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[Nathan Riddle]

Curious on you thoughts on two (3) different deployments. Each with their pro & con.

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Background:

Full contemporary band.

2x J7's
SM100 FF
10x TH118
DNA power

LED wall, Light rig, dLive, QLXD, etc.

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Previously discussed a bit here:
https://forums.prosoundweb.com/index.php/topic,163370.0.html

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For the J7's (assuming nominally stereo coverage for center area).


Ground Pros:
-Easier to deploy (I don't have the most skilled labor, everything requires a bit of my supervision).
-Easier to load out
-Venue suggested (they said ground-stacks were always best).

Flown pros:
-More even sound coverage

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I'm leaning towards ground stacked (on road cases, not subs) simply because it will be easier to setup for my lower experience crew.
And the benefits aren't super huge given the render and crowd elevation change.

PM me for a link to the direct files if you want to play with it yourself.

[Nathan Riddle]

I said 3 designs because of the sub arrays. But I'm fairly set on a delayed arc.

I don't think there's much debate on which sub deployment is best.

Plan is to use Merlijn's split audience phase alignment (not FOH) method.

Note: in none of these designs are the subs flown; only mains.

[Paul Johnson]

Ground stack usually isn't the best for coverage, but many venues just can't cope with flow rigs. I'm talking as a person who puts PAs into venues and also as somebody from a venue with visiting people.

When I get a rider that says we'd like to fly our line array if possible, if not we will ground stack, I usually say flying is not possible. This is actually a lie. We do have a couple of points  in the perfect position and they could hang a motor or chain hoist and put the things in the air. The snags are simply that because of the way the roof works, the pickup points are just below the ceiling - which isn't that high - about 6.5m. what they cannot do is go into the roofspace and drop down a line to pull a hook up. There are obstacles - so we have a permanent steel that has it's lowest point inaccessible from the roofspace. This means an A-frame ladder to get the hook onto the ring. It also means a stretch with the heavy chain to get it on. If they want a fore and aft pair of points that can be done, but even more tricky to attach to. It also means we need to do this for the visiting people. It is not fun to do. It's actually safe, risk assessable but just not a nice rig. A ground stack is perhaps in, up and wired in 20 minutes, probably less. Two hangs is at best an hour - on a good day. Even worse for the out. My crew of six has just two people who can do this, and they're also the people needed elsewhere.

From the visiting crew's perspective - it's also extra work they might not want to do, when the ground stack will do the job fine. Perhaps the flown rig would have been better, but is the extra time justified?

When I used to tour with a band, our old PA - an old EAW had flying hardware, although it wasn't a line array, but sometimes venues would offer flying, but as most of our toured to venues did not, we groundstacked automatically because the sound for the stalls was consistent. When we had a circle to cover too, we could do it with extra top boxes tilted up, or we'd take up an offer to tail into their system if they suggested it. We got a new system that could be flown properly - but we decided to carry on with the ground stacking. With covid, it never happened.

[Peter Morris]

If you are doing a reasonable size show, your FOH (except your subs) needs to be up high. This usually means flying.

I would suggest getting too close to a J7 is dangerous, so they need to be well above head height.  What can happen just above a large audience can have a dramatic effect on how things actually sound especially at the back of the audience.  This will not be shown in the SIM.

This explains a little bit of what I'm talking about.

 https://www.youtube.com/watch?v=yA3HrpZpA1M

[John Schalk]

This explains a little bit of what I'm talking about.

 https://www.youtube.com/watch?v=yA3HrpZpA1M

I was going to suggest watching that video by Dave Rat too.  He also has a series on subwoofer deployment and he isn't a fan of delayed arcs, so you might want to watch those videos as well.  Both of these topics are beyond my small system's capabilities, but I have been binge watching Dave's channel lately just to expand my understanding of these larger concepts. 

[Nathan Riddle]

If you are doing a reasonable size show, your FOH (except your subs) needs to be up high. This usually means flying.

I would suggest getting too close to a J7 is dangerous, so they need to be well above head height.  What can happen just above a large audience can have a dramatic effect on how things actually sound especially at the back of the audience.  This will not be shown in the SIM.

