Fender AB763 vs. AB763 vs. AB763

[SirJackdeFuzz II]

Yes, you read correctly.
Here is my predicament.
A gentleman is selling an amp, made by a reputable amp builder on this side of the world.
The seller says it is based on an AB763 circuit, albeit with a master volume and 'only'' 40watts.

So, did some research, and found that the Twin Reverb, Super Reverb & Deluxe Reverb is linked to the AB763 circuit.

Can anyone shed some light on this topic please ?

 

[Lewguitar]

AB763 refers to blackface Fender amps from 1963 until CBS took over Fender and started making the silverface series of Fender amps in the late 1960's.

AB763 would include the amps you mentioned and also Deluxe Reverbs, Pro Reverbs, Showman amps, etc. Those amps didn't have a master volume control.

The master volume was added to the silverface Fenders in the early 1970's and most people thought it didn't sound very good.

Basically, "AB763" means "the classic blackface Fender amp".

If you want more detail just do a search for Fender AB763 and read all about it.

 

[FuseG4]

Yup, ab763 is the fender amp circuit with normal channel, vibrato/reverb channel, and big difference between a deluxe reverb, super reverb and twin reverb is the number and type of power tubes and the associated transformers and other power supply stuff.
and on the deluxe they replace the mid control with a fixed resistor and hard-wire the bright switch ON permanently.
Ab763 is "the common blackface circuit" AB designated a revision over version AA, and 7 63 indicates roughly the month and year it was implemented.
​​​​​​So essentially you'd be getting a super reverb (head?) With a master volume. Should be easy to delete the master volume or leave it wide open if you want.

 

[Lewguitar]

Yup, ab763 is the fender amp circuit with normal channel, vibrato/reverb channel, and big difference between a deluxe reverb, super reverb and twin reverb is the number and type of power tubes and the associated transformers and other power supply stuff.
and on the deluxe they replace the mid control with a fixed resistor and hard-wire the bright switch ON permanently.
Ab763 is "the common blackface circuit" AB designated a revision over version AA, and 7 63 indicates roughly the month and year it was implemented.
​​​​​​So essentially you'd be getting a super reverb (head?) With a master volume. Should be easy to delete the master volume or leave it wide open if you want.

I would hope the master volume in the amp the OP is considering is a new design and not the silverface era design.

That was one of the first master volume designs and not a very good one.

Didn't give satisfying overdrive and turning it to 10 did not sound the same as just removing it from the circuit altogether. Kind of useless.

 

[SirJackdeFuzz II]

Yup, ab763 is the fender amp circuit with normal channel, vibrato/reverb channel, and big difference between a deluxe reverb, super reverb and twin reverb is the number and type of power tubes and the associated transformers and other power supply stuff.
and on the deluxe they replace the mid control with a fixed resistor and hard-wire the bright switch ON permanently.
Ab763 is "the common blackface circuit" AB designated a revision over version AA, and 7 63 indicates roughly the month and year it was implemented.
​​​​​​So essentially you'd be getting a super reverb (head?) With a master volume. Should be easy to delete the master volume or leave it wide open if you want.

Thank you very much.
So i still do not know what type of sound i am getting . . . seeing as all these amp sound very diff from one another.
All i know, is that it has two 6L6 valve in the circuit.
I will ask the seller more questions.

 

[Lewguitar]

Thank you very much.
So i still do not know what type of sound i am getting . . . seeing as all these amp sound very diff from one another.
All i know, is that it has two 6L6 valve in the circuit.
I will ask the seller more questions.

Most likely the actual amp will sound like a Super Reverb or Pro Reverb if it has reverb, and like a Bandmaster if it doesn't.

Personally, I think the Bandmaster sounds a little "blah" compared to a Pro Reverb or Super Reverb.

The reverb circuit gives the amp another gain stage that gives the circuit just a little more oomph.

The rest of its sound will be determined by whatever speakers you plan to use it with.

 

[jeremy]

the different bf amps do sound different but the preamps, other than the deluxe which runs at lower voltage, are almost the same. the power section is where the big differences lie, different transformers, tubes, and voltages. the reverb amps have a third gain stage on the vibrato channel that non reverb amps dont have like lew said. if its a reverb amp itll probably be very nice. even non reverb amps can sound good but most people prefer the reverb amps even if they dont use the reverb. 40w with a good master volume is a great size amp. speakers will influence the voice of the amp a lot

 

[Lewguitar]

That "third gain stage" also puts the vibrato/reverb channel out of phase with the normal channel.

The reason I never liked using a Y cord or jumpering the channels on a Fender amp with reverb.

 

[jeremy]

yep. each gain stage flips phase. ive modded my old dr a bunch over the years and put reverb on both channels which was ok but ive reverted back to the normal channel not having reverb and made a bunch of other changes too. the vibrato channel is pretty much stock to get the classic fender bf tone though

 

[Securb]

I would hope the master volume in the amp the OP is considering is a new design and not the silverface era design. That was one of the first master volume designs and not a very good one.

Lew, once again you are stating an opinion and not fact. The Silverface is a widely used great sounding amp. Almost every recording studio in the 70's and 80's had a Silverface Twin or Deluxe, those amps are on the majority of recorded guitar tones of those eras.

