Time for new filter caps?

Discussion in 'Amp Tech Center' started by dougstrum, Mar 30, 2018.

  1. dougstrum

    dougstrum Tele-Holic

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    My favorite amp a 5e3 homebrew has been giving me fits. Notes are crisp
    on attack but get fizzy as they decay.

    I've changed tubes, and used cleaner on the pins.
    Plugged amp into a different cabinet, and plugged speaker into a different amp.
    Looked for cold solder joints, and chop sticked around.

    Have not found any trouble spots or any problems; it's getting a bit frustrating.
    I can't remember how long ago I built it. Perhaps it's time to put in new filter
    caps not sure what else to try at this point~arghhh!
     
  2. Smokingheadstocks

    Smokingheadstocks Tele-Meister

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    which tubes did ya change
     
  3. dougstrum

    dougstrum Tele-Holic

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    Changed the 6v6's first, no change.
    Then did the preamp tubes, also no change.

    Figured filter caps next logical thing to try?
    Is there something else that might cause notes to fuzz out
    as they decay?
     
  4. Smokingheadstocks

    Smokingheadstocks Tele-Meister

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    I would test the voltages first. The rectifier tube needs to be checked before the caps. Those caps are not likely to fail so soon (homebrew amp).

    Sounds like a tube problem to me. Check those voltages and post´em here

    Also perform a very detailed and in depth visual check, look for burned resistors, for cap bulges, for any weird thing...
     
  5. JD0x0

    JD0x0 Poster Extraordinaire

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    Bad/weird ground points or cold/bad solder joints can do strange things
     
  6. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Gold Supporter

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    Make sure it's the amp fizzing and not the cabinet - take off back panels and try it out. Make sure the speaker isn't too
    loose or too tight as well.

    Reflow the pre-amp tube socket connections with a nice hot iron would be one place to start - only takes a minute to do all of them on a 5E3 - leave the tubes in - a/c disconnected, discharge the filter caps, and one hand behind the back, all of the precautions -

    Make sure that nothing is in the back of the speaker between paper and cone - once I found a fizz due to a packing popcorn material bouncing about back there.

    Rob's site has mention of adding grid stopper to the PI as well IIRC...

    I imagine there are a lot of things that could do this fizzing and more folks will chime in, but these are three things that I have seen. Good Luck!
     
  7. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    Think it's more than 10 or 12 years? If so, caps are relatively cheap.

    I will say, when my Bassman RI started getting that fizzy decay, and I knew the tubes were good, I cracked it open. I found three of the five caps physically leaking goo... It was time. Honestly, it was past time. Of course, my amp is like 20 years old. But, still.
     
    Ricky D. likes this.
  8. wmsimpson

    wmsimpson Tele-Holic

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    I bought a '69 Twin Reverb a few years ago and got a great price on it because the owner thought one of the speakers was blown. Turned out to be a chassis-mount nut rattling around in the back of the speaker frame. :)
     
  9. schmee

    schmee Poster Extraordinaire

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    Is it "bacon frying" or Fizzing? Certain notes worse? Seriously doubt filter caps.
     
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