0.00)
Posted by DAK on 2018-06-01, 22:55:28 (141.239.96.151)
It could be. Even in the last gasp days of tubes, 70s and 80s The only source besides Russia and China was some short lived manufacturing of tubes made on Mullard jigs in Japan. While not the equal of .......
364: Tubes Asylum, Maybe Japanese Mullard (0.00)
Posted by DAK on 2018-06-01, 09:55:01 (141.239.96.151)
They look almost exactly like the UK versions. But no date or factory codes .......
365: Tube DIY Asylum, At least only the tube was affected (0.00)
Posted by DAK on 2018-06-01, 09:51:27 (141.239.96.151)
Have you ever seen the other failure that can take out components? I was wondering how often that can happen. .......
366: Tubes Asylum, Here are the 2 5992 with the bluish glow (0.00)
Posted by DAK on 2018-05-29, 02:52:29 (141.239.96.151)
Sorry about the unsteady pics, i was using a slow shutter speed with hand held. .......
367: Tubes Asylum, Very good article, TYVM! nt (0.00)
Posted by DAK on 2018-05-27, 17:49:45 (66.91.168.87)
. .......
368: Tubes Asylum, Exactly. (0.00)
Posted by DAK on 2018-05-27, 09:00:32 (66.91.168.87)
My other power tubes do not exhibit this. Everything else seems ok so i was wondering what is causing it. May be some gas being charged with electrons? .......
369: Tube DIY Asylum, My FWBR imparts a bit too much hardness (0.00)
Posted by DAK on 2018-05-26, 16:34:58 (66.91.168.87)
it sounds very hi fi at first blush but after a bit it starts too wear on you. I find this true in general, after 2 or 3 hours I start longing for some relief. .......
370: Tube DIY Asylum, That sounds intriguing (0.00)
Posted by DAK on 2018-05-26, 13:33:45 (66.91.168.87)
If i understand you correctly, i would connect pins 4 and 6 together, and run the output from the FWBR into 4 or 6? Would there be any benefit besides the slow voltage turn on and a loss of 5% of B+. .......
371: Tubes Asylum, Bendix 5992 cool purple glow (0.00)
Posted by DAK on 2018-05-26, 13:24:03 (66.91.168.87)
I just wondered if others with the same Bendix 5992 type tubes have a similar phenomenon when the tube is working? .......
372: Vinyl Asylum, RE: Electrics (0.00)
Posted by DAK on 2018-05-26, 10:59:43 (141.239.96.151)
Ok, you seem to be knowledgeable about these tables. I hope you won't mind if i come back with more questions. I will check the fuses first. .......
373: Tubes Asylum, No Wait! This is pertaining! (0.00)
Posted by DAK on 2018-05-26, 09:45:25 (141.239.96.151)
With the heat generated from the tubes, one can conceivably heat the chips over the amp with a suitably designed rack and through careful monitoring pull it off the heat when the warp has eased back i .......
374: Tube DIY Asylum, My PS is choke loaded. (0.00)
Posted by DAK on 2018-05-26, 09:37:43 (141.239.96.151)
I can maybe fit in a bigger L2 but that would realistically not give much of a voltage reduction maybe a percent or 2. I would hate to drop in a resistor in the mix. I dunno why this PT seems to put m .......
375: Tube DIY Asylum, It has a FWBR now (0.00)
Posted by DAK on 2018-05-25, 10:15:29 (66.91.168.87)
I am using some FREDs. And a CL to help with the voltage surge. The resulting voltage is still a little high by about 10% so, i was searching for a way to make it better. Maybe i will get a small 5v t .......
376: Vinyl Asylum, thank you for that. (0.00)
Posted by DAK on 2018-05-25, 09:46:37 (66.91.168.87)
Is the turn table motor electrics also on the circuit board. Could the reason it doesnt turn be a problem here. I mean, i could dispense with the vacuum hold down as the vast majority of my lps are fl .......
377: Tube DIY Asylum, Heater requires 3.8 Amps! (0.00)
Posted by DAK on 2018-05-24, 22:57:30 (141.239.96.151)
The PT is a big potted unit but the 5v supply is listed at 2A. So, that would be a no go. I was thinking of adding another 5v PT and another socket for 2 x 5ar4 , but the dang thing weighs more than 5 .......
378: Tube DIY Asylum, Not the news i wanted to know (0.00)
Posted by DAK on 2018-05-24, 20:58:53 (141.239.96.151)
I was hoping there was hybrid bridge, with a 5ar4 that would be able to handle the situation. What about using a 5r4wgb? The peak current is quite high and the max current is right at the limit. My AC .......
379: Tube DIY Asylum, I am thinking about about a 5ar4 (0.00)
Posted by DAK on 2018-05-24, 17:07:59 (141.239.96.151)
With hi voltage Schottky's. My use is in a SEP KT120 amp . I am using a bridge rectifier which gives about 450vdc B+. I think the amp might sound better at a lower voltage so i would like to try somet .......
380: Vinyl Asylum, RE: Sota star sapphire table not working (0.00)
Posted by DAK on 2018-05-24, 10:05:05 (141.239.96.151)
Nothins working now. No pump motor, no table motor. .......
