Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on November 21, 2016, 08:20:04 am

Title: AA764 e-caps question
Post by: kagliostro on November 21, 2016, 08:20:04 am
I'm planning a Vibro Champ with a 1625 Power Tube (same as 807) with ~350V B+ for 10-11W of power

the PS will be with a FWB so, no 5Y3 tube there

the original amp uses a 3 node PS with 20uF 450V electrolytic caps

(http://www.thevintagesound.com/ffg/schem/champ_vibro_aa764_schem.gif)

I have a few 47uF 450V e-caps under hands, do you think I can use it or they are too big ?

Sometime I've read that too big e-cap on PS can affect the tone response of the amp in a bad way, but I'm not a player .......

One other thing, as to tame the possible noise (at the end it is an SE amp not a PP) what do you think about to add a node to the PS ?

I mean one other 47uF e-cap and a ..... 220R (?) resistor

Thanks

Franco



Title: Re: AA764 e-caps question
Post by: sluckey on November 21, 2016, 08:43:32 am
Quote
I have a few 47uF 450V e-caps under hands, do you think I can use it or they are too big ?
I would use them.

Quote
I mean one other 47uF e-cap and a ..... 220R (?) resistor
Absolutely. Consider changing the 220Ω resistor to a choke.
Title: Re: AA764 e-caps question
Post by: kagliostro on November 21, 2016, 08:51:17 am
Thanks Steve

Franco
Title: Re: AA764 e-caps question
Post by: Willabe on November 23, 2016, 01:07:55 pm
K, here's my PSU I'm going with for my 5F2A SE Princeton. 

I'm using a wired ground with insulated/isolated input/speaker jacks, like K. O'Connor/Merlin and heater DCV feeding a 100R/5w humdinger pot. Filter caps are Panasonic EE series radials, I like them a lot so far. I added the last 10uF B+ filter cap because of the wired ground and the DCV stand off. The NFB goes to the 2nd gain stage so the OT gets grounded there. A lot of current is there because of the OT ground and too many ground wires on 1 turret. Also I didn't want the DC stand off filter cap grounded with the OT. I might change the value of the last 2 @ 10K B+ dropping R's that feed the D/E B+ nodes. I've had it on my BB and it has worked well and is very quite.  :icon_biggrin:
 
I know your going with SS rectifier B+, I'm using GZ34, I don't like a 5Y3 so far.  :dontknow:

A little cleaner with the higher B+DCV.