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More Pwr and Headroom for SF Champ

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  • More Pwr and Headroom for SF Champ

    Hi-

    I'm new here - Happy to have found this site.

    I have a SF Champ. I am looking for ways to increase the power AND headroom. Most mods seem to make things dirtier - I want to go the other way.

    Heres what i have going currently (btw my guitar is an G&L ASAT w/ the p-90 style MFD pu's).

    Stock 8" alnico spkr, 5V4 rectifier(for more headroom) 5751 preamp and RCA 6V6. Original filter caps - soon to be replaced.

    The amp sounds great this way but the bass response isnt happening and the spkr while it sounds good lacks bass response and is a bit farty

    I know replacing the cap can will tighten things up.

    What about removing the feedback loop? With it add more pwr or just make things dirtier?

    Same for tone stack? I like to be able to adj the EQ - at least the treble
    does running the tone knobs at 10 achieve the same things as removing the tone stack?

    I've heard some guys replace the 6V6 with a 6L6 for more pwr - but I've heard that its not good for the Pwr xfmr - I know to increase the voltage rating on the bypass cap to 50V if I do this.
    Any other tube substitutions for more pwr & headroom?

    I plan on replacing the spkr w/ either a 10" weber or 8" Jensen - are the MOD series decent?
    I want to stick with the combo package - ie no separate cabs.

    What about biasing? I know these amps are cathode bias but I suss that installing a variable bias control or biasing it a certain way is probably key to my achieving my goal.

    Any info/help much appreciated.

    Thanks in advance!

    JPH
    Last edited by JPH; 08-08-2007, 10:44 PM. Reason: duplicate post

  • #2
    Hi JPH.

    Well, you pretty have it sussed. Don't remove the NFB, it'll make things dirtier, but also increase a bit the volume. I think the best way would be to make it fixed bias, use a 6550, change the output trany to cope with thoses, use GZ34. And obviously change your caps.

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    • #3
      Thanks!

      I credited the wrong person for your 6550 suggestion - my apologies...

      How much pwr can be gained by doing this? what kind of OT?

      Cheers,

      JPH

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      • #4
        As per http://tdsl.duncanamps.com/tubesearch.php

        up to 20 watts with a 6550.

        http://www.mif.pg.gda.pl/homepages/f...35/6/6550A.pdf

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        • #5
          JPH,you have 2 threads going at the same time on this subject,maybe one of the administrrators can put them together somehow?

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