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Trace Elliot 250SMX thumps on shutdown

Discussion in 'Amps and Cabs [BG]' started by ttyR2, Dec 15, 2013.

  1. ttyR2


    Feb 23, 2003
    Athena, OR
    My wife has a pre-Gibson Trace Elliot AH250SMX that pops through the speakers a few times when power is turned off with the power strip, but doesn't if it's shut off with the onboard switch. Plugged directly into the wall, it does the same thing if I pull the power cord. If she turns the onboard switch off and then unplugs the unit (to move off stage at a jazz concert), it will make the same pops as the unit discharges.

    Other than that, the amp works flawlessly. She never has to worry about needing more power :)

    Is there a bad cap in the power supply somewhere?
  2. I always use the poweramp engage button on the front, it still gives a little thwop, always has, it's the little monster inside grunting goodnight. Power up is same in reverse, little monster is saying "lemme at it!"
  3. Scottkarch


    Sep 11, 2012
    My ancient Peavey Bass MKIII does the same thing.. Small thump during powerup.. really noticable THUMP whenever it powers down. It's been doing it since it was brand new in about 82 so I assume that's just the type of power amp section.

    Some of those old transistor amps weigh as much as a tube head.. . or feel like it.
  4. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Older SS amps "thump" on power up and power down. Modern amps can too but most have a delay in connecting the speaker which allows the electronics to stabilize.
  5. ttyR2


    Feb 23, 2003
    Athena, OR
    The curious part is that using the onboard power switch on the back turns it off silently....but if you don't let it sit that way for a long time, pulling the power plug still causes it to thump.

    I just tried it again. Amp off, waited 30 seconds. No pop. The moment I turned off the rack power strip (a Furman RR-15) even after 30 seconds, there's a few loud pops. It does this with *any* power connection I hook the bass in to.

    If it's just "normal" operation, I won't worry about it. It's just annoying when she has to tear the gear down and move it off stage in a short amount of time before the next group goes on.

    I s'pose I could rig up a good quality industrial relay with platinum/gold contacts as a speaker relay and have it cut the speakers off immediately.