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[Kevin Maxwell]

Acoustic problem – Subwoofer cancellation in the Booth.

I worked with a sound company on an install of a newly built venue (nightclub/bar) that has live bands and also dance music (DJ). I don’t have the measurements of the venue. I am supposed to go there tomorrow and I plan on taking some measurements. The owner had it built with the (DJ/Live Mix) booth into the house right wall. I think it is about 30’ from the edge on the stage. It is partially sticking out into the room (maybe about 2 feet) so you can see the stage to your right. And it is about 2 to 3 feet above the dance floor. They didn’t listen when told not to build the Booth that way.

There are 4 powered subwoofers under the stage. The problem is the sound for the subs gets significantly reduced in the booth and it is most noticeable with what a DJ plays. In the room the bottom end is A LOT louder than in the Booth. I found that if I position myself in the back left corner on the Booth I can hear the subs much better. I think that corner is causing the cancellation in the Booth. One day when testing some of the setup in the room I stacked some boxes in that corner to see if would affect the sound but it didn’t seem to break up the cancellation. Also that corner is at the top of the stairs to the Booth so I can’t take up much room there. I was thinking of trying a Sono Tube stuffed with some insulation stuffed inside of it and placing that in the corner. They come in 4foot lengths and a bunch of different diameters. I just remembered while writing this that I have 2 - 2’x4’ (I think it is 2”thick) acoustic panels made from Fiberglass duct board that are framed and covered with speaker cloth. I am going to bring them tomorrow and play around with placement and see if that makes any difference.

I have worked with a very high end acoustic consulting firm on a couple of projects and someone there would probably know the answer to this problem. But they are VERY expensive and this Venue owner would never pay what they would charge. I just put in a call to an acoustic consultant that is probably more reasonably priced to see if he makes house calls. He is located not too far away from this place.

Does anyone with experience with thus kind of situation have any recommendations?

[John Roberts {JR}]

How about a microphone out in the room to monitor SPL? Feed that mic to a RTA.

Having less bass in the sound booth sounds like a possible benefit.

JR

[Tim McCulloch]

How about a microphone out in the room to monitor SPL? Feed that mic to a RTA.

Having less bass in the sound booth sounds like a possible benefit.

JR

Kevin's description is giving me a Marty McCann flashback, JR.  His tech note about subwoofer placement relative to boundary surfaces.

I'm thinking the protruding part of the booth, 2-3 feet above the floor, is creating a phase cancellation that is transmitted structurally into the booth, which also has its own resonance(s).

@Kevin - yeah, this is one of those "doc, it hurts when I do *this*" and doc says "then don't don that."  The correction for the problem the club owner created will be expensive.  Not correcting it will be expensive in subwoofer repair costs and neighbor complaints.  If the DJ can't FEEL the LF, he/she/they are gonna turn it up, guaranteed.

[John Roberts {JR}]

Kevin's description is giving me a Marty McCann flashback, JR.  His tech note about subwoofer placement relative to boundary surfaces.

I'm thinking the protruding part of the booth, 2-3 feet above the floor, is creating a phase cancellation that is transmitted structurally into the booth, which also has its own resonance(s).

@Kevin - yeah, this is one of those "doc, it hurts when I do *this*" and doc says "then don't don that."  The correction for the problem the club owner created will be expensive.  Not correcting it will be expensive in subwoofer repair costs and neighbor complaints.  If the DJ can't FEEL the LF, he/she/they are gonna turn it up, guaranteed.

Do they still make those bass seat shakers?  Maybe have the DJ sit on an extra sub facing up with a seat cover. [/joke]

JR

[Helge A Bentsen]

Put a sub in the booth?

[Caleb Dueck]

Kevin's description is giving me a Marty McCann flashback, JR.  His tech note about subwoofer placement relative to boundary surfaces.

I'm thinking the protruding part of the booth, 2-3 feet above the floor, is creating a phase cancellation that is transmitted structurally into the booth, which also has its own resonance(s).

This is my first thought as well, followed by horizontal pattern collapse due to the subs, I assume, being spaced horizontally under the stage.  This is a great example why going against audio recommendations to save money rarely saves money - and often costs a whole lot more to fix.  I've had this conversation with owners too many times.

[Rob Timmerman]

Do they still make those bass seat shakers?  Maybe have the DJ sit on an extra sub facing up with a seat cover. [/joke]

JR

As it sounds like the booth is elevated, bolting a shaker (the Buttkicker units are still available for sale and not especially expensive) to the booth floor might actually be a reasonable solution here.

[Paul G. OBrien]

The location of low frequency nodes (which includes cancellations nulls) indoors are a product of the sound wavelengths in question and the subwoofer and listening positions. One of those 3 has to change to affect the nulls, sound absorbing materials can dampen a buildup but that has no effect on a null.

[Dave Garoutte]

Our sound booth is the opposite; it's a big bass trap.

[Steve-White]

Put a sub in the booth?

Exactly what I was thinking.  Keep in simple, if the house sounds good and it's a booth issue, then make it a booth solution.

[ProSoundWeb Community]