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I just recently finished building my power scaled Express (the amp part...still awaiting the cab and no faceplates yet). I sort of expected it to be pretty bright. Another thing about the Express (lots of amps) is that the tone stack is right after the first stage...so you have virtually no tone shaping after the distortion. Adjusting the tone controls affects the flavor of the distortion a lot but it doesn't really affect the overall tonal balance (bright/dark, thin/bassy, etc.). So it seemed that I was compromising the 'flavor' of the distortion in an effort to just get it a little less bright. I also find them to be bright and gainy enough with the Presence control on zero...I almost never use the Presence control. And finally, the power scaling calls for a post-PI MV which when turned down low renders the Presence control useless anyway. So I wanted to replace the Presence control with another, more useful control.
The power scaling kit calls for a cross-line post-PI MV but I never seem to like those so I went with a dual-pot post-PI MV. I considered replacing the Presence control with a Vox-style 'Cut' control but that's just a cross-line post-PI MV with a cap. Since I prefer dual-pot post-PI MVs over cross-line MVs I decided to try a dual-pot post-PI 'Tone' control. It's just two parallel 'treble bleeds' to ground...the wires come right off of the dual-pot post-PI MV. I used a dual 1M-A pot and two .0022uF caps. So far I love this control...I find it infinitely more useful than a Presence control on this amp.
Here's a pic of the guts. As much as I tried to pre-plan this amp...I still ended up with a bit of a kluge over there by the PPIMV. I might clean it up a bit but it's actually fine the way it is (IMO). This amp is extremely gainy...between 4 and 6 on the preamp volume is old ZZ Top to early EVH territory. No hum or oscillation but it does have the usual Express hiss...but the PPI Tone control helps with that too.
I'm not a pro...just a hobbyist/enthusiast...if anything 'jumps out' at anybody as a problem or potential problem let me know. It's hard to see but the MOSFET for the power scaling is tucked down there by the pilot light...mounted on the side wall of the chassis using an insulator (the aluminum chassis is the heat sink)...it does get warm.
The power scaling kit calls for a cross-line post-PI MV but I never seem to like those so I went with a dual-pot post-PI MV. I considered replacing the Presence control with a Vox-style 'Cut' control but that's just a cross-line post-PI MV with a cap. Since I prefer dual-pot post-PI MVs over cross-line MVs I decided to try a dual-pot post-PI 'Tone' control. It's just two parallel 'treble bleeds' to ground...the wires come right off of the dual-pot post-PI MV. I used a dual 1M-A pot and two .0022uF caps. So far I love this control...I find it infinitely more useful than a Presence control on this amp.
Here's a pic of the guts. As much as I tried to pre-plan this amp...I still ended up with a bit of a kluge over there by the PPIMV. I might clean it up a bit but it's actually fine the way it is (IMO). This amp is extremely gainy...between 4 and 6 on the preamp volume is old ZZ Top to early EVH territory. No hum or oscillation but it does have the usual Express hiss...but the PPI Tone control helps with that too.
I'm not a pro...just a hobbyist/enthusiast...if anything 'jumps out' at anybody as a problem or potential problem let me know. It's hard to see but the MOSFET for the power scaling is tucked down there by the pilot light...mounted on the side wall of the chassis using an insulator (the aluminum chassis is the heat sink)...it does get warm.