Recent Posts

61

Tube Amp Building - Tweaks - Repairs / Re: Deville Transformers Reuse

« Last post by sluckey on July 20, 2026, 09:23:40 pm »

Transformers will be fine for a 6L6 AB763. But the PT is designed for a FWB rectifier so you should just use the Deville HT power supply. Forget about a tube rectifier.

62

Tube Amp Building - Tweaks - Repairs / Re: Princeton Reverb circuit refinements

« Last post by Carlsoti on July 20, 2026, 09:12:40 pm »

You're unlikely to get the deep drip of an old Gibbs pan with a new one from any manufacturer. That's just the way things are. I don't futz with old broken reverb pans anymore. The juice is not worth the squeeze.

63

Tube Amp Building - Tweaks - Repairs / Deville Transformers Reuse

« Last post by king_me on July 20, 2026, 08:34:31 pm »

Hello !!!

 New to the forum and ive been searching high and low but maybe someone here can help me. Looking to build a Hoffman AB763 One Channel or Bassman 6g6b circuit  out of a fender deville chassis that has a damaged tube board. Not looking to save the circuit board but would like to save the transformers, chassis and 410 cab. Jus need to know if the transformers are good for either of the builds. Thanks for reading this and hope some can answer this or point me in the right direction.

64

Tube Amp Building - Tweaks - Repairs / Re: Anyone care to help me finish my build ?

« Last post by AlNewman on July 20, 2026, 05:16:04 pm »

Maybe you need to adjust the voltage divider after the PI?
Maybe you need to adjust the ratio of the NFB circuit?

You might just be hitting the power tubes too hard.

What happens if you lift the NFB?  Maybe it's as simple as reversing the OT primaries.

65

Tube Amp Building - Tweaks - Repairs / Re: Anyone care to help me finish my build ?

« Last post by antolc37 on July 20, 2026, 04:15:47 pm »

oh ok that's good to know, I had hoped this was the origin of the hiss though and not the lead dress or something wrong with the layout

66

Tube Amp Building - Tweaks - Repairs / Re: Anyone care to help me finish my build ?

« Last post by sluckey on July 20, 2026, 03:41:11 pm »

That tone stack is drawn weirdly but if you rotate the bass and mid pots and line them up under the treble pot you will see a very familiar TMB stack.

Those 22K grid stoppers should not be a problem.

67

Tube Amp Building - Tweaks - Repairs / Re: Anyone care to help me finish my build ?

« Last post by antolc37 on July 20, 2026, 03:16:36 pm »

sure here it is, the exercise was interesting I had to trace it back from the actual circuit which showed me two odd things :
- Tone stack is weird
- 22k grid resistor for V4 is too big I don't rember why I put so much

68

Tube Amp Building - Tweaks - Repairs / Re: Princeton Reverb circuit refinements

« Last post by johnfromcyrene on July 20, 2026, 01:34:45 pm »

i have a new accutronics tank that i heard are not that good anymore.

What do you mean not good, how so?

they say you get a weak reverb from it. they use a press on wire for the transducer i guess. not sure why but thats what i hear.

69

Tube Amp Building - Tweaks - Repairs / Re: Anyone care to help me finish my build ?

« Last post by Lectroid on July 20, 2026, 12:49:48 pm »

Schematic?

70

Tube Amp Building - Tweaks - Repairs / Re: Kay 703 grouding scheme and crazy squealing

« Last post by sluckey on July 20, 2026, 12:01:41 pm »

That original amp is mostly safe to play just as is. Just add a 3-prong power cord with the green connected to ground. The only issue is the filament circuit is still connected to AC line. It's really only an issue if the filament circuit becomes shorted to chassis, but that's not dangerous to the player. Just might trip the house breaker. So, it would be a good idea to isolate the filament circuit from the AC line. You could do it as shown in my schematic. Or you could just use the second iso tranny to only power the filaments. Connect both red wires to the series filament string and also connect one of the red wires to chassis. Now you have everything safely isolated from AC line and the filament circuit is referenced to chassis ground which may help with any filament hum.

Still requires two iso trannies. I don't know what AI told you, but there is no reason to float all your grounds.

Your sound clip indicates a problem in the amp. Most likely a wiring error. We need to see a schematic of your actual circuit. Hi-rez pics of the actual amp may be useful too.

EDIT... added schematic