This explains a little bit of what I'm talking about.

 https://www.youtube.com/watch?v=yA3HrpZpA1M

I was going to suggest watching that video by Dave Rat too.  He also has a series on subwoofer deployment and he isn't a fan of delayed arcs, so you might want to watch those videos as well.  Both of these topics are beyond my small system's capabilities, but I have been binge watching Dave's channel lately just to expand my understanding of these larger concepts. 

Good points, I had watched much of Dave Rat's videos with enjoyment.

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Peter, I might not have portrayed the ground-stack well.
But they are elevated (in the render) 8ft above the pit floor, so 2.5ft or so above the crowd.
Attached photo - showing elevation.

Why wouldn't a SIM show heat/humidity issues with that calculation turned on?

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John, do you recall a video where Dave solves the subwoofer problem? I can't find one.

[Art Welter]

Peter, I might not have portrayed the ground-stack well.
But they are elevated (in the render) 8ft above the pit floor, so 2.5ft or so above the crowd.
Attached photo - showing elevation.

Why wouldn't a SIM show heat/humidity issues with that calculation turned on?

Nathan,

Your render shows a level variation at 4kHz of 21 dB ground stacked, 12 dB flown.

As you (should) know, above 1kHz a variation of 9-10 dB sounds twice as loud.
The flown cabinets (at whatever trim height you rendered) would have about half the variation in SPL as cabinets stacked only 2.5 feet above head level.
Using cabinets to their 140+dB potential at that low of a height would exceed NIOSH and even OSHA noise exposure limits by a large margin if you were within the dark red (+27dB) zone.
The 60+dB noise induced hearing loss at 4kHz I now “enjoy” is a very real consequence of exceeding noise exposure limits. The damage is irreparable.

A SIM is not designed to predict thermal gradients, which can re-direct high frequencies up, down, or sideways from a “direct” path- the difference in level could vary significantly, the ground stack variation from front to back suffering by “twice as much”.

Art

[Nathan Riddle]

Nathan,

1) Your render shows a level variation at 4kHz of 21 dB ground stacked, 12 dB flown.

2) As you (should) know, above 1kHz a variation of 9-10 dB sounds twice as loud.
3) The flown cabinets (at whatever trim height you rendered) would have about half the variation in SPL as cabinets stacked only 2.5 feet above head level.
4) Using cabinets to their 140+dB potential at that low of a height would exceed NIOSH and even OSHA noise exposure limits by a large margin if you were within the dark red (+27dB) zone.
5) The 60+dB noise induced hearing loss at 4kHz I now “enjoy” is a very real consequence of exceeding noise exposure limits. The damage is irreparable.

6) A SIM is not designed to predict thermal gradients, which can re-direct high frequencies up, down, or sideways from a “direct” path- the difference in level could vary significantly, the ground stack variation from front to back suffering by “twice as much”.

Art

Not to sound overly defensive....

1) A single frequency certainly looks bad, but turning probes on, shows a 16dB gradient (dBA) from front mic to rear mic ground stacked, and 9dB flown (worst case, this gets better away from the power alleys).
2) Quieter in the back is usually preferred for these types of shows.
3) Good point.
4) Just because J7 can get loud doesn't mean it will.
5) I have never run sound over NIOSH or OSHA (integrated) limits for anyone ever. Nor will I start now.
I do concede the point that if I was to run FOH at 100dBA Slow (A bit loud for me) (15m NIOSH) that the hottest part of the crowd would be 109dBA Slow (2m NIOSH).
6) Fair enough.

[John Schalk]

John, do you recall a video where Dave solves the subwoofer problem? I can't find one.

Not specifically, but you might try watching his video on Rat Sounds "super sub" at Cochella(sp?)  Dave built his own subs using Powersoft's M-force driver and he might talk about deployment in that video.  He's also got a hilarious video out there where he uses one of the test M-force drivers outside of a cabinet to demo some low frequency concepts.  He ends up trying to hold the driver down while it vibrates like crazy.

[Caleb Dueck]

I'm probably not much help, since our mindset back when I did live production was simple.  If the coverage was more even with flying - we would fly.  Rather than debate which method performed better - that was clear so our focus was how to quickly, safely rig whatever needed to be rigged. 

I vote go with the better (flown) option. 

[ProSoundWeb Community]