Satriani-style amp...

[bluefoxicy]

http://www.sewatt.com/files/sewatt/Marshall.pdf

With the following values:

R8 - 680R
R7 - 270K
C1 - 0.022uF / 0.0015uF (SPDT)
R6 - 270k in parallel with a 1M pot and a bunch of caps (tone control)
R9 - 820R
R5 - 470K
R14 - Pot (bias), adjusted properly
V1 (12AX7) - JJ gold-pin 12AX7 (replacing with a Tung-Sol)
V2 (EL84) - 6V6 Electro-Harmonix
C12 - gone
Filaments - AC, twisted leads to cancel hum

The tone pot at R6 does some freaky bypassing that I want to undo, and replace with a tone pot like Big Muff or such.

Aside from the unknown variable introduced by the tone pot, does anyone have any comments on this amp? It's not very smooth and it rings harmonics above fret 12 (sounds like a bell sometimes). Trying to get a Santana sound out of some DiMarzio Steve's Specials and a 6V6 (Black Magic Woman, reference). Thinking I'll get something akin to Joe Satriani's sound with some Evolutions and a JJ 6V6 (closer to EL84 type overdrive).

At this point I'm just directionless, not looking for "the fix" because I don't quite understand what's causing the tone I'm getting. I'm not sure I understand how the amp's interacting internally right now.

[bluefoxicy]

Hmm. Some messing with my pick attack and guitar settings actually got me a perfect reproduction. Sweet.

[tubeswell]

I hate to say this but, why not try putting it back the way it was and doing 1 mod at a time until you find a sound you like? Keep notes and recordings of what you are doing so you can go back if you need to.

If you want more "Satriani" type gain, you'll really need a different amp with more gain stages (and a push-pull type output stage). Otherwise you won't be able to drive the output tube grids at sufficient voltages to get that creamy distortion. Those hi-gain amps use about 4 or 5 gain stages in the pre-amp. This allows the amp to get the voltage up gradually whilst allowing sufficient buffering to filter out unwanted extra noise from each previous stage and get the frequencies passing through each stage right so that you don't end up with muddy mush. Based on my own experience with modding a factory amp, trying to distort your amp by lowering cathode Resistor and upping plate resistors in a couple of gain stages, will most likely just either give a grainier sound or a muddy mush.

[bluefoxicy]

Yeah, I noticed the preamp sounded bad after a while and dropped the second stage to 100k and 820R instead of 270k and 680R. I'll have to look into a few more gain stages in the next amp I build, maybe 12AT7 into 12AX7?

I'm confusing Satriani and Vai btw... I don't think I've ever heard any of Satriani's stuff :s What gives? Something's wrong with me lately.

[BackwardsBoB]

You're scaring me.