Lab Subs

[TJ Cornish]

Re: Lab Subs

You are correct, I was thinking in "olden day" terms where the PA was aligned to the backline with a DDL on the mains outputs, not individual channels.

I made the same error on a thread in the other forum a few months ago. It's always good to sweep the moth balls out once in a while.

That said, the LabSub horn path requires front loaded mains to be delayed around 11 ms to be in sync, added to around 2 ms overall latency in most DSP =13 ms system delay from the get go.
Assuming 15ms time of flight from the back line to the front of the time aligned Labhorn/ front load PA, anything over 2 ms delay added to the backline results in it arriving behind the mains.
Actually, there is already around another 2 ms latency in the digital console, so adding almost any delay to a properly aligned Labsub PA would put it behind (assuming 15 ms time of flight from back line to mains PA front line).

Now on to Randy Pence's third question:

" delay monitors to combined PA? "

The LF omni back wash of delayed monitors would be less apparent (Haas effect) out front, but the performers may not appreciate the extra delay time.
At any rate, what we hear of the monitors (or back line) in the house is a combination of reflections (echoes) of various lengths from around the stage walls and ceilings, alignment of all those sources to the mains is impossible.

I agree on all counts. It's not possible to eye-ball delays based on distance anymore.

My current system consists of ITech HD amps with some amount of latency - 4ms I believe for the FIR presets I'm using, and some conventional amps driven by a DriveRack 260, which has a different delay time. As this rig is pretty new to me and I'm pretty green as a system tech, I've spent some shop time trying to better understand sticking the pieces together. Walking around my shop reveals just how important listening position is relative to what you're measuring, as well as how dominant the room's effect is on low frequencies.

 

[Tim McCulloch]

Re: Lab Subs

My current system consists of ITech HD amps with some amount of latency - 4ms I believe for the FIR presets I'm using, and some conventional amps driven by a DriveRack 260, which has a different delay time. As this rig is pretty new to me and I'm pretty green as a system tech, I've spent some shop time trying to better understand sticking the pieces together. Walking around my shop reveals just how important listening position is relative to what you're measuring, as well as how dominant the room's effect is on low frequencies.

TJ, this is great stuff. Really. The more you experiment & measure & listen the better you'll get, sooner.

 

[Matt Lillie]

Re: Lab Subs

Now on to Randy Pence's third question:

" delay monitors to combined PA? "

The LF omni back wash of delayed monitors would be less apparent (Haas effect) out front, but the performers may not appreciate the extra delay time.
At any rate, what we hear of the monitors (or back line) in the house is a combination of reflections (echoes) of various lengths from around the stage walls and ceilings, alignment of all those sources to the mains is impossible.

Very true. I spent a lot of time trying to accomplish this in a troublesome room. No go....