Recent Posts

41

Tube Amp Building - Tweaks - Repairs / Re: LOW Output from 50's GA20

« Last post by BrianS on March 10, 2026, 10:32:04 am »

Altering the design of the amp by changing component values is not a troubleshooting technique.

42

Tube Amp Building - Tweaks - Repairs / Re: Reverb bleed at 0 on RVB pot on a '65 blackpanel Fender Vibrolux

« Last post by Sansteeth on March 10, 2026, 10:31:57 am »

Hello pdf64, thanks for chipping in!

Not by me but they have been changed by F+T caps not long ago it seems, 22uF instead of 16uF but I doubt that would be the problem.
You think the wet signal could have bled through this way?

43

Tube Amp Building - Tweaks - Repairs / Re: LOW Output from 50's GA20

« Last post by passaloutre on March 10, 2026, 10:29:58 am »

What's the AC voltage on the primary when you inject 3VAC on the secondary?

44

Tube Amp Building - Tweaks - Repairs / Re: Tube ID

« Last post by Rontone on March 10, 2026, 10:03:48 am »

Is that batch/date stamping near the bottom or just a sharpie pen from someones testing results?

Can't quite make out the letters/numbers

45

Cabinets-Speakers / Re: Options on reparing/ replacing integral baffle?

« Last post by bmccowan on March 10, 2026, 09:59:01 am »

That's not bad at all. Do you have a glue syringe? That would help. Even pressure with the clamps and Titebond should work fine. I think Gorilla Wood Glue is similar to Titebond. I would agree with you as to not using the Polyurethane glue. Let us know how it comes out!

46

Tube Amp Building - Tweaks - Repairs / Tube ID

« Last post by pbman1953 on March 10, 2026, 09:44:02 am »

Can anyone ID this tube as far as the maker?


It has long grey plates

Thanks

47

Tube Amp Building - Tweaks - Repairs / Re: Why did Marshall use the EL34 vs. the 6L6?

« Last post by pdf64 on March 10, 2026, 08:33:39 am »

The El34 is a 25 watt tube

That's under the design centre rating system.

The 6L6 is a 30 watt tube

That's specifically the 6L6GC, and it's under the design maximum rating system.
Hence the numbers are not directly comparable.
A 6L6GC would probably have an anode dissipation limiting value of about 26W under the design centre rating system.

Also the EL34 anode voltage limiting value is much higher than that of the 6L6GC.

The EL34 ... current draw of 1.5 amps

The 6L6 ... current draw of .9 amps

I'd think you could go with the same PT to run cooler with the 6L6

3.8W difference in heater power per valve seems trivial?
I can't perceive an advantage in reducing the loading by that degree for a mains transformer designed to accommodate EL34?

I'd think you could go with ... the 6L6 and get more power

You may not be considering the differing anode curves / characteristics, and hence 'best fit' loadlines, of those valve types?

Generally, swapping 6L6 family valves into EL34 circuits will result in a slightly lower maximum power output.

https://frank.pocnet.net/sheets/010/e/EL34.pdf
https://frank.pocnet.net/sheets/093/6/6L6GC.pdf
https://www.one-electron.com/Archives/RCA/RCA-AppNotes/RCA%201958%20AN-174%20Design-Maximum%20System%20for%20Rating%20Electron%20Tubes.pdf

48

Introduce Yourself / Re: Hello, from Connecticut!

« Last post by EL34 on March 10, 2026, 07:19:08 am »

Hi,
The DIYLC board is here
https://el34world.com/Forum/index.php?board=26.0

49

Buy - Sell - Trade / Re: JTM45 chassis for sale

« Last post by Blooze on March 10, 2026, 06:09:43 am »

Still available.

50

Tube Amp Building - Tweaks - Repairs / Re: Reverb bleed at 0 on RVB pot on a '65 blackpanel Fender Vibrolux

« Last post by pdf64 on March 10, 2026, 05:56:08 am »

Have the HT decoupling caps been replaced recently, especially the D node that supplies the preamp?