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Ceiling Speakers - Back box or not?


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I noticed some speakers don't use back boxes and instead use the ceiling cavity, while others use a back box. However, I've noticed that the back boxes are pretty small which makes me wonder if that means it hinders it's performance (not the actual optimal size for the driver). Cavity sizes can vary which might also hinder their performance if a back box isn't used (possibly too big). Is it a lose lose scenario compared to traditional speakers where volume is carefully calculated?
 
I'm wondering if it is possible to custom build proper size boxes that can be mounted in the ceiling? Has anyone ever heard of people doing this before? If so, would just a normal driver be used instead of one called a 'ceiling' speaker? This is a custom build commercial space so there should be plenty of room above the ceiling height in our situation.
 
 
What do traditional back boxes do for:

Efficiency
Frequency response
Control
 
 
Regards,
Midget
 
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midget…this is something have researched quite a bit …in my explorations of retrofitting some atmos speakers to my existing setup….

 

my conclusions ….back boxes as americans call them…. are really just there to keep out the dust, moisture…the thing plastic... tin… screw on enclosures most supposed "sealed back" ceiling speakers come with can't provide more than that given the tiny size of them…they aren't anything remotely resembling conventional speaker enclosures or anything.

 

ceiling speakers used without back boxes work as "infinite baffle speakers" where theory goes the front baffle separating the front waves from the back is infinite infinite….sealed boxes are also called infinite baffle because the front is separated from the rear :)

 

ceiling cavaties I would suggest are too large to effectively impact in any ways with respect as speaker enclosure. i.e. they equate quite closely to a free air type installation.

 

main effect is the cushion of air behind the driver in the sealed enclosure acting as a compliance that needs to be overcome vs the non compliant free air installation.

 

its probably hard to suggest much in way of effects as with sealed depends on the size of the box…which modelling would tell the effects vs free air and for both would need all driver parameters :)

 

I would suspect …due to lack of compliance in the free air installation (I've used many speakers like this in car audio setups) is lower efficiency, better control, lower frequency response with the sealed installation…i.e. where box is small enough to start impacting :)

 

depends what hoping to achieve in the in ceiling setup…in my case its not breaking the integrity of the room and pumping sound through the ceiling space between floors taking sound all the way through the house. this is where a proper back box will help

 

what to be careful about is not using one physically hard coupled to structures…otherwise sound and vibrations will transfer to some extent through those. there are things such as "whisper clips" etc can buy to get around those if going for a whole solid enclosure that need to affix.

 

I myself I think will be going for a "flexible back box" they do exists but are expensive…however remove the need to pull the whole sealing to install 4 or so speakers for atmos through the ceiling space.

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There is nothing to stop soffit (flush) mounting of 'real' speakers provided they are not rear ported. Eliminating diffraction and reflections by soffit mounting as well as removing the sound of cabinet resonances, is a huge boost to perceived fidelity, which is why many professional studios mount speakers this way in walls.

 

Surround or atmos speakers are not normally required to produce heavy bass, which is fortunate as one of the purposes of an enclosure is to control cone excursion either by constraining the air behind the cone as in a sealed system, or by resonance where the tuning port / passive radiator produces the volume displacement of low frequencies at resonance, and the cone hardly moves at resonance in bass reflex designs.

 

I found that most ceiling speakers made for home theatre worked quite well just pushed up into the bulk insulation above, which also serves to stop debit falling on the cone and causing noises and buzzes.

 

One reason for back boxes is sound isolation with incoming (e.g rain on an iron roof) or outgoing (e.g. to bedrooms on a floor above). A sealed enclosure has the effect of causing bass tip-up or peaking, before an earlier and steeper rolloff, and this needs to be taken care of in the design. Dynamat make some excellent pliable back boxes out of lossy polymer material to deal with both problems, and from the drivers perspective appear to be larger cavities than the volume of constrained air in the enclosure. http://www.dynamat.com/architectural-home/architectural-home-dynabox/

 

The Dynaudio IC and IP ranges of in ceiling/wall speakers are truly excellent when installed and powered well. http://www.dynaudio.com/home-audio/installation/

Edited by Guest
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There is nothing to stop soffit (flush) mounting of 'real' speakers provided they are not rear ported. Eliminating diffraction and reflections by soffit mounting as well as removing the sound of cabinet resonances, is a huge boost to perceived fidelity, which is why many professional studios mount speakers this way in walls.

 

Surround or atmos speakers are not normally required to produce heavy bass, which is fortunate as one of the purposes of an enclosure is to control cone excursion either by constraining the air behind the cone as in a sealed system, or by resonance where the tuning port / passive radiator produces the volume displacement of low frequencies at resonance, and the cone hardly moves at resonance in bass reflex designs.

 

I found that most ceiling speakers made for home theatre worked quite well just pushed up into the bulk insulation above, which also serves to stop debit falling on the cone and causing noises and buzzes.

