Sure? Speaker are about reproduction... I'm not convincing at alla that a speaker should "work" like a music instrument. So many different instruments with their individual way of emitting sound in different directions. A speaker model for solo violin, an other for solo congas? Hm...
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This extensive project definitely deserves its own thread. I hope you start this up soon because I am not very familiar with the ESL concept so I have a lot of questions.
if its so difficult to combine good time response and omnipolar response still the classic configuration can be a problem solver:
like this one but with a dsp'ed fullrange like Fane Sovereign 12-250tc.
but a concentric design would do, too.
last one from canon s70 has the advantage of not collecting dust over time
like this one but with a dsp'ed fullrange like Fane Sovereign 12-250tc.
but a concentric design would do, too.
last one from canon s70 has the advantage of not collecting dust over time
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Of course, however a conventional forward-firing loudspeaker will have a polar distribution quite unlike most acoustic instruments. I'm quite open to the possibility that the ideas cited above have real merit, but of course any omnidirectional speaker is only omnidirectional to a single listener if it has something to reflect off, and that's where its effect - for good or bad - gets difficult!
A speakers radiation must have something to do with how microphones "listen"... I suppose there must be some symmetry in the rec/repl chain in order to make a faithful reproduction. Multi mic/ studio/electrical instruments can only hope to be "nicely" played.
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@Freedom666
Stu Hegeman developed an approach that Don Morrison took over in 1977 and since then adapted significantly.
It seems to have informed the designs you've put forward
Stu Hegeman developed an approach that Don Morrison took over in 1977 and since then adapted significantly.
It seems to have informed the designs you've put forward
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In post 52 I argued that adding four tweeters to the omni's could solve some problems.
Although I still think this is possible I am not going to continue down this path for the following reasons:
1) the approach requires a lot of (measurement) work.
2) the end result is still quite uncertain.
3) during the project I cannot listen to music in my living room.
I am now thinking of building new omni's with a sphere shape controlled by active electronics. I expect less risk with this approach and better results.
Although I still think this is possible I am not going to continue down this path for the following reasons:
1) the approach requires a lot of (measurement) work.
2) the end result is still quite uncertain.
3) during the project I cannot listen to music in my living room.
I am now thinking of building new omni's with a sphere shape controlled by active electronics. I expect less risk with this approach and better results.
in this construction the tweeters do the omni effect. Close to back wall the 20cm bass gets some compensation of baffle step for free.
And it sounds good. I understood well why these sonab boxes were so popular in northern europe in the 70ies. They nearly had a monopole standing in sweden.
https://www.diyaudio.com/community/...oupled-up-firing-speakers.121385/post-6707993
It sounded much better with the felt below the tweeters.
And it sounds good. I understood well why these sonab boxes were so popular in northern europe in the 70ies. They nearly had a monopole standing in sweden.
https://www.diyaudio.com/community/...oupled-up-firing-speakers.121385/post-6707993
It sounded much better with the felt below the tweeters.
and I learned: so close to floor and back wall you get some serious +6db horn like amplification "for free".
(carlson coupler boxes which are close to the floor and back wall, too)
(carlson coupler boxes which are close to the floor and back wall, too)
@jaapVL
if you take one of your small drivers and put an acoustic lense on it like 3-4cm diameter opening it would beam less and not worse than some tweeters.
With nearly 90 to 120 degree dispersion you would only need two of them one on front and one in the back keeping the box as little as possible like a small ball.
With a subwoofer it would certainly give a nice response if DSPed linear.
if you take one of your small drivers and put an acoustic lense on it like 3-4cm diameter opening it would beam less and not worse than some tweeters.
With nearly 90 to 120 degree dispersion you would only need two of them one on front and one in the back keeping the box as little as possible like a small ball.
With a subwoofer it would certainly give a nice response if DSPed linear.
Thanks for the advice. Could you perhaps send a rough sketch of this setup. In particular, I am curious about the implementation of such an acoustic lens.
if your driver is 2.5 inch just put a round opening before it with only one or 1.5 inch. You get dispersion like with smaller driver.
its like the opening of a carlson coupler but only round and smaller than the driver.
if EQed it should give good results aiming at enhanced dispersion.
Just keep an eye on distortion. If the opening is too small there is too much compression.
BBC did that with an old model
its like the opening of a carlson coupler but only round and smaller than the driver.
if EQed it should give good results aiming at enhanced dispersion.
Just keep an eye on distortion. If the opening is too small there is too much compression.
BBC did that with an old model
Thanks for the hint. Although a cube is quite different from a truncated octahedron, I made an attempt to simulate the behavior of the omni with Boxsim.
For the simulation I placed the four drivers on a cube (riblength 20 cm) as below, resulting in the frequency response as shown.
The agreement between the simulation result and the REW measurement is clear (see post 33 of this tread).
Also the directivity plot of the simulation is not in disagreement with my REW measurements.
Next I gave the direct driver the amount of delay necessary to virtually place it in the plane of the indirect drivers. This plane is perpendicular on the listeners axis (see post 19 of this thread), The applied delay was 350 usec.
It is clear that the nasty dip at 1300 Hz on the listening axis has disappeared, as expected.
The above exercises have given me confidence that Boxim can be a useful tool in the further development of the omni.
As stated before, I am already happy with clear and open sound of the omni. The aspect I want to improve is quality of the stereo image.
To achieve this, I want to reach the following:
- a reasonable flat SPL function on the listen axis
- better reproduction of high frequencies for better directivity
- minimize edge diffraction
What I have in mind is a spherical enclosure with 4 woofers and 4 tweeters, delayed in such a way that they all drivers virtually lie in the same plane. It then becomes, in effect, an omni directional version of a small 2 way speaker.