Electrostatic Subwoofer
Ron Folk
works. It's suppose to work without any moving parts, is this posible, and
does it work?
Bob Trosper
Um - what do you mean by "moving parts"? The diaphragm in an
electrostatic and the plasma in a plasma speaker certainly do move,
and thereby move air. Now, as I understand it, the plasma "vibrates"
in response to an external magnetic field, but I suppose you might
not consider that a "moving part". There is no voice coil moving in a
gap with an electrostatic speaker, as there is in a dynamic speaker,
but the diaphragm does move in response to a voltage difference
between the diaphragm and the stator. There were those speakers
touted for a while that worked by some sort of interference (beat
frequency) effect, but I think they still had vibrating transducers,
did they not? And whatever happened to them?
I have heard the Soundlab electrostatic subwoofer, and it certainly
is a nice piece. Unfortunately I don't have either the space or the
money for it and the required amplification.
-- Bob T.
Cat
does indeed move. Plasma drivers do not have moving parts per se.
They charge the air within the 'throat' of the driver and move that
air with high voltages.
In both cases, however, they are not well suited to the function of
subwoofer. A plasma driver would not only have to be enormous to do
such work, but it would take tremendous power to operate at low
frequencies. They are however occasionally used as tweeters. Once
again, with the electrostatic, it would need to be very large to be
an effective subwoofer. I have the Martin-Logan CLSes which are
'full-range' devices. They stand approxiamately 5' and are about 3'
wide. Still, they only reach down to about 30-35 hZ effectively.
Worse yet, since the panels of the electrostatic doesn't have a large
excursion, bass doesn't have tremendous slam.
I hope I have help clear things up a bit... If not, feel free to ask
more questions. =)
Happy listening!
Dayna b
Ron Folk wrote in message <739o36$6a9$1...@agate.berkeley.edu>...
John Kotches
>
> Does anyone know how an electrostatic or how an ionic/plasma subwoofer
> works. It's suppose to work without any moving parts, is this
> posible, and does it work?
Well something has to move :-)
In an electrostatic speaker, you have a few designs... about the
easiest to understand for me is in my Acoustats.
+5000v | Mylar | -5000v
Static | Film | Static
Charge | w/ metal | charge
The audio signal is a varying voltage which is applied to the
Mylar panel. It's light and very very fast, so it doesn't need
a lot of power to move it. When the varying voltage is applied,
the film moves back and forth between the two static electric fields
to reach electrical equilibrium.
Push-pull planar magnetics (Magneplanars and Eminent Technology)
work similarly to this, with positive and negative poles of magnets
interspersed so that the magnetic field is what moves the panel.
The downside with both Electrostatic and Push-pull planar magnetics
is that (typically) they aren't quite as efficient as their dynamic
brethren. The typical efficiency of these speakers is about 86db
at one meter. When compared to the typical dynamic loudspeaker
efficiency of ~90 db/m it's like cutting the power of your amplifier
in half.
Another downside with most Electrostatic and planar magnetics is that
in most cases they don't have enormous amounts of bass, because the
panels just can't move enough air. The bass that is there, is
smooth and accurate. I think my acoustats bottom out at around
40-45 Hz, but I have a nice little Phase Tech sub that takes me down
to around 30 Hz which is good enough for me :-)
I can't help with how the ionic/plasma drive works.
--
************************************************************
* A goofy Unix SA working for a large computer equipment *
* manufacturer and services provider. Opinions expressed *
* are mine and not my employers. jkotches@_pobox_.com *
Barry/Muriel Wilkinson/Turner-Wilkinson
originates in an electric field between two pointed electrodes. I
don't remember if it worked as a subwoofer but I remember it's big
drawback was the poor milage for the gas used in the charged field.
It requred regular replacement.
as for electrostatic woofers the only ones I know about are made by
Sound Lab if they are still making them but they work the same as any
electrostatic speaker they are just, BIG!!!!!!!!!!!
Barry wilkinson
----------------------------------------------------------------------
Email harvesters won't want this address
ab...@cadvision.com
----------------------------------------------------------------------On
Richard D Pierce
Barry/Muriel Wilkinson/Turner-Wilkinson <wilk...@cadvision.com> wrote:
>The Ionic/Plasma speaker is a true point source speaker as it's sound
>originates in an electric field between two pointed electrodes.