 

One reason for back boxes is sound isolation with incoming (e.g rain on an iron roof) or outgoing (e.g. to bedrooms on a floor above). A sealed enclosure has the effect of causing bass tip-up or peaking, before an earlier and steeper rolloff, and this needs to be taken care of in the design. Dynamat make some excellent pliable back boxes out of lossy polymer material to deal with both problems, and from the drivers perspective appear to be larger cavities than the volume of constrained air in the enclosure. http://www.dynamat.com/architectural-home/architectural-home-dynabox/

 

The Dynaudio IC and IP ranges of in ceiling/wall speakers are truly excellent when installed and powered well. http://www.dynaudio.com/home-audio/installation/

 

the dynabox flexible back box is the one I was talking about...its extremely well made and as illustrated in various videos around on the web quite effective in use. unfortunately EXTREMELY expensive in australia...and thread have started in the us to discuss them have also shown that even they regard as a very expensive way to go. still for retrofitting quite ideal. just have to find a way to source even at the 50% less US price and without the exorbitant shipping cost for each ! 

 

with atmos all the installer feed back I have (both online and in person) has suggested in my kind of situation where ceiling space separates living areas ....the use of a back box is an essential...and not necessarily the rubbish plastic/tin affairs most makers supply m talking proper back boxes :)

 

plenty of makers do supply full in ceiling speakers with cabinets etc...but cost is ridiculous as well...almost better off just using a conventional forward ported or sealed stand mount mounted into the ceiling ...the only tricky bit if figuring out how to do that without them literally sticking out like dogs b@@LLS :lol:

 

the mk sound ceiling speakers I recently heard thought well off..but there are  other brands have come across that are excellent too in the B&W, focal, monitor audio and would have no hesitation in suggesting. when get around to it finally will stick with focal though for consistency with the other speakers in my setup.

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 better off just using a conventional forward ported or sealed stand mount mounted into the ceiling ...the only tricky bit if figuring out how to do that without them literally sticking out like dogs b@@LLS :lol:

 

 

I have made speaker flanges from steel angle with mitre cut corners welded together and then powder coated in a suitable colour. The flange slips like a collar around the bookshelf speaker and then the whole assembly flush mounts into a cutout in the ceiling or wall, with a suitable gasket for sealing. It is very effective both for mounting and for noise ingress and egress.

 

 

the mk sound ceiling speakers I recently heard thought well off..but there are  other brands have come across that are excellent too in the B&W, focal, monitor audio and would have no hesitation in suggesting. when get around to it finally will stick with focal though for consistency with the other speakers in my setup.

 

The aforementioned Danish manufactured IC and IP series speakers are vastly superior to the likes of "branded" products made in low cost countries mentioned above, IMHO (and I have installed / heard pretty well all of them).

 

In one installation of IP24s in a ceiling in a cafe and driven with a big Bryston, we almost caused a riot in the street when we cranked it for the first time as everyone came running to hear the system. You couldn't get the grin off the audiophile cafe owner's face for weeks!

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Haha, I don't think we will be using Brystons. Was thinking of the Sonos Amp's for each zone so 55w a channel class D. I hope it's relaxing enough.

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  • 5 years later...

Reviving an old thread, this was discussed in

 

So looking at making on back box myself to enclose some Focal 300ICW6 ceiling speakers.

I don't want the box to be too big so looking at a pretty tight enclosure.

 

I need the inside to be at least 26cm wide.

To minimise the overall size (as it impacts speaking placement on the ceiling), I was thinking of using 19mm yellow tongue particulate board  covered with 6mm fibre cement sheet.

All glued and sealed together with Green Glue Noise Proofing Sealant / Compound.

 

Would you think I will need to use acoustic foam on top? This would add an extra 50mm on each side, I'd prefer to get away with it. I'm hoping the cement sheet will do the job.

 

I'll then have this box placed over the ceiling speaker and glued to the plasterboard.

 

 

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I found the plasterboard to be the weakest link and made a total box with cutout hole for the speaker. (19mm yellow tongue leftovers)

I made the box volume to the speakers specs for sealed enclosure ensuring the width fitted perfectly between two ceiling joists.

Then I glued the box to the plasterboard and joists using plasterboard acrylic (no green glue at the time) and screwed it as well from the sides.

This gave a good solid mount for the speaker as well.

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5 hours ago, LogicprObe said:

 

I found the plasterboard to be the weakest link and made a total box with cutout hole for the speaker. (19mm yellow tongue leftovers)

I have trouble picturing how you you make the speaker come out of the plasterboard then.

5 hours ago, LogicprObe said:

I made the box volume to the speakers specs for sealed enclosure ensuring the width fitted perfectly between two ceiling joists.

Where did you get those?

The speakers I got are Focal ceiling speakers, they don't even recommend the use of a back box. So I'm going blind on what dimensions would be most suitable.

 

5 hours ago, LogicprObe said:

Then I glued the box to the plasterboard and joists using plasterboard acrylic (no green glue at the time) and screwed it as well from the sides.

This gave a good solid mount for the speaker as well.

so your speaker is slightly recessed in the ceiling and is only attached to the box?

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15 minutes ago, jya said:

So I'm going blind on what dimensions would be most suitable.

for my focals the dynamat dynabox worked extremely well. can use them for dimensions..

 

 they are rubber walled but use a combination of dynamat(noise deadener (kind of like lead, to line walls and back and have acoustic foam laminated to it. works extremely well, once assembled its like a very tough acoustically dead speaker cabinet. Can see basic construction for ideas from page below, 

 

  https://www.dynamat.com/products/dynabox/?tab=home

 

and pdf below has dimensions spelt out, 

 

https://dynamat.com/wp-content/uploads/2021/02/2044-Dynabox-Sell-Sheet-Web.pdf

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