DV array size proportional to LF response?

[Chris Greco]

I was talking to a buddy of mine the other day and he told me of an experience he had that made me do a double take and I wanted to put it out there to see if this could be true.

He was on a festival type multi stage summer outdoor show with a 16 box flown DV rig, 8 tops 2 subs per side. During the day they were running kids bands with a substantially smaller audience which was close to the stage. So they ran the rig 4 bottom boxes only to minimize the coverage area to the near field area. At some point during the day another event on the fairgrounds needed additional boxes so they dropped the array and removed 4 from each side, adjusted the angle, turned on the top (only boxes now) and continued on. He claims that the low frequency response of the 4 box array was much less than that of the 8 box array with only 4 boxes on? Is it possible that the physical size of an 8 box flown array with only 4 boxes on would exhibit that kind of LF behavior? ???

I have to give him the benefit of the doubt as far as the obvious stuff but yea it was a festival and quite possibly they were serving festival juice, but I doubt they were setting a bad example for the kids and partaking early on during the kids shows...

Right?

 

[Ivan Beaver]

Re: DV array size proportional to LF response?

I was talking to a buddy of mine the other day and he told me of an experience he had that made me do a double take and I wanted to put it out there to see if this could be true.

He was on a festival type multi stage summer outdoor show with a 16 box flown DV rig, 8 tops 2 subs per side. During the day they were running kids bands with a substantially smaller audience which was close to the stage. So they ran the rig 4 bottom boxes only to minimize the coverage area to the near field area. At some point during the day another event on the fairgrounds needed additional boxes so they dropped the array and removed 4 from each side, adjusted the angle, turned on the top (only boxes now) and continued on. He claims that the low frequency response of the 4 box array was much less than that of the 8 box array with only 4 boxes on? Is it possible that the physical size of an 8 box flown array with only 4 boxes on would exhibit that kind of LF behavior? ???

I have to give him the benefit of the doubt as far as the obvious stuff but yea it was a festival and quite possibly they were serving festival juice, but I doubt they were setting a bad example for the kids and partaking early on during the kids shows...

Right?

The additional boxes were probably working as a boundary to the other boxes-basically directing the energy towards the audience instead of letting it "spew" out into the sky.

The whole "boundary addition" worked centuries ago and still works today.

Some cabinet designs make better use of the "free sound" from this than others.

It is not so much in the higher freq in which the reflections become an issue-but it really does work on the low freq side of things.

 

[Bennett Prescott]

Re: DV array size proportional to LF response?

The additional boxes were probably working as a boundary to the other boxes-basically directing the energy towards the audience instead of letting it "spew" out into the sky.

This would be my guess, but it also makes a huge difference how the "extra" four boxes in the array were turned off. Were they unplugged, was the processor muted, were the amps turned down? Are you sure they didn't just mute mids/highs and leave the lows running? When they re-hung the PA, did they use the same angles as before? It could be there was less HF aimed at FOH so the perception was more LF.

 

[Chris Greco]

Re: DV array size proportional to LF response?

This would be my guess, but it also makes a huge difference how the "extra" four boxes in the array were turned off. Were they unplugged, was the processor muted, were the amps turned down? Are you sure they didn't just mute mids/highs and leave the lows running? When they re-hung the PA, did they use the same angles as before? It could be there was less HF aimed at FOH so the perception was more LF.

Not actually being there, I thought its a possibility that the other 4 boxes were not completly off. But the guy who was telling me about it is pretty trustworthy and a pretty hardcore technoid so I trust his judgement, although now being armed with Ivans info and also other information I recieved via email it seems like it indeed is a possibility. The degree of increase LF gained by this technique obviously far outweighs its useability in our industry otherwise I think we would be seeing alot more of it in commercially avail pro speaker systems.

 

[Ivan Beaver]

Re: DV array size proportional to LF response?

The degree of increase LF gained by this technique obviously far outweighs its useability in our industry otherwise I think we would be seeing alot more of it in commercially avail pro speaker systems.

I disagree-for most manufacturers

It is in no way in the manufacturers best interest (of selling cabinets) to have simple things that would reduce the number of cabinets sold.

To most manufacturers it is all about selling more boxes (the main reason they don't make high efficiency cabinets), NOT providing a good solution to the customer in a sonic and cost effective manner.

The general attitude is "If they want it louder-then they will buy more boxes". NOT how about if we give them louder better sound for less space and less money. THat does not apply to all products however.

 

[Rob Timmerman]

Re: DV array size proportional to LF response?

I disagree-for most manufacturers

It is in no way in the manufacturers best interest (of selling cabinets) to have simple things that would reduce the number of cabinets sold.

To most manufacturers it is all about selling more boxes (the main reason they don't make high efficiency cabinets), NOT providing a good solution to the customer in a sonic and cost effective manner.

The general attitude is "If they want it louder-then they will buy more boxes". NOT how about if we give them louder better sound for less space and less money. THat does not apply to all products however.

I thought that manufacturers were in the business of making money by selling customers products that the customer wants. Note that for loudspeaker companies, this does not always mean selling more boxes.
Customers typically care about many things when they are buying loudspeakers. Among those things are scalability, box size and weight, price point, and how it fits into the customer's business model. Physics dictates that there are output and efficiency tradeoffs for smaller, lighter, more scalable boxes, and customers vote with their wallets. Obviously, things are a bit different between the install and portable worlds, as the customers have different requirements.

To the OP, there are some manufacturers that make LF only line array elements for use in improving array directivity and pushing the near field transition to a lower frequency. There are also come manufacturers that allow subs to integrate into line array hangs for similar reasons. Both of these approaches can get you some "free" LF output out of the array.