I finally got round to doing some work on converting this to the marshall PI as seen in the 1959T schematic you quoted earlier.
There are a few things that I have not completed yet, but I fired it up to try out and as it stands, the gain appears worse.
Im putting this down to too much negative feedback, as Im yet to swap out the 4.7K feedback resistor with a 27K as per the schematic.
I still have the 82K grid leak resistors installed too, which I hope the 150K will increase the gain.
Your right about the presence boost however, interestingly enough this definitely has far more presence boost, especially when I crank it right up.
There are a couple of differences in this schematic that differ from the 2003 too, firstly the negative feedback is connected to the 16 ohm tap, whereas i have it connected to 8ohms on the OT like the 2203.
The other difference I see is the presence control on the 2203 alters the resistance between the capacitor to ground, whereas this 1959T model always sees 5K to ground, but the wiper of the pot takes the capacitor to ground, will this have any bearing? Im considering modifying this configuration too.
Are any of these likely to make any impact?
I am going away for most of next week, so hope to finish it off in the weekend.