Cardioid Subs in a Smaller venue.

Re: Cardioid Subs in a Smaller venue.

Jay Barracato said:
This seems to support what I amtrying to say as well, but I am also trying to add that I believe the physical bulk of the speaker box allows you to position them closer together without coupling.
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It should have the same effect as just moving them farther apart would, it's not a tremendous effect. The whole goal here is to have the two woofers interact, a meaningful boundary would detract from that and make the pattern less, not more, regular. There is always going to be a frequency at which there is maximum forward addition, and below which there is a (1st order?) rolloff, and that frequency is set by driver spacing. With a reasonable LPF it is totally possible to get subs close enough that it appears they are just canceling, however if you would remove that low pass you would see the same behavior you're trying to get just pushed an octave or two higher than you'd like it to be.
 
Re: Cardioid Subs in a Smaller venue.

Jay Barracato said:
This is the point I have been trying to make. In order to have wave cancellation, you must have two separate waves. Where the drivers couple, only one wave is formed. If one of the two drivers is out of polarity, most of the energy is not converted into wave form, i.e. the driver does no or little work on the air. I am using WORK in the physics meaning.
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I am not quite sure I follow your thinking all the way, but if you want to place the drivers facing the same way and aligned on the same plane, the original concept that I assumed I was answering no to, the factor that makes that proposition a no go is not the ability or not to make waves, but the lack of physical distance along the axis perpendicular to the plane they are aligned on. You simply lose the mechanism that enables the directionality, the distance/delay=speed of sound thingie that govern all of this. You would still produce soundwaves and you would have cancelling, and equal rear and front cancelling, not what you'd want. Add some delay to the inverted, and you get cancelling at some frequencies and addition at other, but still nothing you can use for any constructive purpose that I can think off. Since the close proximity of the cones will mean that the opposing actions of the cones will reduce the air load that the elements see, the response, excursion etc. will change, but the membranes will still produce the sonics.
 
I know this is old but .... a question :-)
I have 4 JBL 4645C's (single 18's built mainly for cinema installs) to go under a 15m wide stage for a dance concert in a venu of about 350. The wooden stage is about 20m wide and the 4 subs live under a stage with about 6" of clearance on a concrete floor covered in very thin lino. The 2 FOH sides consist of 2 Evsx300's at about 15' up on wall mounts with another 4 at the venue rear, plus 4 monitors set at the same height as FOH for stage left and right (rear and front) monitoring back to the performers (particularly for heavy tap dance numbers). I've got a centre fill channel for FOH as well to fill a hole centre stage in the first few rows. Under the stage are 6 mic's to pick up tap dancing live which are gated to stop the sub output bleeding through. The cast are a variety of performers including some excellent tap dancers who need the monitors turned up - they all use a mix of recored music for ballet/tap/jazz numbers.
I have various DSP incl dbx venue 360 and PA+ and carvers.
So I can pretty much set up any array I choose.
front row is only about 3m or so from the front stage so I have to be careful how much sound I push.
So last year I deloyed the JBL's as 2 front (together and centre) + 2 rear exactly behind(the 2 rear subs were front facing).
set around 60Hz with 180 degree shift plus the delay for the cone-to cone distance around 1.2m (from memory)
Question - I have the options to place the subs anywhere under the stage in any config I choose.
So do any or you have suggestions based on your experiences.
Eg I could go 4 straight across the front and put up with the rear bass on stage for better punch (not that I actually need more power out front).
Other options include centre cluster 3 + 1 rear facing ; centre cluster 2 + 2 rear facing ; 2 pods of 2 each side - 1 behind the other at 135 degrees facing out ; or use 2 pods and add 2 more in the centre.
Hope that's enough info for some thoughts - Of course I could try all of the above myself but i'm not certain I have the time or energy to move those big boxes around that much !!!
 
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