381: Tube DIY Asylum, Hybrid voltage rectifier question (0.00)
Posted by DAK on 2018-05-24, 08:47:50 (141.239.96.151)
I was checking out the hybrid voltage rectifier in Eli's El Cheapo power supply schematic and i was wondering what would be the voltage and current limits to that type of rectifier. I was also wonderi .......
382: Vinyl Asylum, Yeah, that is the kind i have. (0.00)
Posted by DAK on 2018-05-24, 08:23:15 (141.239.96.151)
How do you take out the fuses? sorry for the question, but maybe mine are stuck and i did not want to break the holder. Where is the serial number located and what do i need it for? Thanks for the hel .......
383: Vinyl Asylum, RE:I thought you wanted me to send my table to Sota. (0.00)
Posted by DAK on 2018-05-23, 21:02:29 (66.91.168.87)
I checked their rebuilding prices and it is pretty much the same as buying a new table. Will Donna help me trouble shoot my problem/s with the Sota? Does the separate box that comes with my unit also .......
384: Vinyl Asylum, RE: Call Donna Bodinet at the number in the link... (0.00)
Posted by DAK on 2018-05-23, 19:32:04 (66.91.168.87)
What was wrong with the units you worked on? For me the shipping problem is huge. .......
385: Vinyl Asylum, RE: Sota star sapphire table not working (0.00)
Posted by DAK on 2018-05-23, 19:18:01 (66.91.168.87)
I actually moved across the street. Maybe 300 yds. , So I did not use that. I believe it was working when i initially moved. but i did not use it much. Then it stopped working. .......
386: Vinyl Asylum, RE: Sota star sapphire table not working (0.00)
Posted by DAK on 2018-05-23, 18:29:54 (66.91.168.87)
No, i did not see any user questions place or enquiries. .......
387: Vinyl Asylum, Sota star sapphire table not working (0.00)
Posted by DAK on 2018-05-23, 17:50:02 (66.91.168.87)
I have the STar Saphire with vacuum holdown. I had excellent performance from it before it stopped working. the story is i had to move and so it did not get properly setup for maybe a year or a little .......
388: Tubes Asylum, Adjusting the bias should be easy (0.00)
Posted by DAK on 2018-05-23, 15:04:11 (66.91.168.87)
Many newer amps only require you to turn the adjustment pot until the LED changes color. Some require the use of a meter. If you don't have a meter and the amp requires one for biasing just get a chea .......
389: Tubes Asylum, I agree with Jonesy (0.00)
Posted by DAK on 2018-05-23, 11:04:01 (66.91.168.87)
There is no need buying a bunch of new tubes when the problem is bias. If the bias is cold the amp will sound thin with less bass and midrange, which kinda sounds like your issue. So, you definitely n .......
390: Tube DIY Asylum, I don't use an input cap in my custom builds. (0.00)
Posted by DAK on 2018-05-23, 10:57:45 (66.91.168.87)
Caps can cause some loss of signal integrity so, you can dispense with them in a home audio situation as long as you know that signal is going to be AC. If you are loaning your amps out or using them .......
391: Tubes Asylum, And just for your entertainment value!!!! (0.00)
Posted by DAK on 2018-05-20, 12:51:31 (66.91.168.87)
Inquiring minds want to know what that ol' rascal OGR, aka BangyBang, is up to? Here you go; for a 'measly' 500 smackeroonis Matched Quad Vintage 6350 RCA Gold Pin Black Plate - BangyBang Tubes www.eb .......
392: Tubes Asylum, OGR is now Bangybangtubes (0.00)
Posted by DAK on 2018-05-20, 09:38:57 (66.91.168.87)
CAVEAT EMPTOR! Yes the leopard has changed his spots. But still up to his same old tricks. I guess he has read "the Capitalist's playbook". It is up to the "masses" to spread the word that this mofo .......
393: SET Asylum, I thought 112 were 93 db efficiency? (0.00)
Posted by DAK on 2018-05-17, 09:17:57 (66.91.168.87)
I used to play my 112 with SE 6bq5 amps that puts out 5 watts at the most, and the sound was also very good. The overall tone and musicality was very good. when you put more power you would get more s .......
394: Tube DIY Asylum, RE: Modding my Motos: Lets Jump Down The Rabbit Hole (0.00)
Posted by DAK on 2018-05-17, 09:11:42 (66.91.168.87)
Well, it sounds like you have good iron to work with which is the most expensive items. The leaky stuff on the power trans is probably some tarlike material that was put on to quiet the transformer. U .......
395: Tube DIY Asylum, You should never watch you tube instructional videos. (0.00)
Posted by DAK on 2018-05-16, 22:13:14 (141.239.96.151)
When a supposed you tube guru, doing a rebuild of an eico integrated amplifier doesn't know what the feedback resistor in the preamp circuit is doing there. I would watch any youtube video with a huge .......
396: Tubes Asylum, There needs to be a better way (0.00)
Posted by DAK on 2018-05-15, 07:36:23 (66.91.168.87)
My kids are more fortunate than others that grew up around them. In my area, lack of support for the next generation has lead to widespread drug use and its attendant ills, like homelessness, thiever .......
