Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: spacelabstudio on April 01, 2014, 05:44:54 pm

Title: Name this mod -- Heavily modified AB763 Super Reverb
Post by: spacelabstudio on April 01, 2014, 05:44:54 pm
A customer brought in a CBS era black face AB763 Super Reverb that has been heavily modified.  The reverb has stopped working and he says it just doesn't sound the way it used to.  He says that someone told him that it was *probably* modded by this guy who did this particular type of famous mod back in the 80s or 90s, before anybody thought old Fender amps were worth anything.  Couldn't remember who it was supposed to be.  Not really sure what it is.  Anybody recognize it from the pic?

https://drive.google.com/file/d/0B14xDNFTytUgWV95M1hEODRYczA/edit?usp=sharing (https://drive.google.com/file/d/0B14xDNFTytUgWV95M1hEODRYczA/edit?usp=sharing)

The mod seems to involve:

- Getting rid of the tremolo (oh, the 80s)
- Adding a 6 stage tone stack lift on the "vibrato" channel via a 6 way rotary switch in place of the "Speed" knob
- Making the tone stack lift defeatable using the "vibrato" foot switch, now labeled "Fat"
- Adding a master volume in place of the "Intensity" knob
- Adding a pull switch on the "vibrato" volume knob that makes the gain go insane (probably by repurposing the tremolo tube)
- There is a three position small mini-toggle on the back that allegedly deals with assignment of reverb to one channel, the other, or both.
- The reverb knob has a pull switch whose function is unknown

Ring any bells?  If anybody can identify it as a particular mod then the internets might cough up a schematic.

The customer is leaning towards just "fixing it" rather than restoring it.  I'll probably pitch something more substantial to undo a lot of this craziness.  The customer doesn't use the overdrive feature, so it would be nice to get the tremolo back and maybe get rid of some of the extra wiring by permanently assigning the reverb to both channels.

Chris
Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: tubenit on April 01, 2014, 08:29:08 pm
Sounds like some type or Torres mod?

With respect, 10thtx
Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: spacelabstudio on April 02, 2014, 08:05:16 am
Quote from: tubenit on April 01, 2014, 08:29:08 pm
Sounds like some type or Torres mod?

With respect, 10thtx

I did some Googling.  The "Super Texan" seems like the best candidate so far, but I don't think that's it.  Enough stuff that doesn't quite match.

Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: spacelabstudio on April 02, 2014, 08:06:42 am
That may very well be what this guy's friend thought it was, though.  It's entirely possible this is something one guy somewhere did once or only a few times and it never made the annals.
Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: LooseChange on April 03, 2014, 04:33:41 am
Gut shot would help a lot.
Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: spacelabstudio on April 03, 2014, 06:16:57 am
Quote from: LooseChange on April 03, 2014, 04:33:41 am
Gut shot would help a lot.

There's a link in the first post.
Title: Re: Name this mod -- Heavily modified AB763 Super Reverb
Post by: LooseChange on April 03, 2014, 06:27:09 am
If it were a Torres mode it would be filled with Orange Drops.