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  • B52 AT-100 (don't laugh)

    Good morning.

    I purchased an AT100 back in 2006, and never had an issue until 2013 or so (surprising, I know) I gigged with it, practiced with it, it traveled a lot. Reverb circuit went on it so I just disabled it, I never used it anyway.

    One day, I was playing and the sound just faded away and had no output. A few months ago I replaced the tubes, and when I tried to bias it, the trim pot broke into pieces.

    I finally replaced the trim pot on the PS board, reassembled everything and to my complete astonishment, it is just like new as far as operation and sound and I am thrilled!


    I know these amps are average at best as far as reliability, but I REALLY like the way it sounds and it fits my style.

    My question is this: Is there an upgrade that can be done to this amp that will make it a more reliable piece or is it just not worth it?

    Thanks in advance!

  • #2
    Re: B52 AT-100 (don't laugh)

    Well you can upgrade it to a Marshall

    Just take it to the curb set it there for a moment while you drive up to Guitar Center and buy a Marshall


    I'm kidding
    Glad you got it working
    So you think the trim pot was causing it to fade out?

    Hmmm
    EHD
    Just here surfing Guitar Pron
    RG2EX1 w/ SD hot-rodded pickups / RG4EXFM1 w/ Carvin S22j/b + FVN middle
    SR500 / Martin 000CE-1/Epiphone Hummingbird
    Epiphone Florentine with OEM Probuckers
    Ehdwuld branded Blue semi hollow custom with JB/Jazz
    Reptile Green Gibson Custom Studio / Aqua Dean Shire semi hollow with piezo
    Carvin Belair / Laney GC80A Acoustic Amp (a gift from Guitar Player Mag)
    GNX3000 (yea I'm a modeler)

    Comment


    • #3
      Re: B52 AT-100 (don't laugh)

      That's awesome you were able to fix it.

      There used to be a dude here that would post videos of him with a B52 head and an OD pedal. They sounded killer.

      Comment


      • #4
        Re: B52 AT-100 (don't laugh)

        Originally posted by ehdwuld View Post
        Well you can upgrade it to a Marshall

        Just take it to the curb set it there for a moment while you drive up to Guitar Center and buy a Marshall


        I'm kidding
        Glad you got it working
        So you think the trim pot was causing it to fade out?

        Hmmm
        Nah, the trim pot wasn't the root cause of the signal fade out, I now believe it was a bad power tube. I removed two of the tubes and set the impedance to 4 ohms instead of 8 to just see if the thing would operate, and it did. So, knowing it was still functional and I had a bad tube, I replaced the entire set. Upon trying to bias the new set is when the trim pot broke. It turned into a more lengthy repair than I had hoped, but I have a load of other amps so this was just a test, I guess.

        Comment


        • #5
          Re: B52 AT-100 (don't laugh)

          I had one of those, they really weren't that bad. Best thing you can do is add a fan if it doesn't have one (mine didn't). Overheating was the biggest issue with the ones that didn't come with something to aid in cooling.

          Comment


          • #6
            Re: B52 AT-100 (don't laugh)

            Got one from a friend 15 years ago.
            They're junk, couldn't get rid of it fast enough.

            I saw that thing floating around CL for years.
            Bruce Egnater designed that and he told me they had alot of problems because the Chinese cut too many corners.

            You'd be best to move on to a Boogie or something thats going to last.

            Oh and good luck trying to sell those POS.

            The "resonance" & "contour" knobs on those are useless.
            I still have the schematic for that amp i got from Avi.
            Last edited by JMP/HBE; 06-02-2020, 02:08 PM.

            Comment


            • #7
              Re: B52 AT-100 (don't laugh)

              Originally posted by JMP/HBE View Post
              Got one from a friend 15 years ago.
              They're junk, couldn't get rid of it fast enough.

              I saw that thing floating around CL for years.
              Bruce Egnater designed that and he told me they had alot of problems because the Chinese cut too many corners.

              You'd be best to move on to a Boogie or something thats going to last.

              Oh and good luck trying to sell those POS.

