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Tube amps

Discussion in 'Amps and Cabs [BG]' started by Davidoc, Feb 12, 2002.

  1. I remember something about tube amps not caring about impedence. Can anyone clarify or correct me?
  2. PICK


    Jan 27, 2002
    Sydney, Australia
    It the other way around!!
    Solid state amp dont care about impedance as long as you dont go below the minimum rating. E.G You can run Epiphani 310 on a solid state amp and it has some unusual rating of 5.3 ohms or something like that.

    With tube amps you must match the impedance exactly or the amp starts fluctuating and sometimes dies!! Therefore i dont recommend runnig the epiphani 310 on a tube amp!! Unless the amp has a switch that makes it run at 5.3 ohms but i dont think that that exists.

    Hope that helps.
    If im wrong can someone please correct me!!

  3. Tapp


    Aug 29, 2001
    USA, Mississippi
    Dave, I would say that most tube amps in the old days and probably the new ones of today (esp Aguilar, Trace, etc) are made with output transformers that can tolerate at least a 100% mismatched impedance. Still, you are correct that tube amps "like" to be run at certain impedance ratios to keep the outputs "happy". Fortunately many amps have selectable impedances so matching is usually easy.

  4. Matthias


    May 30, 2000
    Vienna, Austria
    Tapp is right.

    But an important difference to ss amps is that a tube amp puts out the same amount of power into each impedance which is selectable (e.g. 300W into 2, 4 amd 8Ohms)
    A ss-amp puts out less power as the load increases
    (e.g. 300W@2Ohms, 250W@4Ohms, 150W@8Ohms)

    If you look at it this way, you could say that a tube amp does not care about impedance (but this would be misleading)


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