Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on June 17, 2023, 12:43:47 pm

Title: Vox preamp schematic check
Post by: fossilshark on June 17, 2023, 12:43:47 pm

Hi all, my friend wants a Vox top boost style standalone preamp so I drew up this schematic. I am used to Marshall style designs so I am trying to expand my horizons. I am not 100% confident I am reading the AC30/TB schematic properly nor do I have experience with such amps.

R11, R15, R16 will be fiddled with to tweak the voltages just right.

The output section V3A, V3B is the same one I used on my Wendigo preamp design since the cleans on that sounded so good, and I will also be using the same power transformer (Antek AS-05T280) as the voltages seem pretty similar.

Does anyone have any recommendations? I am surprised an AC30 doesn't have any tone controls for the normal channel, although there is 1,000,000 models of the amp and I was not sure what circuit to go with.

Any advice greatly appreciated!

Title: Re: Vox preamp schematic check
Post by: Williamblake on June 17, 2023, 07:07:19 pm

Who would not want this? Except for maybe an 1:1 Output transformer? Maybe unneccessary.

Title: Re: Vox preamp schematic check
Post by: sluckey on June 17, 2023, 07:23:34 pm

Look at Hoffman's AC-30. May be easier to compare to your drawing.