Patchbay - balanced/unbalanced?

[DarkSky Media]

Originally Posted by vowel

I have a small home studio with some nice gear.
I have a patchbay which I have set up.
I have a mixture of balanced and unbalanced gear which I have plugged into the back. The patch cables are balanced (I think) and it is all connected to an MBox 2 pro and I can't hear any problems.
Am I being naive or should I being doing something else to optimize my setup.
Impedances, resistance and the like confuse me - so do you think I'm ok if I can't hear any noise/problems?

The choice between balanced and unbalanced connection methods (eg grounded or floated -ve) is not just a question of impedance or resistance, but is dictated by circuit topologies.

In general, gear that has transformer balanced outputs needs to have the -ve grounded and/or the screen floated, whereas gear that has active (op-amp driven) balanced outputs generally needs a floated -ve when going to unbal. That's regardless of the question of level matching (eg you may also need to pad 10dB or more to bring a +4dBu signal down within the headroom limits of most -10dBv unbal inputs).

Conversely, when going from unbal to bal it's usually okay to connect the input -ve to the shield (but you may need a line driver to step up the levels and match the impedance to drive a +4dBu low impedance input).

It's not only a question of noise or other obvious/audible issues - although that's certainly a concern. Active balanced outputs don't generally like to be grounded on one side (pulls the power rails down as well as generating a fair bit of heat in the circuit/chips). So you should really check the documentation for each unit to see how it should be wired into your particular setup.

If you're correct that the patch bay is balanced, then you should probably look at anywhere you are patching into gear that has unbalanced inputs, to make sure that the output stage of the gear that will be patched in is compliant with the way you have it wired (which is probably defaulting to -ve to ground at present).

[mijome07]

I have a balanced 'bay and use, guess what? Unbalanced gear. No problem(s).

[Silent Sound]

Originally Posted by vowel

so do you think I'm ok if I can't hear any noise/problems?

Yes. If you can't hear any noise or problems, then you either don't have a problem, or you have other problems that are big enough to mask these particular problems. Either way, if it ain't broke, don't fix it. Save your money. Almost all audio circuits are unbalanced one you get inside the device. It's typically just the input and outputs that are balanced, and that's mainly to help with the problems associated with long cable runs. But if you don't have a problem, then you don't have a problem.

[DarkSky Media]

Originally Posted by mijome07

I have a balanced 'bay and use, guess what? Unbalanced gear. No problem(s).

Correct. If all your gear is unbalanced, then the fact that the patch bay will support balanced connections becomes irrelevant because you don't have any.

It's only when connecting balanced gear to unbalanced gear or vice versa that some issues (mentioned above) can arise.

[vowel]

thanks for all the info....
if I pick up the finer details over time it might be good to re-read dark-sky's answer.
I might even understand it one day.
Will leave it for now, thanks.

[drBill]

As a person who has rebuilt, revamped, redone, and reconfigured more patchbays for myself than I care to think about, my advice is to do it right from the first time out of the gate. Spend the money once instead of constantly "upgrading". I only wish there was someone out there to give me this advice 20 years ago.

Balanced.
TT ONLY, no TRS.
Elco rear 90 pin if at all possible. (This will future proof you to mars and back.)

Anything else is a compromise that will end up getting revamped if you plan on staying in the studio "biz" for any length of time.

My $.02. Take it for what it's worth....

[Steffmo]

I totally agree with Dr. Bill...although I would add that the DSub24 are a perfectly viable alternative to the Elco. Its also a lot easier to get off the shelf wiring for the DSub, even if you only use a prewired DSub to fan.

The thing is, once you bite the bullet and start with TTs you are in the game and moving forward. Every other option leads to...."I wish I had TTs".

[drBill]

Originally Posted by Steffmo

I totally agree with Dr. Bill...although I would add that the DSub24 are a perfectly viable alternative to the Elco. Its also a lot easier to get off the shelf wiring for the DSub, even if you only use a prewired DSub to fan.

The thing is, once you bite the bullet and start with TTs you are in the game and moving forward. Every other option leads to...."I wish I had TTs".

For a lot (maybe most) DB25's are cool and a logical choice. I just had a nagging feeling that if I didn't go ALL they way with Elcos, I'd end up regretting it - yet again - and be doing the whole thing all over for the 5th or 6th time. Also, I like being able to securely (better than Dsubs IMO) tie down 24 lines in seconds with no screwdrivers involved behind racks. (I'm using 24pair mogami into 90 pin Male to male Elco interconnects. Other than that, if you don't mind 8 channels at a time and a screwdriver, Dsubs are a great alternative.

The other thing I'd bring up is in regards to futureproofing and NEVER having to rebuild. If you want this, you should have a Female gender of whatever M to Male connector interface cables you are using (Elco, Dsub, whatever) at the rear of EVERY rack. This female connector should have short (18"-3') tails to XLR's which are telescoped and balanced. THEN, you can have a short XLR to whatever to terminate directly to your particular piece of gear. You can go unbalanced, telescoped, shield tied, untied, etc. at the short cable from XLR to unit. This makes unbalanced, balanced gear swaps a breeze with no re-soldering or connecter-izing. I can literally reconfigure my entire studio - location and wiring in a few hours instead of a couple of weeks. Incredible peace of mind for me.

For what it's worth.... $.02