397: Tubes Asylum, Ah, the 50s and 60s. (0.00)
Posted by DAK on 2018-05-14, 10:47:46 (66.91.168.87)
I like to go through those old electronics and audio mags. While time moves forward, you still wonder what happened to all of our (American) manufacturing and production capabilities. The corporate gu .......
398: Tubes Asylum, Those GE 7581 are the ones i collect. (0.00)
Posted by DAK on 2018-05-14, 09:04:20 (66.91.168.87)
They have the tan colored base that seems to be like a ceramic material instead of the usual plastic. .......
399: Tubes Asylum, Have you found similar info on Westinghouse 7591? (0.00)
Posted by DAK on 2018-05-13, 10:15:47 (66.91.168.87)
I have read second hand info about that tube's ability to produce lots of power from a relatively small plate because of special metallurgy in the design. I have not seen this described in an official .......
400: Tubes Asylum, RE:Sorry, i don't see the merit of taking pics of that kinda stuff (0.00)
Posted by DAK on 2018-05-12, 12:20:10 (66.91.168.87)
I suppose i am exposed to similar images all the time but even a pile of vintage indicator lights are posted on ebay all the time. And so it reminds of stuff an ebay seller might post. .......
401: Tubes Asylum, Frame grid tubes (0.00)
Posted by DAK on 2018-05-11, 08:20:52 (66.91.168.87)
i believe were invented by Amperex. It just maybe that their invention was coming when the american tube factories were already starting to close down. Amperex/Phillips later bought out Sylvania which .......
402: Tube DIY Asylum, RE: Floating ground (0.00)
Posted by DAK on 2018-05-09, 12:33:17 (66.91.168.87)
If your bus bar is connect to the chassis at 2 points then you have a ground loop. So the one end that is connect to the chassis is also grounded to the 'earth ground' through the chassis at the 3 pro .......
403: Tube DIY Asylum, Floating ground (0.00)
Posted by DAK on 2018-05-09, 12:00:13 (66.91.168.87)
If 2 prong plug it is just using only a chassis for ground. Needless, to say if this is not double insulated like 2 prong power cords in modern equipment, then that is not allowed. That is why in some .......
404: Tube DIY Asylum, RE: A lot of vintage amps have grounds all over the place (0.00)
Posted by DAK on 2018-05-09, 11:14:22 (66.91.168.87)
I think he that article mentions something about keeping the safety ground which directly ties to the house ground, away from your amp ground. .......
405: Tube DIY Asylum, A lot of vintage amps have grounds all over the place (0.00)
Posted by DAK on 2018-05-09, 11:08:49 (66.91.168.87)
Having multiple ground points can be good too. I use a star ground or a bus ground and have had no problems. whichever is more adaptable to the layout is what i employ. If it works then you are ok, no .......
406: Tube DIY Asylum, Did you read Fender Lovers link about grounding? (0.00)
Posted by DAK on 2018-05-09, 10:49:25 (66.91.168.87)
That article is geared towards music amps, but the concepts are very sound. In your case depending on your layout the bus can be grounded anywhere along its length as long as it goes to the central .......
407: Tube DIY Asylum, RE: Would you use these chokes? (0.00)
Posted by DAK on 2018-05-09, 08:55:18 (66.91.168.87)
You do realize that used chokes are already broken in. That copper from back in the day is copper made from ore and not from recycling, of which most currently available copper is made from. Chokes ra .......
408: Tube DIY Asylum, The ungrounded end of the busbar is isolated (0.00)
Posted by DAK on 2018-05-09, 08:48:06 (66.91.168.87)
It is tied to a ungrounded lug. Otherwise you have made a nice ground loop. .......
409: Tube DIY Asylum, I got a set of trannys rescued from a trash heap (0.00)
Posted by DAK on 2018-05-09, 08:45:22 (66.91.168.87)
The amp itself was salvaged after some Hurricane devastation in Florida and was sitting outside for awhile. They check out ok but look like they have been through a hurricane. .......
410: Tubes Asylum, Thanks but trying to stay with an octal base. cheers! (0.00)
Posted by DAK on 2018-05-07, 21:14:10 (66.91.168.87)
. .......
411: Tubes Asylum, Not a fan of Chinese tubes (0.00)
Posted by DAK on 2018-05-06, 19:12:27 (66.91.168.87)
I am hoping to avoid them with a close substitute of old usa made if possible. .......
412: Tubes Asylum, Is there a GT version of the 6AG7 or 6P9P? (0.00)
Posted by DAK on 2018-05-06, 13:51:27 (66.91.168.87)
I don't like to use metal tubes with glass tubes if the GT version is available. Or a suitable tube sub for that number. Thank you for your suggestions. Dak .......
413: Tubes Asylum, RE: It's quite a small rectifier for its capabilities and is / was specified (0.00)
Posted by DAK on 2018-05-05, 12:44:09 (66.91.168.87)
While i agree with you in principle i find that using a tube rectifier in single ended amps allows you to have flexibility in B+ voltage output. This becomes useful if your amp is setup to use differe .......
