Patch bay basics! How to wire a patchbay.

Posted: Thu Aug 12, 2004 5:48 pm

Hey everybody!! I was hoping for some input and helpful ideas for my studio!!! I have two 48 point patch bay (AP 1/4" in's and out's) and I have my 100' live room snake patched up to it via HOSA XLR to 1/4" balanced snake and then normalled into my O2R96 via the HOSA 1/4" balanced to XLR. this is done only on the last Eight channels of the snake. this is so I can patch in to the pre-amps of my O2R96 from the control room and use my pod pro and outboard FX procossores as well as DI the bass from the control room for over dubs. with the bass I am gettiing a very bad distorted buzz kind of noise that almost sounds like a blown tweeter on my mackie HR824's. this cannot be the case as the mackies are fine with loud DI clean guitar. also playing back music and what not on the speakers this sounds does not happen. I also am getting a ground loop or buzz noise when i use a Mic on the patch bay channels that I do not get on the channels that are snake'd straight into the board and not through the patch bay.
is this a fault of how I have wired things up? should I get rid go the snake and build one that goes straight to 1/4" balanced for these 8 channels. or should I get differant patch bays? should I get TTP bays and hard wire everything!?!?! will this fix my noise and buzz problems?. any ideas would be really helpfull as I want to ensure I am getting things sounding the best I can right into the computer from the O2R96 but I also need to maintain this hardware routing flexablity in the control room.
thanks Curran

Athalon XP2000+
MSI k7t266 mobo
1 Gig PC2100 DDR ram
Matrox G550
RME hammerfall 52/96
Adaptec 21960 SCSI card
windows XP pro
36gig 10,000rpm SCSI drive
40gig 7,200 apps drive
80gig 7,200 backup drive
Nuendo 2.01
Yamaha O2R96 usb'ed to the computer
Midi Sport 8x8/s usb'ed up to the computer

Posted: Fri Aug 13, 2004 11:46 am

Curran,
Its difficult to say for sure without being there but it sounds to me like you have a ground loop problem. This occurs when you have two sources to ground, tied together.

One way to cure ground loops is to have an electrician wire all your wall plugs that are in use for your studio gear and amps in the C/R and live rooms wired to the same circuit / leg and ground source on the main electrical panel. Or you can drive a stake 9 feet into the earth and tie all the grounds for all your gear to it. This is called "star grounding". Have a qualified electrician help you with this.

The best way to find the source is to disconnect all your gear from the patchbay and then start hooking it up one piece at a time, starting with the mixer and the monitor system.

Each time you hook up a new piece, stop and listen to the system and make sure no hum is added. When you do hear added hum, you know what is causing it and can find a cure for it. Some gear has a chassis / line ground switch, you can use cables that have the ground disconnected at one end or ground lifts as a last resort, in desperation, (not widely recommended) solution.

Go one piece at a time ... it is an additive process that can be very weird ... a hum can be caused by a combination of different elements put together ... so one at a time, fix noise, next piece, until it all works. It's like a puzzle but it really is the way all studios are wired up.

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