Omnidirectional speakers. The future?

Eldartford - The fact that an instrument is larger than a cone driver doesn't mean the driver can't reproduce the sound that we, as humans with ears, would hear if we were sitting a reasonable distance in front of it. The "planar speaker" argument which keeps popping up here completely misinterprets the mechanics of both recording, wave theory, and human perception.

1. Our ears, like the microphone, also only sample a small portion of the "wavefront". All we need, and in fact, WANT, to do is accurately reproduce that little portion of the wave. The whole point is that the microphone's diaphragm takes the place of our ear. It's "sample" is about the same size as an eardrum. Therefore, any driver larger than the mic's diaphragm is capable (theoretically) of fully reproducing the same sounds the mic heard. The only issues governed by driver size are volume and distortion - (the larger the driver the louder it can play a certain frequency range, but the more prone it is to distortion at a given level of power input.)

Otherwise headphones wouldn't work. They're much smaller than a cello. The reason planar headphones sound good has nothing to do with the size of the wavefront or the drivers, and the reason some people like planars has nothing to do with the "shape" of the original or reproduced wave.

2. All a speaker can be asked to do is accurately regenerate the information that was recorded (sampled) by the microphone. Making the driver bigger or smaller doesn't add any data that was lost in the size of the "sampling", if there really were. Even assuming that a cello created a strange, planar wavefront*** (see #3. below) that had different properties along it's "face", a planar speaker can't reproduce the waveform that was created by the soundboard - it can only reproduce the sample that was picked up by the mic. It brings to that sample certain sonic attributes of its own - but not more of the cello's attributes than a cone driver of equal quality.

3. There is no "cello-soundboard-shaped wavefront" that zooms by the listener. If there were, by the time it got to the back of a symphony hall, all you would be hearing would be the vibration of a 1000ths of an inch specific section of the soundboard. Someone sitting in the seat 5 over from you would hear a different concerto than you. Waves don't work that way.

If you drop a brick in a pond - are the ripples that emanate outward rectangular? Yes and no - for a very short distance they are, then very quickly they're not.

Why - because the wave and it's medium constantly interact with each other. This rapidly "smooths" the sound to a uniform waveform (at reasonably equal angles from the source). Within a few feet the wave IS the same as if it came from a point source. 20 feet out in the pond you would not be able to tell me whether I dropped a brick or a bowling ball by lookint at an ear-sized sample of the rings emanating from the center.

Have a good weekend all.

I'm not disagreeing that many might find the Shahinian sound pleasant. But it is just that, a "sound". I, personally would rather hear (usually) the piece as it was recorded.

Don't take this as directed personally but: One thing people don't seem to get - the acoustics of the hall are ALREADY IN THE RECORDING - as recorded (if it's done right)! You may enjoy adding your own reverberation, but if you play back a CD recorded in St. Paul's Cathedral on a great system in an anechoic chamber, it's going to sound more like it was recorded IN ST. PAUL'S CATHEDRAL, than if you play it back in a large tiled bathroom.

The reason people like to sing in the shower is because the reverb from the tiles makes them sound "better". That doesn't mean they're ready for the Met. So if you like adding reflections from your walls that's perfectly fine - I have no prejudice about what people like - but it's not a more accurate reproduction of what was recorded.

Dear Newbee - I wasn't really serious about the DSP. But I listen only to vinyl and the DBX (even a 3bx) is IMHO essential. I really have pretty good ears and have tried to find a fault with this thing and can't. It's the only add-on I have. The sound is soooo much improved. I haven't had anyone listen who wasn't floored by it. It's takes compressed analog (like almost every record ever made), and restores the dynamic range and punch that it had - there's no going back once you hear it. There's nothing magic about compression that can't be reversed with a proper algortihm.
I know many vinyl/audio snobs would have a kneejerk negative reaction to such a device, but then they've just bought a $5,000 tonearm to listen to highly compressed source material with numerous clicks and pops? It ain't that accurate to begin with.

Damned if you don't and damned if you do I guess....

Any Audiogoners in the SF Bay area who'd like to stop by hear it are welcome. You'll be on Ebay buying one within hours.

OK - I really have to get out of here this time...

Opalchip: A microphone picks up whatever is fed into it, both direct and reflected energy. It can't discern if the primary or reflected signal should should dominate as it can't differentiate between arrival times and their individual intensities. In effect, it becomes a recorder of acoustic activity at that specific point in time and space based on the specific pick-up patterns of the mic being used.

The Walsh driver simply re-radiates the energy that was captured at the mic as a point source and re-radiates it into the listening environment as a point source. The fact that the original ambient sounds heard during the recording could be heard at every point in the room, and are pretty much preserved and reproduced due to the pseudo-omni radiation characteristics of the Walsh design, is one of the most endearing properties of these speakers. The fact that there is only one driver acting as a point source for each channel reduces time / phase distortions to a minimum, hence the preservation of natural harmonic structure. This too is a very endearing quality of this speaker design. The effects of binaural recordings as heard on these speakers is pretty amazing.

Other than that, each musical note has a primary frequency and multiple harmonic frequencies. These harmonics vary in spectrum and intensity. Any device that tries to separate the audio spectrum into different segments will introduce distortions into each note reproduced. That's because the time, phase & amplitude of the primary note vs that of the harmonics will not remain cohesive in presentation.

As a case in point, the specific device that you mention is capable of expanding multiple different frequency regions at different rates. When doing this, it means that a harmonically rich instrument ( like a Cello ) that is centered in one specific frequency section may be expanded at a different rate than the harmonics, which might fall into one or two different frequency spectrums. As such, each spectrum is / can be expanded at different rates, which in turn varies the amplitude of the harmonics in respect to the amplitude of the primary notes.

The reverse of that is also true. That is, an instrument that covers a very wide range of the audio spectrum ( like a piano ) can have different levels of expansion applied to it across the entire band due to the spectrum segmentation that the device does as part normal processing. This would take place on both the primary note and the harmonics.

As such, expanding a compressed recording could only be done optimally if the algorythms used during recording and playback were exactly the same. Given that this is next to impossible given the differences in recording, mixing and processing techniques, the end results of attempting to expand a compressed recording can be very "interesting" to say the least. I will agree that "expanded" music sounds noticeably more dynamic and "punchy", but at the same time, it also has a certain "artificiallity" to it. On top of that, quite a bit of electronically generated music IS compressed, even when played live. Electric guitars, bass guitars, electronic keyboards, etc... are often processed in a certain manner with the musician specifically desiring certain sonic attributes that compression / clipping bring along with them. Trying to "undo" what was meant to be, both live and on the recording is nothing more than a distortion. These distortions may be pleasant on certain recordings, but it all boils down to a matter of personal preference vs articulate preservation of what is on the recording. Sean
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Opalchip...The sound generated by a point source speaker becomes, within a few feet, a planar wavefront, just as you have described. By generating a planar wavefront to begin with the planar speaker is (neglecting for the moment any reflections) simulating a point source at a greater distance. As a result of this the SPL falls off much less rapidly as distance to the listener's position increases, producing (IMHO) a very stable and uniform soundstage throughout most of the listening room. This characteristic of planar speakers, more than their inherent bidirectional nature, accounts for the sound that some people like.