? Installing speakers in suspended ceiling

[zxcvbob]

Next project at the little church I goto will be installing ceiling speakers in the nursery and basement.  The ceilings are 2x4' grid acoustic tiles.  Will those safely support the weight of a two pound 8" round speaker?  Even if it is safe, will they sag and look like crap?  I could probably mount the speakers in the middle of 1x2' pieces of white 1/2" plywood and put them at one end of a grid, then cut the corresponding ceiling tiles down to 3'.  I also saw something called a "tile bridge" for about $8, Is that what I need?

It's an 8 foot ceiling.  How do I figure out how many watts I need and how far apart to space the speakers?  (just one in the 8x10' nursery, and I know that one will need a wall-mounted volume control.)  We have an unused 100W PA amplifier already, and it has a 70V output as well as 4, 8, and 16 ohm, so I'm planning to use 70V so I can run smaller wires and can add and remove speakers easily.  Do these speakers look OK?  http://avguy.com/atlas-gd87w.htm  There's another speaker that's cheaper, but I dunno if the frequency response is hifi enough (there's a word you don't hear anymore) http://avguy.com/atlas-sd72w.htm

And I'm looking for some 20/2 unshielded twisted pair wire to use, probably thermostat cable.  I think it needs to be CL2P or CL3 or CMP rated since it will be run in the space above a ceiling...

I'm talking to myself as much as I am to you guys; trying to collect my thoughts.  But I'd appreciate any advice y'all have.  Thanks.

[TechMan]

If the drop ceiling is being used for a return plenum then you will have to get plenum rated cable.  If you are not sure then it is better to be safe than sorry.

As for the rest of the questions, I work with some guys that are sound system designers and I will ask them tomorrow.

[zxcvbob]

The space is not being used as an air return, but I think I want to use plenum-rated cable anyway unless the cost is totally ridiculous.

It'll be a month or two before I start on this because I spent a couple of hundred dollars last month adding phone lines and Internet service, and a stage monitor to the sound system; we don't really *need* the ceiling speakers yet, but when I start on 'em I want to know what I'm doing.  Thanks.

[Brad Johnson]

Yes, the panels will sag.

For a nursery a single 8" speaker is puh-lenty.

For the basement are you wanting to play lots of louder music (background type stuff) or will it be mostly spoken stuff with the occasional song?  If it's the latter one speaker for every 200 sq ft should be more than enough.  Amp needs will be determined by the number of speakers (or number of speakers determined by the ability of the amp you already have).

You will want a speaker support.  Mounting the speaker directly to the panel will eventually cause the panel to bow out and fall.  You can make your own with a couple pieces of light angle or channel scrap metal (you can use 1x3 boards turned on edge in a pinch).  Simply cut the length to match the width of the panel and drill holes for the speaker mounting screws. Or you could save yourself the hassle and get a couple of the $8 ceiling bridges.

They used the bridges when they redid our office last year.  IIRC the brand was Qualm or Quam.

*edit to add* Google Fu still works.  It's Quam.  Part number SSB2.

*edited to also add* I don't recall 70v being all that sensitive to cable type.  IIRC cheapo zip cord should work fine, but someone with a better (or clearer) memory please correct me here.

Brad

[TechMan]

Zxcvbob,
One of the guys here says that you definitely the tile bridge for all your speakers.  He seconds the 1 speaker the the nursery.  He says that your first speaker link is good, but you should get a back can with each speaker as well.  You should start out with 1 watt per speaker.  How big are the rest of the rooms?

[sanglant]

just an idea, you could run cable from the real ceiling. and have it supporting most of the weight. i'm thinking something like this to tighten it. oh and a volume control next to the light switch can be handy.

[Bogie]

Get thee over to the tech talk forum at www.partsexpress.com, and start asking... They'll know. And they'll tell you how to do it better and cheaper at the same time.

[geronimotwo]

if you can't find a tile bridge, you could use a plywood backing for all or part of the tile supporting the speaker.  this may give better sound as well.

[zxcvbob]

Thanks.  I think the main room is about 20x50' with an 8' ceiling.  It's all one room, with movable partitions that go almost from floor to ceiling, but for big events when we would most need the speakers the partitions would be folded up.  I don't need to be able to get high volume levels, but I want speech and a little music to be easily intelligible, including to old folks with hearing aids.  I'm not sure if there needs to be a volume control for the main room or not (I don't think so, but it might be a nice touch.)  The nursery definitely needs a wall-mounted volume control that goes ll the way to zero. 

One good thing about using 70V (or 25V or 100V) is that I don't have to have all the speakers at once.  I can put in just two or three at first and figure out the coverage from that.

It's tempting to try 6.5" car speakers with added-on 70V transformers, but then I would have nonstandard stuff to cause headaches for the next guy after I'm gone.

[sanglant]

the car speakers, really aren't that odd. just 2-4 ohm instead of 8-16. wire them up serial and you can get a 8-16 load. and you can get 4ohm power amps for this. (oh that's just an example, i have no idea how bad that one is. )


edit: just something to consider. you can put in wall jacks and use speaker cabs or stage monitors.(that way you can move them when the partitions are moved) and you would be able to get much more volume and better sound when you wanted it. a nice set of jbl's and well you get the idea. i know for a fact these sound great. i have heard a few good bands using them live.

[Brad Johnson]

I don't need to be able to get high volume levels, but I want speech and a little music to be easily intelligible, including to old folks with hearing aids. 

Hate to tell you but that last one is a losing battle.  Ain't gonna happen.  You'll never be able to get them the proper sound quality or quantity until you allow them to control their own volume.  Best thing to do is get some kind of inexpensive wireless assitive listening device. A simple headset.  I understand some of the new ones have bluetooth-compatible devices that looks like an over-the-ear hearing aid.  The transmitters plug into the amp's auxiliary or monitor out.

Brad

[zxcvbob]

Hate to tell you but that last one is a losing battle.  Ain't gonna happen.  You'll never be able to get them the proper sound quality or quantity until you allow them to control their own volume.  Best thing to do is get some kind of inexpensive wireless assitive listening device. A simple headset.  I understand some of the new ones have bluetooth-compatible devices that looks like an over-the-ear hearing aid.  The transmitters plug into the amp's auxiliary or monitor out.

I like that.  Since most of the church is over 60, I might move that ahead of the speakers on the priority list.  I still want the ceiling speakers for special events overflow and for the nursery, but bluetooth headsets would help on normal Sunday services.