DB 25 patch bay

[stevegries]

Hello everyone -

So I finally finished buidling and wiring my home studio, and for a DIY job, was pretty thrilled by the results in terms of room sound, finish, isolation, etc.

I thought setting up gear would be the fun part, but naturally I have major hum problems. The guy I wired with (not an electrician, but holds a masters in electrical engineering from Columbia University) and I read Rod's book, followed NYC code to a t, used star grounding, etc.

Initially, when I started plugging in guitar amps, etc. I was very impressed by the nearly non-existant hum levels.

Running my board, powered monitors, interface, etc - everything was great.

Then I started plugging condenser mics into my live room panel which runs to my db 25 patch bay ( built by Audio Accessories) . The party came to a screeching halt.

Just to give you one example of a problematic signal path (because anything even remotely similar that I've tried has failed similarly), if I run an Audio Technica 4033 through a 20' XLR cable to XLR insert 1 on my panel which then runs out of a 25 pin dsub to my patch bay and out of my patch bay to my Toft ATB 24 (or a Grace 201 or a MOTU828mkII or a Mackie1202VLZ...you get the point) I get some grizzly combination of radio and ground hum. The patch bay is directly grounded to the sub panel.

The patch bay has switched allowing for "Grounds Vertically Strapped" "Grounds Buddes" "Grounds Bussed to Row 1" "Grounds Bussed to Row 2" and "Grounds Bussed R1 and R2 isolated." I've tried all configurations with no success.

Does anyone have any ideas?

Thanks!
Steve

[Aaronw]

The patch bay is directly grounded to the sub panel.

Your electrical panel? Lift it and see if it helps. You may want to ground it to a console ground point instead.