Amp crackling loudly intermittently

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jezzzz2003, Jan 13, 2011.

  1. jezzzz2003

    jezzzz2003 Member

    Messages:
    2,792
    Joined:
    Dec 6, 2005
    Location:
    aussie
    I had to plug into the PA last week and it sucked.. Not as bad as you'd think but it still sucked.
    A bad crackle started and got louder until a few seconds later there were all lights on, but no sound.

    I thought I fixed the problem and I may have, could be something different but as I was playing at home tonight it started crackling again.. I still had signal though, had the back off as it happened so I tapped tubes, no difference. Then I moved the power tubes in a circular motion and it went away.

    Is it possible for power tubes to do this?

    Thank you.
     
  2. RackCrew

    RackCrew Senior Member

    Messages:
    396
    Joined:
    Jul 24, 2010
    Location:
    A quiet place
    It's not that uncommon for this to happen. It could be a tube going bad or a tube in a socket not being fully seated. Ih that's all it was it should be an easy problem to fix.
     
  3. jezzzz2003

    jezzzz2003 Member

    Messages:
    2,792
    Joined:
    Dec 6, 2005
    Location:
    aussie
    Thanks for that.

    I removed all tubes last night and sprayed with Lanolin to seat them better and inhibit corrosion.

    First thing this morning I checked the amp and can hear a faint crackling sound, and some pops thrown in too. Is this likely a tube, dry joint or capacitor thing?

    I've had sooo many things break on me this week...! First it was two airconditioners, then my fence in a storm, TWICE! my amp, AND my TV aerial. Geez...
     
  4. rydia is hot

    rydia is hot Supporting Member

    Messages:
    529
    Joined:
    Sep 2, 2005
    Try replacing them. I've had more than one set of powertubes get a little crackily/rustling when they are on their way out.
     
  5. wizard333

    wizard333 Member

    Messages:
    2,209
    Joined:
    Mar 14, 2008
    Tubes, plate resistor, bad solder connection are the things that leap to mind. Tubes are the easiest thing to test, just replace them with known good tubes. If it stops, it was your tubes! If it doesn't, isolate what section of the amp its happening in by pulling pre-amp tubes to isolate the stage, then open it up and check plate resistors and look for gimp solder connections. If you don't know what that means, get it to a tech.
     
  6. sixstring531

    sixstring531 Supporting Member

    Messages:
    3,143
    Joined:
    Mar 8, 2007
    Location:
    sw mo
    I had intermittent popping in my Super Reverb and, according to ye old Fender Certified Repair Man, it was a bad volume pot. Took him 3 months to - well, two to diagnose and one month waiting on the exact pot from Fender.

    If you're careful, you can take the chassis out, plug in the speakers, turn it on and use a wooden poking device (I've used a drum stick) to tap on some solder joints/caps and see if you can pin-point some noise (ie, try to make it make the noise without whacking it too hard). I found a cold solder joint this way in another amp.
     
  7. jezzzz2003

    jezzzz2003 Member

    Messages:
    2,792
    Joined:
    Dec 6, 2005
    Location:
    aussie
    Thanks guys. Well I gigged with it last night with a whole new set of pre and power tubes. All went well and sounded GREAT!

    I couldn't hear any more crackling after I replaced the tubes, still a little early to tell 100% but I'm pretty sure it's fixed now.
    I've been using EH EL-34 as of late and have noticed they don't generally last anywhere near as long as the Svetlana's I used to use, BUT, they are really sweet sounding tubes so that's good enough trade off for me and they also have a deeper, tighter bass. Plus some really great harmonically rich feedback.

    Thanks again.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice