Some research on TMV/ORL engineers.
Was hoping to find out some information about the Ipecac albums based on the few credits we got.
But first, let's analyze the early years:

- TMV -> bigger budgets -> different recording/mixing/mastering engineers (with additional help from Omar's crew).
- Some of them (Newport, Scheps, Carranza) helping out Omar with his solo stuff in the early years.
- Jon Debaun = Omar's personal engineer until suffering from a mental breakdown during the making of TBIG.
- Is replaced by Lars Stalfors, who isn't credited on the earlier Amsterdam albums and was likely the engineer for additional recordings made in 2007.
- Shawn Sullivan established himself as Omar's main mixing engineer at the time, Pete Lyman as the mastering engineer. Lyman is also the founder of Infrasonic Sound, the label that put out Apocalypse, ORL&JMW & Absence in the US.
- Absence credits are taken from Telesterion. They seem plausible, Shawn Sullivan probably mixed it and Jon Debaun probably engineered whatever was recorded after 2001 (similar to AMD). We don't know who engineered the sessions in 2001 though. Alex Newport confirmed he did not.
Let's continue:

- Lars Stalfors is very present, also takes over mixing starting with Xenophanes.
- Co-engineering Octahedron / mixing Crypto were Shawn Sullivans last credits in the old TMV/ORL world. His name did not appear on anything until Ipecac series.
- Jon Debaun returns on Solar Gambling & Ciencia De Los Inutiles and a few 2012 releases..
- Xenophanes is the only ORL record mastered by TMV guy Howie Weinberg. Another hint this record had a bigger budget (besides being recorded in a big time studio).
Now, the Ipecac series:

- Chris Common started working with Omar in 2012. I got the USM credit from his old website.
- Omar moved from Mexico back to El Paso around that time when his mother died.
- The Rodriguez-Lopez house was turned into a recording studio called Twin Hills Recording and is operated by Chris Common (to this day).
- The information about Sworn Virgins being one of the last solo albums Omar recorded, Corazones being finished after his mother died & Blind Worms Pious Swine being the first one recorded after his return to El Paso all coincide with Chris Common engineering.
- Therefore Umbrella Mistress is probably among those recorded in El Paso in 2012/13.
- Seems like Jon Debaun reemerged as Omar's main engineer in Mexico at some point and continued working with him in El Paso.
- Shawn Sullivan reappears on a few of those. He and Lars never engineered with Chris Common.
- The albums that have Shawn's name could be the older ones from circa 2007-2009, when he was still working with Omar.
It's not as clear as I hoped it to be. It still might be interesting to some of you Volta nerds.