Fender Twins

[C Moore]

I am gutting a 1969 Twin that is old and worn out. My first thought was AB763, but what about the three versions before that. Would there be any advantage of going with a:
AA270
AA769
AB568
If you guys were going to redo a Silver Face Twin, what version would you build?
Thank You

[Structo]

Can I have the transformers?

[M Fowler]

Yeah those trannies would make a nice Dumble.

[BTF]

Actually, HH, the three versions you mentioned came after the 763. If you want the "classic" Twin, the 763 is the way to go. I reworked my old PA100 head into a 763 (without the tremolo which I don't use) and really like the sound. One neat idea you might try is re-voicing the preamps. I went through various voicings before settling on a plate-driven '59 Bassman stack. For a big '50's jazz sound a la Bob Bain or Clarence White country rock, it's my go-to amp.

Hope I've helped and Good Luck, BTF.

[C Moore]

Actually, HH, the three versions you mentioned came after the 763. If you want the "classic" Twin, the 763 is the way to go. I reworked my old PA100 head into a 763 (without the tremolo which I don't use) and really like the sound. One neat idea you might try is re-voicing the preamps. I went through various voicings before settling on a plate-driven '59 Bassman stack. For a big '50's jazz sound a la Bob Bain or Clarence White country rock, it's my go-to amp.

Hope I've helped and Good Luck, BTF.

Good Grief, I don't know what made me think those were earlier versions.......then I guess it is the AB763
Well, yes I do know why I assumed that. It is because of the way Hoffman has the schematics listed. Typically they have the schems in chronological order. I guess they changed it up with the Twin for some reason.
Structo and Fowler.....no, you vultures can not have my trannies

[M Fowler]

I have a Twin Reverb I am putting together.

But the C.Diaz board I have doesn't quite match up to AB763 so will have to figure that out as I go.

[David Root]

I would probably vote for the AB763, but with a 100W Marshall JMP OT, ideally an old one (you should be so lucky!).

Mo' OT Iron be Good with a Twin!

OTOH that old '69 OT is going to sound real smooth too!

[roadkingbluzs]

I'm in the process of converting '72 twin to AB 763. OT is non original 100 watter. I have a Merc Mag. 85 watter to install, but after replacing power filter caps this thing is so fat and punchy, will leave in for now. Next is to eliminate M-vol. etc. A '69 twin is much easier to convert to AB763, and lead dress is better. Good luck with your conversion. These amps are great bang for your buck. BTW what speakers are in there now? Bob

[BTF]

When I was reworking my PA100, I seriously flirted with mating an AB763 preamp to a Blonde Twin power amp. I still may try that one day. Every Blonde and Brown I've ever tried has just been a stellar amp.

At any rate, Best of Luck!

[Gibsonman63]

What's to wear out? Change out all of the electrolytics and put some decent tubes in it and have fun. If you want to get serious, convert it to AB763, which is mainly changing the bias to bias voltage adjust instead of bias balance and removing the snubbing capacitors on the power tubes, as long as the amp is stable, and a few other resistor values here and there .

The other fun thing to do with these old two channel Fenders is to play with the voicing of the two channels and to increase the gain and mids of the normal channel and channel switch externally using an A-B switch.

Don't forget to check the power tube heater wires. Fender didn't pay attention to it and with 4 power tubes it is unlikely that they got it correct.

There are lots of good tweaks for these amps and tons more poor mods. Get it working, go in steps and DON'T DRILL ANY HOLES!

[Structo]

I know nothing about Bassman's but I see the AA864 model thrown around as a good and desirable circuit.

http://www.schematicheaven.com/fenderam ... _schem.pdf

[C Moore]

I'm in the process of converting '72 twin to AB 763. OT is non original 100 watter. I have a Merc Mag. 85 watter to install, but after replacing power filter caps this thing is so fat and punchy, will leave in for now. Next is to eliminate M-vol. etc. A '69 twin is much easier to convert to AB763, and lead dress is better. Good luck with your conversion. These amps are great bang for your buck. BTW what speakers are in there now? Bob

It had Oxfords, now it has a Weber California (ceramic, paper dust cap) and a Eminence Tonker.

[Baxtercat]

Man, that's a frame-up restoration you got going.

You could do what I did...I turned mine into a.....'69 Twin!
[Kidding....it came to me in great shape.]
[IMG:326:241]http://i914.photobucket.com/albums/ac34 ... ster-1.jpg[/img]
Yes, one of the 6L6's has crossed heater wiring. Nonetheless, it's certainly not a noisy amp.

The PT voltage on these [and the Showman of that series] is a little lower than the BF. [Correct me if I'm wrong, guys.]
I think my plate V is about 405V.

[Gibsonman63]

That really is a frame up restoration. I turned a 65 Twin into a ...


... working 65 Twin. The electronics were fairly simple. The cosmetics took some work.

[Bill Moore]

BTF, did you voice more than one channel to the bassman circuit? I too have a DR AB763 project, but want to voice one stock, and the other to the bassman circuit. Did you lower the voltage to the bassman channel tubes, or leave it at AB763 levels? I'm thinking I need to add 1 more cap, and resistor in the rectifier circuit to power the 59 bassman channel tubes. I appreciate any ideas.

hired hand, that is really a nice project! Did you decide to stay AB763 on both channels?
I built a Twin clone and used the OT from a 94 Twin. 4.8.and 16ohm outputs, and a winding for a line out,(XLR). leaves lots of possibilities open.