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What the heck is wrong with my amp...

Discussion in 'Amp Tech Center' started by rugrat, Mar 29, 2013.

  1. rugrat

    rugrat TDPRI Member

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    Andover, MN USA
    Hey guys,

    (this is a bass amp... but I am posting on here because you guys know your stuff.. and besides you can play guitar trough it...:D)

    Anyways 4 years ago I bought an ampeg b200r (chinese) it sounded fantastic! Everytime I played live people asked what it was because it sounded great. It also had a really nice xlr out the put out some awesome tone. The sound guys loved her!

    Anyways maybe like two years ago she started to crackle and pop a little bit after I turned her on. Then it would speed up (the crackling) make one final pop and then you could here the bass guitar. I was told it was the tube by the tech. I never replaced it as it never happened after the amp warmed up.
    The time began to get longer and longer...

    Anyways I am at a music school now (focusing on guitar) so my bass gear doesn't get as much play time.. Anyways played my amp 6 months ago and it was nigh unusable it would fade in and out crackling... so around Christmas last year I switched out the tube with an EHX she sounded fantastic as ever... although I still have a rattling problem from the amp chassis (need to tighten some screws)
    Anyways played the amp for like 2 hours then left to hit the road for a month. When I came back it was worse then before...
    Now the amp doesn't even pop really it does a little when I turn it on ,but my signal is not going through... The tube is literally almost brand new with probably like 3-4 hours play time on it.
    Since m amp isnt working when I practice bass Ijust my IEM setup now and in the past few monthes...

    Also the balanced out/head phone out stopped working at some point two years ago... didn't noticed exactly when it happened as at the time most of my gigs I just played through my amp and no extra PA... Never dropped my amp or anything.

    Anyways was kinda hoping to make the amp useable by sunday if possible... any ideas.IS there something in my amp making the preamp tubes go micro-phonic?

    thanks for the help guys...
    Such a great amp.. but I am so fed up with it right now! :neutral:

    thanks,
    rugrat
     
  2. JD0x0

    JD0x0 Poster Extraordinaire

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    Could be anything. IME electro harmonix tubes aren't very good and they DO tend to go microphonic sometimes. I'd spend some cash and try a different tube.
     
  3. printer2

    printer2 Poster Extraordinaire

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    Could be your socket pins have oxidized. Wiggle the tube some.
     
  4. rugrat

    rugrat TDPRI Member

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    a tube going totally microphonic with 6 hours on it though?

    and hmmm should I spray some oxidizer in there?
     
  5. rugrat

    rugrat TDPRI Member

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    Was thinking about going to a tech, but that would cost $200... and I feel like there is a good chance I could fix it....

    two questions

    1. Is it possible there is something wrong in my bass amp causing the tubes to go micro-phonic very quickly? something physical like vibration or a circuit causing undo strain?

    2. Any guesses on the xlr out.headphone out not working... guessing that since they both don't work that the problem around the U2B area or slightly before? :confused:

    Ill try moving the tube around and sticking the old one in (since it still worked not well but it worked) and maybe spraying the inputs/outputs...
     
  6. Daywalker

    Daywalker TDPRI Member

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    I would check these things before I change tubes because some places don't take returns on tubes.

    1. Unplug and check for loose wiring or broken solders
    2. Ensure that your speaker jack isn't loose inside the cab
    3. Isolate your signal buy removing all pedals and tuners from the chain
    4. Try multiple cables from the bass to the amp to see if one is going out
    5. Check to see if the cable jack on the base is tight.

    Those are all the things I've done in the past to correct amp problems. Good luck!
     
  7. rugrat

    rugrat TDPRI Member

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    Andover, MN USA
    The speaker cable is plugged in, and it was going straight from the bass to the amp... anyways I went to go buy a tube from the tech ended up talking to him about it for like 10 minutes and he said it didn't sound like a tube problem. So ended up leaving with him which is more expensive, but he is going to look over everything in it and fix anything amiss... I don't trust the manufacture of the amp so much (they ended the b200r line because they couldn't keep up with the QC on it!) so it will be fixed tonight or tomorrow afternoon most likely. Really nice guy who likes to take his time on his amps (often takes more time then he charges for) seems like he really enjoys fixing amps and such...
    thanks for the help :)
    rugrat
     
  8. Daywalker

    Daywalker TDPRI Member

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    Be sure to let us know what the corrective action was and what troubleshooting it took to get there!
     
  9. rugrat

    rugrat TDPRI Member

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    I will ask tomorrow... looking forward to having her up and running again. Best amp I have ever played.... just the last 6 months she has been a pain to try and play through... she will hopefully have no more quirks for a long time :)
     
  10. rugrat

    rugrat TDPRI Member

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    Hey,
    Picked the amp up from the tech yesterday.
    --- I realize reason I was getting no sound because of bad 1/4 on my part, but even with that the tube was stilling be funky (which made the amp unusable playing wise)

    anyways the tube was not the root of the problem it was fine (probably the old one is too)
    He told me what was having the problem was the way the power went to the tube.
    Its this very little metal connection (he wouldn't recommend putting that much power through it)
    That part he said was put there to making manufacturing easier rather than being needed. By itself that probably wouldn't cause problems, but who ever put it together and soldered it did a very bad job. So he took that out and rewired it.

    The reason my xlr and headphone outs weren;t working was because the op amp chip before them went bad so he replaced that too.

    My amp also rattles really bad on some resonant notes (like the A on the low E string or when I play my low B string) I knew from taking the amp apart this last Christmas that it was the amp chassis. I assumed it was loose screws.

    Anyways he showed me what the problem is.

    If you can imagine the amp chassis being the shape U. The sides of the U are where it screws into the cabinet. Located on the middle of the U on left side of the amp(if looking at from the rear) is the transformer. (which probably weighs 15-20lbs by itself. Anyways the metal chassis has started to tear at both sides. Leaving the transformer effectively on vibration diving board.

    Anyways he said it would need to be welded (as he does not weld stuff he could not fix that, but I wouldn't have noticed that) and didn't think glue would work since there would be so much pressure/vibration... Any glues or epoxy you guys would recomend that would be strong enough?

    I can take pics this week sometime. Playing a whole bunch around Chicago this week and next weekend so just sent my amp ahead with the gear trailer..

    The rattle isn't terrible. Its usually not very noticeable playing live.. I wouldn't want to mic the cab in a studio... anyways thanks for the help :)


    Glad to have my bass amp up and running. It makes a fantastic studio DI also! just sounds beautiful... So excited to be able to do better bass recording.

    thanks,
    rugrat
     
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