They're mostly from mix tutorials from other sites. There's a good sound on sound video talking about recording guitar for QOTSA where they mention cranking the mids to 11 on a few pedals going into the amp.
The Schepps one is from puremix. https://www.puremix.net/video/inside-the-mix-the-heavy-with-andrew-scheps.html
There's also a Mix with the Masters video of CLA talking about adding 500hz on guitar with a UAD trident EQ emulator.
Unless they're all thinking of adding EQ for colour and then mixing it like Al Schmitt, I have no idea how to approach the style of a mix.
- This reply was modified 3 years ago by ChrisW.