Group Delay/Phasing?

[Lee Lundgren]

I was setting up a alt. mix using the PQ yesterday. Using the L/R as a base mix, I was adding channels and groups that were a little soft. I've done this before fine. But yesterday I noticed a phasing issue when I added certain groups. My first thought was plugins, but all of the groups had plugins inserted, some more than others. I do have delay compensation turned on.

[Jeff W.]

Settings for Delay Compensation
The Options > Pickoffs page provides three settings for Delay Compensation:
Off, Mix Only, and Mix and Inserts.

-Off No Delay Compensation is applied.

-Mix Only VENUE automatically compensates for delays in-
curred by the use of Groups routed to the Mains busses.

-Mix and Inserts VENUE automatically compensates for delays incurred by the use of plug-ins as well as those incurred by the use of Groups routed to the Mains busses.

[dstagl]

Originally Posted by Lee Lundgren

I was setting up a alt. mix using the PQ yesterday. Using the L/R as a base mix, I was adding channels and groups that were a little soft. I've done this before fine. But yesterday I noticed a phasing issue when I added certain groups. My first thought was plugins, but all of the groups had plugins inserted, some more than others. I do have delay compensation turned on.

Here's my experience with PQ's when adding Groups to them. Whenever you route a Group to the L/R, there is latency in the routing of the Group's to the L/R. I think it's only a few samples. SO, when you have a Group feeding the L/R and you place both that Group AND the L/R in a Matrix or PQ, the Group in the L/R is late relative to just the Group. Unfortunately delay compensation doesn't currently account for this.

Dave

[Lee Lundgren]

Originally Posted by dstagl

SO, when you have a Group feeding the L/R and you place both that Group AND the L/R in a Matrix or PQ, the Group in the L/R is late relative to just the Group. Unfortunately delay compensation doesn't currently account for this.

That makes sense. Thanks Dave!

[Jason Stygar]

Originally Posted by dstagl

Here's my experience with PQ's when adding Groups to them. Whenever you route a Group to the L/R, there is latency in the routing of the Group's to the L/R. I think it's only a few samples. SO, when you have a Group feeding the L/R and you place both that Group AND the L/R in a Matrix or PQ, the Group in the L/R is late relative to just the Group. Unfortunately delay compensation doesn't currently account for this.

Dave

So then is this not corrected with the "alignment" channel?

[dstagl]

Originally Posted by Jason Stygar

So then is this not corrected with the "alignment" channel?

I've never had that work. An alignment channel can be used to align two groups with different plugin latency's to arrive at the L/R, but it doesn't seem to take care of this issue.

I think it's important to remember that the delay compensation in the console was a brand new thing 6 years ago when the platform launched to the public. Nobody was doing it. All the compensation was geared towards making the L/R work, and I think it does this very well. For a large portion of users I bet it's still more than adequate.

I know this particular issue bit me a long time ago since I'm mixing in a house of worship. With a dynamic range of a service in the 30-40 dB range, it's important to level different program types closer together in our PQ's and Matrix's that feed smaller areas like hallways, tape, control rooms, etc.

The solution presented to me by Robert Scovill probably 4-5 years ago was to feed the everything including the PA via a Matrix or PQ section. I use the L/R strictly for music and use a couple groups for additional programming busses like spoken word and playback elements. Those groups DO NOT feed into my L/R. Then I pull everything up in a matrix or PQ and feed whatever needs to be fed with a mix that works for that destination.

So in the room music is at or near concert level while spoken word is closer to conversation levels. In the feed to the PA, music is wide open and spoken word is down a bit. In the halls everything needs to be closer in perceived loudness so music is down and spoken word is wide open.

I have no phase problems with this, and I don't need crazy amounts of limiting and compression to make the smaller room mixes work. I also have flexibility to build program content specific mixes as needs arrive.

Dave