Tube Amp Archive

Maybe an authorized repair guy here?

As I understand it, the amp has been discontinued, but Vox only posts the vintage schematics.

I picked up the amp at Sam Ash on closeout, and I kind of like it, and I'm curious to what's going on inside.

Thanks,
Chris.

Thanks again for the replies and ideas, I've been pretty busy with work and some family stuff, so the amp project got put to the side. I plan to order some parts including new pots, and some metal film resistors. I plan to change everything in the bass channel, and put in new B+ voltage dropping res...

Latest update: I decided to try to tweak the Bass channel. All of the resistors (new carbon comp)and caps on the board are replaced (ecept for the stock 330pf ceramic treble cap). I replaced the 1M and 68K input resistors with metal film, and I ran shielded wire to the grids (grounded at the pot and...

That's disappointing news, since I already did the star ground thing. My solder iron wasn't doing the trick on the brass plate. It was good enough to un solder the wires on the plate, but soldering back on was a different story. I saw some posts from Milkman recommending not to use the brass plate, ...

Hey thanks for all of the info. As for the caps, I've read somewhere that the TAD's are made by F&T (I hope so). I have a 16uf of each brand and they appear to be the same size and shape. Now some good news (sort of)... I cleaned up the grounds by rewiring all ground wires going to the brass plate w...

Hi, I'm back... I returned the third stage to stock with the 470K feedback resistor, 47oK grid load resistor, and a removed my screw-up ( the two 220K resistors befor the PI input cap). Basically I have the stock (almost) AB165 pre amp (all caps across plate resistors removed and the tone stack mods...

Errr...I'm a dope. Yeah, I have the the two 220K resistors going INTO the PI cap, so yes I have the resitor to ground coming off of the V2 plate through the other 220K resistor. I guess that because I had the resistors placed in a V-shape on the board, the signal would know which way I wanted it to ...

On the input to V2, I have the two 220K mix resistors going to a .01 input cap (or maybe .02, I forget now)...After that I have a 220K grid to ground resistor just befor the grid to V2. Cathode Restistor (1.5K) is not bypassed.

Thanks again

Hi Firestorm, I cant make a drawing now (or more honestly, I dont know how to put it in computerland) The phase inverter section right now is pretty much exactly like an AB763 inculing the two 22oK mix resistors into the .001 PI input cap. The one resistor gets the signal from the 3rd gain stage (V2...

In all honesty I didn't consider the signal going into the phase inverter. My intention was to have a gain structure more or less somewhat equal to an AA864 of an AB763 without trem or reverb on both channnels (3 stages before the PI) At this point, I've added what I think is a voltage divider in fr...

Hi Firestorm, I think you're right about the gain being too high. I was trying to attenuate the signal AA864 style by swapping out the grid to ground resistor to 220K as in the AA864. I figure that I have the same series resistance entering the 3rd stage with the two 220K mix resistors.. The schem f...

Hi Stevem, I changed most of the preamp plate resistors in the amp (with new 1/2 watt carbon comp resistors) The only ones that I left original, are the two plate resistors on the Normal Channel (I figured that I'll leave that channel stock, and mess around with the bass channel. For the bass channe...

Hello Everyone at The Amp Garage. I've been reading posts and trying to fool with amps on and off for a couple of years now. I just picked up a project amp (AB165) and it's time to try and fool with amps again...Which leads me to my current problem... The amp is a '66 or '67 Blackface AB165 in need ...