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Help with unwanted amp static!

Discussion in 'Amps and Cabs [BG]' started by LukeMan970, Jun 27, 2012.


  1. LukeMan970

    LukeMan970

    Jun 22, 2005
    Seattle, WA
    So I have a Mesa 400+ running through an Ampeg 410 hlf and I'm getting some odd static coming through. It sounds kind of like the static on Useful Idiot from Tool's Aenima CD if your looking for an reference. I recorded a bit just to show what the static is as well:

    http://soundcloud.com/luke-wyman/bass-amp-noise

    It's just at the beginning and end of the short clip and you can hear it almost cycle through the static. Careful the middle section's loud with the different pedals. So far I've found that it's not the bass or the pedals and it does it through both inputs 1 and 2. Also it doesn't matter how loud I turn up the amp the static stays the same volume. Could it be an issue with needing new power tubes or a loose connection somewhere? This is my first all tube amp and the tubes in it a pretty old so I was thinking that but would like to hear some other ideas first.

    Also this just started happening about a week or 2 ago. I've gigged the same set up a couples over the last year and practiced weekly with it over the last year and had no static issues.
     
  2. dounds like a tube change is in order
     
  3. f64

    f64

    Oct 31, 2009
    Static, if it's internal to the head could be tubes, or something might be loose. A trip to your tech will give you a heads-up.
    I just started reusing an SVT Classis that sat for a while after a two year tour. After about 25 hours I had static, 60 cycle hum and 120 cycle hum. Nothing could be isolated to any of the control functions. I hate to say it but this can be the case with St. Louis heads sometimes. After 4 hours on the bench (and almost electrocuting the tech - there would have been a few pissed off pro's if he had taken a dirt nap on my amp) it was fixed. Aside from a few loose items and a few touchy caps there was a pre tube that had good readings but was causing fits for the head. Chances are it will work great in another amp – just not this one. Two caps, some solder and one new 12AX7 and we're back in business.
     
  4. LukeMan970

    LukeMan970

    Jun 22, 2005
    Seattle, WA
    You guys think I should try and start with a retube? I know it's super expensive to do on these but I've been wanting to do it for a while so I have the money. Would it be a wise choice to start with that and if it doesn't stop THEN take it to a tech?
     
  5. LukeMan970

    LukeMan970

    Jun 22, 2005
    Seattle, WA
    Bump for any added advice
     
  6. Take it to a tech first before you possibly waste money on unneeded tubes.
     
  7. That. I'd guess it's a bad cap(the hum reinforces this idea) or a loose connection.
     
  8. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Have you tried turning your cabs L-pad adjustment all the way down/off?
     
  9. LukeMan970

    LukeMan970

    Jun 22, 2005
    Seattle, WA
    Excuse my ignorance but what are you guys referring to when you say bottles and L-pad?
     
  10. Bottles= tubes. L-pad= tweeter level control on speaker cabinet.
     
  11. rickdog

    rickdog Gold Supporting Member

    Mar 27, 2010
    Before you go out and spend $$$ on replacing all the tubes, there are a few simple things to try that might isolate the problem.

    Since the volume control doesn't affect the static, the problem is more likely to be in the power amp than the preamp. With the amp on, try tapping gently on the output and driver tubes with a chopstick or pencil - is there one tube that obviously makes more noise in the speaker than the others? If it's a preamp or driver tube, try replacing just that one (you'll want a matched set if you need to replace an output tube). Try simply removing and reinstalling the tubes (one by one so you don't mix them up), maybe there's bad contact in one socket. If you have spare tubes of the right type, try swapping them in.

    I got an SVT-CL in trade a while back - it didn't have static, but it would pop occasionally, the bias would drift, and it would start to hum. Tapping on the output tubes produced a pretty good clonk out of one of them. Replacing them with a sextet of Tung-Sol reissue 6550s was under $200, it's great now.
     
  12. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Complete retubes are a waste of money unless the tubes have been tested and they're all dead. It could be as simple as a single preamp tube. Swap in a known good tube of the same type until you find a culprit. If you don't find it, take it to the tech.
     

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