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Sub placement under stage behind stairs

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Blake Ross:
Hi, we're looking for some help finding a place for our subs on or around the church stage and I'm hoping others out there have some thoughts for us. The church has been upgrading its sound system to support its growing musical theatre ministry. We recently bought a pair each of Yorkville U15's and USC1's. The U15's will be flown, but we're having trouble finding a home for the subs. The 19.25 inch wide subs would fit under the stage, but the stage has 3 seven inch steps attached, so the center clustered subs would be baffled by the risers and any vertical supports needed.
The stage space is at a premium with a choir loft, organ pit and pulpit competing for space in a 40' wide area. The subs need to be placed so they will not interfere with the actors which only leaves under or above.

Is the understage/behind the stairs a viable option for us, or should we be looking elsewhere in the church for placement? The USc1 is not designed to be flown, but it could be rigged for sidewall placement. The subs would then be up and out of the way on one of the laminate beams. This would mean less design and carpentry, but we give up the benefits of having the subs center clustered.

We would appreciate your ideas on the pros and cons of placing them under-stage, or any other placement you think we should look at. Thanks!

Tom Young:
Provided the architectural/structural elements in front of the under-stage subs do not represent a whole lot of acoustic obstruction, you should be fine.

Ideally you would build a solid "closet" for the subs to help contain some of the diffracted energy so it does not as freely enter and bounce around in the understage and eventually find its way out the front (and therefore is mislaigned with the direct energy).

Be sure that the stage floor is fairly substantial (no pun....) in its construction. Subs beneath a flimsy floor can cause vibrations which are mechanically transferred through the mic stands and on into the mic's. Perhaps worse would be if the subs are in physical contact with the stage, or its support structure.

One more suggestion:  if you play the system loud, the subs will "walk" (move around) over time. You can prevent this by placing neoprene pad material below them (between them and the floor).


Blake Ross:
Thanks Tom, I hadn't given any thought to containing the sound using a 'closet' for the subs - great idea, as is the neoprene mat underneath to help keep the subs at home. I don't foresee the system being played loud enough for sub movement but I've certainly been wrong before...
Should a sub closet be built pretty tight to the subs (2 inches clearance all around?) or is more clearance than that a better idea? I'm envisioning 1/2 inch plywood glued together in a box, screwed down to the floor with the front open for the grills and enough of a hole at the rear to feed in a speaker cable.
Please let me know if this is what you had in mind, thanks!

George S Dougherty:
Tight to the subs is fine, leave yourself room to maneuver and drag them out if necessary.  The ideal is for them to be airtight to the stairs and room so the pressure isn't being lost behind the subs under the stage.  

Blake Ross:
Thanks George and Tom. Getting these subs out of the way under the stage will be a huge help for us.


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