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Best DIY speaker type (and radiation pattern) for listening to podcasts and audio books in a large room?

Any chance you would 3D print it instead of CNC? For a shape like this I feel like using wood is doing it the hard way. I have seen a few projects that 3D printed a shell in parts, then filled the shell with concrete or plaster to achieve a similar or greater density vs wood.

Of course if you went to 3D printing, you could just make it a sphere with speakers on it, no need for facets at that point.
I 3d print mine. You can also 3d print individual panels. The panels can have curvature so the end result is basically a sphere with flat circular drivers.

The issue isn't fabrication it is finding appropriate drivers which balance even HF dispersion and overall output. The dodecahedral speakers made by B+K have enormous output and produce quite a bit of bass.
 
I 3d print mine. You can also 3d print individual panels. The panels can have curvature so the end result is basically a sphere with flat circular drivers.

The issue isn't fabrication it is finding appropriate drivers which balance even HF dispersion and overall output. The dodecahedral speakers made by B+K have enormous output and produce quite a bit of bass.
To add onto this. I have studied the matter and although there is a certain design appeal to an all-in-one unit, you have a ton of problems with center-to-center distance. Conventionally we consider CTC between for example an M-T-M, but all these drivers are on a single plane in a line. With a spherical array, you not only have interference with the adjacent drivers, which are hopefully pretty proximal, but also with the drivers which are 180 degrees away, facing in the other direction. At a certain point speaker designers like to say radiation of this sort is 'uncorrelated' to paraphrase the late great Jeff Bagby, and many speaker companies include a dash of dipolar or bipolar radiation to augment the mids and highs eaten up by the room.

However, in the case of a spherical array, every driver is interacting with every one, and resolving the HF undulations you see in the technical documents from eg. B+K is not that easy. At the end of the day, even if you miniaturize the HF unit to say 5" diameter, which is tiny compared to these other units, you're still talking about a 5" diameter spherical dome tweeter in some kind of dodecahedral satanic breakup mode, and that's assuming your 2-3" drivers don't break up themselves, which of course they will.

If sound quality can be achieved, and that is a big if, it is because we are proceeding under the assumption that a flat directivity index is good, that all this chaos balances out, and the diverse HF radiation is desirable. But this is probably not the case - we probably don't want to hear a tweeter 2 feet from our wall while we also hear one 2'5" from our wall. This then raises the question - if we were to restrict directivity somewhat, how would we do so? Well - wide dispersion speakers like the Philharmonic BMR do a decent job as well, and dipoles remove the sideways stuff while keeping a nice amount of delayed mids and high frequencies.

My opinion is that omnidirectional radiation has very few uses. It can provide coverage radiating from the center of a large space, or in an outdoor venue (good luck getting serious output without a spherical horn, however - and if you're outside, do you really need to radiate up and down?) It might be nice as a pendant PA system in some tall spaces like a multi level shopping mall - but an array of speakers will always be better, and more easily controlled. For domestic spaces? Plenty of good wide and narrow radiating designs, and let's not forget why we restrict radiation - it makes sound clearer. For stereo or multi channel? Terrible idea in my opinion. The human ear has an enormous tolerance for comb filtering but even I have limits.

To summarize, I am building mine because I am curious about how they might sound, and to form a reference for restricted directivity speakers. We discuss this on ASR a lot - what is the ideal directivity? Some claim it is narrow horns or cardioids, but many people clearly prefer Philharmonic BMRs, Revel speakers, or any number of audiophile speakers clearly designed to accent wide treble dispersion with omni bass. Some prefer headphones, which eliminate the room entirely. This is, to me, a matter of preference, and if I could have any hifi setup in the world it would probably be LX521s or a Philharmonic BMR and a big Horn or powerful cardioid.

TLDR get a Sonos.
 
TLDR get a Sonos.
LOL, as I was reading this post I thought, "yeah, or maybe just put a few small speakers with WiiM minis around the room"... similar thought.

I personally like the idea of going with a simple lifestyle speaker, or doing a corner horn like @Duke suggested. As you note, spraying treble everywhere without prejudice could end up sounding pretty wooly.

True 3D omni speakers are really interesting but I am not at all sure they sound good.
 
LOL, as I was reading this post I thought, "yeah, or maybe just put a few small speakers with WiiM minis around the room"... similar thought.

