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[Michael Cordes]

A follow up to my how much SPL above crowd noise topic.

 My church is looking at replacing some 1970s vintage wall mounted 8 inch full range speakers in what we call the Fellowship hall. It is a multipurpose trapezoid shaped room ~65ft on the narrow end ~100 ft on the wide end and ~60 ft long. It has folding partition walls that can divide the room into 3 separate ~20x40ft meeting rooms. Ceiling height 9 feet, ceiling is concrete. The system will be used for meetings, announcements during dinners and possibly acoustic coffeehouse style events. Room capacity is 325 people.

A couple of years ago they asked for quotes for a sound system with out any real specifications and got back 3 quotes with different design approaches. I would like to come up with a design and write up a specification document so we can get new quotes all based on the same design specs. Your opinions on the 3 designs would be appreciated.
Basic information: We would like the three rooms to each be a zone that can be used independently when the room is divided and have the capability to use the three zones together when the room is open. I have a block diagram attached.
The three earlier quotes differed in the speaker choices and deployment.
Company A: specified 24 each 4 inch ceiling mounted Community brand spread throughout the room (no model number or actual placement info)
Company B: specified 10 each Electrovoice EVID 4.2 and 3 EVID 12.1 subwoofers (no specifics on placement)
Company C: specified 6 each Tannoy VX-8 speakers http://www.tannoypro.com/#!Page=Product&Id=121.397 mounted on the ceiling 2 in each room. I drew up this arrangement on the attached floor plan.
FYI when used for meetings the presenter will usually be on the East end of the room. We will be setting up a couple of A/V carts with small mixer, projector, Wireless mic, spot for laptop and appropriate input connections. The cart audio output will go to the wall jack input for the room.

[Scott Carneval]

Delays aren't usually necessary for a 40' room, but you have 9' ceilings so that may be why he spec'd them.  Unless your presenter is going to be speaking from the same position every time (according to your drawing, this would be on the right side of the floor plan) you should avoid wall mounted speakers.  For a multi-purpose room I will typically spec distributed ceiling speakers (or pendant, depending on the design of the ceiling).  4" speakers without subs is going to sound pretty thin, even for spoken word.  I would also address acoustic treatment of the concrete ceiling.  I would assume there's no means to cut a speaker into the ceiling, so pendants or another type of surface mount speaker would be necessary.  Depending on the processor, you should be able to use DSP presets to combine and separate the three rooms.  Most even can be triggered via contact closure, so you can use air-wall sensors to automatically combine the rooms when the walls are open. 

With a 9' ceiling height, I would expect at minimum of 8 speakers per room in a 2x4 configuration.  Most manufacturers have their own software to calculate coverage. 

[Jonathan Kok]

Delays aren't usually necessary for a 40' room, but you have 9' ceilings so that may be why he spec'd them.  Unless your presenter is going to be speaking from the same position every time (according to your drawing, this would be on the right side of the floor plan) you should avoid wall mounted speakers.  For a multi-purpose room I will typically spec distributed ceiling speakers (or pendant, depending on the design of the ceiling).  4" speakers without subs is going to sound pretty thin, even for spoken word.  I would also address acoustic treatment of the concrete ceiling.  I would assume there's no means to cut a speaker into the ceiling, so pendants or another type of surface mount speaker would be necessary.  Depending on the processor, you should be able to use DSP presets to combine and separate the three rooms.  Most even can be triggered via contact closure, so you can use air-wall sensors to automatically combine the rooms when the walls are open. 

With a 9' ceiling height, I would expect at minimum of 8 speakers per room in a 2x4 configuration.  Most manufacturers have their own software to calculate coverage. 

Not much to add, so...what he said.

[Michael Cordes]

Thanks Scott and Jonathan,

This must be a situation where the typical adage on posts here of fewer sources for less interaction does not apply as strictly as it does in the live band/stage performance world.

I too thought that 4 inch units would be thin sounding.

Speakers will have to be ceiling mounted on the surface.

More research on ceiling mounted options is next on the agenda.

Mike

[BenFranske]

What the others have said, in a room split/combine situation distributed ceiling speakers are about your only good option (which is one reason you see them in hotel ballrooms). You may end up needing to manufacture your own enclosures for typical ceiling speakers in order to make them surface mountable. It's probably not going to be the nicest looking thing, but with a concrete ceiling the aesthetics are probably less of a concern anyway.

I might look at a shallow depth full-range 70v ceiling speaker and then price out a metal shop making enclosures they could be mounted into. Alternatively, it would be better from an acoustical standpoint to put in an acoustical dropped ceiling (though I realize that would involve modifying room dividers, lighting, etc.)

I really, really, really like the QSC Q-SYS DSP systems, they are not the cheapest things, but they're really flexible, easy to work with, and have support for room combine/split and that can be controlled via an iPad/iPhone without any other control devices.

[Hal Bissinger/COMSYSTEC]

What the others have said, in a room split/combine situation distributed ceiling speakers are about your only good option (which is one reason you see them in hotel ballrooms). You may end up needing to manufacture your own enclosures for typical ceiling speakers in order to make them surface mountable. It's probably not going to be the nicest looking thing, but with a concrete ceiling the aesthetics are probably less of a concern anyway.

I might look at a shallow depth full-range 70v ceiling speaker and then price out a metal shop making enclosures they could be mounted into. Alternatively, it would be better from an acoustical standpoint to put in an acoustical dropped ceiling (though I realize that would involve modifying room dividers, lighting, etc.)

http://www.lowellmfg.com/tinymce/jscripts/tiny_mce/plugins/filemanager/files/2a-304_iMount_8inch_50W_rectangular_systems.pdf

http://www.lowellmfg.com/tinymce/jscripts/tiny_mce/plugins/filemanager/files/2a-301_iMount_12inch_150W_rectangular_systems.pdf

-Hal

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