I've never been able to perfectly intonate the low B it seems. I've had this on every 7 string I've owned more or less. I'll intonate the open note with the 12 fret but when I play a B chord it still sounds off . What I've been doing is tuning it by ear to the E string and it sounds in tune that way . Until you actually check the pitch of the low B and you see its super flat . What am I doing wrong ?