I personally like the idea of going with a simple lifestyle speaker, or doing a corner horn like @Duke suggested. As you note, spraying treble everywhere without prejudice could end up sounding pretty wooly.

True 3D omni speakers are really interesting but I am not at all sure they sound good.
I am almost certain they sound bad, but of course nobody has ever made a good one, so I'm curious. Which is the best one? The MBL and Walsh ones are omni in one plane only and have crazy breakup issues, not that this is is disqualifying - doing really good omni with pure pistonic radiation might actually be impossible.

Everyone worries about bass reproduction but treble transducers are where the real engineering is, especially if you have to generate power. Fortunately the 300-5k region is where most of the music is, and is blissfully easy to create and control.
 
Just out of »geometrical curiosity«:

I wonder how to construct this shape, as it is a dodecahedron with additional triangles. From an aesthetically standpoint, it looks nicer (smoother and better balanced) than the basic dodecahedron. But again: how to construct it?
As someone else mentioned - CNC machining (or printing) both faces for all of the parts. Another option would be to make it a normal dodecahedron (with additional meat on the inside) and belt sanding the extra triangles in shape, marking the desired shape beforehand with a pencil.
Poly.png

I'm a big fan of machining complicated shapes!
1708764369002.png

Haven't figured out the gluing yet, could 3D print some angle guides / dedicated clamps. I'm sure there's a way to make it doable.
 
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I 3d print mine. You can also 3d print individual panels. The panels can have curvature so the end result is basically a sphere with flat circular drivers.

The issue isn't fabrication it is finding appropriate drivers which balance even HF dispersion and overall output. The dodecahedral speakers made by B+K have enormous output and produce quite a bit of bass.
Yeah, this is also what I was balancing my mind around. The smaller the dodecahedron the closer the drivers and the higher the frequency before the polar pattern starts going whack, though the bigger you make it the more low end you'd get out of it.

Also getting smaller drivers would result in them radiating further out at higher frequencies, which might not be desirable from the frequency onwards where the inner-driver-distance becomes an interference problem, as you'd get more interference this way? Perhaps there's an ideal driver size vs dodecahedron size proportion where the driver start radiating more narrowly at the frequencies where the inner driver distance becomes a problem.
 
So the basic segment would be like this? Forming again a pentagon, in a way?

1708765289225.png
 
I have by now borrowed a Bose SoundLink Revolve+ II, which is sort of omni, and have it hanging (from the convenient handle) in the center of the room. The speaker itself is small and boomy - will try tuning a bit later - but I'm so far enjoying the way it's sounding up the space. The direct and short line of sight from most places in the room is quite nice, and having it at 'people voice height' (which could also be done with a corner speaker!) adds nicely to the spoken content.
 
You see that corner behind the left-hand LX521? From that corner you can illuminate the entire space. I suggest two fairly narrow-pattern prosound-style speakers stacked in that corner. Like maybe a 60-degree pattern horn + 12" or 15" midwoofer. They don't need to have much low end for this application, and the corner will boost what low end they do have. Feed them both a mono signal, aim one at the kitchen area and aim the other at the desk.
If I'd be standing in the kitchen area, would the proportion of direct sound from the speaker, and the reflected sound from the wall behind it, not be lower in the case of the corner speaker?

Imagining 80dB at 1m coming from the speaker in the center of the room, the room being 10m long, and me being 1m from the back wall (which would make me 4m from the speaker) - I'd receive 68dB from the speaker (4m), and 64.4dB from the wall (6m).

With the corner speaker, 80dB at 1m, I'd be 9m away and get 60.9dB from the speaker, and 59.2dB from the wall (11m)

That's a 3.6dB difference with the center speaker, and a 1.7dB difference with the corner speaker.

I suppose there'd be more reverb with the center speaker, but that might not be a problem with a higher direct sound ratio like this.

The general sound pressure in the room would also be equal throughout, with the center speaker. Not having a much higher volume near the corner the speaker it's in.
 
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To summarize, I am building mine because I am curious about how they might sound, and to form a reference for restricted directivity speakers. We discuss this on ASR a lot - what is the ideal directivity? Some claim it is narrow horns or cardioids, but many people clearly prefer Philharmonic BMRs, Revel speakers, or any number of audiophile speakers clearly designed to accent wide treble dispersion with omni bass. Some prefer headphones, which eliminate the room entirely. This is, to me, a matter of preference, and if I could have any hifi setup in the world it would probably be LX521s or a Philharmonic BMR and a big Horn or powerful cardioid.

