I'll give you an example.
http://www.diyaudio.com/forums/multi-way/194578-vifa-dq25sc.html
One wavelength of path difference, on-axis, far away, happens at 9.1 kHz with this unit. Supposing that you want no more than 1/2 a wavelength, 4 kHz would be the highest frequency that you want to have wrapping around the unit. I don't think there would be too much trouble designing a muffler to substantially attenuate the 4kHz and above that passes around - though of course it will not be so precise as a filter.
Very interesting. But I can't see how they arrange the transducer(s) by the photos, even though there's a cutaway view.
Up firing Bass. side/forward firing treble.
I have heard this, they sound pleasant for low volumes, VERY limp wristed/gutless, certainly not for Rammstein or Mahler at full bore!
First Look Reviews: The AmpLamp... The lamp amplifier - YouTube
How far is "far" into the reverberant field?
How do we interpret reflections given intensity and distance vs. that of direct sound?
Note: I'd mentioned that it was preferable to be closer to the speakers than the speakers are to any wall.
Possibly. When I think of problems however, I start thinking of the absorption material effectively blocking sound while creating a longer path resulting in lower freq. diffraction point.
IMO it would have to be a *really* lossy material. Perhaps a small toroid ofv very loosely packed rock-wool?
Thanks for sharing.
As I saw the footage, there's a small cylinder containing 2 side-firing small cones.
Pity that it's not thier NXT(DML) technology. I thought it's the lamp shade radiating sounds... (yet another omni device other than German Physiks DDD and MBL 101)
Correction: not 9.1 kHz but 6.4 kHz, meaning >3.2 kHz needs to be attenuated.
But, extrapolating from this chart:
http://www.rpginc.com/products/absorbor/Absorbor Panel_Acoustical Data.pdf
It seems as though only one or two layers of heavy fabric might do the job.
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another interesting a bit Pluto-like omni project: Parallel Audio
"omnidirectional point source to 5 kHz/bipole above 5 kHz" - 7" up-firing woofer crossed to 2x1" front-rear bipole tweeters at 1290 Hz with 8th order L-R
"omnidirectional point source to 5 kHz/bipole above 5 kHz" - 7" up-firing woofer crossed to 2x1" front-rear bipole tweeters at 1290 Hz with 8th order L-R
another interesting a bit Pluto-like omni project: Parallel Audio
"omnidirectional point source to 5 kHz/bipole above 5 kHz" - 7" up-firing woofer crossed to 2x1" front-rear bipole tweeters at 1290 Hz with 8th order L-R
Hi Graaf,
I have seen this website before. Interesting, now he has solid physical product instead of CGI mock ups (due to the suspicious nature these are a pet hate of mine -have they even bothered to make this for real?).
It is good to see Pluto having its influence.
The main driver being larger than Pluto's will start beaming earlier than the Seas midbass in Pluto (also it will not act quite as well as a small point source) and the standard silk dome tweeters will not to be able to be crossed as low as the fullrange Aura driver in Pluto, also the dispersion from the treble will not be as broad due to the tweeter faceplate and mounting plate so I it seems he is not going for the even power response with broad dispersion constant directivity like the Pluto design.
As he is using a larger bass mid (beams earlier) and a small treble unit (cannot go as low as the Aura) maybe he will reduce the output around the crossover to the treble like the BBC dip to give a subjectively more even sound and give smoother power response.
It would be interesting to hear if the bipole tweeter arrangement is detrimental or improves performance.
With the larger bass mid maybe he would be better off with a much lower crossover point to a drive unit acting as treble unit with very broad dispersion like the 2.5 inch units on this website (provided the manufacturers can make them low enough distortion):
CSS
One very small UK manufacturer is already using these:
http://www.arcaydis.com/model_1_75.html
CSS
One very small UK manufacturer is already using these:
http://www.arcaydis.com/model_1_75.html
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Hi Jamikl,
A larger fullrange drive unit would be completely wasted in this application. Those drive units are not designed for constant broad dispersion or to handle reasonable amounts of power in the bass so they would suit neither the bass/mid duties or the treble. Such drive units are better suited to low playback levels run fullrange or with a bass helper or two.
Mr Linkwitz used the relatively tiny Aura whisper (tiny for a so called fullrange) as a treble drive unit because of its broad dispersion and low crossover capability. That is a 2 inch drive unit. importantly it has a long stroke motor system for low distortion in the low treble (octaves below the crossover point) and no faceplate which would otherwise cause the drive unit to have more narrow dispersion.
The BMR units do not behave like normal so called "fullrange" drive units my understanding is that they have continuous frequency independent broad dispersion, whether they also have suitably smooth enough frequency response and low enough distortion is another thing.
It looks like BMR's are still a bit of a work in progress, nonetheless interesting. Even high end omni developers German Physiks have shown interest in the development of BMR technology:
German Physiks - High End Technology Loudspeaker Manufactur - DDD Driver - Why is the DDD Truly Revolutionary?
thanks for the link, yes, those BMRs are very interesting alternative in such configurations to the old champions of midtweeter business like small Jordans and Bandors
I bet I would too, slight price differential though!
The most high end speakers yet to feature BMR's (to my knowledge) is in Naim's Ovator speakers, which are larger units run full range. Cost wise Ovator is Chicken feed compared to German Physik's typical prices.
Like you say BMR's are relatively cheap to produce so they could suit the mass market and DIY.
I do not see the DDD driver ever getting there somehow, even though I have little doubt that it could be produced massively cheaper than it is now with mass production (perhaps say a mere one hundred fold more expensive than the BMR's). Large, expensive and fragile the DDD will always be physically expensive to ship and produce with very low real world domestic acceptability. Like Electrostatics the DDD's high end only status is assured.
Maybe with a high elastic modulus polymer (e.g. PEKK) doped with short carbon fibers such a diaphragm could be injection molded, but than it is doubtful that this would still have the neutrality of metal or carbon fiber/resin. And for a continuous production process one of those expensive ultra low tolerance molds wouldn't be sufficient, for sure.
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Last winter I restored pair of Sonab OA-12 omnidirectional speakers from -70's.
I installed new Obi T22-oa cone tweeters, Carlsson B65oa II woofers and modifiet crossovers for those new tweeters.
Very nice livingroom speakers since those are designed to be placed agains wall on the floor. Because omnidirectional behavior there is not so big difference where in room you are listening than "normal" speakers.
I installed new Obi T22-oa cone tweeters, Carlsson B65oa II woofers and modifiet crossovers for those new tweeters.
Very nice livingroom speakers since those are designed to be placed agains wall on the floor. Because omnidirectional behavior there is not so big difference where in room you are listening than "normal" speakers.