No, it is NOT a true point source. A point source is physically
unrealizable, because to achieve a finite sound pressure level at any
point away from the point source requires that the instantaneous
particle velocity at the point be infinite. The source may be small
relative to some wavelength, but it is and was NEVER a "true point
source" despite claims to the contrary.
In fact, the effective sound generation area in most plasma system
was on the order of 1-2 cm in diameter. Worse than that was the fact
that all of these drivers had dreadfuly low efficiency, and all
required horn loading in order to get ANY reasonable efficiency into
a listening room. Whatever advantages such drivers had, be they
theoretical, prctical or (in many case) imagined, those advantages
were pretty much squandered by the effects of horn loading. Wide
bandwidth? Forget it, the banwith was fully constrained by the horn?
Superb transient response? Nope, not with the bandwidth the horn had.
Point source disperison? Sorry: the dimension of the mouth of the
horn determined the disperison.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4963 Voice and FAX |
| DPi...@world.std.com |
BJRICHMAN
>An electrostatic device will have a tympanically stretched panel that
>does indeed move. Plasma drivers do not have moving parts per se.
>They charge the air within the 'throat' of the driver and move that
>air with high voltages.
>In both cases, however, they are not well suited to the function of
>subwoofer. A plasma driver would not only have to be enormous to do
>such work, but it would take tremendous power to operate at low
>frequencies. They are however occasionally used as tweeters. Once
>again, with the electrostatic, it would need to be very large to be
>an effective subwoofer. I have the Martin-Logan CLSes which are
>'full-range' devices. They stand approxiamately 5' and are about 3'
>wide. Still, they only reach down to about 30-35 hZ effectively.
>Worse yet, since the panels of the electrostatic doesn't have a large
>excursion, bass doesn't have tremendous slam.
>I hope I have help clear things up a bit... If not, feel free to ask
>more questions. =)
>Happy listening!
>Dayna b
I basically agree with Dayna's comments. As a point of
clarification, and as one who *also* owns Martin-Logan CLS IIs, the
panels per se are 4 feet high by 2 feet wide (total speaker size is
about 5 feet high x 28" wide). My findings are the same as Dayna's -
extension to about 30-35 Hz, but with relatively reduced volume
compared to comparable dynamic speakers. That said, I find the bass
that *is* there to be very accurate with excellent pitch definition
. Also, while ultimate slam may not be there - on well recorded
acoustic bass (e.g. Roy Brown LP's) or electric bass (e.g. on some of
the Bela Fleck CD's), the superfast transient attack and decay
conveys, IMO, the *illusion* of more slam than the speakers may
actually be transmitting.
If I'm correct in assuming *Dayna B* is the same as the lady that
reviewed the CLS IIs in Ultimate Audio about a year ago (and I'd
recommend it highly to all interested in these speakers - along with
Cordesman's review in a recent issue of Audio), I have a question for
Dayna. I noted that you reviewed the CLS IIs in combination with the
REL Stadium II subwoofer and found this combination very effective
indeed. I'd be interested to find out what your opinion might be (if
you had a chance to do this type of evaluation even informally) of
pairing one of the smaller REL models (e.g. the Strata or Storm) with
the CLS IIs.
I'm considering adding a REL to my CLS IIs in the future, and hence,
would be very interested in your opinion re. their use with my
speakers. For reference, the rest of my system (which is primarily
analogue) includes C-J PV-12 and Premier 11A driving the CLS IIs, VPI
Mark IV/Eminent Technology 2.5/Grado Platinum Reference and Cal Labs
Delta/Alpha combo as sources - with all interconnects and speaker
wires from Straight Wire.
Your comments will be appreciated.
Bruce J. Richman
Randall Bradley
The "ionic/plasma" speakers that I have the most experience
with were the "Ionofane" and the "Ionovac." Both had lousy
metal horns, and therefore it is unfair to judge the
inherent potential from that. They were "fast" to the ear-
of course, they were tweeters.
The main problem was *noise* due to the plasma.
Then there were the Hill Plasmatronics.
