Slipknot-Slipknot. Engineering.

Ive used them on bass, and guitars too.
It can be a CLEAN tube pre if you want. Provided the caps are still good.
(one of them is starting to hum a little. time to break out the soldering iron)
between the 3 of those, the two viking pres and the two akai/roberts tape pres I've got I am going to do my next session with the drums all hitting a tube stage and passing through tape on its way to the computer. see if I can get a mega distorto Boris-type vibe just for fun.
It shouldn't be too hard to find a stoner-sludge band around here
 
just to throw my 2 cents in here

slipknot has been through so many different amp configurations through-out touring and recording, its impossible to say

"slipknot uses ______________ amp."

unless you're referring to the present tense.
 
I know one of the guitarists (or both?) used an old Mesa DC-5 amplifier. Can't remember what cab or guitar though.

~e.a

i think James was using the one using the DC-5 back in the days, but IIRR he wasn't in the band yet when the self-titled album was recorded, so i don't know what they used for the guitar tone on this album, but i agree it's a sick tone.

I love the production on this album (especially the drums).