TLDR get a Sonos.
I'm also mainly exploring this as a DIY adventure fueled by curiosity (and lead by a practical solution for equal clear podcast sound throughout the space). Having the LX521's for music I'm amazed at their reproduction (or, rather, nice illusion) of acoustical instruments, and wonder how a full onmi would sound.

Have you seen the Qoms2? Measurement speaker again, but an interesting design with a great radiation pattern:
1708766571682.png


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I'd also see myself making something like this, with two fullranges, but have no clue how to calculate the shape of the waveguide for something like this.

Also, again no WiFi, so no Sonos. :/

I also think I'd prefer a single speaker (and dealing with the room reflections) over having multiple sources reach me at once
 
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Also, again no WiFi

Wi-Fi I’d guess could help maintaining a (near) perfect balance of the structure, as you won’t need any terminals. But then – there has to be some sort of »hanging mount« anyway, affecting the balance at least theoretically.
 
So the basic segment would be like this? Forming again a pentagon, in a way?
Yeah, exactly.
Wi-Fi I’d guess could help maintaining a (near) perfect balance of the structure, as you won’t need any terminals. But then – there has to be some sort of »hanging mount« anyway, affecting the balance at least theoretically.
Bluetooth works. :)

I'd imagine it hanging from a single two strand cable with internal steel wire, at the corner of three of the segments.
 
I'm a big fan of machining complicated shapes!
1708764369002.png
Would you mind if I asked about your process here? I'd think a second CNC'd part would be required to stabilize the second side's machining, right?
Beautiful work.
 
If I'd be standing in the kitchen area, would the proportion of direct sound from the speaker, and the reflected sound from the wall behind it, not be lower in the case of the corner speaker?

Imagining 80dB at 1m coming from the speaker in the center of the room, the room being 10m long, and me being 1m from the back wall (which would make me 4m from the speaker) - I'd receive 68dB from the speaker (4m), and 64.4dB from the wall (6m).

With the corner speaker, 80dB at 1m, I'd be 9m away and get 60.9dB from the speaker, and 59.2dB from the wall (11m)

That's a 3.6dB difference with the center speaker, and a 1.7dB difference with the corner speaker.

I suppose there'd be more reverb with the center speaker, but that might not be a problem with a higher direct sound ratio like this.

The general sound pressure in the room would also be equal throughout, with the center speaker. Not having a much higher volume near the corner the speaker it's in.

In my opinion it makes sense to consider all of the in-room reflections instead of only the ones coming from the wall behind the listener.

For a given direct sound SPL, a speaker with a directivity index of 6dB will generate a reflection field 6 dB lower in SPL than an omnidirectional speaker would, and a higher direct-to-reflected sound ratio contributes to speech intelligibility. In your application this is offset by positioning which places the omnidirectional source closer to the listening positions, with the specifics varying from location to location within the room.

I think either approach is capable of meeting your requirements, so I think you can go with whichever is the more practical... OR with whichever interests you the most. After all, we delve into this stuff because we enjoy it.
 
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Would you mind if I asked about your process here? I'd think a second CNC'd part would be required to stabilize the second side's machining, right?
Beautiful work.
Not necessary, it can be machined from one block of stock with holding tabs, thicker than the piece, which keeps a solid frame that can be aligned and clamped. Then after machining these can be cut and sanded off.
 
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I spend a lot of time in my kitchen- and living room listening to podcasts and audio books and would like to build a dedicated speaker for the purpose, prioritizing clarity.

I have a set of dipoles at one end of the room, but listening to those on the other end presents me with a 'fuzzy wall of sound', where I feel like I'd prefer a point source in the center of the room (hanging from the ceiling?). I've seen dodecahedron speakers used as point sources for acoustics measurements, but am unsure what would happen with those at the higher frequencies when the drivers would start beaming. I also don't think I'd need the vertical channels in this case? Or would it be wiser to keep those to keep it as a proper point source?

Another idea would be half of one of those, stuck to the ceiling. I feel that would give less ceiling reflections, but would also place the source quite high, where more towards ear level seems preferable from an experience standpoint.

I'm not sure where to take this yet, but would love to brainstorm with you all for a bit!
- David
I have an upcycled pair of Snell E4 that have good spoken voice clarity throughout the downstairs.
 
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