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question about mesa 400+

Discussion in 'Amps and Cabs [BG]' started by erikwhitton, Apr 16, 2003.

  1. erikwhitton

    erikwhitton Guest

    Sep 20, 2002
    Portland, ME USA
    so i picked up my mesa 400+ last night brought it home and plugged it into my 6x10 for initial reactions...mind you it's a used amp, and I don't know the history of it.

    it has a bit of a hiss whenever the speakers are engaged (swicth the standby to 'on') - and i'm just wondering if this is normal.

    my last amp, svt 3 pro, was dead silent.

    the mesa sounds like a record player hiss - i don't think it would be a problem once i'm playing loud - and i don't even think it's a problem now - but i figured i'd put it out here and see what everyone has to say. any ideas what is causing this?

    other than that - i was impressed by the power, the tone shaping knobs and sliders are very reactive, and the thing is damn heavy.

    but i likey. :p

  2. since you dont know the history, I'd assume that the tubes are not new and maybe the problem. take a pencil and tap the tubes lightly while powered on to see if they are microphonic. if they are...Bingo!

    if not, then i'd look into the cables, esp the power cable and/or a power conditioner. but look into the tubes first.
  3. erikwhitton

    erikwhitton Guest

    Sep 20, 2002
    Portland, ME USA
    thanks for the reply...so the amp should be silent then? if everything's up to snuff?
  4. Is there a slight hum in the background of the noise? If there is, and even if not, check the coupling capacitors and plate load resistors and the power supply filter caps, too. Coupling caps and plate resistors (EVERY resistor for that matter) can all induce noise.

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