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Author Topic: Subwoofer under platform extension  (Read 3730 times)

Aaron J. Percy

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Subwoofer under platform extension
« on: March 01, 2008, 05:18:38 PM »

Hello all,
  We are looking into placing a subwoofer enclosure under a wood framed platform.  The existing platform is concrete and the new extension will be wood frame with hardwood flooring and steps.  I am interested in how to go about treating the cavity that the speaker box will be in and how to vent the space under the platform into the room.  I do wish that I had another option for location, but this is it.  We are looking at the BagEnd D12E-DA or (as I would like) the L'Acoustics SB15P as it is matched to our main speakers.  Thanks for any help you might have.
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Peace,  Aaron

Ivan Beaver

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Re: Subwoofer under platform extension
« Reply #1 on: March 01, 2008, 11:28:32 PM »

Just build a box that is double wall sheetrock- glued, screwed and caulked with acoustic caulk, that is air tight all under the platform.  Top-back and sides.  You don't want any sound getting under the stage.

This chamber should not be much bigger than the sub itself and it would be  good idea to shove fiberglass around the sub (not in front).

Have the exit into the room the same size as the front of the cabinet.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Tom Young

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Re: Subwoofer under platform extension
« Reply #2 on: March 02, 2008, 06:52:14 AM »

Just to be clear: you also do not want the subwoofer and its outer sheetrock shell in contact with the wooden stage extension.

You should secure the subwoofer so it doesn't "walk" and end up touching something (coupling to the stage extension). The fiberglass will keep it secure from the sides and rear, but you way want to also put neoprene pads on the bottom, between the subs and the floor.

And the sheetrock shell needs to be very well braced (2x4's or 2x6"s).
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Aaron J. Percy

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Re: Subwoofer under platform extension
« Reply #3 on: March 02, 2008, 03:46:00 PM »

Tom and Ivan, Awesome, thanks for the help.  I will be talking with the builder soon to see if this will work.  The only hitch is that the entire front of the extension will be steps, four steps up to the platform.  I need to come up with an aesthetically pleasing way to "vent" the subwoofer into the room through the hardwood steps.  I am thinking about maybe some nice wood vent grilles like this... index.php/fa/14532/0/
What do ya think?
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Peace,  Aaron

Tom Young

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Re: Subwoofer under platform extension
« Reply #4 on: March 02, 2008, 04:27:28 PM »

I cannot think of anything that would look as good. But there may be a loading effect (on the sub drivers) that could occur with this wood slat grill treatment.

I think it is probably OK.

Lets see what Ivan (or anyone else that wants to chime in) says.

If this is to be installed at the rear of each step, I wonder if it could be inadvertently kicked in, over time ?

Another tried-and-true grill would be a sandwich of heavy gauge perforated metal (on back) covered in cloth.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Ivan Beaver

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Re: Subwoofer under platform extension
« Reply #5 on: March 02, 2008, 07:38:22 PM »

My biggest concern would be air turbulance and possible "whistling".  That would vary with level.

He would also need ot be sure the vents are securely fastened so they do not buzz.

Tom is correct in that you do not want any mechanical vibration transferred to the stage.

Another concern would be access to the sub for service with that setup.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Tom Young

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Re: Subwoofer under platform extension
« Reply #6 on: March 02, 2008, 08:47:07 PM »

And then there is the issue of balance between the subs and fullrange ldspkrs.

This project will take a considerable amount of work. Befor venturing down this road I would make sure that the folks nearest to the subs will not be severely effected by their close proximity. If so, you (OP) may need to rethink their location or add some near fill ldspkrs to rebalance the sound.

No one said live sound was gonna be easy..........
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Aaron J. Percy

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Re: Subwoofer under platform extension
« Reply #7 on: March 10, 2008, 02:17:44 PM »

Tom and Ivan, Thanks so much for your valuable input on this topic.  I have decided to fly the L-Acoustics unit above the main speaker.  This will simplify the whole thing.  Your input has been greatly appreciated.  Thanks
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Peace,  Aaron
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