Patchbay Normalling Question

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workshed
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Patchbay Normalling Question

Post by workshed » Tue Feb 15, 2005 9:35 am

In line with my other thread about having fried my Soundcraft board, I want to make sure I understand my patchbay before I screw up more gear.

There are two things I can think of that may have caused me to fry my board:

1) Normalling: I have an AP Audio 24 point "Master Patching System." If I have the Mixer out on #1 top, normalled to the MOTU in on #1 bottom, will it break that normalled connection if I patch into #1 bottom ONLY? Or do I have to actually patch out of #1 top -> external processor in -> external processor out -> #1 bottom to break the normalled connection?

What I fear is that by not patching out of #1 top, I may have opened up the mixer direct outs to getting hit by the phantom power somehow. It doesn't make sense to me, but I am a moron when it comes to electronics.

2) Using unbalanced cables: My MOTU is unbalanced, using RCA ins and outs, so the snakes I have for it to run to the patchbay are 1/4" TS cables to RCAs. I sort of figured that if the signal is unbalanced at that point, it didn't make sense to send balanced from the mixer. Would balanced have protected the board more? I'm guessing not, but trying to isolate the cause here.

Any thoughts are welcome.

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Re: Patchbay Normalling Question

Post by kayagum » Tue Feb 15, 2005 10:19 am

I think if you searched on "phantom" and "patchbay", that will get you plenty of information.

http://messageboard.tapeop.com/viewtopi ... m+patchbay

For phantom powered preamps, I'm liking the snake/breakout box approach better- that way, there's no way phantom power can affect other channels.

You can also get XLR jacks into a rackpanel if you're not into a stage floor breakout box.
Examples: http://www.sweetwater.com/store/category/c885/

I take the Warren Buffett approach to normalling. ("I don't invest in anything I don't understand"). At the very least, if you want to normal, I'd normal the line outs, not anything that can carry 48v.

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workshed
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Re: Patchbay Normalling Question

Post by workshed » Tue Feb 15, 2005 11:23 am

kayagum wrote:I think if you searched on "phantom" and "patchbay", that will get you plenty of information.
I just realized that I didn't explain my setup correctly because I was spacing out. I now realize that I don't have any preamp inputs hooked up to the patchbay. Only preamp OUTS. So this leads me to believe that because I didn't fully break the normalled connection between mixer and MOTU, the output of the Tube MP went to the MOTU and the was also sent into the mixer's direct out. That's all I can think of -- as I am not feeding phantom power through the patchbay. All mics connect directly to the pres, and the pre outputs are sent to the patchbay for routing to the MOTU, compressors, etc.

So this is my new question, and it's probably a dumb one, but:

Could the output of a mic pre sent INTO the direct out of a mixing board fry the board? I'm thinking the answer is a resounding "yes."

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Re: Patchbay Normalling Question

Post by psychicoctopus » Tue Feb 15, 2005 12:32 pm

workshed wrote:1) Normalling: I have an AP Audio 24 point "Master Patching System." If I have the Mixer out on #1 top, normalled to the MOTU in on #1 bottom, will it break that normalled connection if I patch into #1 bottom ONLY?
test it yourself. run audio in thru the mixer, monitor it on the computer, and plug a cable in to one jack at a time. sorry, I know your mixer is busted, but you could easily substitute another 1/4" line source for this test.

a full normalled connection will break the MOTU input if you plug into either jack. a half normalled connection will only break the MOTU connection if you plug into the bottom jack. there may be something weird about your patchbay, so the test is worthwhile.
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