Patch Bay Hum Problem

[Caldo71]

Yo Doodz,

My apologies if this is a common post...I tried the search function/F.A.Q.s and didn't see anything. This is a long-ass diatribe but I wanted to be thorough in describing my problem. Okay, on to the question...

I just finished my first-ever patch bay. A huge project for me: 216 points thus far, and I did all the soldering myself, which included not only the connector ends but a lot of the patch bay contacts as well. The patch bays were bought used and although the snake was already soldered to it, a lot of the soldering was shitty and had to be re-done. Plus I had to do most of the heat-shrink tubing up the length of every single cable as well, because the snakes came to me already connected but "raw"...no outer jacket for each group of three wires.

It's a long-frame (a.k.a. military-grade) 1/4" TRS balanced rig. It was a lot of work, and this is it's second incarnation: I failed miserably at my first attempt to wire this up last year, but since have been able to educate myself on the electrical principles of how patch bays actually work and on soldering technique as well. Also, this time I decided to start with a fully non-normalled rig and to add that normalling/mult'ing kinda stuff later once I was sure that each point was done up right so as not to confuse routing problems with other issues and so forth.

So, I plugged it into all my gear yesterday to do the "big test", and to my amazement almost every single point functioned properly this time...very little mis-soldering or other problems. EXCEPT....

The rig seems to be giving of just a wee bit of overall "hum noise". It doesn't seem to matter which particular points are connected to my gear or how many points are plugged in at any given time. My speakers just issue this low-level hum noise if any portion of the bay is plugged in at all. The hum does not show up on any of my input monitoring meters, but I don't know if that's because it's elsewhere in the chain or simply because it's just too quiet to show up on the level meters. But I can hear it.

All my soldering work is ship-shape. Every contact has it's little insulating "bootie" on there, there are no accidental goopy solder blobs accidentally bridging contacts anywhere, or overlapping wires accidentally touching extra contacts. It's all super-clean work.

So, is this a common problem? Is there something simple I'm overlooking? Does it have something to do with grounding? Any insight would be appreciated!

Cheers,
Adam

[Paul.E]

Having worked on some ADC's in the past, I believe that everything should be grounded together with one big conductor from left to right, grounding onto the faceplate of your rackmount patchbay. You solder this conductor on every contact point across the 'modules' of the patch.

[NewOrleansSteve]

Hi Caldo,
Good to see you over here. I know where we usually hang has been temp. shut down!

Are you sure this is a ground related problem? While you did not saw so, It seems like that is a foregone conclusion.

Is your room / power always clean? That is have you maby had a small problem all along, and now, with the patchbay, it is compounded?

The patch bay - Is it ballanced or Unball.?

What about the gear conected to it - does it all go to the same A.C. leg ?

The only openion I can offer is thet the meter thing is that the livel IS too low to be seen.

Talk to you soon - Steve

[Caldo71]

Originally posted by Paul.E
Having worked on some ADC's in the past, I believe that everything should be grounded together with one big conductor from left to right, grounding onto the faceplate of your rackmount patchbay. You solder this conductor on every contact point across the 'modules' of the patch.

Yeah...I wondered about that...I've seen it done in pictures: one wire going from screwpost to screwpost all the way across. It's a quick fix so I'll try it.

Originally posted by NewOrleansSteve
Are you sure this is a ground related problem? While you did not saw so, It seems like that is a foregone conclusion.

Is your room / power always clean? That is have you maby had a small problem all along, and now, with the patchbay, it is compounded?

The patch bay - Is it ballanced or Unball.?

What about the gear conected to it - does it all go to the same A.C. leg ?

Steve! Glad to be here. I'm NOT sure it's a ground-related problem, but I'm fairly certain that it's not related to sloppy wiring on my part, so beyond that I'm open to suggestions. It's a balanced patch bay. All the gear in my rack is plugged into a quartet of "Juice Goose"-style power strips, and those in turn all end up connected to the same outlet coming out of my wall, which happens to be the only outlet in the whole house which is grounded (I grounded it myself).

Hope that helps...any more insights greatly appreciated in advance from either of you guys.

Steve: coming to TapeOpCon this year?

[claveslave]

One thing you might want to implement to avoid ground loops if you're not using the Star Grounding Protocol.
Choose either inputs or outputs to and from your gear as the connection to which you have the shield connected to ground. Do not use both. Decide whether you will ground the input/s or the output/s of all your equipment and maintain that exclusively without deviation and you will have a much cleaner, quieter and logical patching system.

BTW, hi to all you fellow maniacs

[Caldo71]

All good stuff guys.

I'm gonna end this thread here, though, because I also posted the question on the Geekslutz forum and got the problem pretty much solved between the two forums. That thread is here if you're into it:

http://www.gearslutz.com/board/showt...threadid=28453

Adam