1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
     
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

High pitched squealing/screeching through amp

Discussion in 'Amps and Cabs [BG]' started by FireBug, Nov 28, 2005.


  1. FireBug

    FireBug

    Sep 18, 2005
    Houston
    I had my M-Pulse at practice a week ago and everynow and then it would start to hum loudly and then start screeching madly. It happened a couple of times and when it started happening one time, I turned down both pickup volumes on my bass...still the sound came and I had to shut the amp off.

    The conditions:
    *We were playing loudly in flannel shirt weather. I've run the amp very loud in hotter weather.
    *Using a speaker cable and 8 ohm cab
    *We practice in an old guest house in the backyard...possibly unstable voltage

    Any ideas what this could possibly be? It's never happened in my house, but then again I never run it that loud in my house. The vents are always unblocked. Could this possibly be a sign of bad tubes?

    Please :help:
     
  2. AlembicPlayer

    AlembicPlayer Im not wearing shorts

    Aug 15, 2004
    Pacific Northwet, USA
    yes..sounds like it could be a preamp tube going.

    use a pencil...when the amp is running...tap each tube until you find the microphonic tube. then replace it.
     
  3. yup, i agree..... get some new tubes :)
     
  4. FireBug

    FireBug

    Sep 18, 2005
    Houston
    Ah ok good. This initially sounded like a much worse problem...I didn't know tubes could literally scream "replacement". I've heard bad tubes whistle before, but how often is it you get a screecher?