Tube Amps / Music Electronics
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|previous: Benjamin Fargen Hello all,||View Thread|
|7/5/2000 5:30 AM|
|Chip||Re: I want your thoughts on Marshall mods.........when to just say no?|
If your customers want a really heavy, high-gain sound, and that's all they want (no ch. switching, etc.), here's one that I have used for several years now. No extra tube stages.
I can't take credit for it, I copied most (if not all) of the component values from an already-modded amp back when I was just getting into amp mods... I think (and this is by no means certain)this mod originated with Frank Levi (spelling??) in LA......
Hard to "draw" with words, but this is simple enough, so hopefully it will translate OK:
-about 34k resistance from input to first stage (parallel 68k input resistors)
-1st stage: 3.3k c resistor, parallel with 330mf
-out through .022, into 1meg aud. pot with .001 bypass cap, into 470k res. bypassed with 470pf cap, into second stage.
-2nd stage: 2.7k c resistor, with .68mf
-out through .022, into 1 meg aud. pot bypassed with .005 cap, into 470k res. bypassed with 470pf cap, then into 3rd stage.
-3rd stage: 3.3k c resistor, parallel with 330mf
-change tone stack cap from 470/500pf to 220 or 250pf
That's it. Pretty simple. The "Low" sensitivity input can be removed and the additional pot added there. This mod sounds great with head/4x12 cab set ups. Don't know how a combo would fare. Keep the mids low, set gain on both pots to about 6, and let 'er rip. If the amps too bright, remove one of the pot bypass caps.....
I've squashed many a Boogie-owner with this one. Best part is the parts cost squat, and it takes only a few minutes. Easily reversable, too. Hint: the second stage is a stock first stage. For less work, just swap wires.......
Hope this helps!
|Benjamin Fargen Chip,|