Marshall 2205 Extra Gain

[lovetone]

The manual advises that for max overdrive, the boost channel volume control be turned up full, see p3 https://drtube.com/schematics/marshall/ ... manual.pdf
That makes sense, as it will result in V3a, the stage after the diode clipper, being overdriven.

Additionally, I suggest that all the normal channel controls be turned up full, as their circuits act to load the input stage when they're set low (in the upper registers at least). It may not make much difference, but for the want of a moment's twiddling, it's certainly worth trying

See if those changes are enough, before diving into mods. The downside is that compared to those currently used, the control adjustments might change the boost's overdriven tone a bit.

Your quite right, the normal channel does make a difference, as does the level control on full, and correct again these all effect the tone. The setup used now is for the best tone.

I think this is the best he is going to get.

Cheers

[pdf64]

OK, worth a try anyway
With the boost gain maxxed, R11 and R12 (in parallel with the gain control track) form a potential divider at the input of V1b.
I suggest to link out R11, increase R12, eg 330k or 470k, and to mitigate for excessive bias shift / oscillation, add a grid stopper to V1b, eg 47k to 100k.
That should add a few dB gain whilst keeping things stable and the tone / response close to stock.
I guess that R11 needed to be there originally to prevent the clipping at V1b's grid bleeding back into the normal channel.

[lovetone]

Excellent thanks for the ideas

I'll look at this at the weekend and report back.