Fairly incredible from the mids up, where the plasma part
cut in. Perhaps the *best* mid/highs I have heard. Hard to
know how good for sure, as the medium and gear have improved
to a great extent in 20 years. That speaker used He/Ne/Ar
gas to create a plasma, which was then modulated by 4 x 572B.
That's about 2kW available.
Again some noise, and of course a tank of inert welding gas
to discharge into the house.
:)
_-_-randy
BEAR Labs
Lynn Olson
>was on the order of 1-2 cm in diameter. Worse than that was the fact
>that all of these drivers had dreadfuly low efficiency, and all
>required horn loading in order to get ANY reasonable efficiency into
>a listening room. Whatever advantages such drivers had, be they
>theoretical, prctical or (in many case) imagined, those advantages
>were pretty much squandered by the effects of horn loading. Wide
>bandwidth? Forget it, the banwith was fully constrained by the horn?
>Superb transient response? Nope, not with the bandwidth the horn had.
>Point source disperison? Sorry: the dimension of the mouth of the
>horn determined the disperison.
>
>--
>| Dick Pierce |
>| Professional Audio Development |
>| 1-781/826-4963 Voice and FAX |
>| DPi...@world.std.com |
I hate to contradict the esteemed list Dick Pierce, but I saw and heard
the Hill Plasmatronic speakers at the 1980 Winter CES. This unusual and
very large speaker featured the Hill-designed helium-plasma tweeter. Dr.
Hill, who worked at Los Alamos as a plasma physicist (not too difficult to
guess what his day job was back in the Cold War days), showed me the
helium tank stashed in a compartment of the subwoofer. It needed a new
tank about once a month, depending on how often you fired it up
(literally) and listened to music. Since the ionized gas was helium
instead of air, it sidestepped the health issues of ozone generation.
Helium may have offered some performance advantages as well, but I am not
a particle physicist and have no ideas on the relative behaviour of
different ionized gases.
*No* horn loading was used, and the plasma was plainly visible in the
darkened room as a blurry disk about 1 to 2cm across. It pulsed in time
with the music, and made quite a show. There was plenty of HP FFT data
showing response going beyond 100kHz and distortion well below 0.1%. What
did it sound like? Well, if you know the difference between a dynamic and
an electrostat, well this made the 'stat sound like a dynamic. Once heard,
never forgotten, like the 1970's Stax condensor phono cartridge or Stax
headphones.
The downside? Well, aside from the obvious helium-tank issue, the tweeter
only went down to about 3kHz or so. And the dynamic midrange and (big)
woofer just didn't quite match the startling performance of the tweeter
.... akin to the old AR-1W + JansZen 130 mismatch, but on a higher plane of
performance.
For all I know, maybe someone bought a Hill system back then. If they were
really crazy, maybe they could mate the plasma driver to a Martin-Logan
CLS ... maybe it's already been done! Any volunteers?
Lynn Olson
Editor, Valve & Tube News
Ariel Page: http://www.teleport.com/~lynno/Ariel.htm
Richard D Pierce
Randall Bradley <ra...@rdrc.rpi.edu> wrote:
> At the risk of disagreeing to some extent with DP:
>
> The "ionic/plasma" speakers that I have the most experience
> with were the "Ionofane" and the "Ionovac." Both had lousy
> metal horns, and therefore it is unfair to judge the
> inherent potential from that.
I never stated that the limitations were "inherent." Rather, as you seem
to have agreed with me, the limitation were imposed due to the inevitable
practicalities that a smalle effective radiating area with a small total
volume velocity is, by definition, and extremely inefficient acoustic
radiator: the horns were, in these case, absolutely essential to even have
a chance at keeping up with even moderatly low-efficiency mirange and low
frequency drivers.
>They were "fast" to the ear- of course, they were tweeters.
Well, the may have sounded "fast,", but the throat dimensions of the horns
pretty severely limited their upper end cutoff frequencies and, as a
result, they were, in fact, not as fast as some good contemporary
electrodynamic tweeters. Add to that the bandwidth limitations imposed by
the coupling transformers some of these driver required.
