Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Lambertini on April 09, 2024, 03:27:12 am
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Hello
After few months searching the EL34 forum, fishing good tips from the community and a lot of learning, I would like to share with you few pictures of my last AB763 build.
It's almost a clone of the original solid state rectified AB763 circuit, 6L6 quad, with few minor mods:
- The grounding schema is changed to add a bus bar for preamp and a single ground point for power section
- V1 and V3 cathodes shared by several triodes have been split
- Resistor powers have been increased following Rob Robinette recommandations
For components:
- Most of the resistors are Vishay Dale RN65 when available, except PI tail and plates that are carbon comp for mojo
- Mercury transformers
- The fiberboard is a TAD Twin Reverb AB763 slightly modified
- Coupling caps are SoZo Blue
- Filter caps are F&T 220µF 350V for reservoir, and JJ 30µF 500V for B+
Speakers: Jensen C12N x 2.
Reverb tank: MOD 4AB3C1B.
One regret: I wish I knew go-to 25µF 25V cathod bypass caps are Sprague Atom before I soldered the TAD ones.
The amp is very loud, sensitive, punchy. It's also nicely quiet, except for a tiny hum that can be heard at loud volume.
Compared to the '76 Fender Twin Reverb Silverface I used to play before, it's night and day, another world of tone, not even better, incomparable.
Thanks to all of you who spent time to teach and advise me, I couldn't have done this without your help.
Photo set here (https://photos.app.goo.gl/Bfzy7h9DuZmKC6f89).
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Looks great, you must be pleased!
Is it going in the vintage cabinet or is a new one in the works?
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Looks great, you must be pleased!
Is it going in the vintage cabinet or is a new one in the works?
I am ;)
I'm selling the old Silverface to recover from the Mercury transformers, shipped from Los Angeles to Montpellier, and attentively inspected by custom...
I'm not gonna build the cab by myself, won't be able to make it clean due to lack of skills and tools.
I've ordered one from TAD, their cabs are always very well built, in massive pine instead of the cheap chipboard wood from CBS.
I'll cheat by adding a Fender logo and a nice Twin reverb decal. Will post pics when ready.
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I'll cheat by adding a Fender logo
Nothing wrong with that, but IMO I'd say make up your own label / logo. This is yours!
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Hi Lambertini
Nice Job :worthy1:
+1 on your cabinet idea, the completed chassis is worth it.
consider " LamberTwini" :l2:
Kind regards
Mirek