414: Tube DIY Asylum, So this pic is just a computer drawing? nt (0.00)
Posted by DAK on 2018-05-05, 12:37:05 (66.91.168.87)
/ .......
415: Tubes Asylum, Could one use a regular PP output tranny? (0.00)
Posted by DAK on 2018-05-04, 15:35:30 (66.91.168.87)
Since the CT is at 50% of the windings? I guess it would need to have a gap, though. .......
416: Tubes Asylum, Who winds a 50% UL tap? (0.00)
Posted by DAK on 2018-05-04, 15:33:33 (66.91.168.87)
I did not know what that 50% PE meant. Also I don't like global -fb. I did like the tube line up. Aesthetically it would have been nice to have the tubes symmetrically spaced which would be pleasing t .......
417: Tubes Asylum, Here are some other schemes (0.00)
Posted by DAK on 2018-05-04, 14:56:30 (66.91.168.87)
http://4tubes.com/SCHEMATICS/BY-TUBES/813/ http://boutailh-tan.pagesperso-orange.fr/ampli/ampli.htm (this one looks interesting) .......
418: Tube DIY Asylum, RE: Are you using tubes for voltage regulators? (0.00)
Posted by DAK on 2018-05-04, 12:10:33 (66.91.168.87)
Wow, i applaud your commitment to an all tube approach. Regarding the ground location; there is much leeway in where you put it. The "ideal" location would be the center of the chassis, but, others fe .......
419: Tubes Asylum, Tango OPT are crazy expensive. (0.00)
Posted by DAK on 2018-05-04, 10:44:57 (66.91.168.87)
Might it be the reason for excellent sound quality? Also The 150v supply i think comes from a SS regulator. But i suppose i could just use a regular voltage ladder. .......
420: Tubes Asylum, I am looking for more schematics (0.00)
Posted by DAK on 2018-05-04, 09:23:09 (66.91.168.87)
The RH813 uses a 12ax7 / 6sn7 front end which is nice, since i have lots of those. But the use of the VR tubes seems overly complex. Pete's design uses a single tube front end and some transistors for .......
421: Tube DIY Asylum, Are you using tubes for voltage regulators? (0.00)
Posted by DAK on 2018-05-04, 09:16:56 (66.91.168.87)
So each rectifier 6v4, 5ar4, handle regulation for different circuits? .......
422: SET Asylum, I have never bought an aftermarket power cable (0.00)
Posted by DAK on 2018-05-03, 22:48:50 (66.91.168.87)
I just use regular 16 awg power cord and hardwire it! No more than 15 bucks for the power strip wire and toss the molded end. Prolly not want you want to hear though. I would rather save my money and .......
423: Tube DIY Asylum, What type of amp is this? (0.00)
Posted by DAK on 2018-05-03, 22:39:08 (66.91.168.87)
I see only one output tube. But yet, many rectifiers and different front ends. I am guessing this is your own design? cheers. Dak .......
424: Tubes Asylum, RE: I was going pentode mode (0.00)
Posted by DAK on 2018-05-02, 10:32:43 (66.91.168.87)
I was not considering triode mode to begin with since the RH813 is pentode mode. I will check out Pete Millets scheme as i did not look it over yet. .......
425: Tubes Asylum, I was going pentode mode (0.00)
Posted by DAK on 2018-05-02, 09:45:47 (66.91.168.87)
Although it would be an easy thing to put in a switch to run it both ways. I still have not decided on the schematic to use. Alex K. has a nice schematic, too. His uses plate to plate feedback ::: TOP .......
426: Tubes Asylum, 813 output transformer specs? (0.00)
Posted by DAK on 2018-05-02, 09:05:15 (66.91.168.87)
I am looking to start a single ended 813 amp project and was wondering what i should ask the trans maker what to make for me. Or are the specs something that i should leave up to the winder? regards, .......
427: Tube DIY Asylum, I use the Beau or Cinch connectors (0.00)
Posted by DAK on 2018-04-28, 22:10:26 (66.91.168.87)
They have large metal contacts with very firm gripping receptacles. Current rating is high 20 or 30 amps but i don't remember the voltage rating. I believe the Rogers amps used them for a preamp hook .......
428: Tubes Asylum, The funky deposits fooled a lot of people (0.00)
Posted by DAK on 2018-04-25, 21:28:57 (66.91.168.87)
When i first started collecting tube audio, i could mostly afford el84 based amps. Mullard was one of the largest producers of el84 and probably out competed the other tube makers on price. Hence thei .......
429: Tubes Asylum, Only the early versions do that (0.00)
Posted by DAK on 2018-04-25, 10:20:12 (66.91.168.87)
The rX1 and rX2 types. After that they must have changed some material in the construction which did not out gas that deposit. As funky as it looks it has no bearing on the sound or functionality of t .......
430: SET Asylum, I was wondering what the effect on the B+ would be (0.00)
Posted by DAK on 2018-04-24, 12:10:13 (66.91.168.87)
In the second case. Creating a higher voltage would not be a good thing. I need to keep the voltage to the same amount as it is. I guess that would leave the first option since that should not change .......
