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When to change tubes?

Discussion in 'Amps and Cabs [BG]' started by RS, Jun 28, 2001.

  1. RS


    Aug 27, 2000
    Cleveland, OH
    How do I know when to change the tubes in my preamp?
    Should I attempt this or send it to a trained professional?
  2. Preamp tubes rarely, if ever, need replacing. If they ever do need to be replaced, you open the amp, pull the old one out, and pop the new one in. Takes ten seconds.
  3. brewer9


    Jul 5, 2000
    I have a Mesa Boogie 400+ with 12 tubes. They say to replace them every 2 years.
  4. They are talking about the power tubes. RS was asking about preamp tubes.
  5. brewer9


    Jul 5, 2000
    Uhh, OK. What are those?
  6. Power tubes are the 12 large tubes in the back of your amp. Preamp tubes are about 1 inch tall, and are usually hidden under metal canisters.
  7. brewer9


    Jul 5, 2000
    Inside the amp? or in a seperate piece of equipment?
  8. The are inside the amp. You may be able to see them behind the power tubes. They will look like metal cylinders sticking out of the amp chassis.
  9. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador
    When to be replaced?
    When they begin to distort at the same levels you were normally using.
    New Tubes also bring new life to Preamps and PowerAmps.
  10. I find it hard to believe that you own a 400+ and don't know what a preamp tube is or where it's at...

    Changing preamp tubes is a pull and plug deal.
    No biasing. No tech needed.
    The hardest thing about replacing a preamp tube is unscrewing the plate and deciding which type of 12AX7 tube you want to use.

    (I like Sylvania JAN 5751's)
  11. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    " The are inside the amp. You may be able to see them behind the power tubes. They will look like metal cylinders sticking out of the amp chassis"

    ....... Jeezus!
    If you don't know what your doing DON'T TOUCH!
    Those "metal cylinders" could be Capacitors.
    Ever had a shock off one of those? - they keep their charge for a VERY long time - IT COULD KILL YOU!
    Take the amp to someone who KNOWS what they are doing - I't'll be cheaper in the long run - funeral costs are pretty high these days!
  12. CS


    Dec 11, 1999
    Ditto the safety thing-theres up to 600v with enough amperage to kill stored in the caps.

    There are ways to discharge them but learn from someone who knows what they are doing (a good pointer is that they are still alive).
  13. brewer9


    Jul 5, 2000
    Uhh, like what are you saying? That I'm lying? Believe it or not I own a car and dont know a thing about the engine either. Oh, I must be lying about owning a car too.

    To everyone else, thanks for the info.
  14. CS


    Dec 11, 1999
    You are not a real musician if you do not know the grid voltage of every valve amp ever made.

    Brewer 9-bow your head in shame and play a Peavey TNT for 3 months as penance.
  15. No, I know you were telling the truth. Better not touch anything, it might blow up or kill you.
  16. brewer9


    Jul 5, 2000
    A Peavey TNT! Oh no, not that!! Oh the shame.
  17. CS


    Dec 11, 1999
    It's a bit harsh, but that'l learn you.

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