Patching MIC lines?

Posted: Wed Feb 06, 2002 10:37 pm

I've gotten some new preamps, and I'm worndering how best to set things up for convenience.
I have a 24 channel snake from the studio to the control room. My console's XLR inpts are hardwired to the on board pres, and separate multipin cables feed the 2 line inputs on each channel.
What I'd like to be able to do is patch the mic line to either the console preamp or an outboard pre as necessary.

Is it safe to terminate the snake from the studio into a trs patchbay? I worry that at some point I'll forget to kill the 48v supply and it seems like a TRS cable will momentarily short, or apply 48v across the tip and ring (in effect de-phantomizing the phantom power).
SO, the question is: is it OK to do this, or must I patch with XLRs

Posted: Wed Feb 06, 2002 11:33 pm

You are correct in assuming that phantom power can blow up mics if using a TRS patchbay. Don't do it. Wire up a panel with some XLR jacks, in and out. Check out patchpays.com to see if they have any ready to go.

Posted: Thu Feb 07, 2002 9:28 am

Thanks, thats what I was afraid of. Oh well...it's only money.

Posted: Fri Feb 08, 2002 2:11 am

that's patchbays.com

Posted: Sun Feb 17, 2002 2:31 pm

I worked in 3 different places that had TT patchbays on the mic lines and those PB conducted phantom power to them and we neverhada problem... do you need to wire something different to do this?

Posted: Wed Feb 20, 2002 8:07 am

Hosa has a patchbay that has 12 male and 12 female xlrs that you can pick up for under $90,cool item.
Luke

Posted: Wed Feb 20, 2002 12:00 pm

Larry, Geronimo - One possible explanation why people "get away with" using phantom on TT bays - If you look at a TT plug alongside a 1/4" TRS plug, you will notice that they are not just "me and mini-me" the TT plug tip is noticeably smaller in diameter than the rest of the plug, where the tip, ring and sleeve of the TRS are all nearly identical diameter. If the TT bay has no "ring" contacts that are bent in too close to center, it is possible that inserting a TT plug never causes the "ring" contact to touch the tip of the plug. I haven't measured this electrically yet, but that could explain why a TT bay wired for mics with phantom "gets away with it" and a TRS one couldn't. Just a thought... Steve

Posted: Thu Feb 21, 2002 10:12 am

Interesting theory. Thanks.

BTW the Hosa XLR patchbays arrived today, and they look fine, I mean they seem to be well made. The connectors are screw mounted, so I you needed to invert the male/female it's readily done. The cable is at least 22 ga and the soldering looks to be fine. I think they'll do fine for me. I've not really been able to hear cable anyhow.

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