This one is beyond me. I just finished my "dual mono" Poseidon. I went to ground the OPT on the common as the manual says to do. I can ground the right channel and it is fine, but if I ground the left channel, it makes an awful sqelching sound. Any ideas? It still has some hum which is beyond me because it is the same components as I used minus the PS caps for the last build and it used to be quiet. Any obvious reasons for hum or the squelching sound?
A few notes are that the IEC goes directly to the chassis and nowhere else, and the entire circuit is grounded via, RCA ground from the preamp which is a Parasound PHP-850. It is a very quiet preamp typically.
This is what it looks like up top with the recessed 9 pin tubes. I will probably drop the another 1/4 inch. I wanted them to look more recessed.
Thanks if anyone can help,
Blair