On September 23, 2018 at 12:39, buzz said...
We outfitted an outdoor restaurant with a SONOS based system. There was a sound stage about 70 feet from the dining area. Wiring was very difficult. We used a CONNECT to bring an audio feed from the stage to the dining area. Since there is a 70ms latency for Line-In, the alignment between direct and amplified audio was perfect. (This was not something that we discovered after the fact. It was designed in. As soon as we noted the 70 foot dimension, we rejoiced -- otherwise we could have had a nasty timing issue to deal with.)
Is the amplified audio, which plays away from the stage, AT ALL audible halfway to the stage, or worse yet, at the stage?
The audio signal going to the dining area is delayed by 70 msec. That matches perfectly with the physical delay of the sound from the stage to the dining area. Now let's say you stand directly in the middle between the two locations. The stage sound will be physically delayed by 35 msec; the dining sound's audio signal will be delayed by 70 msec and another 35 msec in the air, so at that point the dining signal will be 105 msec behind the stage signal. That should be very audible unless the dining area sound is much lower in volume than the stage sound.
As for speaker spacing, the reason that always should be considered is that if you have, say, a 20 msec tme difference between two zones that are 20 feet apart, the electronic delay will only be half of your delay.
This is why background music systems for large rooms use speakers that are not terribly far apart. Those systems are almost universally monaural,* and if you move around in the space, by the time you get from one speaker to another, the speaker you're closest to is enough louder than the next closest one that you hardly notice the delay.
*we recently had a client complain about a design for multiple speakers in a LARGE dining area, them saying "it's not even stereo"! In such a case you have to educate them about stereo not being worthwhile.