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Ampeg SVT-CL preamp tube(s) and gain factors

Discussion in 'Amps and Cabs [BG]' started by johnnysomersett, Feb 12, 2016.

  1. johnnysomersett


    Apr 23, 2015
    Search brought up WAY too many threads to compile a definite answer. So, I'll keep this short.

    SVT-CL...power tube distortion is obviously the best, but you have to destroy the room to get it. Changing the V1 a 12au7 (or other lower gain pre-amp tube) to force the 6550s to work harder should get poweramp grind earlier on the volume scale? Or should I change more than just V1?
    Or am I chasing rainbows?

  2. Amps do not work that way. The output stage will distort when it runs out of head room. That’s true whether you have one or fifty tubes in front.
  3. pablomigraine

    pablomigraine Commercial User

    Feb 9, 2005
    New York
    VP & Managing Director - Willcox Basses
    Paul's correct. That won't work. Is your concern overall volume being too high to get the tone you need? Or is your concern premature tube wear and the attendant cost?

    We can better give you suggestions once we know what your considerations are...
  4. johnnysomersett


    Apr 23, 2015
    Sorry, been out and couldn't reply.
    I've used guitar tube amps for a couple of decades and noted that keeping the power amp tubes hotter often resulted in more (and earlier) P-amp distortion so was kinda thinking in/out the box with regards the SVT preamp.
    Not overly concerned with shortened tube life but crave the 'grind' at slightly less than nuclear volumes. Not keen on the preamp drive, seems weak.
    Used to use an OR120 but not loud enough, but it breaks up beautifully.
  5. MJ_Sotti

    MJ_Sotti formerly "Mike in Chicago" Gold Supporting Member

    Apr 3, 2011
    I've used my RPM into the power amp in and it's ungodly loud and cleaner. the stock JJs in the preamp break up pretty early. I like tube, but not a lot of distortion. I just grabbed a high output, more headroom tube for V1. we'll see.
  6. That's an opinion, and many times an often repeated misunderstanding.

    What would be helpful is to really understand what is happening in that amp when it "breaks up beautifully". Sometimes seeing what the signal looks like at various stages can help understand what it is your hearing.
    b-b-b-bass likes this.

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