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From: Archimedes' Lever on 31 Oct 2009 10:44
On Fri, 30 Oct 2009 23:32:08 -0500, Lostgallifreyan <no-one(a)nowhere.net>
wrote:

>
>Btw, that original symbol of the circle and bar wasn't originally omni. it
>wasn't specified at all, it was purely based on the ball and biscuit shape of
>an early form.

Which were generally omni. The symbol, at one time, most certainly did
have variants that related DIRECTLY to the type of mic.
From: Archimedes' Lever on 31 Oct 2009 13:14
On Sat, 31 Oct 2009 11:39:09 -0500, Lostgallifreyan <no-one(a)nowhere.net>
wrote:

>
>Given that it was a while before anyone invented any kind of high quality
>directional mic after the spherical omni type moving coil mic, it's not
>surprising that the original symbol seems to equate with omni types.

The first one was in 1876, so I think we have had a while to play with
the engineering.

Directional mikes (cardioid) were being used in the late 30's and the
40's and 50's ushered in a LOT of audio gear, both in the military
channels and the commercial realm as well.

Laser mics are cool...

A new type of laser microphone is a device that uses a laser beam and
smoke or vapor to detect sound vibrations in free air. On 25 August 2009,
U.S. patent 7,580,533 issued for a Particulate Flow Detection Microphone
based on a laser-photocell pair with a moving stream of smoke or vapor in
the laser beam's path. Sound pressure waves cause disturbances in the
smoke that in turn cause variations in the amount of laser light reaching
the photo detector. A prototype of the device was demonstrated at the
127th Audio Engineering Society convention in New York City from 9
through 12 October 2009.

Very fresh!
From: Lostgallifreyan on 31 Oct 2009 13:40
Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote in
news:blroe551fus02u6uf68e70kqlipri70rdc(a)4ax.com:

> On Sat, 31 Oct 2009 11:39:09 -0500, Lostgallifreyan <no-one(a)nowhere.net>
> wrote:
>
>>
>>Given that it was a while before anyone invented any kind of high quality
>>directional mic after the spherical omni type moving coil mic, it's not
>>surprising that the original symbol seems to equate with omni types.
>
> The first one was in 1876, so I think we have had a while to play with
> the engineering.
>
> Directional mikes (cardioid) were being used in the late 30's and the
> 40's and 50's ushered in a LOT of audio gear, both in the military
> channels and the commercial realm as well.
>
> Laser mics are cool...
>
> A new type of laser microphone is a device that uses a laser beam and
> smoke or vapor to detect sound vibrations in free air. On 25 August 2009,
> U.S. patent 7,580,533 issued for a Particulate Flow Detection Microphone
> based on a laser-photocell pair with a moving stream of smoke or vapor in
> the laser beam's path. Sound pressure waves cause disturbances in the
> smoke that in turn cause variations in the amount of laser light reaching
> the photo detector. A prototype of the device was demonstrated at the
> 127th Audio Engineering Society convention in New York City from 9
> through 12 October 2009.
>
> Very fresh!
>

Yep, I'm sort of watching that space too. At first I thought it wouldn't be
viable, horrible SNR etc, but I was told (by Phil Hobbs I think) that it
worked fine, so I'm likely to want to play with one at some point. /dreaming

Also given the high energy density that powerful lasers can make, I wonder if
the idea might be reversible somehow. Plasma tweeters never really took off
(too expensive maybe), and plasma wide-range speakers maybe don't even exist
except as a kind of audiophile monument that is about as out-of-reach as a
Cray computer was for most of the last few decades. I wonder if some kind of
laser might put enough modulated energy into a tiny space to make it work
though. But this is the very loosest kind of wondering, I really haven't a
clue if it would work well, or what other ways might be better.
From: Archimedes' Lever on 31 Oct 2009 13:47
On Sat, 31 Oct 2009 12:40:33 -0500, Lostgallifreyan <no-one(a)nowhere.net>
wrote:

>Plasma tweeters never really took off
>(too expensive maybe),

The military has eximer lasers that can punch a dent in a missile body
in flight.

So, maybe a variant of a ribbon tweeter, where photons impinge on the
ribbon backside, causing emission on the face of it.
From: Lostgallifreyan on 31 Oct 2009 14:26
Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote in
news:gutoe5tbnf9deb8u1o9o3uc3fu6u1p5kjt(a)4ax.com:

> On Sat, 31 Oct 2009 12:40:33 -0500, Lostgallifreyan <no-one(a)nowhere.net>
> wrote:
>
>>Plasma tweeters never really took off
>>(too expensive maybe),
>
> The military has eximer lasers that can punch a dent in a missile body
> in flight.
>
> So, maybe a variant of a ribbon tweeter, where photons impinge on the
> ribbon backside, causing emission on the face of it.
>

But with some vicious harmonic distortion. :) I was thinking of some kind of
gas state only, or actual plasma, just not derived from HV. A small Q-
switched YAG like the Abrams tank rangefinders can, if focussed, make a
snapping sound as it burns the air (and a flash at focal point). Maybe if
there was some way to control it... But I bet it would end up just as
unfeasible and dangerous as doing it with HV. And probably harder to do.
Might not need huge peak power at all though, if a few hundred watts could be
focussed onto some fluid that can then have its rate of expansion modulated.
Anyway, I'll leave it there, I'm going to sleep. And I also know that people
in alt.lasers (and likely Phil Hobbs who haunts here and there too) would
have talked about this if it was anything like viable. Besides, I think the
idea that uses a closed, sealed Helmholtz resonator as a kind of fridge is
cooler. Totally strange and wonderful idea, to use sound as a heat pump.
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