              The "resonance" & "contour" knobs on those are useless.
              I still have the schematic for that amp i got from Avi.
              Kind of what I was afraid of. I must have gotten one of the better units. Would a Dual / tri rec be comparable to this thing? Would you be so kind as to e-mail me that schematic?
              [email protected]

              Comment


              • #8
                Re: B52 AT-100 (don't laugh)

                Originally posted by Diplomat383 View Post
                Kind of what I was afraid of. I must have gotten one of the better units. Would a Dual / tri rec be comparable to this thing? Would you be so kind as to e-mail me that schematic?
                [email protected]
                That was certainly the association they wanted people to make. I don't recall it being a Recto copy in terms of tone, but something like that should cover the same ground and more. Personally, I would suggest looking into a Roadster if you can stretch the budget a bit. Channel 3 and 4 aren't quite as aggressive and more versatile.

                Comment


                • #9
                  Re: B52 AT-100 (don't laugh)

                  Originally posted by Diplomat383 View Post
                  Kind of what I was afraid of. I must have gotten one of the better units. Would a Dual / tri rec be comparable to this thing? Would you be so kind as to e-mail me that schematic?
                  [email protected]
                  sent

                  Comment


                  • #10
                    Re: B52 AT-100 (don't laugh)

                    I own two. I liked the first one so much that I bought the second one as soon as they went on sale. They've both been going strong for over 12 years.

                    Heat was a big problem in these for lots of folks. I have always run a small fan behind my tube amps, and that seems to have paid off for me with my B52-AT100s. I've seen posts where people owning these commented that B52 provided a fan kit for later models.

                    Both of mine got a 1980's era GE 5751 in V1, a Sylvania 12AX7 in V2 and a JAN Philips 12AT7 for the reverb driver. Changing these tubes in the amp makes a big difference.

                    Power tubes: one got Groove Tube CHPs. The other got a pair of SED 6L6GCs paired up with a pair of EH 6L6GCs. Both power tube combinations sound good, but the stock Sovteks sounded pretty decent once you biased them on the warm side. You don't need to break the bank with expensive power tubes to get good tone out of these.

                    Speakers: I use a Fender Tonemaster 4 X 12" cabinet that originally came stock with four Celestion Vintage 30s. I pulled two of the Vintage 30s and replaced them with 1 Celestion G12 blue alnico and 1 10" Eminence Red Fang alnico. The cabinet delivers beautiful tones with the B52-AT100s and with every other amp/head I use it with.

                    It has taken a little bit of care, but my B52-AT100s have delivered great tones for me for over a decade.
                    Last edited by Rick330man; 06-04-2020, 01:42 PM. Reason: Didn't finish

                    Comment


                    • #11
                      Re: B52 AT-100 (don't laugh)

                      Originally posted by Rick330man View Post
                      I own two. I liked the first one so much that I bought the second one as soon as they went on sale. They've both been going strong for over 12 years.

                      Heat was a big problem in these for lots of folks. I have always run a small fan behind my tube amps, and that seems to have paid off for me with my B52-AT100s. I've seen posts where people owning these commented that B52 provided a fan kit for later models.

                      Both of mine got a 1980's era GE 5751 in V1, a Sylvania 12AX7 in V2 and a JAN Philips 12AT7 for the reverb driver. Changing these tubes in the amp makes a big difference.

                      Power tubes: one got Groove Tube CHPs. The other got a pair of SED 6L6GCs paired up with a pair of EH 6L6GCs. Both power tube combinations sound good, but the stock Sovteks sounded pretty decent once you biased them on the warm side. You don't need to break the bank with expensive power tubes to get good tone out of these.

                      Speakers: I use a Fender Tonemaster 4 X 12" cabinet that originally came stock with four Celestion Vintage 30s. I pulled two of the Vintage 30s and replaced them with 1 Celestion G12 blue alnico and 1 10" Eminence Red Fang alnico. The cabinet delivers beautiful tones with the B52-AT100s and with every other amp/head I use it with.

                      It has taken a little bit of care, but my B52-AT100s have delivered great tones for me for over a decade.
                      Its not the tubes its the transformers. Egnater told me the Chinese under-wound the trannies. The PT on mine was so hot you could fry your breakfast {not kidding}. I put a fan on mine too but didn't make much difference. I also put a $280 output transformer on mine, again not much difference.
                      Even with all that & 12 spaces of rack gear the AT-100 was just "average" sounding.
                      You'll never find me buying another amplifier made in China guaranteed.
                      China does make some cool stuff ... but guitar amps aren't one of them IMO.
                      Last edited by JMP/HBE; 06-04-2020, 02:22 PM.

