Patchbay problem - weak signal!

sean · Post by **sean** » Fri Apr 20, 2007 6:28 am

Hey guys, hope someone has some input on my problem. Any advice would be appreciated.

I started wiring up the first of 3 patchbays last night in my three room studio that has been under construction for about 2 years. I am running Mogami 20pr multicore between the the control room and 2 tracking rooms. XLR channels 1-8 connect to XLR panels in both tracking rooms. Channels 9-12 only go to tracking room 1 and 13-16 only go to tracking room 2. All 16 XLR channels are routed back to the control room where I planned on running them through a patchbay normalled to the pre's on my Presonus LT and Tascam FW1884 (Yes, I know about the dangers of running phantom power through patchbays). Here's the problem...

I wired up the bay, and the input on the pre's are about 20db quieter running a mic signal throug the tracking room panel and through the patch bay than if I simply plug a mic straight into the preamp input. The patchbay is an ADC 52pt TRS bay. I purchased it used on ebay and it came prewired with about 20 feet of ProCo multi core. Could this be a video patchbay? If so would this cause the problem? Could the jacks themselves have a higher resistance (75 ohms?) and could that be what is causing the problem? Any input here would be much appreciated. The bay is high quality and I got a good deal on it so I would hate to find out its useless for audio but I also hate spending 7 hours soldering only to run into new problems. PLEASE HELP!!!

sean · Post by **sean** » Fri Apr 20, 2007 12:04 pm

I forgot to mention, if I crank the gain enough to get a usable signal (almost all the way with an SM57) I am also getting a radio signal loud and clear. Please help!

Post by **Aaronw** » Tue Apr 24, 2007 1:07 am

Is this bay a Video bay? What is the impeadance rating on the bay and/or wiring harness? Is this 1/4" TRS, TT or video connections? Is there normals, half normals or is it denormalled?

sean · Post by **sean** » Tue Apr 24, 2007 6:10 am

As I said, this is a 52pt. 1/4 in. (not TT) TRS patchbay. It has 1/4 inch TRS jacks on the face. The bay is prewired (solder connections), denormaled, with ProCo balanced multicore on the ins and outs (I had planned on getting normalling looping jacks to manually normal the bay and make it less likely that someone would accidently change patches with phantom power on). The modules are brass/gold colored and are ADC brand. They do not say anything else on them. I cannot tell what brand the frame is. I do not have any way of knowing if this is a "video" patchbay or even if there is some differance between a video bay and an audio bay besides the type of jacks and the resistance of the wiring. The ProCo brand wiring is NOT video or digital wiring. It is intended for balanced mic level signals.

At this point I have just abandoned the idea of having my mic leads connect to a patchbay. I have already soldered XLR connections to the leads and connected them directly to my preamps and the signal is strong and clear from the tracking room panels. However, I would like to use the bay for my outboard compressors and EQ's. Any idea why I was getting such a weak signal and so much RF interference? Thank you for taking the time to respond, I hope my description is now clear enough. Any input would be greatly appreciated. Thanks.[/quote]

Post by **Aaronw** » Tue Apr 24, 2007 6:32 am

Beep out the bay. make sure the harnesses pinout the way they should w/ the bay. It may be possible (depending on where this bay came from), could be wired pin 3 hot.

You might also check to make sure the Lo side and shield are not tied together. That may be part of the problem.