Mark Abbott layout?

[Buschman]

I am tweaking on my Express preamp. While using shielded wire on the treble pot wiper has deadened the microphonics of v1 a bunch, it also has deadened the harmonic bloom effect that I was so after. I was reading a post about a Mark Abbott layout written by Jackie Treehorn. I can't find the layout in the files. There is a board layout but no pot wiring. Anybody know where it is?
I also had to remove the bright cap circuit as it acted like a big hum microphone. Are there any words of wisdom on this?

[Allynmey]

All the real TW's I saw were to some extent "microphonic". Switching the bright switch or standby can be heard through the speakers on all of these amps. The most critical points on these amps are the connection from the Vol. pot wiper to thr tube socket and the bright switch. Strande wire in these places can help as can making right angles in your bends so the wire is not tensioned. This acts like a wire between two cups like when you made a homemade walkie Talkie as a little kid.

[LeftyStrat]

Look at drhulsey's layout of the Liverpool. The idea is to run the leads to bass and treble parallel to each other, and against the chassis, about two millimeters apart, and the treble lead should float in the air away from the chassis. If the treble lead is dressed against the chassis, it can tame things, but often too much.

By shielding the treble lead you're losing some high end due to the capacitance of the cable.

Rather than shielding this, you should try different tubes in V1, and you can also try different caps on the bright switch. As Allyn said, using stranded for these caps can help. I've used hot glue on these caps in one amp and it seems to help.

This is sort of an area of compromise. You've got to live with a little wildness on the bright switch to keep the bloom, IMHO.

[Buschman]

My bad. I said treble wiper but I meant volume wiper. Shielded wire there deadened things almost too much. I have the mid & bass down low against the chassis & the treble lead up in the air. I was fighting hum also. I moved my ct grounds to the 1st filter stage ground which seemed to help.
Was there any more to the Mark Abbott than we have talked about?
I am using stranded wire but it is teflon coated. I will try a heavier pvc coated wire on the volume pot instead of the shielded wire to see if it will liven things up without too much noise.
I can live with hiss but if the amp hums now it will be unusable around neaon bar lights.

I guess the microphonics is a big part of the harmonic bloom.

[LeftyStrat]

Are you testing with a bottom plate? Some noise will go down when the chassis is in a head cab with some type of shielding on the bottom.