431: SET Asylum, RE: Which arrangement for a hybrid rectifier? (0.00)
Posted by DAK on 2018-04-24, 10:37:36 (66.91.168.87)
Right, I could probably use the 5u4gb as well. But, it would be better to keep the higher B+ voltage wiht the 5ar4. I was just wondering if there were a preference in either one. Thanks. .......
432: SET Asylum, Which arrangement for a hybrid rectifier? (0.00)
Posted by DAK on 2018-04-23, 08:42:28 (66.91.168.87)
I have found 2 ways to do it. 1 is the diodes are connected in series ahead of the tube. Attaching the cathode to pins 4 and 6 and moving the B+ wire to the anode attachment point. The other one i fou .......
433: Tube DIY Asylum, There are far too many stories about this type of equipment (0.00)
Posted by DAK on 2018-04-21, 19:28:14 (141.239.96.151)
That is equipment without proper documentation and support. All too often it is a price that is too attractive to resist. But the hidden cost is sometimes more than its worth. I am not saying that som .......
434: Tube DIY Asylum, thanks but not this one. nt (0.00)
Posted by DAK on 2018-04-21, 18:20:23 (66.91.168.87)
. .......
435: Tube DIY Asylum, Right, DCV drop. nt (0.00)
Posted by DAK on 2018-04-21, 18:19:39 (66.91.168.87)
. .......
436: Tube DIY Asylum, Voltage drop thru a choke calculator (0.00)
Posted by DAK on 2018-04-20, 15:09:07 (66.91.168.87)
I found this neat calculator to find the voltage drop thru a choke. But, alas i lost it when my computer crashed. I have been looking for a long time for the calculator but have not found it again. Th .......
437: Tubes Asylum, You should switch to the 6x5 (0.00)
Posted by DAK on 2018-04-14, 11:03:50 (66.91.168.87)
A more interesting tube with a longer history and many variations. Exactly same specs but in an octal socket. Plus they are very cheap because no one uses them much. .......
438: Tube DIY Asylum, They are most likely leaking DCV (0.00)
Posted by DAK on 2018-04-14, 11:00:14 (66.91.168.87)
My experience with checking caps, and i check all the caps before i put them in any amp, whether the cap is new or used. Is that when the cap measures over spec that it is leaky. Why waste time? Just .......
439: Tube DIY Asylum, What is the value of the choke needed? (0.00)
Posted by DAK on 2018-04-13, 09:49:09 (66.91.168.87)
I got some excess stock that i should pare down. I can put it on Asylum trader if you would be interested. cheers, Dak .......
440: Tube DIY Asylum, Hi Rage, i have lots of big chokes (0.00)
Posted by DAK on 2018-04-12, 18:56:13 (66.91.168.87)
I collected a lot of them but i mostly use smaller one since i don't make too many high power PS. Most are mil spec potted units so shoot me an PM if you are interested. Shipping is reasonable with fl .......
441: Tubes Asylum, kt90 and kt120 (0.00)
Posted by DAK on 2018-04-12, 09:35:45 (66.91.168.87)
I usually run those for everyday listening. They extra power can really be noticed in the percussion. .......
442: Tube DIY Asylum, G1 to ground resistor value (0.00)
Posted by DAK on 2018-04-11, 11:25:33 (66.91.168.87)
My amp is a PP EL34 with fixed bias. I am wondering how do you determine the value of the G1 to ground resistor. I put in a 200k and measured from the coupling cap to ground and that was almost 50K . .......
443: Tube DIY Asylum, did you check your fuse value? (0.00)
Posted by DAK on 2018-04-10, 11:36:31 (66.91.168.87)
I hate rats too, but i dunno if anyone asked, what is the value of your fuse? I had a problem recently where i thought the fuse i was using was 3A but it was actually 1A! And it would blow after a min .......
444: Tubes Asylum, RE:Sometime stuff get left behind (0.00)
Posted by DAK on 2018-04-09, 07:48:40 (66.91.168.87)
It is not that unusual. Maybe a piece of flashing or some wire trimming with solder that was previously lodged and has now gotten loose. If it is not shorting out elements, it should be ok. It certain .......
445: Tube DIY Asylum, RE: Sockets Too Tight? (0.00)
Posted by DAK on 2018-04-09, 07:42:02 (66.91.168.87)
So even the pin openings are too small? .......
446: Tube DIY Asylum, RE: 12ax7 can be noisy (0.00)
Posted by DAK on 2018-04-08, 20:12:34 (66.91.168.87)
Just pull the ax7 and if the noise goes away it is coming from that circuit. .......
447: Tube DIY Asylum, 12ax7 can be noisy (0.00)
Posted by DAK on 2018-04-08, 12:06:48 (66.91.168.87)
Have you tried different ones? What about going DC on the ax7 filaments? I found that helped on a build. .......
448: Tube DIY Asylum, RE: Sockets Too Tight? (0.00)
Posted by DAK on 2018-04-08, 11:57:46 (66.91.168.87)
I have no experience with those sockets but maybe you can insert a jewelers screwdriver into the retainer and gently spread the jaws apart. They look like nice sockets though. .......