Remember that the lowly KEF T-27 was roughly contemporary with the
Ionophane (which was superior to the Ionovac, in my opinion). The T-27 had
nearly an octave higher cutoff frequency, and its transient response was
superior in every way: faster rise time, less overshoot, less ringing. It
also had significantly higher efficiency and was far easier to cross over.
Richard D Pierce
Lynn Olson <ly...@teleport.com> wrote:
>>In fact, the effective sound generation area in most plasma system
>>was on the order of 1-2 cm in diameter. Worse than that was the fact
>>that all of these drivers had dreadfuly low efficiency, and all
>>required horn loading in order to get ANY reasonable efficiency into
>>a listening room. Whatever advantages such drivers had, be they
>>theoretical, prctical or (in many case) imagined, those advantages
>>were pretty much squandered by the effects of horn loading. Wide
>>bandwidth? Forget it, the banwith was fully constrained by the horn?
>>Superb transient response? Nope, not with the bandwidth the horn had.
>>Point source disperison? Sorry: the dimension of the mouth of the
>>horn determined the disperison.
>I hate to contradict the esteemed list Dick Pierce, but I saw and heard
>the Hill Plasmatronic speakers at the 1980 Winter CES. This unusual and
>very large speaker featured the Hill-designed helium-plasma tweeter.
Where did you contradict me? I said:
"In fact, the effective sound generation area in most plasma
systems was on the order of 1-2 cm in diameter."
"Most" is not "all," and the Hill was an exception, which is why I
said "most."
>The downside? Well, aside from the obvious helium-tank issue, the tweeter
>only went down to about 3kHz or so. And the dynamic midrange and (big)
>woofer just didn't quite match the startling performance of the tweeter
>.... akin to the old AR-1W + JansZen 130 mismatch, but on a higher plane of
>performance.
Well, one of the reasons for the huge apparent difference is the huge
difference in radiation patterns between the low and high
frequencies: they obviously interact with the room in very different
ways. This alone can go a long way to explain the obvious audible
differences between the woofer and tweeter.
And, as someone noted, they could be quite noisy.
But, given that some have claimed the superiority of these drivers
(and others have made similar, often technically unsupportable claims
about a variety of interesting technologies, like the Heil AMT or the
Walsh drivers), where are they today? Even if they cost a mint to
make and sell, given some of the absurd prices people get for whyat
are little more than collections of fairly straightforward parts,
there is CERTAINLY a place for these things as well, no?
Well, there are a couple of potential reasons: they were simply
impractical, unreliable, whatever; they did not due what the
proponents claimed. Yeah, these and other systems sounded VERY
spectacular at shows. But on longer and more careful listening, they
revealed that muchof of their initially impressive sound was the
result of little more than simply unflat frequency response well
within the audio bandwidth, NOT some hugely expansive bandwidth
beyond 20 kHz (and precisely WHAT audio delivery medium existed, then
or now, that would benefit from a 100 kHz+ bandwidth. Even today,
many highly regarded recording microphones struggle to make it beyond
18 kHz!).
A classic example was the Heil AMT. Claimed to be some new and unique
principle of sound production (complete with a watermelon-seed
explanation), it was little more than a badly horn loaded transverse
ribbon that had a LOT of poorly damped resonances and a significantly
rising high-end. The magnet was constructed in such a way that the
pole faces WERE a horn, adding about 10 dB to its overall efficiency.
Take the 10 dB from the horn loading away, and the much-vaunted
efficiency of the tweeter evaporated. Couple that with a less-than
ordinary woofer and a porrly designed crossover, you had essentially
new-technology JBL-like sounding speaker with none of the power
handling and a worse frequency response.
Ho hum, yet another breakthrough.
John Busenitz
>A classic example was the Heil AMT. Claimed to be some new and unique
>principle of sound production (complete with a watermelon-seed
>explanation), it was little more than a badly horn loaded transverse
>ribbon that had a LOT of poorly damped resonances and a significantly
>rising high-end.
Is this true for all implementations of the AMT?
By the term "transverse ribbon", do you mean that it doesn't operate
as claimed (accordian motion, with the presumed quadrapolar
radiation)?
>The magnet was constructed in such a way that the
>pole faces WERE a horn, adding about 10 dB to its overall efficiency.
