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AMPEG SVT4 Pro Tube Question (AMPEG Insider... Help!)

Discussion in 'Amps and Cabs [BG]' started by Joebass, Oct 27, 2004.

  1. Joebass


    Dec 24, 2003
    Central NY
    Which Tube drives the solid state mofsets? I ask this to get a better idea where I should place my mullard tube to get the best results (tone). If Ampeg Insider is out there I would appreciate an education on what tubes in positions 1, 2, and 3 (looking down from left to right)on the SVT 4 Pro have in relation to tone/ drive.


  2. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Are you talking about SVT4PRO or SVT3PRO?

    The 3PRO is the one with the "tube driven mosfet" amp.

    On the 4PRO, the tube nearest the input jacks is the input and bright stage tube, the third in line handles tone controls, and the second is the output.

    Normally the "best" tube would go in the input stage, if "best" means quietest as far as noise and hum, microphonics etc are concerned. That way you (obviously) have the least of those troubles.

    As far as tone, well, I guess that would depend.....the input stage is the one with no volume or gain control before it, so the reaction to any overloads at the input would be affected by tube quality.

    On the other hand, the tone control stage or output stage handles the largest signals, so there is a good argument for them as well.

    I don't know if I have a clear choice as to which would be the best place, other than putting the least noisy one in the input stage.

    Clearly, if you were referring to the SVT3PRO, the tube which directly drives the mosfets would be a very good candidate.
  3. Joebass


    Dec 24, 2003
    Central NY
    AMPEG Insider,

    I just purchased the SVT 4 Pro, replacing my SWR Bass 750. I'm looking to optimize (punch/clarity) the 4 PRO tube pre-amp performance. I have lots of tubes from my experments from trying to get that POS SWR to sound like a bass amp. Solution was easier than I thought! Trade it in for an AMPEG! Thanks again for any guidance/ advice on the subject of tubes for the SVT 4 PRO.

    Joe B.