449: Tubes Asylum, RE:I have to check my notebooks, i will let you know (0.00)
Posted by DAK on 2018-04-08, 10:10:54 (66.91.168.87)
if i find something meaningful. Just off the top of my head i don't remember exactly which circuit i was trying to use. I have vague recollection of trying one but not having any success for some reas .......
450: Tubes Asylum, He gives many mods to various circuits. (0.00)
Posted by DAK on 2018-04-07, 16:08:58 (141.239.96.151)
Maybe not many mods, but he has definite ideas about some circuit improvements that he favors. Evidently he has been repairing audio amps for a long time and has opinions about what makes a better sou .......
451: Tubes Asylum, Do you realize how much it cost to put that extra hole in the plate? (0.00)
Posted by DAK on 2018-04-06, 11:12:06 (66.91.168.87)
OGR aka Bangy bang (isn't there an asian porn star with that name?) explained the process to me and the reason why it was necessary and the fabulous results obtained. First he had to put the whole tub .......
452: Tubes Asylum, Orangemen! (0.00)
Posted by DAK on 2018-04-04, 08:50:34 (66.91.168.87)
The Danes want to be distinguished because they have a better football team. No seriously, for people who have the same ancestors all those European countries are awfully nationalistic. .......
453: Tube DIY Asylum, RE: I just got some too (0.00)
Posted by DAK on 2018-04-04, 08:45:16 (141.239.96.151)
Hi Merdy, i am using fixed bias so i set the current measured at the cathode to 100 MA more or less. But it depends on Plate and screen voltages. Fixed bias is the way to go so you can find the settin .......
454: Tubes Asylum, Inspite of his opinions the schematics are worth it. (0.00)
Posted by DAK on 2018-04-03, 20:06:40 (141.239.96.151)
Also i believe he is from the Netherlands. So, there maybe translational errors in the text as well. It seems that his understanding of English is not as if he were a native speaker. Also there are ty .......
455: Tubes Asylum, Good reading material but... (0.00)
Posted by DAK on 2018-04-03, 09:43:41 (66.91.168.87)
I would be wary of his mods. Most are not vetted and are just "what i would do" if he rebuilt it. I tried one mod on a PP el84 amp and it has not been performing to my satisfaction. Great reading, in .......
456: Tube DIY Asylum, I just got some too (0.00)
Posted by DAK on 2018-04-03, 09:34:20 (66.91.168.87)
I am using a pair in a SE amp. They sound like a powerful kt88. i have no complaints. .......
457: Classical Court, awesome! thanks.....nt (0.00)
Posted by DAK on 2018-04-02, 20:11:58 (66.91.168.87)
. .......
458: Classical Court, RE: Listening to RCA Living Stereo audiophile sampler (0.00)
Posted by DAK on 2018-04-02, 19:47:55 (66.91.168.87)
So, is that the sound of the air moving thru the pipes? .......
459: Classical Court, I have only heard that noise on this recording but... (0.00)
Posted by DAK on 2018-04-02, 18:58:43 (66.91.168.87)
i don't listen to much organ music, unless its the Hammond B3. I was just wondering what in the organ makes that noise? .......
460: Classical Court, Listening to RCA Living Stereo audiophile sampler (0.00)
Posted by DAK on 2018-04-02, 18:06:43 (66.91.168.87)
#4, Saint Saens, S 3 in C minor, op 78, Organ. Q. what causes that rumbling noise on the deep or low organ notes? I hope it is not my Altec 19 falling apart?! thanks for the info .......
461: Tubes Asylum, RE: Thank you for checking! 1 question (0.00)
Posted by DAK on 2018-04-02, 18:00:26 (66.91.168.87)
Hi, Rod, renewed my subscription earlier today. I love the freebies too! Makes great gifts. .......
462: Tubes Asylum, Thank you for checking! 1 question (0.00)
Posted by DAK on 2018-04-02, 13:10:04 (66.91.168.87)
Is it possible that we could have a subscription that comes without advertising? I am concerned that some malware will be hidden in one of these pop ups, that is through no fault of the asylum. cheers .......
463: Tubes Asylum, How do we know if our subscription has lapsed? nt (0.00)
Posted by DAK on 2018-04-02, 12:11:42 (66.91.168.87)
. .......
464: Tube DIY Asylum, You should have no problems (0.00)
Posted by DAK on 2018-03-29, 22:18:16 (66.91.168.87)
They are very close to KT88 in electrical requirements. After trying them at the kt88 setting you could bump up the idle current and see if that makes and even better sounding amp. .......
465: Tubes Asylum, RE: NOS Tung SOL black plate vs smooth grey plate (0.00)
Posted by DAK on 2018-03-28, 19:56:21 (141.239.96.151)
Right, i think that the VTL, would be hard on the vintage 6550, no matter the plate color. GE 6550a or current made would be a better choice. The vintage 6550 would be awesome for a SEP amp. ::: TOPIC .......
