OMNI Software Mixer Problem

[dwaynedelario]

I was mixing this morning and realized I was getting distortion on the left channel. Did cable swaps and the problem followed over to the right side. Then sent material to discrete Left and Right, and the problem only existed in the Left output. On a hunch, I disabled the Optical input in the software mixer by deactivating the MON buttons, and boom, the problem disappeared. Clicked it back on, and the problem came back.

I swapped optical adat cables, and the problem seems rectified. BUT...the troubling question is, why was the audio coming directly out of my ProTools session affected by the software mixer?

Here's my rig: Mac Pro Mid 2012 40GB RAM, HDX2, OMNI, Pro Tools HD 11.1.3, OS X 10.8.4 (with a co-install of PT HD 10.3.8 that I rarely use).

[dwaynedelario]

No one has any experience with software mixer problems? I feel like I took the red pill in the Pro Tools matrix. Distortion in the session clearly caused by having the optical input monitor open. Could clocking cause something like this?

[dwaynedelario]

OK well I thought I had solved this issue by replacing the optical cable that is routed into my OMNI. Nope. The distortion is back, and it only happens when I engage the Optical input in the software mixer. As I disengage it, I hear a quick beep.

What da hell is going on? Faulty OMNI?

[Bill Denton]

It could possibly be because there is no "software mixer" as the term is normally used.

Both the I/O setup and the mixing are done in Pro Tools...

[dwaynedelario]

Hey Bill. Thanks. Forgive me if I am missing the point, but I don't understand what you are suggesting? The signal that is being passed through the optical input of the OMNI is monitored through the hardware setup and the levels are set with software (a submixer within ProTools, if you will), then passed directly to the monitor path. Nothing being routed into the session via I/O.

But what's really peculiar about this situation is that I don't have any audio playing through it when I am mixing my sessions. I merely use it to audition sounds from the desktop/CoreAudio. I get distortion when the optical pathway is "open" to the monitors.

[Evil Jack]

Hi, i've had exactly the same issue with my OMNI.

I'm too busy to troubleshoot the stupid thing anymore, and I now mute my software mixer inputs (Optical S/PDIF) in the Hardware Setup menu when mixing off of PT (which does cure the left side distortion)

This is my second OMNI - the first was replaced under warranty after I discovered it had a fault with some of the analog outputs (1-8). AVID returned the unit exactly the same saying they couldn't find the fault, and it took my dealer to intervene to get a new one (he reproduced the fault easily).

I'm no longer under warranty, & not going through all that again, so I put up with the current issue.... Absolutely crap.

[dwaynedelario]

Evil Jack... THANK YOU for confirming this. I thought I was losing my mind. Just curious, what was the fault with your prior OMNI's outputs?

I am going to get my dealer on this. I have had this OMNI for a few years but this is not an acceptable fault.

[nst7]

Bill may not have been aware of the separate mixer function of the Omni.

[Evil Jack]

Originally Posted by dwaynedelario

Just curious, what was the fault with your prior OMNI's outputs?

Zero signal on analog outputs 5 & 8 (via the rear DB25 outputs). AVID couldn't reproduce

Then I got this new one and noticed the left side clipping last year while working on a solo piano album....like you, I thought I was going crazy!

Let me know how you get on and if it's a known fault....I may still chase it up...

[vieris]

I have setup 10 or so OMNI setups, all have this toslink problem coming from a mac pro host. It's like the toslink signal has an extreme dc offset or low frequency blasting away corrupting the monitoring path. Anyone find a solution?