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'74 Ampeg v4b fluttering noise. More inside

Discussion in 'Amps and Cabs [BG]' started by TussinBot., Jun 21, 2014.


  1. TussinBot.

    TussinBot.

    Aug 21, 2010
    Burbank, Ca
    Someone tried to plug in an instrument to my Ampeg v4b while it was on and at volume. Made a loud noise (obviously) then wouldn't produce any sound. I turned it off and let it sit for about 20 mins and flipped it back on. Bass is coming through fine but theres this intermittent fluttery shushing sound. As if an instrument cable weren't making a good contact. Ive tried swapping out cables and another bass and its still there. Might be able to do a sound clip if that helps at all. Possibly a simple fix like swapping out tube? Would like to avoid taking it to an amp tech if it may not be too complicated. Any advice appreciated.

    Edit: Turned it on again to see whats up. After a couple mins of it being on, with my bass just sitting there untouched and volume down on it, the noise gradually comes in and then starts making the speakers bounce around as it gets louder. crackling and shushing.
     
    Last edited: Jun 22, 2014
  2. May have fried a speaker, did you try it with a different cab?

    What version (year) is this V4B?
     
  3. TussinBot.

    TussinBot.

    Aug 21, 2010
    Burbank, Ca
    Its from 1974. I thought it may be a speaker too but I tried one of my cabs out, then the other (both mesa diesel evm 15l's) and it occurs in both. Neither look or feel torn.
     
  4. A sound clip would help a lot.
     
  5. TussinBot.

    TussinBot.

    Aug 21, 2010
    Burbank, Ca
    Tried doing one but the speaker started jumping out of control so I flipped it back off. Tried again after taking the back off and tapping on the tubes and now the sound doesnt start happening. Maybe one of the tubes just ended up loose? Ill try tomorrow so as not to annoy the neighbors above me.
     
    Last edited: Jun 22, 2014
  6. Sounds like someone needs a cap job. The drivers pumping in and out visibly indicate a low frequency oscillation called "motor boating".
     
    coreyfyfe likes this.

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