Yet another sub array question

Mike Caldwell

Mike Caldwell

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Jan 13, 2011
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Let's say you have six matching double 18 sub woofers, limited DSP (at this time) and some shows coming up that the space, the stage and the general layout would allow for some form of sub array deployment. The general audience area will be about 150' wide and 300' deep. As of the now the set up time will allow for a little experimentation day of show, if it ever warms up around here I may even have time to do a prototype set up!
I've read the many post and articles on sub arrays and had limited success with a couple modeling programs. What's your thoughts, horizontal line with a couple of them reversed for cardioid, a stepped / curved horizontal line, two rows of three set up in an end fire configuration or one stack of three on each side of the stage and just let'em rip.
 
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Re: Yet another sub array question

If you can turn six matching double 18 sub woofers in to two stacks of three on each side of the stage (12 cabinets) you don't need any more advice ;^).
 
Re: Yet another sub array question

It all depends on how limited your limited DSP is.

Cardioid patterns give you the most 'loss', in the sense that they use a lot of boxes/amps/dsp to change the pattern without providing more volume for your audience. Cardioid can be very useful, although in a typical gig (by gig, i mean band on a stage, audience out front, very simple production) it only really serves to change the amount of sub energy onstage, which you may or may not care about in reality

Again, with delayed arc deployments, these serve to overcome the natural narrowing of coverage in the horizontal when you use broadside arrays. With a space thats 150' * 300', these might actually be quite desirable...
 
Re: Yet another sub array question

Mike Caldwell said:
Let's say you have six matching double 18 sub woofers, limited DSP (at this time) and some shows coming up that the space, the stage and the general layout would allow for some form of sub array deployment. The general audience area will be about 150' wide and 300' deep. As of the now the set up time will allow for a little experimentation day of show, if it ever warms up around here I may even have time to do a prototype set up!
I've read the many post and articles on sub arrays and had limited success with a couple modeling programs. What's your thoughts, horizontal line with a couple of them reversed for cardioid, a stepped / curved horizontal line, two rows of three set up in an end fire configuration or two stacks of three on each side of the stage and just let'em rip.
Click to expand...

You've touched on the fundamental choices and each has implications. I'll ask the questions first: indoors or out? SPL expectations and program material?

You can do a 3 box end-fire on each side of the stage - you get forward directivity - but it's still a dipole array so you'll have the usual power alley down the middle, flanked by a null lobe, all of which will vary depending on frequency. Likewise if you were to do 'reversed box, polarity flipped and delayed' cardioid array on each side. The benefit of either choice is that you put less LF behind the PA and somewhat less LF on the stage (frequency dependent). The old-skool "stack 'em up and let 'em rip" puts lots of LF on the stage and behind the PA with all the power alley issues.

A center cluster puts lots of LF on the deck. Lots of it. A delayed/stepped horizontal deployment tends to affect the horizontal coverage much more than it affects the front-to-back, so you still have the LF on the deck issue. One deployment I saw recently used a center clustered cardioid arrangement, 2 clusters in center and 1 more off-stage (each side) of the center cluster by about 6'. Total of 4, 3 box clusters. I wasn't on stage while it was in use so I can't comment on it was for the performers, but if you can model that it might be a possibility.

An endfire array, 2 wide/3 deep on one side of the stage might be useful.

Ultimately I think it depends on the program material and SPL expectations. You're covering 45,000 sqft. That's not a small area.
 
Re: Yet another sub array question

Have a backup plan. I pulled into a big festival in SC. The production company had been setting up for an entire week. The system tech proudly walked me through his complex sub arrangement.

Sound check for the headliner started. After the first song he said it was too much sub, turn them off. Not turn them down, not any discussion of compromise, just turn them off.

Sent from my DROID RAZR HD
 
Re: Yet another sub array question

Tim McCulloch said:
You've touched on the fundamental choices and each has implications. I'll ask the questions first: indoors or out? SPL expectations and program material?
Click to expand...

