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my old Galien-Krueger GMT 300B likes to snap, crackle and pop, any help please?

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  • #1

    my old Galien-Krueger GMT 300B likes to snap, crackle and pop, any help please?

    Hello everybody,
    So I have an old Galien-Krueger GMT 300B bass amp that I run through an old Sunn 2x15 cab. Its a real sturdy, loud, and well-built amp and I love the vintage sound I get from the rig, however there's multiple strange problems with the amp and I think its confusing itself with a bowl of Rice Crispies.
    Im wondering if any of you could help me out- as im very inexperienced with amp electronics/maintenence.
    When I first turn the amp on and play my bass it sounds fine for about 5 minutes, but then my signal will gradually start to crackle and break up more and more until the signal is almost totally gone and is just a mess of snapping and crackling noises. There is also a hissing/feedback? noise that's present and becomes louder with succesive popping noises. Sometimes, but not often, the signal will dissapear completely but will return when I turn the amp off then on again. These sounds will inevitably show up when I have the volume lower than about 3. However, if I turn it up above 3 or use the contour feature (which nuturally increases the volume somewhat I beleive)the snap/crackle/pop sounds show up immediately- and louder.
    Im thinking it might be just a problem with some old, burnt-out capasitors, resistors...etc? But honestly I have no idea. Like I said, I know very little about this stuff.
    Any advice on how to tackle this situation is much appreciated!!!
    Tags: galien-krueger, galien-krueger gmt 300b
  • #2
    The connections can all be re-soldered. That's what I would try.
    The controls and jacks can be cleaned.
    But there may be parts that are breaking down with temperature.
    These parts can sometimes be found with technicians freeze spray...canned air turned upside down...
    spraying a part that is failing may identify the location, by suddenly cooling it.
    (it will work when cool) and fail when hot...

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    • #3
      I have an old G-K head that had similar symptoms until I read a suggestion---might have been on this forum---to try connecting the effects out jack to the effects in with a 1/4" cable. Evidently G-K had some problems with the reliability of their plastic connectors inside the head, and connecting the effects out to the effects in bypasses some internal wire routing. Whatever it is, the head has been fine since, and I haven't bothered to have the root problem fixed by someone who actually knows something about electronics.

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      • #4
        Yes, the break jack is a problem on lots of amps. Try taking a cord and plug it in from the preamp out jack to the power amp in jack. If the sound comes back then the power amp in jack will need to be cleaned.

        If that doesn't fix it, then try giving the amp a good Enzo whack with your fist or a rubber mallet. Anything happen like noise or stopping of noise? If you do this and there is some reaction, that means that there is something loose inside that needs to be resoldered. There are also plug in connectors that can come loose or get dirty and oxidized.

        Let us know what you find.

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        • #5
          I have a friend with GK bass head that sat in a closet for about a year because of similar symptoms. He had replaced the head and moved on, but pulled it out when he found out I could fix it. I cleaned all the non soldered connections, jacks and pots and the amp worked perfectly. I was almost sorry there was nothing to actually "fix" since my friend thought I'd performed some kind of magic trick.
          "Take two placebos, works twice as well." Enzo

          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

          "If you're not interested in opinions and the experience of others, why even start a thread?
          You can't just expect consent." Helmholtz

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          • #6
            Originally posted by Chuck H View Post
            I have a friend with GK bass head that sat in a closet for about a year because of similar symptoms. He had replaced the head and moved on, but pulled it out when he found out I could fix it. I cleaned all the non soldered connections, jacks and pots and the amp worked perfectly. I was almost sorry there was nothing to actually "fix" since my friend thought I'd performed some kind of magic trick.
            Dirt is by far, the #1 cause of problems.

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            • #7
              Hey guys, sorry for the late reply, ive been without internet for a few days. Thanks for the replies!

              I will try plugging in cables into the jacks on the back and see if that works. If that doesnt work i will clean all the components like most of you said... i have a feeling thats the problem. I will let u guys know how it goes

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              • #8
                So I connected a cable from the preamp out jack to the power amp in jack in the back of the amp but there was no noticeable difference in my signal and the crackle was still there

                Originally posted by Jot View Post
                I have an old G-K head that had similar symptoms until I read a suggestion---might have been on this forum---to try connecting the effects out jack to the effects in with a 1/4" cable. Evidently G-K had some problems with the reliability of their plastic connectors inside the head, and connecting the effects out to the effects in bypasses some internal wire routing. Whatever it is, the head has been fine since, and I haven't bothered to have the root problem fixed by someone who actually knows something about electronics.
                ...But what effects input and output do you mean? I only see an imput/output labeled DISTORTION/FOOTSWITCH.
                Also, I realised that there's actually no "lag time" after I turn the amp on before the crackle starts appearing. Its always there, but only seems to be heard when the lower notes are played repeatedly like the open E, F, F#, G, G#, and the high D# and E on the E string.

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                • #9
                  Originally posted by tangyzizzle View Post
                  ...But what effects input and output do you mean? I only see an imput/output labeled DISTORTION/FOOTSWITCH.
                  Also, I realised that there's actually no "lag time" after I turn the amp on before the crackle starts appearing. Its always there, but only seems to be heard when the lower notes are played repeatedly like the open E, F, F#, G, G#, and the high D# and E on the E string.
                  Some amps have an FX loop, yours doesn't. Testing the pre-power amp jacks checked the same thing. Have you tried physical vibration tests?

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                  • #10
                    No I havent. You mean like whacking the amp to check for loose components like you mentioned before?

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                    • #11
                      Yes

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                      • #12
                        I was a rep for them in the 70's, and we had a major problem with cold s/joints
                        all over that sucker, the 'G' too (the only diff being reverb). open and tap
                        everywhere, chances are you'll find it. Also, like others said, the jacks get
                        VERY dirty on any amp that old. BTW, that's a great amp, I wish I held
                        on to the ones I had here. Always looking for that type of gear..

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