Im recording a "black metal" Ep with some Portal and Deathspell Omega twist and vibe and I want to know how I can archieve this kind of darkness and "muddyness". I'll use a Marshall SL-X head with an oversized 4x12 celestion V30, Sm57 and Ribbon Mic plus a 7 string guitar tuned to A.

Any thoughs, plug ins, eq's or stuff? I can upload some demos recorded with an UX1 if you need some clues.
TH3 G3Ar
- JCM 900 SL-X and SV MKII 100HD with LIne 6 sv412
-Bunch of pedals ( WD,BM,NR-2...)
-Ibanez Universe uv777pbk,Rg 2550&321mh