466: Tube DIY Asylum, I like the sound of tubes. (0.00)
Posted by DAK on 2018-03-27, 11:19:22 (141.239.96.151)
On my high power SEP KT120 amp i had to go to SSR. It plays loud and sounds great but there is a perceptible hardness to the sound that makes me like to listen to the vacuum tube rectified SE amps mor .......
467: Tube DIY Asylum, Mount an extra filament tranny (0.00)
Posted by DAK on 2018-03-24, 10:40:48 (66.91.168.87)
No Snickering! Just buy a 12.6 vac filament trans. It is pretty much failure proof and will last for generations. That can not be said of the low voltage module you bought from china. .......
468: SET Asylum, I was going to mention that the vintage amps before 1950s .. (0.00)
Posted by DAK on 2018-03-22, 17:48:28 (66.91.168.87)
.. many of them were IT coupled. the unit i was wondering about are UTC A16. .......
469: Tube DIY Asylum, Do you have a tube rectifier? (0.00)
Posted by DAK on 2018-03-20, 11:17:45 (66.91.168.87)
i was having a similar problem, turned out to be a bad rectifier. I guess even SSR will show a similar issue. .......
470: SET Asylum, RE: What tubes are good with these IT trannys? (0.00)
Posted by DAK on 2018-03-18, 19:07:08 (66.91.168.87)
the only other info i have is that it has a hi pot or 1000v, and the max level. .......
471: SET Asylum, What tubes are good with these IT trannys? (0.00)
Posted by DAK on 2018-03-18, 18:07:43 (66.91.168.87)
I was "given" a pair of interstage or intrastage transformers and i am totally new to using these devices so i wanted to know what tubes would be good to use it with. Alternatively, how does one selec .......
472: SET Asylum, Why don't we be inclusive and make this SINGLE ENDED AMPLIFICATION forum? (0.00)
Posted by DAK on 2018-03-18, 14:36:09 (66.91.168.87)
This would make the forum much more universal. Afterall, sharing knowledge, and helping others is one of the guiding principles which established this site. And what makes a good SET amp, good build p .......
473: Tube DIY Asylum, RE: ST 70 Low Voltages (0.00)
Posted by DAK on 2018-03-11, 22:20:50 (66.91.168.87)
It sounds like something "hot" is grounded and drawing your voltage down. Unless your PT is set on AC voltage that is not for 120 or whatever your wall voltage is. .......
474: Tube DIY Asylum, Is the limit of your bias adjustment reached? (0.00)
Posted by DAK on 2018-03-09, 12:05:54 (66.91.168.87)
I just rebuilt a ST70 and after installing a new SS diode, I had to change the second resistor from 10k to 8k this allows more adjustment of the bias. this is the resistor that goes to ground or the b .......
475: Tube DIY Asylum, Some measure of success! (0.00)
Posted by DAK on 2018-03-08, 21:29:07 (72.253.100.160)
I made some changes to the 7A4 inputs and got the buzz down to a much lower level. CHACHACHANGES!to quote the inimitable Bowie. I put in a shielded input cable. Not even 3 inches long but i bet it is .......
476: SET Asylum, It is definitely the 7a4 (0.00)
Posted by DAK on 2018-03-08, 16:17:00 (72.253.100.160)
I pulled the tubes and the amp is dead quiet. So, plan is to go with shielded input wire, and increase the grid stopper from 400ohm to 1K. Also add a grid stopper of 1K to the suppressor grid. If that .......
477: Tube DIY Asylum, I like it! (0.00)
Posted by DAK on 2018-03-08, 10:32:06 (66.91.168.87)
Although i prefer a metal chassis, the 3D technique is a great idea. .......
478: SET Asylum, I ended up with a FWBR (0.00)
Posted by DAK on 2018-03-08, 10:08:57 (66.91.168.87)
It turned out perfect at least for the voltages. After rectification and a 6800uf cap, i have 6.36 vdc. I wired the 2 tubes in parallel. .......
479: Tube DIY Asylum, They come from the UK. nt (0.00)
Posted by DAK on 2018-03-07, 09:47:36 (66.91.168.87)
. .......
480: Tube DIY Asylum, brand new mil spec teflon sockets, not a problem (nt) (0.00)
Posted by DAK on 2018-03-07, 07:47:20 (66.91.168.87)
. .......
481: Tube DIY Asylum, EZ enough to put in. (0.00)
Posted by DAK on 2018-03-06, 18:37:49 (66.91.168.87)
You know what is really holding me back or actually hurting my back, is this freaking mofo weighs over 50 pounds. Since the noise is most evident on the Altecs i have to verify everything on it. I sho .......
482: Tube DIY Asylum, That maybe true but (0.00)
Posted by DAK on 2018-03-06, 17:11:05 (66.91.168.87)
the tubes are NOS, and the pins look like clean metal. Yeah, i am cleaning them now, but they are not really corroded. .......
483: Tube DIY Asylum, I am plugged into the wall (0.00)
Posted by DAK on 2018-03-06, 10:42:25 (66.91.168.87)
I live out in the country with 1 neighbor who is a hundred feet away. My AC wall voltage is 118 almost always. None of the others amp i use or have built have such an issue. I have made about 15 vario .......
