I'm thinking about upgrading my surround system to Atmos so have a need for in-ceiling speakers. In my search I came across these:
https://www.crutchfield.com/S-bYgFC...c2IpAbYCHpZzlSha3oc8dEza696tvhZYaAhdoEALw_wcB
This got me to thinking... these use a single full range driver shoved in a can which seems doable with a 3d printer and a few hours in Fusion 360. Can anyone think why this wouldn't be a good idea? If this isn't a completely dumb idea what drivers should make my short list? I think my starting qualifier would be that they have to get loud enough to be used at reference volume without notable distortion.
https://www.crutchfield.com/S-bYgFC...c2IpAbYCHpZzlSha3oc8dEza696tvhZYaAhdoEALw_wcB
This got me to thinking... these use a single full range driver shoved in a can which seems doable with a 3d printer and a few hours in Fusion 360. Can anyone think why this wouldn't be a good idea? If this isn't a completely dumb idea what drivers should make my short list? I think my starting qualifier would be that they have to get loud enough to be used at reference volume without notable distortion.
It really comes down to how you will actually use the speakers. You're not going to get 100 Hz at reference levels from a 2 inch driver. But plenty of companies sell very small satellite speakers that people happily use.
https://www.soundandvision.com/content/which-ceiling-speaker-should-i-use-dolby-atmos
"They additionally recommend using “conventional overhead speakers with wide dispersion characteristics.” How wide is wide enough? About 45 degrees from the reference axis over the audio band from 100 Hz to 10 kHz, according to Dolby."
. . .
"Since Atmos soundtracks consist of audio objects that can be positioned anywhere in a 3D soundfield, Dolby additionally recommends using overhead speakers that match the timbre, frequency response, and power-handling capabilities of the main speakers."
https://www.soundandvision.com/content/which-ceiling-speaker-should-i-use-dolby-atmos
"They additionally recommend using “conventional overhead speakers with wide dispersion characteristics.” How wide is wide enough? About 45 degrees from the reference axis over the audio band from 100 Hz to 10 kHz, according to Dolby."
. . .
"Since Atmos soundtracks consist of audio objects that can be positioned anywhere in a 3D soundfield, Dolby additionally recommends using overhead speakers that match the timbre, frequency response, and power-handling capabilities of the main speakers."
Definitely not limited to 2 inch drivers.... the speakers I linked were just an example...
I stand no chance of matching timbre with my mains as they are going to be K-402 based MEH's using TAD-4002 CDs.
I stand no chance of matching timbre with my mains as they are going to be K-402 based MEH's using TAD-4002 CDs.
I wouldn't even worry about matching the drivers too much, once the amp is done with it's eq they will sound close enough if they are decent speakers.
It would be good if you could angle the speakers towards the listening position, though, rather than straight down at the floor (not sure what you're planning on doing). I think it would work based on how big the cylinder is and how much bass/power you need from the speaker. What is your idea of reference level and how far will they be? If it's 75db with 95db peaks it would be much easier than 85db and 105db peaks
It would be good if you could angle the speakers towards the listening position, though, rather than straight down at the floor (not sure what you're planning on doing). I think it would work based on how big the cylinder is and how much bass/power you need from the speaker. What is your idea of reference level and how far will they be? If it's 75db with 95db peaks it would be much easier than 85db and 105db peaks
i did a few experiment with how 3d printed stuff "sounds" resonance wise (tho no speakers so far, but i was thinking about something bluetooth speaker wise... or some small wideband driver cases) .... and imo for speaker cabinets it mainly comes down to what filament you use and specially how much infill / supports / wall thickness which will decide how it will sound
if you print something flimsy, dont expect it to sound good but if you use a fairly well design even PLA can do fine
im pretty sure wood infused PLA will have its own tone to it
if you print something flimsy, dont expect it to sound good but if you use a fairly well design even PLA can do fine
im pretty sure wood infused PLA will have its own tone to it
And rightfully so….don’t concern yourself with timbre matching…..IMO and IMe that’s a meaningless requisite.
But you do need wide dispersion from 100hz to 10k for object based audio to work and placement is important……this requires a two way with a dedicated tweeter to get +/- 45 degrees up to 10khz. Wanna explore your 3D skills?……get a pair of KEF Q150’s and harvest the drivers and crossovers…..use those in sealed enclosures for you in ceiling speakers.
To get full-spectum half-space/near-hemispherical dispersion I'd suggest bouncing small fullrange soundwave off of a convex surface. Like my PrimeRadiants without the 15" woofer. (Say SB65 or Mark Audio "50" sized.)
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I still haven't done my 'reading up' about Dolby Atmos, but I think there is sort-of two kinds. One is a proper true full room arrangement,
and the another is a limited situation using 'toy soundbars' and a simple rear pair. Is this correct?
Also, is there some kind standard that is used for 'Auto EQ' with 'certified' Dolby Atmos AV amplifiers?
How much less expensive and low-fi are you wanting to go? There are plenty of small car co-ax's on the market that are cheap.
