The Amp Garage

The "AC" trimmers are probably heater balance... I'll check that, thanks. One channel sounds different than the other. It seems I have a couple volts of AC and DC on the input grid for one of the channels. Not sure what would be causing that....but I think it is a problem on that side. Swapping tub...

Progress. I managed to squeeze my bias probes up under the low clearance chassis lip and made some adjustments to the bias supply. The bias was super cold and was causing the distortion. I know realize the "DC" pots on the front make fine tune adjustments to the bias for each side. I'll have to figu...

Wow, that thing is awesome! You should definitely re-cap it. It is cool and those block transformers are so heavy! Caps for sure, I suppose as the first step. The mallory cap on the board is dated 1977. I'll order some radials for that bank in the row. I put tubes back in it and don't get the same ...

Try looking at some Fisher, Scott, Dynaco or Laffayette schematics. Of course with time on your hands you can always bite the Bullet and just draw out a schematic should you really think you need one. Thanks, I will look at those. I traced as far as the input RCAs to the first preamp tubes.... The ...

Hi guys, I have a little extra time being stuck at home and pulled this beast off my shelf. Someone had given it to me years ago and it is a homemade stereo amp of unknown origins (says William Abel Design but no google info). It has dual 5AR4 rectifiers, 6AU6 tubes, and had a quad of EL34s in it wh...

I saw a great RF show last night in Honolulu. He used his Dumble!

Well here is my weird DR103. I've never been able to sort out what the deal is with this one as the layout is a bit off. These pics were before I replaced the orange drops with mustards but the amp sounds great and I never tried to really figure out all the differences. I didn't pay that much for it...

Try it thru different speakers if you can. I just tried. No change. I've called it done on this amp as the customer does not want to replace all the electrolytics which would be my next step to see if that changes anything. Also, the power amp in jack does not work and the customer does not care ab...

I pulled the treble pot and other caps. Everything checks out. I think there may be an excess of bottom end coming in to the tone stack and is giving a perceived loss of volume. This is the first time I've played around with these older Devilles. Or maybe the filter caps are failing? I'm going to ch...

Well are you seing any DC voltage on the groundward leg of the Treble pot as if c6 or c7 was leaky? If not then a circuit trace on one side of the pot may be bad. No DC voltage that I can measure on C6 but I can't measure C7 as it is pinned tight on the board. I'm not turning this thing on when it ...

The treble pot seems to measure okay and I replaced the 250pf treble cap but no help there. Hit all the pot solder joints for good measure. Calling it a night. Will try again with the bass and mid caps in the morning and check those pot measurements also.

It looks like a pain but really only takes five minutes to get the board out and flipped. Look for cold solder joints on the pots, and resolder the input jacks too. I hear you. I hate doing in though! Not very possible to test with it pulled out and this one has had the original jacks replaced with...

I've got an older Blues Deville on my bench that has a few problems. I fixed the main power tube problem and the amp sounds pretty good, but when I turn down the treble control, the amp gets a lot louder. When I turn it up, more treble but way thinner and much less volume. I really hate pulling out ...

It's a little circuit for the LED style DC voltage indicator light - check out the 183 schematic.

What kind of indicator light do you plan to use in your build? If you use a Fender style bayonet lamp that runs on 6V AC, you don't need that circuit at all.

Stevem wrote: ↑Sun Apr 14, 2019 11:14 am I would try to implement the reverb from a Ampeg reverbrocket, the models that used no driver transformers and octal tubes have the greatest reverb.

I agree the Reverberocket 2 sounds pretty great but the 6U10 in it has 12 pins! I’ve got 2 of them now.....