He cranked his amp as hard as he could and then used an attenuator.
Eddie used a variac. An attenuator lets you turn down the volume of your amp where as variac lets you lower the ac voltage coming into the amp, thereby effectively lowering the B+/high voltage inside the amp. Attenuators where not around back then but eventually people used a L-Pad and the ideas rolled forth from there (ha, ha).
EVH had sick tone on "For Unlawful Carnage". That was a Soldano SLO100?
Yes it was along with a harmonizer to give it a double tracked feel.
...check it out..accord. to some of the more recent interviews with ed, he has shot down most,if not all, of the fabled "brown sound" legends-he has said the variac,the jose mod,etc..were all just "red herrings"
Ed has said a great deal of things (amazing player nonetheless) however there are photos of VH in the studio during the recording of the first record and you can see the variac. He also used Jose modded Marshalls a great deal and even commissioned Jose to build a signature series head but for what ever reason nothing came from it. At that point Ed starting saying he didn’t use Jose modded Marshalls, etc.
We have worked on several Jose modded Marshalls and have one in the shop right now. It was used on the Dr Feelgood record (Motley Crue) and when you add the additional gain stage it sounds identical to the old EVH tones.
Hope it helps
Trace