VOX AC-30 with O'Connors Recommendations

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by TheAmpNerd, Nov 1, 2005.

  1. TheAmpNerd

    TheAmpNerd Member

    Messages:
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    Location:
    Tejas
    Hi Y'all,

    I've got and older SS Rectified AC 30, that came in.

    I'm toying with the idea of performing Kevin's
    (the TUT author)
    suggested mods to save the output tubes in this
    amp, along with ability to pull two outputs for
    half power (more power scaling for dummies).

    Namely install higher screen 1k1 and grid stoppers 2k2
    in the outputs.

    There is some discussion I've heard about these
    changinging the tone of the amp too much.

    Anyone tried it?

    OR

    Is this one of those...only her hair dresser knows for sure?

     
  2. Yes, I tried this mod!
    Changing any resistor in any amp will change the tone slightly but in this case not enough to notice a significant difference and your tubes WILL last alot longer!
     
  3. TheAmpNerd

    TheAmpNerd Member

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    Thanks ECT.

    I was wondering about how much it would change the
    tone. Kevin does mention how to compensate for it
    though. I wanted to hear from someone other than
    the author, who has done this.
     
  4. TheAmpNerd

    TheAmpNerd Member

    Messages:
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    Joined:
    Sep 23, 2004
    Location:
    Tejas
    So, the tone of tubes frying
    over the brink, when tamed, is not significant?

    If true, then there would be no need for Kevin to
    reccomend a compensatiing "small cap" in the pre amp
    section.

    From chaning any resistor in any amp....well no
    one would probably know, probably when replaced.

    However, these are two very large steps in resistance.

    I'll see how it goes.

    Thanks again.

     
  5. darkbluemurder

    darkbluemurder Member

    Messages:
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    May 6, 2005
    I changed the screen resistors in the Soldano Atomic 16 I once had from 470R to 2k2. At low volumes the amp sounded the same as before. When cranked the amp sounded less brittle so my conclusion is that higher screen resistor values lead to less upper highs in the overall sound - probably not a bad thing if you intend to crank the amp most of the time. I would simply try it and see whether there is an objectionable change. You can always go back.
     

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