 

[jeremy]

the deluxes never had a master volume though. when my old black deluxe was in the shop years ago i used a silver one and it was great, quite different but still really nice. the early sf amps are great, once you get to the mid/later 70's there was a good amount of cost cutting going on and weird circuit changes and the mv on those amps wasnt great. doesnt mean the amps sounded bad but usually not as good as the older versions and there are much better mv circuits out there now. ive played through plenty of sf fenders with the mv and pull boosts and stuff. you can dial them in to sound great, i still prefer the older amps. my '69 dual showman reverb has been modded to '64 twin reverb specs. the differences are subtle but noticeable.

 

[Lewguitar]

Lew, once again you are stating an opinion and not fact. The Silverface is a widely used great sounding amp. Almost every recording studio in the 70's and 80's had a Silverface Twin or Deluxe, those amps are on the majority of recorded guitar tones of those eras.

There's no master volume control on a Deluxe or Deluxe Reverb. And that's a fact.

As for the master volume control being one of the first designs and not being a very good one, that's a fact too.

There's nothing like the experience of owning both a blackface Twin Reverb w/o a master volume and a silverface Twin Reverb with a master volume and comparing them, as I have.

But if you haven't, here's one of many articles you can read online about the differences: https://www.premierguitar.com/articl...-dud-or-dynamo

 

[Securb]

Most of the major changes made in 68 were reverted in 69. The 67s and 69s are so close in circuitry you can rollback the amp in an afternoon. But that is not the problem. Just because you prefer the blackface if doesn't mean the silverface sounds bad or offensive in any way.

 

[jeremy]

67 and 69, even up to 71 are usually consistently good amps. weird things started happening after that and cbs was cutting cost/corners more and more. that doesnt mean a 75 twin wont sound great though

 

[Lewguitar]

67 and 69, even up to 71 are usually consistently good amps. weird things started happening after that and cbs was cutting cost/corners more and more. that doesnt mean a 75 twin wont sound great though

Seems like we see eye to eye on this Jeremy.

I think Suburb just likes to bait and argue.

 

[jeremy]

nah bruce is good peeps. you and i like similar things but that doesnt mean we are more right than someone else who likes different things. a 72 twin is gonna sound different than a 64, you and i might prefer the 64 but bruce might prefer the 72. id take the 72 twin over plenty of other amps though. ive had some nightmare backline amps over the years so if theres a sf amp thats been decently maintained i know ill be fine.

 

[Securb]

Seems like we see eye to eye on this Jeremy. I think Suburb just likes to bait and argue.

No Lew, wrong again. I have a 72 silverface I have been playing since 82 that sounds glorious. And when I see someone post opinion over fact it irritates me. You preaching Internet myths about how Fender amps after 68 are garbage is ridiculous. You can set up any vintage amp next to my crappy silverface and I will blow your wheels off every time and twice on Sundays

 

[Lewguitar]

No Lew, wrong again. I have a 72 silverface I have been playing since 82 that sounds glorious. And when I see someone post opinion over fact it irritates me. You preaching Internet myths about how Fender amps after 68 are garbage is ridiculous. You can set up any vintage amp next to my crappy silverface and I will blow your wheels off every time and twice on Sundays

Yeah I was right. You ARE just looking for an argument.

"Fender amps after 68 are garbage..." Never said that.

"Slverface sounds bad..." Never said that.

Silverface sounds "offensive..." Never said that.

"Crappy silverface..." Nope. Never said that either.

You're just making stuff up and attempting to put words in my mouth that are actually YOUR WORDS, not mine.

And THAT is a fact easily verified by anyone who wants to go back and read what I actually said.

But I'll save them the trouble. Here's what I actually said:

"I would hope the master volume in the amp the OP is considering is a new design and not the silverface era design.

That was one of the first master volume designs and not a very good one.

Didn't give satisfying overdrive and turning it to 10 did not sound the same as just removing it from the circuit altogether. Kind of useless."

Every word I wrote was about the design of the master volume circuit in those early 70's master volume amps.

Never said the amp itself was "garbage" or sounded "bad", "offensive" or "crappy".

Those are all your words. Not mine.

However, here's what Jeff Bober, "Amp Man", writing in Premier Guitar had to say about the master volume in silverface Fenders:

"Now, having a master volume control on a Fender Twin Reverb, or most any other Fender amp of this era, seems like a useless addition. Master volumes are generally associated with and necessary in amps that use considerable front-end gain to overdrive the preamp section. The signal level can then be reduced prior to the output stage to control overall amp volume. There is not a huge amount of gain in the preamp stages of a Twin Reverb, at least not enough to achieve significant overdrive....In reality, the result was far from stellar, and I’m not sure I know anyone who actually uses this feature."

Here's link to the article: https://www.premierguitar.com/articl...-dud-or-dynamo

So there ya go. Enjoy your amp.

And lighten up on your attacks on me and please stop putting words in my mouth that I never said.

 

[jeremy]

enough guys. its stops here. next post going back and forth gets dinged.

 

[SirJackdeFuzz II]

Update :

This is what i got from the original builder, once i asked him if he can remember the 2011 build :

''Yes, it would be more like the AB763 - a Twin Reverb normal channel preamp with half output, plus master volume.''

This build does NOT have a Reverb/Trem channel.
Can I assume it is diode rectified, and not valve/tube rectified ?