484: Tube DIY Asylum, Good tips, thank you (0.00)
Posted by DAK on 2018-03-06, 10:31:49 (66.91.168.87)
When i think back to the first iteration of this amp, i used a 5ar4 rectifier, the amp was definitely quieter. But, my B+ was only 360 and i needed more voltage so i went with a FWBR. With the 5ar4 th .......
485: Tube DIY Asylum, According to the tube manual it is a 6j5 (0.00)
Posted by DAK on 2018-03-06, 08:59:16 (66.91.168.87)
But because of the loctal base the high frequency performance is much better. The tube curves are referenced to the 6j5. .......
486: Tube DIY Asylum, The PT is potted in a metal can. (0.00)
Posted by DAK on 2018-03-06, 08:51:42 (66.91.168.87)
It is a mongo sized mil spec unit. Moving around the transformers would be the last resort as that would require removing everything so i could drill new holes, etc. IME, transformer alignment is not .......
487: Tube DIY Asylum, It is true the 7a4 is a much higher frequency tube (0.00)
Posted by DAK on 2018-03-06, 08:44:01 (66.91.168.87)
I was worried after i made the amp that the tube is just picking up too much high frequency. I did try some ferrite beads on the input lead which is short only 2". Maybe i will put them back again, it .......
488: Tube DIY Asylum, the amp is totally built with all proper terminations. nt (0.00)
Posted by DAK on 2018-03-06, 08:35:41 (66.91.168.87)
. .......
489: Tube DIY Asylum, The buzz is in both speakers (0.00)
Posted by DAK on 2018-03-06, 08:34:19 (66.91.168.87)
and about equal in magnitude. I have a star ground that goes to a buss. I am very thorough with grounding as i check all the grounds with a meter to insure that the reading is very close on all connec .......
490: Tube DIY Asylum, I will try to see how it goes with the drivers. (0.00)
Posted by DAK on 2018-03-05, 21:16:34 (66.91.168.87)
It is hard to notice the problem at the shop because my speakers are not sensitive enough to hear it. But at home on the Altecs the buzz is super annoying. How do you use an oscilloscope to trouble sh .......
491: Tube DIY Asylum, Getting rid of an annoying high frequency buzz (0.00)
Posted by DAK on 2018-03-05, 17:58:13 (66.91.168.87)
I have been trying to rid my amp of this high frequency buzz, kinda sounds like crickets. It has been with this amp since the beginning. I tried changing the out power supply configuration from cap in .......
492: Tube DIY Asylum, RE: LC choke vs resistor (0.00)
Posted by DAK on 2018-03-05, 07:35:11 (66.91.168.87)
I dunno if you will be able to find a 20H 100 ohm choke. My suspicion is that it will be huge. there are "swinging chokes" that come close to your needs but You really need to know the current require .......
493: Tubes Asylum, That is about right. (0.00)
Posted by DAK on 2018-03-03, 09:46:43 (66.91.168.87)
I have noticed that buyers are scooping up 5u4g at a much higher price than before. Is it because of its looks or is there a rumor about magical properties ? I think the tubes are going overseas. ::: .......
494: Tubes Asylum, RE: 1970-80s Tesla brown base, blue glass EL34 and E34L tubes (0.00)
Posted by DAK on 2018-02-26, 10:53:45 (72.253.100.160)
those vintage Tesla brown base are excellent tubes. I believe they were made on Telefunken tooling. Too bad about their political situation at the time. The human misery and death toll is incomprehens .......
495: Tubes Asylum, I mostly do that (0.00)
Posted by DAK on 2018-02-26, 10:36:53 (72.253.100.160)
except this time. NO EXCEPTIONS from now on! cheers. .......
496: Tubes Asylum, I had a bad diode (0.00)
Posted by DAK on 2018-02-25, 11:18:04 (72.253.100.160)
Changed that and the voltages came back to normal. Don't you hate it when a new part lets you down. .......
497: Tubes Asylum, I will try that and let you know. thanks. nt. (0.00)
Posted by DAK on 2018-02-25, 10:05:29 (72.253.100.160)
. .......
498: Tubes Asylum, I have a problem with fixed bias (0.00)
Posted by DAK on 2018-02-25, 09:04:56 (72.253.100.160)
I just rebuilt a fixed bias circuit. Unloaded it tests out perfectly but when i put it in the amp, PP EL34 stereo, the negative voltage goes away. Before i rebuilt the bias circuit the amp was able to .......
499: Tube DIY Asylum, RE: Is there room for anything larger than stock? (0.00)
Posted by DAK on 2018-02-25, 08:52:11 (72.253.100.160)
We can discuss the sonic benefits of different pots but the picture posted shows a cap close by. It doesn't look like there is any room for one of those big ladder attenuators. .......
500: SET Asylum, Thank you for the tip. (0.00)
Posted by DAK on 2018-02-23, 10:24:19 (66.91.168.87)
I have not seen that used before. But i admit the scope of my knowledge is very small. But, working on this will be on hold for now since i just got a Dynaco ST70 and PAS rebuild dropped off yesterday .......
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