There are the SB Acoustics 4, 5, and 6 inch co-ax's that are pretty good, but require a crossover. They provide guidance on that too though.
https://www.madisoundspeakerstore.com/coaxial/sb-acoustics-sb12pfcr25-4-coax-4-coaxial-4-ohms-round/
https://www.madisoundspeakerstore.com/pdf/SBAcoustic_PFC_Coaxial_Crossover_Designs.pdf
There are the SB Acoustics 4, 5, and 6 inch co-ax's that are pretty good, but require a crossover. They provide guidance on that too though.
https://www.madisoundspeakerstore.com/coaxial/sb-acoustics-sb12pfcr25-4-coax-4-coaxial-4-ohms-round/
https://www.madisoundspeakerstore.com/pdf/SBAcoustic_PFC_Coaxial_Crossover_Designs.pdf
It looks like these ones are on sale.
https://www.madisoundspeakerstore.c...cr25-4-coax-6-paper-cone-coaxial-4-ohm-round/
Any reason you can see not to get one and test? How much better are Kef's coaxial for this intended purpose? We are talking about sound effects and not critical listening...
https://www.madisoundspeakerstore.c...cr25-4-coax-6-paper-cone-coaxial-4-ohm-round/
Any reason you can see not to get one and test? How much better are Kef's coaxial for this intended purpose? We are talking about sound effects and not critical listening...
I have the SB12PFCR25-4. With some EQ it sounds pretty good even way off axis, but as you hinted, I'm using it for music where it's more critical that the balance be correct, and I'm touchy about upper midrange prominence. For what you're doing, any of the SB co-ax's would likely be fine without EQ.
The KEFs are a more refined design overall. Their modern co-ax's have been on a steady progression through multiple revisions and lots of commercial production for over a decade. They tend to have smoother/more consistent off-axis behavior than most other co-ax designs, but again this is mostly an audiophile issue. KEFs will typically have less distortion also, but the SB's aren't bad in this regard - just not as good as the KEFs. The distortion rise on the SBs is the fairly common increase you see at lower frequencies and higher levels - and this is something I measured, not something I heard.
The KEFs are a more refined design overall. Their modern co-ax's have been on a steady progression through multiple revisions and lots of commercial production for over a decade. They tend to have smoother/more consistent off-axis behavior than most other co-ax designs, but again this is mostly an audiophile issue. KEFs will typically have less distortion also, but the SB's aren't bad in this regard - just not as good as the KEFs. The distortion rise on the SBs is the fairly common increase you see at lower frequencies and higher levels - and this is something I measured, not something I heard.
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Roger that. Thanks for the advice BTW! I'm going to order one to test with. This will give me an opportunity to try and design a 3d printed enclosure for a speaker that can be filled with plaster of Paris augmented with PVA glue. This apparently deadens the ringing plaster can have? I need to look into what ratio of PVA glue to plaster should be used. I heard about it here...
That would be a good budget choice for you. The off axis response at 20 degrees is great for Atmos with the on axis response having a nice null at 7k which means for humans who use 7-9k for height location, the speaker won’t be obvious.
Some progress modeling the enclosure before the speaker arrives. I'm thinking I'll run to the hardware store and pick up an old work ceiling box for inspiration on how to model the mounting system to the drywall ceiling.
I may not bother with the plaster of paris for this enclosure after all... seems a bit much for a speaker that's going to be enclosed in a ceiling? Maybe I'll just use thick walls with plenty of infill... line the box with dynamat and the acoustic stuff they sell at Parts Express.. a little polyfil... call it a day?
As you can see I'm thinking I'll externally mount the crossover.
Thoughts?
I may not bother with the plaster of paris for this enclosure after all... seems a bit much for a speaker that's going to be enclosed in a ceiling? Maybe I'll just use thick walls with plenty of infill... line the box with dynamat and the acoustic stuff they sell at Parts Express.. a little polyfil... call it a day?
As you can see I'm thinking I'll externally mount the crossover.
Thoughts?
Attachments
No enclosure is also an option. Many in-wall speakers run infinite baffle. Excursion can get out of hand at low frequencies, but if you are running an active crossover on them that should take care of that. Of course more sound can bleed through to adjacent rooms with this approach as well. If you just want to protect the speakers from insulation and dust, you could use something like these:
https://www.crutchfield.com/p_696B0...aker-Baffles-Regular-3-1-4-depth.html?tp=2809
On the printed enclosure, there are many ways to do it. It mostly comes down to what you want to do, how inert and stiff you want it to be, what you like to work with, etc. The cylindrical shape should help stiffness. A spherical or at least rounded end might improve things as well, though something spherical is also harder to cover with Dynamat.
https://www.crutchfield.com/p_696B0...aker-Baffles-Regular-3-1-4-depth.html?tp=2809
On the printed enclosure, there are many ways to do it. It mostly comes down to what you want to do, how inert and stiff you want it to be, what you like to work with, etc. The cylindrical shape should help stiffness. A spherical or at least rounded end might improve things as well, though something spherical is also harder to cover with Dynamat.
Gee, but don’t those take some of us back to our late ‘90s car audio tweaking days.
I'd recommend printing a few enclosures and testing if you have time and filament.
I haven't tried filling with plaster, but I have experimented with a few different approaches.
I did not think thick walls with higher infill did much to improve quality.
For me, the best option ended up being to design an enclosure that will minimize resonance with a thinner wall, and if needed, line it with MLV, or coat it with anything that will harden and stiffen it up a bit.
For example, I have a speaker enclosure behind me that is cylinder shaped with 6mm walls, enough wall loops to be solid (and infill 100% just for any wide spots around edges), I think an 8mm baffle behind the driver and enough along the edge to flush mount. I can't remember how thick the rear baffle is, probably either 6mm or 8mm.
There is this video where different infill percentages were used... seems 100% infill is not the way to go. I've decided to move forward with the plaster/pva after all. My biggest concern now is how to design the drywall attachment mechanism. I have not had time to go pick up a ceiling box from the hardware store yet. Will keep you all posted as I get further...