Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on August 09, 2014, 09:48:18 am
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I went schematic hunting for post pre tone-stacks n found the next build. It was always gonna be a preamp section only. I found both in the 1959 Marshall schematic in Doug’s library. Found other references, was following the princeton build here n since I have most all the pieces I thought I’d meld the two, JM800(?) preamp with Fenders AA1164s reverb section.
I have the IN for the reverb cap coupled at V2a grid(marshall schm), but I’m not sure where to put it back. The same way in the Princeton build? 3.3m|| 10pf.
I also wanna make sure the preamp out is in-phase with the preamp in, which is the case on the marshall. That got me wondering, does the reverb coils/tank cause a 180 phase shift? By the look of the Princeton I’m guessing not, but wanted to be sure.
Last question, I’ll have a ½ 12ax7 free, my ideas are;
2nd CF after the tone stack?
A PI after the tone stack, for phase matching choices @ preamp out?
Other ideas? Looking for the most real-world practical use.
Thanks as always
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Put in the d,later tube effects , run the first half without the tube like Tubnits 2 CF TOS and use the tube on the second half so you can use the d,later volume for your master volume, just my 2 cents.
Bill
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Thanks tone junkie, like the version where tubnit removed 1 of the 2 CFs? I do have 1/2 a tube free I could use after the tank recovery tube.
EDIT it's a preamp only so I was gonna just have a pot/wiper out for "level"/amp drive.
My biggest problem is tying it to the dry signal, where n how to couple it, direct, via cap, cap/|| resistor? I put up a working sch. none of the component values, tube numbers etc have been set yet.