Hey guys! Sorry for the late reply, I was kind of busy over the week. I just uploaded a new remix of this cover, so you can compare it with the first mix.
Hmm, 12k lowpass can't be a problem. You should try different amp/cab+mic settings to get more high frequences, or you can add some db's at 6k for precense and at 14k for air(don't be shy with that, you can add up to +10 db on each of boost if that would work, but avoid a fizz that can appear at 8 to 12 kHz area).
As for your drums. How many room tracks do you have? Normally I'd like to have at least two different room tracks - one mono track for hard compressing and other one for ambience. When you compressing a room track heavily, you should avoid that cymball fizz, you're right. But on your stereo ambient track, which shouldn't be heavily compressed, you may not use and lowpass filters at all. But in this case you should make sure your cymbals are not too loud in a mix.
I have 2 room/amb tracks. One stereo, one mono. The whole kit is from the Made of Metal EZX, except for the snare and the toms, which are from Metal Machine. I just realized the rooms in the Original Mix section are still raw sounding.
-In the remix, I basically used the Velvet preset from Made of Metal as a reference, since I use the same kick as the one in the preset, and I eq the rooms until they sound pretty identical to the preset. I also used the ReaFIR plugin to analyze and compare the curves on the rooms with the preset and the rooms I eq from scratch. The only difference I did from the preset is the highpass around 80hz. In the first mix, the rooms were highpassed around 110hz, so this time I try to keep as much low end as possible. I might be wrong though. Other than that, the rooms sound more alive than before. I have to say, this mix reminded me that I should mix rooms according to the song, and the quality and the size of the rooms. Before that, I usually just highpass, lowpass and scoop the rooms. I never thought about boosting certain parts of the rooms until now.
-For compression, I set it around -5db gain reduction with 4:1 ratio for the stereo track, and around -9db max ratio for the mono track. The attack and release times are the same for both tracks. 0.6ms atk and 50ms rel. It's basically a 1176-ish setting.
Over the week, I was testing different amp sims and Ownhammer cabs with various mic setups. After that, I thought the Thermionik Psycho C (5150 III) and the Marshall Mode 4 cab with EVH speaker would be the one. However, once I put them in the mix, they sound thin and fizzy compare to the original setup, which is basically the JCM800 preamp with a Mesa Rectifier cab. So I ended up using the same amp, but this time I use the Mesa cab from the Heavy Hitters Collection instead of the free one. I think the Heavy Hitters' version sounds fuller and less brittle compare to the free version. Also, I notched out only a few things that stood out to my ears, instead of killing every fizz in sight. And I kept them around -3db. In the original mix, the notches in the 2k to 5k region are around -5db with a -9db in the 5.3khz region. I think it's one of the reason why my guitars sound dull in the first place. The new one sounds brighter, although you can hear some fizz. In Katatonia's LFDGD album, the guitar fizz is tamer compare to the later stuff, which contain a bit more top end fizz, but not unbearable. I don't know if it has anything to do with analog vs digital or if it's simply a sound decision. The LFDGD album is pure analog, since it was recorded in Sunlight Studios.