>Take the 10 dB from the horn loading away, and the much-vaunted
>efficiency of the tweeter evaporated.
Was that all that was vaunted? What about the distortion,
dispersion, power handling, etc?
John Busenitz
buse...@earthlink.net
Randall Bradley
best be equally precise. Which so far as I am concerned is
for the good.
It would be very interesting to see a modern MLSSA or
similar done on the top section of a Hill.
Anyone out there?
If the Hill top section did in fact have peakiness, I for
one failed to notice it. In fact it was the extreme smoothness
of its top end plus the effortless and distortionless quality
that made it so.
The disparity between the cone drivers and the plasma
section did not subjectively appear to me to be due to polar
response patterns or simple frequency response. It seems
likely due to the lack of stored energy in the plasma section
vs. lots of artifacts in the LF section, plus a rather poor
alignment of the woofers as well. Sort of like putting a
ribbon on top of an old acoustic suspension woofer.
Over simplification... ok.
Anyhow some modern measurements might put this speculation
to rest.
Btw, the mass of the plasma has to be *lowest* of any
driver yet.
Also of interest is the undeniable fact that the unsmoothed
FFT response curves show substantial narrow peaks plus and
minus the nominal "curve" of better than 6dB peak in each
direction. I do not know if this is a mathematical artifact
of the process or a true picture of how drivers actually
operate. DP???
If the latter, I wonder if there is a direct correlation
between these artifacts, the waterfall response, and the
overall driver's perceived quality. In which case, mightn't
the Hill then show *less* of this extra deviation energy??
Something to think about.
_-_-
dgh...@my-dejanews.com
(Why did I think they ran on Argon?) The odor in the room seemed clearly to
me to be ozone. Maybe it was a differant varient of the normal air-based
variety, but somthing gave me a headache; It certainly wasn't the sound- I
agree with your comments.
David Ginsberg
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
dgh...@my-dejanews.com
of any design do have a moving part; the diaphragm. Ionic/plasma
drivers do not have any moving parts, unless you consider the air
molecules, which do have mass. I am aware of a design by Coombs of a
"Corona Wind Loudspeaker" in the 1940's or 1950's that should have
gone down pretty low, perhaps to near-DC; but I have only seen a
paper on it, not a built piece. Dr. Hill's Plasmatronics speaker only
went down to, I seem to recall, 700 Hz crossing over to dynamic
driver(s). My Ionovacs were origionally designed to go to ~2500 Hz
using a small horn. I removed it and built a direct-drive amplifier
(inside the Ionovac cage) with a 6db/oct. rolloff at 8 kHz. One
important drawback: ozone generation. The Ionovacs don't really have
any problems but the Hills drove me from the room where I auditioned
them, rumor was that OSHA felt that they exceeded healthy levels. Any
owners out ther care to comment? BTW, I'm sure the Corona Wind
Speakers, if they were ever built, would have had the most oxone
output of all!
AudioMaven
(Why did I think they ran on Argon?) >>
It was an inert, noble gas but Hill used Helium for the speakers.
Myles Astor
Publisher
Ultimate Audio magazine
www.ultimateaudio.com
DUNCLIF
>Speakers, if they were ever built, would have had the most oxone
>output of all!
I think I saw this at the Las Vegas CES about 10 years ago. It was brought
over from France. It was full range, whatever that really means. It was also
about 8 ft. tall and 12 ft. wide. I only heard it briefly. The ozone was so
bad that you had to hold your breath to go into the room! It also played at
about 75 db with 400 W input.
Richard D Pierce
John Busenitz <buse...@earthlink.net> wrote:
>Richard D Pierce wrote in message <73epk2$d...@news01.aud.alcatel.com>...
>
>>A classic example was the Heil AMT. Claimed to be some new and unique
>>principle of sound production (complete with a watermelon-seed
>>explanation), it was little more than a badly horn loaded transverse
>>ribbon that had a LOT of poorly damped resonances and a significantly
>>rising high-end.
>
>Is this true for all implementations of the AMT?
>By the term "transverse ribbon", do you mean that it doesn't operate
>as claimed (accordian motion, with the presumed quadrapolar
>radiation)?
