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Fender AB763 vs. AB763 vs. AB763

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  • Fender AB763 vs. AB763 vs. AB763

    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 ?
    Formerly known as; SirJackdeFuzz (7400+ posts)

  • #2
    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.
    Last edited by Lewguitar; 09-09-2020, 05:31 AM.
    “Practice cures most tone issues” - John Suhr

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    • #3
      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.

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      • #4
        Originally posted by FuseG4 View Post
        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.
        “Practice cures most tone issues” - John Suhr

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        • #5
          Originally posted by FuseG4 View Post
          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.
          Formerly known as; SirJackdeFuzz (7400+ posts)

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          • #6
            Originally posted by SirJackdeFuzz II View Post

            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.
            Last edited by Lewguitar; 09-08-2020, 05:45 AM.
            “Practice cures most tone issues” - John Suhr

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            • #7
              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

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              • #8
                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.

                “Practice cures most tone issues” - John Suhr

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                • #9
                  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

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                  • #10
                    Originally posted by Lewguitar View Post

                    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.


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                    • #11
                      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.

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                      • #12
                        Originally posted by Securb View Post

                        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
                        “Practice cures most tone issues” - John Suhr

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                        • #13
                          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.


                          | Gear Reviews | Beer | Babes | The Internet's Only Unedited & Uncensored Musician's Forum | Sports |

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                          • #14
                            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

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                            • #15
                              Originally posted by jeremy View Post
                              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.
                              “Practice cures most tone issues” - John Suhr

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