Marshall jvm 410 mod question

[Rod]

My question is, if i increase the value of the resistor R93 to 470k (see preamp schematic pdf file bellow) will i get more gain on overdrive 1 freen mode? on overdrive 1, green mode the signal goes trough V6B-V7A-V7B as you can see bellow?



jvm410-60-02-iss2-1.pdf

[Helmholtz]

Pdf link doesn't work.

[Helmholtz]

Here is the preamp schematic

Doesn't open. Message: Invalid File Specified.

[g1]

Maybe this one will work.

[Helmholtz]

Increasing R93 will not influence gain, but will attenuate treble after V6a.

[g1]

What exactly do you want? According to your block diagram V6A is not even in use for OD1 green mode, so nothing around V6A should affect OD1 green.

[Rod]

I wanted to add more gain in the crunch channel and on overdrive 1 green mode.

[Rod]

If i increase the resistor R117 it will increase gain on overdrive 1 green mode, increasing R93 will not?

[Helmholtz]

If i increase the resistor R117 it will increase gain on overdrive 1 green mode, increasing R93 will not?

R117 loads the signal - R93 does not (no signal current through R93).

The purpose of R 93 is to cut HF together with the (invisible) input capacitance of V6a.

[J M Fahey]

Add a clean gain booster pedal between guitar and amp input.
"Mods" struggle to get a couple dB extra gain out of already maximized gain stages (hint:little or nothing extra available) while you can *easily* add 10-20-30-40 dB in pedal form.
Distortion will still happen at the tube stages.

[Chuck H]

FWIW I'm having trouble finding any gain controls in the schematic as indicated in the drawn block diagram. Don't even know what I'm working with here or I might have a suggestion or two. I plugged the schematic values into my spice cad and I can't really understand where more gain is necessary!?! The clipped wave form is shitty asymmetrical though. Maybe there's something you don't like about the amp that's NOT related to gain? Because it seems to have plenty of that.

[g1]

FWIW I'm having trouble finding any gain controls in the schematic as indicated in the drawn block diagram.

This is one of those typical 'modern' marshall schematics. You have to follow all the connectors to other boards where the pots live, but none of the connector numbers really correspond to others.

[Helmholtz]

This is one of those typical 'modern' marshall schematics. You have to follow all the connectors to other boards where the pots live, but none of the connector numbers really correspond to others.

Fully agree, but miss the second part (rest) of the schematic.

[g1]

Fully agree, but miss the second part (rest) of the schematic.

Here are more pieces.