Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: JayCobie on March 13, 2020, 05:45:05 am

Title: Rebuilding a Twin with Harmonic Tremolo - Any prior art out there?
Post by: JayCobie on March 13, 2020, 05:45:05 am

I'm going to rebuild my Twin Reverb 65' Reissue and swap out the PCB for a hand-wired version.
It'll be mostly an AB763, but the main change I want is to remove 1 channel and the "roach" tremolo in order to make room for harmonic tremolo.

The old Brownface Fender's give me a place to work from, but none of the 6GXX schematics had spring reverb, so I'd have to redesign an AB763 preamp with harmonic trem.

Instead of me having to draw the schematic and layout from scratch, does anyone have or know of any amplifier schematics/layouts that contain harmonic tremolo and spring reverb?

Title: Re: Rebuilding a Twin with Harmonic Tremolo - Any prior art out there?
Post by: Adrien on March 13, 2020, 01:48:54 pm

Nice idea!  I've thought about making a similar amp and drew this schematic up a while ago.  Never got around to building it so I can't guarantee it's correct, or even sounds good.  Use at your own risk.  Should be a good starting point for you though.  Also there's no power supply drawn but if you're building an amp of this complexity I'm sure you can sort that out.

Also see this thread:  https://el34world.com/Forum/index.php?topic=18529.0

I also had another schematic in my files that uses mosfets for the trem oscillator and cathode follower, no idea where I got it unfortunately but I've attached it..

Title: Re: Rebuilding a Twin with Harmonic Tremolo - Any prior art out there?
Post by: JayCobie on March 15, 2020, 06:20:43 am

Thanks! Lots of good info in that Harmonilux Reverb thread and you also gave me some ideas with your schematic.

I'm sure I'll make a separate build thread for my Harmonic Twin when I've finished some of the prep-work for this mod.