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Bass Amp Trouble...PLEASE HELP!!

Discussion in 'Amps and Cabs [BG]' started by BassoMatik, Aug 23, 2012.


  1. BassoMatik

    BassoMatik

    Aug 23, 2012
    Hello, it's my first post as a new Talkbass Member :bag:

    I have an old Peavey Combo 300 (Black Widow) and about two weeks ago I started to notice that my amp was making popping and squeaking noises after I turn it off. I mainly notice it when I'm playing hard on the E string and then turn it off. I am suspecting voice coil trouble?

    ***I have an audio file attached*** (Very sorry about the quality, I recorded it using a camera and then recorded that onto my ipod and then into my software on the computer) of me playing and turning it off and then the sounds appear, I know it sounds like someone passing gas, but that's actually the speaker making that noise. I love the amp and will get a new driver if need be.

    Please tell me everything you might know about this problem :)
     

    Attached Files:

  2. BassoMatik

    BassoMatik

    Aug 23, 2012
    I thank you in advance for any help you can be :)
     
  3. bumperbass

    bumperbass Supporting Member

    Jun 19, 2012
    I think you have an IC going bad. Speakers don't MAKE sound unless they're rubbing. Your power supply caps are discharging through something that's creating that sound. Sometimes it's normal. I've had amps do this. Your sound clip was about a thousandth of a second so I couldn't really get anything out of it. What I'm talking about is a kind of squeak, then POP. Don't worry about it unless it gets worse. What happens when you turn your master volume all the way down before turn off?
     
  4. ddnidd1

    ddnidd1 Supporting Member

    That noise is an electronic problem - nothing to do with the speaker.
     
  5. BassoMatik

    BassoMatik

    Aug 23, 2012
    Is there any way to fix this? Should I take it to a specialist?
     
  6. BassoMatik

    BassoMatik

    Aug 23, 2012
    Bumperbass:

    I did an experiment with doing the same thing that triggers the noise, turning the volume all the way down and then turning it off. It didn't make the noise. I'm knowledgable in audio and stuff like that, but I'm totally in a different world when inside an amp. I know the basics, but I wouldn't know enough to actually service the amp myself.

    What's an IC? Something circuit?
    Power supply caps?

    And yes, the sound could be thought of as a squeak and then a pop. And from what I can tell from the amp, the sound has gotten louder. It was sort of a thing that I looked at the speaker the first time it did it and was like, that wasn't very loud, must've been a fluke. But now it's as loud if not louder than the level I was playing at.
     
  7. bumperbass

    bumperbass Supporting Member

    Jun 19, 2012
    An IC is an opamp amplifier. IMO, I wouldn't worry about it unless it got terribly bad. Might stay this way for the life of the amp. I know some amps did this from day one (I've had a few). Don't worry about it yet.
     
  8. Standard operating procedure for all amps is to turn down gains before switching off. I didn't listen to the clip but you have nothing to worry about if the amp sounds good when playing.
     
  9. João Bourgard

    João Bourgard

    Jan 21, 2010
    this....

    I have had that problem with a laney combo..
    It is the capacitators discharging on to the board probably and then that signal goes trough the speakers... happens...
    its not that bad at all... but it might get worst.. mine did....
    Any tech can swap the caps and it is not too much expensive...

    if it were the voice coils or something to do with the speaker you owuld probably ear the sound all the time...

    cheers
     
  10. BogeyBass

    BogeyBass

    Sep 14, 2010
    Never owned a combo 300 so dont know if it is normal.

    Some older amps can have a little pop when you first turn them on. And also when you turn them off the power supply caps will slowly drain. So there is still enough voltage to operate the amp and it can still make sound as they slowly drain. There is no extra circuits to cut the sound to the speaker at power up and power down. More modern design would have a soft start to get rid the turn on pop, and also have a shutdown sequence so the amp wont make sound when it shuts down and the caps begin to drain.

    So far as you might know the amp always did it, you just never noticed, or after turning off after now using higher volumes. There is just more energy in the caps to make audible noise as it slowly drains.

    You would have to confirm with someone that knows peaveys if it is a known symptom for the amp. Then it is no big deal.
    Otherwise it sounds like a little self oscillation squeal from a opamp. Might be no big deal, the opamp is designed to run at certain voltages when on. So when off it is slowly draining voltages are randomly draining below the operating levels, there might be a point when it becomes unstable and lets off a little squeal. Then just dies out as the voltage finally drains away.

    Otherwise if the issue is not suppose to be there, electrolytic de coupling caps in the preamp might be getting old. They are polarized for +/- voltages but often due to circuit design are exposed to voltages of opposite polarity and can make them go bad faster. No way around it sometimes the only downfall in using electrolytic capacitors as audio decoupling caps. So after 10 to 20 years of service they might need replacing.
     
  11. bumperbass

    bumperbass Supporting Member

    Jun 19, 2012
    True, but those decoupling caps seldom go bad, and when they do, they usually short, which would give you no sound. The only electrolytics in the preamp are coupling capacitors and when they go bad, you lose lots of low end.
    I wouldn't worry over it.
    Yep, you're right about modern day amps. Mute on power on AND power off.
    I've owned a few Peaveys that did what the OP describes, and they never needed repair.
     
  12. BassoMatik

    BassoMatik

    Aug 23, 2012
    Thanks everyone for the help
     

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