strange amp problem...

Discussion in 'Amps and Cabs [BG]' started by JamesTaylor85, Aug 14, 2009.

  1. so i have an ashdown EVOIII 900 running into an ashdown ABMII 8x10,
    lately when i turn the amp on to play its been what sounds to be feeding back, just a nasty screech unless i mute the amp using the inbuilt mute.
    if i pull my bass out of the input it stops, if its plugged in but bass volume is down and tuner mute is on it still happens.
    only lasting for 30seconds or so ive just turned it on and left it for a bit on mute then played, but its a little annoying/worrying...

    ive also changed basses and still same thing, ive tried a number of different things to see if its one problem or the other but no to avail.

    any ideas?
  2. bump
  3. bumpp
  4. MIJ-VI

    MIJ-VI Inactive Supporting Member

    Jan 12, 2009
    Hi JamesTaylor85.

    It sounds like your ABM 900 EVO III Head may have a microphonic (bad) pre-amp tube (valve).

    Your amp's owners manual doesn't explain how to replace said tube.

    Please contact Ashdown for advice on how to proceed.
  5. BassmanPaul

    BassmanPaul Inactive

    If the amp is under warranty take it back. If not take it to a tech.

  6. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    I would probably just try replacing a tube first. They're cheap and you can use a spare if it doesn't fix it.
  7. cheers guys, i thought it might have been the tube, since its a switchable in/out tube pre i guess i can run without it in for a while see if that works.

    thanks again

    edit: yeah was the tube, changed her over and works fine now.
  8. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Nice! Tubes are great but they do go out now and again.
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