Omnidirectional speakers. The future?

The microphone "samples" one point of a planar wavefront generated during the performance. A planar loudspeaker recreates the planar wavefront, and what happens after that, regardless of what kind of loudspeaker is used, is at the mercy of room acoustics.

Can you give some examples of point sources? Every instrument I can think of, with the exception of a human vocalist, has a sounding board larger than the typical cone driver.

Hi AudioKinesis - IMHO the reverberant energy in a hall is either a fortunate or unfortunate attribute of that hall - depending on one's tastes and location. I would call it distortion, as compared to the piano in an anechoic chamber. Except that, to get philosophical about it, certain genres, forms, and specific pieces of music were developed/composed with certain assumptions about the acoustical properties of the places or media where they were likely to be heard - especially with regards to classical music, e.g. Russian church choral music wouldn't sound right in a jazz club.

But my point is that the best a speaker can do is re-create what you would have heard at the point where you were sitting - and a microphone has ALREADY picked up all those reflections, time-delayed, and out-of-phase sounds.

As far as the ear's diaphragm is concerned, there are never "sounds arriving at different times in different ways" - there is only one complex waveform which already IS the net sum of all those primary and secondary elements hitting you at any point in time. (That's why there is only one groove necessary in a record). This is what the microphone records, and is all that needs to be re-amplified. Adding omni-directional characteristics to speakers is simply like changing the acoustics of the hall that the piano was recorded in. Some will like it, others won't - but it's not what was there in the first place.

I'm not a purist in the sense of maintaining the original if something else is more pleasing or fun, but personally, I'd rather have a Yamaha DSP that gives all sorts of acoustic playback options - including the option of turning it off. And I'm a big fan of the DBX 5bx dynamic range expander (which actually DOES restore the signal to more like the original.)

I just think that if you want to alter the signal that's on that CD or LP, having your speakers bouncing sound off the walls and ceiling is really not the best way do it.

Opalchip, I agree with most of what you had to say about hearing what is on the recording unedited by the design of certain speakers types. And it was well said. BUT a Yamaha DSP or a DBX5bx? Boy, did you lose some ground there! :-)

Just give me my hair shirt thank you......

Opalchip,
Come listen to my Shahinian Diapasons. Then you might change your mind. I think of sound like light. Direct light in the eyes is irritating. Reflected and diffused light is pleasant. The word distortion does not come to mind when listening to the Shahinians. The word real does.

If reflections are distortion then you must think the ideal listening room is an anechoic chamber. I can assure you that it is not. The most experienced acoustic engineers use both diffusion and absorption in room design.

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.