Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: warioblast on July 15, 2018, 07:49:42 pm

Title: Looking at the AB763 deluxes for my next build. Got some Qs
Post by: warioblast on July 15, 2018, 07:49:42 pm

Q1 - Reverb
I already have a 6G15 reverb unit clone. So the deluxe lite had my attention. But I keep reading comments on how the 3rd gain stage is a big part in the deluxe sound. I read that this stage could be bypassed and turned the amp in a true NO reverb deluxe. Do you think it would be usefull to have a switchable 3rd stage? Would a deluxe with a 6G15 be close to a deluxe reverb ?

Q2 - Tremolo
I like tremolos. I have a Demeter tremulator pedal (LDR based) and I like the idea of a bias tremolo.
Would it be possible to use the 6G3 tremolo instead of the 5G9 trem used in the Hoffman AB763. And therefore use the 2nd half of the tube used for a possible bypassable 3rd gain stage. How would you compare a 1 triode Vs. a 2 triodes trem ?   

FWIW, I don't intend to use 6L6s. I don't have access to a lot of amp and so I make my mind up based on Youtube demos and your worthy inputs. I'm all ears  :wink:

Title: Re: Looking at the AB763 deluxes for my next build. Got some Qs
Post by: pdf64 on July 17, 2018, 07:05:18 am

I've never compared them but I think that the 6G16 reverb is such a different circuit architecture to the BF reverb that their tone and response will inevitably be rather dissimilar.
Sure the DR AB763 3rd stage could be made bypassable; it adds slight gain and a high frequency lift, so helps to push the power stage into overdrive at higher volume settings; also flips signal polarity, which some folks think is a big deal  :dontknow:
(I suspect that if signal polarity did make such a difference, then there would be a dedicated pedal on the market that make it footswitchable).
The 6G3 bias trem should work fine, but it may not produce such a deep trem effect as the buffered 2 stage 5G3 trem.

Have you considered a BF Princeton https://el34world.com/charts/Schematics/files/Fender/Fender_princeton_reverb_aa1164.pdf https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf
They would seem to have everything you want and nothing that you don't need, eg 2 channels, and would get into their sweet spot at more domestic friendly SPLs.