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Deminishing Output?

Discussion in 'Amps and Cabs [BG]' started by banjo5, Oct 14, 2013.


  1. Aw, I miss the old PBG, rants and all. But welcome to the "new" PBG.
     
  2. As do I. He could, and did, get his knickers in a twist at times but I think his heart was in the right place. :)
     
  3. deminishing is not a word, diminishing is. :)

    Didn't your spel cheqer let you know??
     
  4. hodgy

    hodgy

    May 5, 2004
    Bothell, WA
    Customer Support- Ampeg/ Line 6
    I'd check the bias. The 5 pro only has the one 12AX7 for the drive circuit, not the 3 preamp tubes like the 4pro. If it was a 4 pro I'd say check the pre tubes first, then the bias. In this case, check the bias first.
     
  5. Psychobassguy

    Psychobassguy Banned

    Oct 14, 2013
    Sneedville
    There are no power tubes in this amp. Preamp tubes are cathode biased, "self-biasing." The amount of voltage output to drive the power section from them is fixed.
     
  6. But to be clear, tube (output) amps are not alone in needing proper bias. Many SS amps are stable their entire life, others may need the output bias "touched up". The SVT 3/3 Pro seems to be the most common for bias drift and the most touchy to do properly.
     
  7. Psychobassguy

    Psychobassguy Banned

    Oct 14, 2013
    Sneedville
    Your question is a very intelligent question, and pertainant to the measurement. A power measurement should be made by a qualified technician, who will check the amp's output at drive voltage specifications in various parts of the circuitry. Your amp may need an adjustment to its output transistor bias, which is what the representative from Ampeg alludes to-

     
  8. Psychobassguy

    Psychobassguy Banned

    Oct 14, 2013
    Sneedville
    Bear in mind that many of the "original" PBG's comments are not present on this board in their entirety or context. He's a friend of mine, and his reputation on this board for being a curmudgeon has been largely shaped by others, often at the expense of the truth. That said, I do doubt that he would have been as dry as I am. He is a character.
     
  9. If you see the "original" PBG anytime soon, tell him that we hope he's doing well!
     
  10. georgestrings

    georgestrings Banned

    Nov 5, 2005
    +1...


    - georgestrings
     

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