Greetings. I've got a Schecter and a set of GHS 7-String Boomers (10-60), and there are intonation problems on 7th string I fail to comprehend. The neck and frets are ok, the action is ok on both 1st and 12th frets (a tiny bit higher on 7th but nothing that could explain that), and I've made the most of Tune-o-matic. I ended with decent intonation on high E to low E. But open fret is 7 to 10 cents lower than 1st and higher frets on low B. So I've made some calculations and quickly prototyped a compensation nut to see if it helps. Now the intonation seems decent on low B (+-3 cents, but I don't expect it to sound or intonate good after 12th) and nice (+-1 to 2 cents) on the rest. High E to low E were compensated for 1-2mm, but for low B it's 6mm! I wonder what's going on there. I've never witnessed or even heard of a problem like that for a single string. Can this be specific to current set of strings, and if it can, then how? What's the theory behind this beautiful phenomenon? Please, enlighten me.