Nope, it's radiation was purely bipolar in every imaginable way. What
deviations occured from pure bipolar radiation was due to the
interference and loading due to the huge magnet structure.
>>The magnet was constructed in such a way that the
>>pole faces WERE a horn, adding about 10 dB to its overall efficiency.
>>Take the 10 dB from the horn loading away, and the much-vaunted
>>efficiency of the tweeter evaporated.
>
>Was that all that was vaunted? What about the distortion,
>dispersion, power handling, etc?
Well, it's distortion was, in fact, quite high compared to contemporary
drivers. Dispersion at high frequecnies was that of a poorly horn-loaded
ribbon, not very good. Power handling was okay, though I hd seen some with
the diaphragm blown out of the gap. I suspect this may have been due to
curious fingers as much as overdriving.
All in all, I felt it was an interesting but hardly unique implementation,
with utterly unremarkable performance and obviously far more imagination
in marketing than in design and implementation.
Tang Huyen
his LFT-VI speaker. A pair of either type costs $3250. I have not seen
or heard the woofer panel. Perhaps it could be used with other
speakers, too. Heaven forbid, if you are a bass freak, you could buy a
stack of these woofer panels to dig deeper ... Or you could buy a
pair of gigantic, room-sized panels named Tolteque AHL Series S
Electrostatic loudspeakers, each one approximately 8 feet tall & 6 1/2
feet wide, at the dirt-cheap price of $16,500 (picture at
http://www.hififarm.com/mainframe.htm)! They don't need woofers, do
they? And that is still cheaper than some cables ...
Tang Huyen
Barry/Muriel Wilkinson/Turner-Wilkinson wrote:
> as for electrostatic woofers the only ones I know about are made by
> Sound Lab if they are still making them but they work the same as any
> electrostatic speaker they are just, BIG!!!!!!!!!!!
>
> Barry wilkinson
AudioMaven
Series S Electrostatic loudspeakers, each one approximately 8 feet tall & 6 1/2
feet wide, at the dirt-cheap price of $16,500 (picture at
http://www.hififarm.com/mainframe.htm)! They don't need woofers, do they? And
that is still cheaper than some cables ...>>
I don't think so! They were at a CES Show many years ago - and they had a
sensitivity in the 60's at that time. Needless to say, they played only in a
whisper. Guess you'd need a Krell Master Reference Amp to make them bark.
dgh...@my-dejanews.com
Wind Loudspeaker was invented by Dr. David M. Tombs of the EE Dept. of
Imperial College (London, England). The paper is in the JAES 1/57, Volume 5,
Number1. It's by a Gerald Shirley and is a good description of the proposed
device. The Audio Engineering Society has a website that should get access to
this interesting paper. And the inventor of the Ionophone (marketed as the
Ionovac and Ionofane) is Dr. Siegfried Klein; try US Patent 4,306,120 for all
the juicy details.
My Ionovac file is almost an inch thick, perhaps someday I'll start an online
Ionovac Registry and put this stuff up.
Randall Bradley
Thus the nice purple glow! The main component was Helium.
_-_-randy
BEAR Labs
Randall Bradley
by Gerald Shirley - see the AES Loudspeaker Vol 1. for the
original ariticle - who I had the pleasure to meet.
He told me that it didn't make much noise.
I made a mini version for test, which wasn't too bad at
night at a distance of 12"!!
The Totecs or whatever were a version of this design,
so far as I am aware...
I wanted to try this sort of idea with the He/Ne/Ar gas
inside a thin, thin polyester bag - sort of an indirect
drive ESL?
Anyone want to put up the research money??
_-_-randy
BEAR Labs
Tang Huyen
designers intentionally make their speakers hard to drive so that Krell can sell
more amps? And Larry Archibald, now a multi-millionaire (if he was not before) like
John Atkinson, says that the 1000WPC $51,000 Boulder 2050 amps wimp out on his
Thiel 5.1 speakers. Though Tolteque is probably not an American company ... but
great minds meet ...
Tang Huyen
Richard D Pierce
AudioMaven <audio...@aol.com> wrote:
><<I must have been standing next to you in the Plasmatronics room back then.
>(Why did I think they ran on Argon?) >>
>
>It was an inert, noble gas but Hill used Helium for the speakers.
