Has anybody made a AB763 Deluxe without the vibrato

[Platefire]

I know they made a AB763 Deluxe Vibrato without reverb. Has anybody just made the basic amp circuit with just the normal channel. Would you need to add any circuitry to mimic the vibrato channel connection(that would be gone). If this has been done, please point me to a thread or schemtic. Plate   

[FYL]

The two channels go thru 220K mixers and coupling caps. If you build a single channel version you may forget them and just boost the PI input coupling cap to 10n or so.

Something like the following should be OK:

[Geezer]

Hey Plate!

Check out your previous thread about this.... http://www.el34world.com/Forum/index.php?topic=4523.0

especially the 2nd post (by Sluckey) stating:

"Add a 0.1µF and a 47K to the plate of V3A (Refer to the schematic I linked to). The 47K simulates the load that the original roach trem circuit puts on the signal path. Without it the amp will have a LOT MORE GAIN than an AB763. It will still work and you may like it, but it ain't AB763."

[Platefire]

Yeah, got ya. Did that on the old AB763 project your referenced where I had a bias tremolo instead of a roach type. That would also take an upgrade in transformers from the tweed and fixed bias. Guess nobody has done this before?? Huh? Plate

[bluesbear]

I've made a number of amps very like FYL's schem. My differences:
Mid
Raw
Pre-PI master
Presence
5Y3 (instead of GZ34)
Cathode bias
2 - 12AX7's
SF voltages to PI and preamp (for more headroom)
Of course, 3 prong plug with fuse before the on/off switch
I just use standard BF Deluxe trannies.
It's a great sounding little amp and I've used mine with guys playing though 45 watt amps and been told I was too loud! It goes from very warm clean to screaming violin smooth OD, depending on how you dial it in. I've used mine for clean Motown rythms, blues, '60's/'70's rock, country, southern rock, even Glem Miller. Versatile.
I'm not sure what else you need to know... but ask and if I can figure it out, I'll tell you.
Dave

[Platefire]

Thanks Bluesbear

Did you start off with the original AB763 circuit and progressivly make changes or did you decide right off the batt that you didn't want the circuit in its orginal form? I would love to see a shematic if you don't mind sharing.

On my first AB763 Dekluxe Reverb I put into an old Peavey Pacer chassis and cab, in its normal form was a little to brittle and clean for me.  The mid/raw deversion has been a life saver as far as making the amp usable for me. I turn the mid/raw to 100% and everything is well. I can see where a master volume would be a valuable asset because I use my MV a lot on my Allen Accomplice version of that circuit. On the Allen using humbuckers I turn the master up 100%(removing it) and just use the pre-vol but with strats and teles turning the pre-vol up and MV down is a must. I do have a raw control on the Allen but for some reason I don't like the way it responds on that amp, so I mostly use the MV to get what I need. Plate  

[bigdaddy]

I gigged for years with an amp like that. Just a simple fender preamp into a Deluxe power amp. But I used the smaller Princeton PT.

All I did was add another 220K to ground as though it was the second channel. Yes the amp had a lot more balls and gain so I used a 500pf coupling cap to choke off a lot of it right before the PI. The sound was great. I built it into those old Musicmaster bass amps and used an old Jensen C12N. I had a pair and they proved to be the best sounding amps I could use for small gigs and blues gigs. Just the right volume since I cranked them. I built a third one with an SS rectifier and 6L6GC JJs and that really sounded awesome. So much thicker but it would have been too loud so I gave it to a friend.

[bluesbear]

The first one was a gutted Super Champ. I don't use trem or reverb. At the time, I was in a band that was playing 3 to 4 nights a week so I was going for something as small and light as possible that would hang with the other guy's Blues Deluxe. I knew what I was going for right from the start. I was lucky! Luck seems to be a major part of any new build. I added a little cooling fan since it got pretty hot in that small box. Other than that, it was a done deal. BYW, I didn't simulate a second channel. I have no schematic. I just used bits from the BF Deluxe and the SF Deluxe. The rest (raw, presence, mid, etc) I just picked either from my head or other assorted schematics. I've built a few since then and I just copy the first one.
If you need any info specifically, I'll be happy to share. In the meantime, I'll see if I can cobble together a schematic... but it may take a while.
Later,
Dave

[Platefire]

Bluesbear

If you haven't already made a schematic, don't go to that much trouble! I'm glad you already been down the bare bones AB763 deluxe route already that you can share your experiance. I'm just in the thinking/what if stage. I'm going to to build a 5E3 pretty close to original and while I've been planning that amp it crossed my mind to build a bare bones AB763 that would kind of resemble the simple 5E3 schematic except blackface specs.

I'm not sure yet how far I would want to stray from the AB763 Deluxe original. That's all just a consideration at this point. I like mods that are switchable or adjustable. That way you can always switch/adjust back and return to the original circuit. A good example of that is switchable NFB loop---Raw pot is another! The attached normal channel AB763 posted  previouly by FYL is a good starting place. I would be interested in you explaining:

a-What values did you use on your cathod bias for your power tubes and why you like it over original fixed bias.

b-Your raw control hookup/how you did it? Did you do it like Allen Amps on the mid control.

Thanks, Plate

[bluesbear]

I just added a 25k pot for a midrange and dropped in a 250k between it and ground... yes, like Dave Allen's setup. I used a 250 ohm 5w resistor with a 25mf bypass. I went with cathode bias because I didn't have room for anything else. I also made one with adjustable fixed bias. The cathode bias seems a little softer but there's not much difference. I like both ways.
Dave

[Platefire]

OK, Thanks! Sounds like a good plan. How did the pre PI MV work? I've become pretty attached to MV's last couple of years! Plate 

[bluesbear]

"How did the pre PI MV work?"

Tone recovery stage - .022 mf cap - center lug of 500k pot, one lug to ground, other to - .022 mf cap - PI

This type of MV won't give a ton of preamp distortion (I wasn't looking for that). With volume up full and MV just brought up to 3 or 4, it gives smooth, subtle OD a that's easily controlled with the guitar's volume. What I like about this MV is that with the MV up full, it's electrically the same as no MV. also, I'm not a heavy distortion kind of guy so this works perfectly for me.
Dave

[Platefire]

Yeah, that's kind of how my master volume works on my Accomplice--and it's post PI. I like the amp to operate vintage style (only one vol)with MV full up--because with humbuckers I don't need the MV. Sounds like you kind of operate like me mostly using the volume on the guitar. I like a blackface type tone not set very bright with the pre and MV set where its just starting to go into breakup with guitar volume full up. I do use distortion but I usually use my route 66 for any distortion beyond the before mentioned clean setting. For really screaming blues I got this thing I do where I click on my OD pedal and turn the guitar volume down to where its pretty clean with a bit of grit for rhythem chomping and when you go into your lead, go to about 3/4 vol for a really cranking burn and if you really want burn down the house, go to full volume.

 The great thing about good MV control is you can adjust the overall volume for any room or location and pretty much get your feel and volume right--just takes a little pre-gig tinkering with the tone/volumes. Plate