Tube swap question...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Jemlite, Dec 5, 2005.


  1. Jemlite

    Jemlite Member

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    Is it safe to change out preamp tubes with the amp on? How bout Standby?

    (I know it's not cool with power tubes).

    Thanks.
     
  2. hipfan

    hipfan Member

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    I swap both pre-amp and power tubes with the amp on "standby." I haven't had any problems, but I'm no expert on whether this is entirely adviseable or not.

    However, I can say that you should not swap any tubes with the amp completely "on." Bad stuff there.
     
  3. Shea

    Shea Member

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    I don't. The heater voltage is still on when the amp is on standby. So pulling tubes out and sticking them in while the amp is turned on will cause abrubt, sudden changes in the loading on the heater winding. Does that hurt anything? Hell if I know. But one time I put the amp on standby and pulled out a preamp tube, and the amp made a loud pop. I didn't like that.

    Shea
     
  4. Wakarusa

    Wakarusa Member

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    If the amp's "standby" position turns off the high plate voltage to the tubes (preamp and power) then the tubes can be safely removed and inserted with the amp set to standby.

    If you've taken the amp to standby and immediately pull a preamp tube, the main filter caps may not have had time to discharge - so there's still voltage on the plates that'll cause the audible pop when you pull the tube.

    When in doubt, just turn the amp all the way off and you don't have to worry about it (tho' you can still get the pop if you pull a tube before the power supply has discharged).
     
  5. doctord02

    doctord02 Member

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    I'd turn the amp off myself. If the tube was to break while you were jamming it in the socket you might get a zap you'll never forget...
     
  6. Igneous

    Igneous Supporting Member

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    I agree. Do not do this!! You can kill yourself. always turn the amp off and even, unplug it. It can still kill you without it plugged in!!!!!!!!!!!!!!
     
  7. Jemlite

    Jemlite Member

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    Thanks to everyone for the help.
     

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