...I'm still having problems with my internet access, unable to do forum sessions or pms! May be solved next beginning of the week (!)... so excuse me...
Still deeply grateful for your appreciation!
First of all, I never meant to have suceeded so far, and aside from this (silly) justification I'd like to share my experiences and answer your questions!
- My SLP is heavily rebuilt, only chassis, PT and some pots are left. Any build (maybe still not mine?) using very good parts should succeed.
- Yes, low (early plexi) filtering is a key to this, I think. It's always best to benifit from properly formed filter caps (I got F&Ts recently, doing this)! Mine has single 32uF on PI filtering right now.
- Look at the attached circuit, assuming that this is the earliest drawing of this and that ralle is referring to this (...my 'History Of Marshall' book is on the way

) - so, it's 0.022u for coupling/cascading V1a with V1b.
- I have standard 0.022u PI output couplers right now, expecting bass-couplers to extend the lows as usual, but maybe requiring different NFB combos (100k on 8 ohms for now)!!
- I experimented with the presence circuit and found out that the original version (ralle refers zo this) is not working for me - maybe because I still have 220k bias feeding. I like the '73 combo (0.680u/4.7k), but didn't try yet.
- 100p fizzy cap, not sure if this makes much difference.
- The treble bypass cap on the preamp pot has a very huge impact on the response!!! For me: 1nF is way too much for the 'juicy hid mid gain'-factor, ending up in almost uncontrollable squealing when the amp is played quite loud, also making the trebly hiss too superficial! I prefer 100pF, though sacrificing a hint of smack, gain and sizzle. Cleaning up with guitar pot is more musical, too. Thinking of 'Bottoms Up!!' intro...
MY conclusions, not generalizing:
This spec delivers an upfront, smacking tone due to compressing with cascade gain staging.EVH all the way! The sound in the room is cutting through nicely, a lot of the NVM characteristics remain. You get sustain but loose dynamics. The pot setting is important here, using a lot of PI and powertube distortion, along with full presence gain. I was able to rehearse successfully yesterday (broad classic rock spectrum) although I still have to accustom to this.
Sorry for the long post

, but hope this helps...
Regards, Jost