Craig John Posted October 16, 2006 Share Posted October 16, 2006 I am considering some in-ceiling speakers with backboxes in a dropped, acoustical ceiling as the rear surround speakers in a 7.1 setup. I currently have RB-75's, RC-7 and RS-7's in a 5.1 setup. Would the CDT-5800-C be the best match for my speakers. They will be mounted in the ceiling about 6 ft. behind the LP. Second, I want to use the new backboxes, ME-800-C or (ME-650-C if I go with a 6.5" speaker.) (Actually, I *need* to use the backboxes as the ceiling tiles would not provide an adequate baffle for the speakers.) Are there any special mounting considerations with the backboxes on/in an acoustical ceiling tile? Can they just sit on top of the ceiling tile? Also, do you need an istallation kit, or does the backbox have the installation kit included? Thanks, Craig Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted October 16, 2006 Share Posted October 16, 2006 Craig, The CDT-5800-C should be fine and the one I would suggest. Let me know why you ask about a back box? Code in your area. The ME is a Fire Rated enclosure The ME boxes are designed to install between ceiling joists.The 800-C outside deminsions are 18 x 17.75, so that will not fit between a 24 inch by 24 inch tile. Let me know about why you need to ME box and I will get back to you in the morning Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted October 16, 2006 Share Posted October 16, 2006 The 800-C outside deminsions are 18 x 17.75, so that will not fit between a 24 inch by 24 inch tile. Well they are smaller than the grid. I mean, true- it won't lie exactly in the 24" grid of the suspended ceiling, but what's to stop you from installing it into a fire-rated tile, possibly reinforced with metal bars to bear the weight over to the track itself? M Quote Link to comment Share on other sites More sharing options...
Craig John Posted October 16, 2006 Author Share Posted October 16, 2006 Steve,The ceiling tiles are "acoustic" and absorb mid- and hi-freqiencies, but are transparent to bass. As such they would make poor quality baffles. Hence the need to "seal" them in an enclosure. Does placing them in a "sealed" enclosure change their FR?I am not looking to mount them to the framework of the ceiling, just lay the enclosure on top of the ceiling tile. The tiles are 1/2" thick, so the standard thickness of drywall. I have 6" of clearance to the overhead joists, so 5" of backbox plus 1/2" of celing tile leaves 1/2" of clearance. Assuming these speaker/backbox combo's are not ridiculously heavy, I'm thinking this should work. I just need to know if I need an "installation kit" to install the speakers, or if the backboxes come with the kits. Thanks. Craig Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted October 16, 2006 Share Posted October 16, 2006 It doesn't sound like you need a fire rated box per code. The box does include tile bridges, so it will be fine in that application. The fire box was designed to fit it small areas, studs for instance and to pass code for installation in plenum spaces. The in ceiling was designed for free air space, a box may tighten the bass, however, I have not had the chance to listen to one in this box. Suggestion, cut a piece of 1/2 plywood the size of the tile and lay it on top of the tile. I will offer better bass responce Vs. the tile alone. The tile may not support the CDT. You would not need an install kit. Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted October 16, 2006 Share Posted October 16, 2006 The 800-C outside deminsions are 18 x 17.75, so that will not fit between a 24 inch by 24 inch tile. Is this some new math? Looks like it would fit to me. you have 3 inches excess on all sides. Or am I missing something? I mean, true- it won't lie exactly in the 24" grid of the suspended ceiling, but what's to stop you from installing it into a fire-rated tile, possibly reinforced with metal bars to bear the weight over to the track itself? M I have not had my hands on one yet, no excuse, it does come with a tile bridge. I was concerened by the weight of the box plus the speaker and even with an 1 1/2 less on each side. Doesn't sound like much, but something I may not suggest, needs to sit in the grid, not just close. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted October 16, 2006 Share Posted October 16, 2006 good points Steve. I had some of another brand speaker (inferior to Klipsch) in the 2x4 ceiling tiles at my old gallery. I used strips of wood lath board across the tile (bridging the 2' dimension) to help support the speakers drywall clamps from punching through the fibreboard of the ceiling tiles. Then I placed an approximately 3' strip of 24" fibreglass batting over the installed speaker/tile to act as a sort of 'soft enclosure' and to keep the sound from travelling across the plenum space to neighboring rooms. This system was fairly easy and inexpensive to install and worked well. Michael Quote Link to comment Share on other sites More sharing options...
Craig John Posted October 16, 2006 Author Share Posted October 16, 2006 It doesn't sound like you need a back box per code. Correct, I *want/need* a backbox to seal the backwave from the frontwave, (because my ceiling tiles won't perform this task.) Are the backboxes *only* used for fire-retardation? I thought they helped with sound isolation also. What about improving SQ by reducing wall resonances? Finally, isn't a sealed box better than an infinite baffle, especially if the baffle size is limited? Suggestion, cut a piece of 1/2 plywood the size of the tile and lay it on top of the tile. I will offer better bass responce Vs. the tile alone. The tile may not support the CDT. You would not need an install kit. An "infinite" baffle design generally requires a baffle much larger than a 2' x 2' piece of plywood. To get the full extension of 49 Hz out of the CDT-5800-C, I would probably need a 70" or greater baffle in each direction. http://melhuish.org/audio/baffle.html Also, I'm concerned that adding a 1/2" of plywood will increase the installation "mounting depth". Will the speaker be able to be installed properly with the 1" from the grill cover to the the speaker, (1/2" of ceiling tile + 1/2" of plywood)? In addition, the extra 1/2" of mounting depth will use up all the overhead clearance I have, bringing the enclosure into contact with the overhead joists: not what I was hoping for in terms of sound isolation. You don't seem to think the backbox is a good idea. Why? Craig Quote Link to comment Share on other sites More sharing options...
Steve Phillips Posted October 16, 2006 Share Posted October 16, 2006 Sorry if my suggestions seemed to point away from using the fire box, you seem to be concerned about low end. The Fire box's sealed design would help tighten the lower end, but may limit the lowest frequencies. I am fully aware of the capabilities of this speaker in open air environments for which it was designed. The fire box will limit unwanted mids/lows in the ceiling area and from the floor above by about 10db. The box seems to be the best suggestion here. One thing I would suggest, set the 5800-C back surrounds to "small", it really does not need a full range signal. 50 watts nominal rating. Just a suggestion and an opinion. Check with an install or Reference dealer about purchasing the ME-800-C Quote Link to comment Share on other sites More sharing options...
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