From: Lang Elliott <>
>
> I believe that to have a sweet spot big enough to walk around the entire
> room, one would need sound sources that originate from well beyond the
> confines of the room. Otherwise you can't get around the fact that as you
> approach a particular speaker, it's output will dominate.
Again, you are thinking conventional speaker. Think about the entire
wall surface being the speaker, no concentrated hot spot. The magnaplans
I speak of have very large surface areas, not entire walls, but hardly a
point surface like a conventional speaker. And the sweet spot for them
is larger, and is not of lower quality as some have suggested. It's not
a imitation or smoke and mirrors.
When a conventional speaker fills a room with sound it beams it out in a
concentrated manner to do it. Thus as you approach it the sound level
increases dramatically. When a magnaplane makes the same sound level in
the room it's large surface means there is not that concentrated beam.
Walk up to the magnaplane playing loud and there is hardly any change in
the apparent loudness. It was the first thing I noted about them.
I realize the difference between point sources and area sources is not
commonly thought about in sound. Nearly all thinking is about point
sources. How area sources will behave is not well known. My only point
was and still is that magnaplanes may be a better choice than point
source speakers. Based on what I know from having and using a small
pair. I don't have the money to devote to trying it. I only offered it
as a thought.
> Of course, one could perhaps envision having hundreds of speakers, all with
> their own discrete signals. But this would be quite impractical.
What I've been saying is such a conventional approach may not be
necessary at all to get the same thing.
Now that you bring it up, the magnaplane technology coupled with a
computer makes such a more complex form playback easier. All normal
magnaplanes are a grid of wires bonded to the sound producing film,
suspended in a fixed magnetic field. When sound is sent through the
wires in the form of ac current it causes the film to be vibrated. In
the standard design the current density across the film is even, but
using matrix technology controlled by a computer you could make it
variable across the film. In fact the entire magnaplane film approach
can be changed with modern technology to get rid of the wires for
conductive traces on the film. That takes care of playback.
It would probably be possible to matrix a large diaphragm for a area
microphone in a similar way. Computer power is up to this sort of thing.
Instead of storing discrete channels it would store a matrix.
So, it's possible. Though if it's necessary to do that is a different
story. Note what I'm talking about does not use discrete channels. It
more closely resembles the technology of LCD computer monitors. And
computers run those without any effort at all.
Yep, pretty far fetched, but not impossible. Probably impractical as the
market would be way too small for the development costs. But, even the
simple surround systems have small markets. Unless the full color
surround hologram get's to be practical and cheap. So as to provide a
audio/visual experience. Holographic 3d, walk through movies are what's
going to sell a accurate 360 degree surround. Which brings us back to
filling that room with surround...
Walt
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