Cardioid sub array wih dual driver subs - does orientation matter?

T

TJ Cornish

Graduate
Jan 13, 2011
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St. Paul, MN
I'm looking at the new Fulcrum TS215 subs:
http://www.fulcrum-acoustic.com/wordpress/wp-content/uploads/2012/05/Prod-Spec-TS215-v4.pdf

These are attractive to me because they're small, light, and still go pretty low. In addition, they're pretty short, which offers some interesting options.

I've spent a lot of time in various sims this past week, and it seems like cardioid center-clustered subs are pretty hard to beat for pattern evenness (I'm aware of the tradeoff at the crossover point if the subs aren't under the mains). I'm trying to figure out a sub model that I can manage and also deploy with the usual stage configurations I use:

Situation 1: - 12" - 18" stage, no front access required.
Situation 2: - 30" stage front access required via steps,

For situation 1, laying 3 of the TS215 subs side by side across the front of the stage with the middle one facing backwards seems to be a good fit physically - the subs are only 17.5" tall.

For situation 2, standing 3 of the TS215 subs on end with the middle one facing backwards gives me room to put stairs fairly close to the center of the stage, as the width of 3 TS215s is only 53" wide, meaning the stairs are only 27" off the center line of the stage.

My question is how do these subs with their different shape and dual 15" drivers differ from the standard subwoofer model available in Ray-End, which seems to be a single 18" sub. Is there anything else I'm missing here? If the subs are laying next to each other, does the width of the array detrimentally affect the cardioid behavior in a way other than changing the amount of delay required?

It seems like this could work out fairly well for me if the result could be made fairly similar to what the simulator shows.

Thanks!
 
Re: Cardioid sub array wih dual driver subs - does orientation matter?

TJ Cornish said:
My question is how do these subs with their different shape and dual 15" drivers differ from the standard subwoofer model available in Ray-End, which seems to be a single 18" sub. Is there anything else I'm missing here? If the subs are laying next to each other, does the width of the array detrimentally affect the cardioid behavior in a way other than changing the amount of delay required?

It seems like this could work out fairly well for me if the result could be made fairly similar to what the simulator shows.

Thanks!
Click to expand...

The shape of the boxes doesn't matter, they're bass reflex cabinets. Pretty much an omni-directional thing (that's why you're implementing a cardioid array ;-) ). With the numbers of boxes you're using length of the array will have little affect. Think about what you said in your other thread about line arrays and pattern control. Beware things like walls that may make the "environment" different for forward/backward boxes.
 
Hey TJ,

There are really two answers here.

The short one is that these subs will work perfectly fine. As with any directional setup I highly recommend measuring to determine timing.

The long answer is that subs aren't really omni, and their group delay doesn't always make sense, and you probably can't predict actual acoustic origin... And Ray End doesn't account for that anyway. Which doesn't matter if you get an idea if what you're doing in prediction and then measure to actually set it up. For arrays of this size especially the error in most prediction is meaningless.
 
Re: Cardioid sub array wih dual driver subs - does orientation matter?

Bennett Prescott said:
Hey TJ,

There are really two answers here.

The short one is that these subs will work perfectly fine. As with any directional setup I highly recommend measuring to determine timing.

The long answer is that subs aren't really omni, and their group delay doesn't always make sense, and you probably can't predict actual acoustic origin... And Ray End doesn't account for that anyway. Which doesn't matter if you get an idea if what you're doing in prediction and then measure to actually set it up. For arrays of this size especially the error in most prediction is meaningless.
Click to expand...
If using the same model subs (using different ones would really start to make it hard), it doesn't matter where the acoustic origin is (front middle back etc)-because it will be the same in all cabinets-so the spacing would still be valid.

HOWEVER I do FULLY agree that measurement is the best way to get to the final result. As you change spacing and/or delay-the effective coverage/rejection will change.

AS will anything else that is nearby and changes the reflection path (walls-stages etc). What happens outdoors does not always translate to inside.

As usual-it depends.
 
Re: Cardioid sub array wih dual driver subs - does orientation matter?

Thanks all for the info. I'm aware at least in general of the impact of walls at sub frequencies. I haven't played with the boundary function in Ray-End yet - I'll make a point to do that. I'm glad to know the general shape of these subs isn't a problem.
 
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