low output with XLR to TRS cables

[craigmorris74]

I've tried to use XLR to TRS cables to go from both my N72 and A12 to my patchbay and other 1/4" line interfaces, and in all situations, the signal is unusually weak. When I use and XLR cable with a XLR to 1/4" unblanced adapter I get "normal gain levels.

Any thoughts on this issue?

PS-I've tried both homemade and Mogami XLR to TRS cables.

Craig

[tpryan]

Check your cables first. Make sure they're shielded twisted pair, wired as follows:

XLR ---> cable ---> TRS:
pin 1 --> Shield --> S
pin 2 --> Hot -----> T
pin 3 --> Cold ----> R

XLR ---> cable ---> TS:
pin 1 --> Shield --> NC
pin 2 --> Hot -----> T
pin 3 --> Cold ----> S

Transformer coupled outputs are the easiest to interface. If you're losing level, it's almost certainly a problem with the patchbay or "other 1/4 line interface". Keep in mind that if you connect a TRS cable to a TS input, something needs to connect the R to the S to complete the circuit. Otherwise, you'll just hear a weak, thin output, if you hear anything at all. It sounds like whatever you're plugging your TRS cables into isn't making this connection. It works with your adapter, since that cable most likely connects XLR pins 1 and 3.

[craigmorris74]

Hmm. I've tried plugging them into the balanced patchbay and the line inputs of my computer audio interface with the same results, so it sounds like the problem is with the cables. I've used TRS cables with both the patchbay and interface before with no problems. I'll check my cable wiring and report back.

[tpryan]

What is the interface? Are you sure it has balanced line inputs?

[craigmorris74]

It's the line inputs of a M-Audio Omni I/O.

[tpryan]

Do you mean the OmniStudio USB? Which inputs are you using?

[craigmorris74]

No, this is the Omni (discontinued) that plugs into the Delta 44 or 66. I'm using line inputs 3 and 4 on the rear of the unit.

[tpryan]

So you're saying that with known-good XLR -> TRS cables connected directly to the OMNI you get very low output, but with an XLR -> TS adapter cable you get normal output?

[craigmorris74]

Yes. Just double checked my cables, and they're wired as you posted before. The setup that works is an XLR cable with a XLR to 1/4" TS adapter plug.

[tpryan]

In that case, I suspect the inputs aren't really balanced, or there's something wrong with the IO box.

[craigmorris74]

The interface works with the balanced outs of a Joe Meek 3q and a Bellari 110mp. The N72 worked with a UA 2192 converter thoughh. Very confusing.

[tpryan]

Neither of those boxes has a transformer balanced output, I'm sure. I suspect that the "Ring" contact of the line inputs isn't doing what it should, either by accident or by design. Describe your symptoms to M-Audio and see what they say.