Well, just for the record, helium is also one of the noble gases. The
noble gases are all those in the rightmost column f the periodic chart,
all sharing the characteristic that the outermost (valence) electron shell
is filled, This is why they are (almost) inert. They include helium, neon,
argon, krypton, xenon and radon.
More to the topic at hand, none of these devices are immune from
generating a variety of rather unusual and (mostly) very rective compounds
like ozone and oxides of nitrogen because none of them (as I recal) are
completely sealed from the air in the room.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPi...@world.std.com |
Russell Twining
>
> In article <73g5pj$nga$1...@agate.berkeley.edu>,
> John Busenitz <buse...@earthlink.net> wrote:
> >Richard D Pierce wrote in message <73epk2$d...@news01.aud.alcatel.com>...
> >
> >>A classic example was the Heil AMT. Claimed to be some new and unique
> Well, it's distortion was, in fact, quite high compared to contemporary
> drivers. Dispersion at high frequecnies was that of a poorly horn-loaded
> ribbon, not very good. Power handling was okay, though I hd seen some with
> the diaphragm blown out of the gap. I suspect this may have been due to
> curious fingers as much as overdriving.
By comtemporary due you mean today's drivers or its
contemporaries(1970's).
If the latter what was the comparison between drivers of its own time?
In the cases I have seen it is due mainly to overdriving, I suspect that
most are trashed when the amplifier oscillates at high frequencies.
The diaphragm is usually a mass of fine strands of what looks like glass
fibres and aluminium strands intermixed.
>
> All in all, I felt it was an interesting but hardly unique implementation,
> with utterly unremarkable performance and obviously far more imagination
> in marketing than in design and implementation.
>
I personally use them in preference to other drivers as I feel that they
provide a much clearer sound notwithstanding the above comments.
When compared with other drivers (domes) I have tried a veil seems
to lift from the sound when the AMT's are used.
They do have problems. In my situation they need to have the rear
section partially covered to reduce the rear output to provide a stable
sound image.
This was brought about by not having comparable sound absorption to the
rear of each
speaker in my my multi-purpose listening room (lounge/living room). Its
polar radiation
reduced substantially.
Interesting to see that each person has a different perpective on the
subject.
> --
> | Dick Pierce |
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Russell Twining
Larry Shirley
I hope you get a notification on this 25+ years past original posting update for adding my two cents to the soon to be defunct conversation.
For everyone else reading this post I'm Larry Shirley, son of the eponymous Gerald who first met Randy when he interviewed my father about the original topic of the corona wind loudspeaker. I don't have much to add (technically at least) about its operation, but I'll contribute the postscript to the story that he kept the original demonstration speaker for many years on a shelf in his apartment until he suffered a health issue requiring a hospital visit. As an act intended to be helpful, a family relative decided it would be good to do some housekeeping in his absence and the speaker was sadly relegated to the trash heap. On his return he was very surprised to find it missing and was very depressed about having a memento from one of his favorite development projects disposed of out of sheer ignorance.
An early member of the Audio Engineering Society with an electro-mechanical engineering background, Gerald (or Jerry as he preferred to be called) had many diverse interests including a non-throttling trigger valve which could dispense corrosive liquids by having no metal parts (such as springs) in contact with them and Continuously Variable Transmissions (CVTs). He invested in the Laird Gogins CVT and ultimately became the owner of the patent (US5392664A - now expired), for which I still possess the original machine-tooled working model used for demonstrating the viability of the early design.
Professionally, Jerry started two companies: Aldshir and Televex, which began commercially as a phonograph stylus retipping service. He went on to design, patent, manufacture, and sell several different iterations of OEM and aftermarket universal phonograph spindle adaptors that allowed a wide range of record changer brands to hold a stack of 45 RPM records without requiring individual plastic inserts to accommodate their larger center holes.
As this Google Group is slated to be closed shortly, I maybe reached by email: la...@zebrakart.com for any further inquiries regarding my father.
[ Moderator's note: while it is true that Google will be dropping their access to Usenet groups, rec.audio.high-end has been around longer than Google and may well outlast that company. -- dsr for rahemod ]