They would be outdoor shows, program material is light rock, the bulk of the audience will in the 150 X 150 area, anyone further back are there to socialize. At the 100 foot mark about a 100db will be fine.
I was leaning towards the two rows of three end fire or the physically stepped horizontal line.
 
Re: Yet another sub array question

At an outdoor event event before Christmas I had good success with left and right cardioid stacks; each with 3 double 12's - the middle cabinet on each stack reversed. Each stack was aimed about 40 degrees away from centre to reduce interference and power alley a little, and to point the null's at the stage. Sub filtering was already set beforehand, and alignment (delay/gain) took about 10 mins on site with SysTune. Sub energy on stage was close to zero.
 
Re: Yet another sub array question

Michael Smithers said:
At an outdoor event event before Christmas I had good success with left and right cardioid stacks; each with 3 double 12's - the middle cabinet on each stack reversed. Each stack was aimed about 40 degrees away from centre to reduce interference and power alley a little, and to point the null's at the stage. Sub filtering was already set beforehand, and alignment (delay/gain) took about 10 mins on site with SysTune. Sub energy on stage was close to zero.
Click to expand...

I think since this can be done with 2 DSP channels it might be the easiest with minimal processing power. It is also the smallest footprint.

I have done stacks of both 2 and 3 this way very successfully. It is my usual small rig array method.

Sent from my DROID RAZR HD
 
Re: Yet another sub array question

Jay Barracato said:
I think since this can be done with 2 DSP channels it might be the easiest with minimal processing power. It is also the smallest footprint.

I have done stacks of both 2 and 3 this way very successfully. It is my usual small rig array method.

Sent from my DROID RAZR HD
Click to expand...

+1

Regards,

Merlijn
 
Re: Yet another sub array question

It depends on what is most important to you-SPL out front or rear rejection.

Can you provide enough SPL out front with less subs? If so-then a directional array might be a good idea.

But if you need all the subs for SPL, then a directional array is not for you-since a directional array will not produce the same SPL as if the same number of cabinets all facing forward.
 
Re: Yet another sub array question

Mike Caldwell said:
They would be outdoor shows, program material is light rock, the bulk of the audience will in the 150 X 150 area, anyone further back are there to socialize. At the 100 foot mark about a 100db will be fine.
I was leaning towards the two rows of three end fire or the physically stepped horizontal line.
Click to expand...
A statement like "100dB" really does not say much.

It needs a lot more to have it make any sense. Are we talking A or C weighting? Slow or fast or peak response.

There can be as much as a 30 dB difference with the same material-depending on how it is measured (parameters of the SPL measurement system) or "expected" to perform.

The extremes would be A weighted slow (for the lowest SPL numbers) and C weighted peak or impulse (for the highest SPL numbers).
 
Re: Yet another sub array question

Mike Caldwell said:
When I use my meter for my own reference Db(C) slow is what I normally set it on.

I know I'll lose some SPL with the cardioid set up, that's why at first I was thinking about the other options.

I'm starting to think a warm weather sub array test day will be in order.
Click to expand...
That is exactly what happens on so many questions. YOU know what scale and response time you are looking for-but unless it is stated-nobody else does.

Some people use A standard and others use fast. No bitching-but that is why details ARE important.
 
Re: Yet another sub array question

Chris Johnson said:
Again, with delayed arc deployments, these serve to overcome the natural narrowing of coverage in the horizontal when you use broadside arrays. With a space thats 150' * 300', these might actually be quite desirable...
Click to expand...

I agree totally with the broadside array as they work well, however in this situation six boxes might not be enough to electrically arc and cancel. 3 High cardioid per side would be my first option.
 
Re: Yet another sub array question

Mike Caldwell said:
I know I'll lose some SPL with the cardioid set up, that's why at first I was thinking about the other options.
Click to expand...

Mike, you will lose SPL with any directive subwoofer setup versus a broadside array. You're going from a flat faced array of six subwoofers that all couple and increase directivity, to only 2/3 or less than number facing forwards and coupling. When we did testing on this very subject with three subwoofers outdoors on a tennis court we found approximately the same (although over different frequency ranges) 2-3dB forward energy loss with both "cardioid" and "end fire" arrays.
 
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