                      Comment


                      • #12
                        Re: B52 AT-100 (don't laugh)

                        Originally posted by JMP/HBE View Post
                        Its not the tubes its the transformers. Egnater told me the Chinese under-wound the trannies. The PT on mine was so hot you could fry your breakfast {not kidding}. I put a fan on mine too but didn't make much difference. I also put a $280 output transformer on mine, again not much difference.
                        Even with all that & 12 spaces of rack gear the AT-100 was just "average" sounding.
                        You'll never find me buying another amplifier made in China guaranteed.
                        China does make some cool stuff ... but guitar amps aren't one of them IMO.
                        Ironically, after hearing all of the horror stories, I began to worry. I started expecting my output transformers to fry at any moment. I went so far as to anticipate the failures. In other words I bought two Heyboer output transformers figuring I'd soon be needing to house them permanently in my B52s. Well, the output transformers never failed. My Heyboers are sitting in the boxes.

                        Understand that I never went on tour with mine or anything like that. I kept my day job, noodled around at night and played in bands with friends for fun. My B52-AT100 heads are still alive and kicking.

                        Comment


                        • #13
                          Re: B52 AT-100 (don't laugh)

                          JMP/HBE:

                          You spent $280 on an output transformer. For that kind of coin, I'm guessing it was a Mercury Magnetics. My Heyboers cost me a little less than that for two.

                          But you also mentioned your PT getting hot. Did it ever fail? If it did, what did you replace it with?

                          To stay on topic, the OP is looking for recommendations to help improve the reliability of a B52-AT100 he already owns. To help the OP out, what replacement output transformer(s) and PT(s) would you recommend?

                          Comment


                          • #14
                            Originally posted by Diplomat383 View Post
                            Good morning.

                            I purchased an AT100 back in 2006, and never had an issue until 2013 or so (surprising, I know) I gigged with it, practiced with it, it traveled a lot. Reverb circuit went on it so I just disabled it, I never used it anyway.

                            One day, I was playing and the sound just faded away and had no output. A few months ago I replaced the tubes, and when I tried to bias it, the trim pot broke into pieces.

                            I finally replaced the trim pot on the PS board, reassembled everything and to my complete astonishment, it is just like new as far as operation and sound and I am thrilled!


                            I know these amps are average at best as far as reliability, but I REALLY like the way it sounds and it fits my style.

                            My question is this: Is there an upgrade that can be done to this amp that will make it a more reliable piece or is it just not worth it?

                            Thanks in advance!
                            Day late n a dollar short, ( Jan 2024 $150.00) just picked one up, bias pot fell APART , amp was running VERY hot, the previous owner was runnin it in TUBE RECTO mode ONLY so it WAS ALIVE but still a tad hot.... I have a bunch of mil spec 10K bias pots, pulled PS board ( the 110 ohm cath resistor fell out on one side!) installed a 27K vs ( 22k) Drilled hole installed the pot, wired up, it MAXED out @ ( -52vdc..n sounds AB AMAZING! Even w/worn power tubes ( lettering gone on sovteks not good! But it still sounds grt!) n running WAAY kooler! In TUBE mode the CLEAN channel is UN-reel..n so is the OD channels..What im gonna do is install a 3-5 amp 5vac FIilament for the rectifier tube/..THIS will save the power transformer n UN-load a TON of current obligations.. Cuz this amp sounds GREAT! Heres a short clip.. ESP EC 401VF w/Dimarzios .. https://youtube.com/shorts/XaAa1Ml1C...DPujaDcaUJ2nyq
                            Last edited by Groovtubin; 01-27-2024, 08:43 AM.

                            Comment


                            • #15
                              Welcome to the forum!

                              Pretty tight sound for tube rectified. Good sound overall.

                              There are some volume drops in the recording which I'm guessing are channel switching (or pickup switching?) but not having the levels set the same?

                              Comment

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