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Flat Panel Speakers
ugene sent us a link
to something I've never seen before:
7mm thick speakers. They
claim they sound as good as conical speakers, but they project
sound 360 degrees. Nifty looking if you're aestheticly
anal, or low on space. I wonder if they can be removed from
their stand and hung right on a wall.
Update: 04/11 06:17 by CT : Cyberdiva sent me a review
as did Alan Dang
from 3DGaming.
This is heavily prior art from the Sumo Aria/Museatex Melior. I can and will furnish reference- the Sumo Aria was reviewed in The Absolute Sound, v14 #62 november/december 1989 (yes, the date written on the spine of the mag is Y2K compliant ;) ) It's a very good detailed and insightful review- when I made some speakers along these lines, mine showed many of the same characteristics as the reviewed, $3000 speakers.
One aspect of their claim is very strange- the vibration pattern of center-driven membranes is not remotely random. It is ripple-like, radiating from the center. If the ripples persist too much, the speaker develops unpleasant 'drumheadlike' colorations. If you drive it in lots of places you could overcome the sound pressure level limitations, but the really _phenomenal_ imaging the design can produce is hosed.
All very interesting, though- I'd love to see where they place the multiple drivers they apparently use, if their reports are not misleading.
It's the same idea as the old Sumo Aria (aka Museatex Melior). I wonder if these are using stretched mylar membranes, or something semirigid like flat paper? :P
You can make your own with stretched mylar and a central moving-coil driver. Caveats: 'wide range' means the thing _insists_ on producing super wide range even into areas where the speaker just breaks up (low frequency resonance modes esp.), and the phenomenal dispersion means the efficiency at any given point is really weak- it's just the same really weak anywhere in the room or indeed adjoining rooms- the sound 'carries' phenomenally well. Use a musical instrument speaker for efficiency and surgically remove the cone and basket as much as possible, and do not (trust me) run the little magnet wires over as moving parts- they will crack and cause the speaker to go intermittent and rasp on loud or low notes
Also, the membrane speakers at least are bidirectional- the back wave is _out_ of phase, so you can't reasonably hang them on the wall without obliterating the low end. And, you can't simply make huge versions to get more volume- the whole thing is severely volume-limited as the entire sound output is coupled through a point attached to flexible membrane, so if you want other than ultra faint, make a sphere-like or egg-shaped driver attachment, and make the drive point a _wide_ point on the membrane, not the tip of a cone (easier to construct, but you never heard anything so faint, trust me)
*blink* yeesh, suddenly I'm doing open source speaker design? Guess I'm just surprised- this principle was PATENTED I thought. I could have been making speakers of this type all this time, if only I'd known... I know, I'll write them and _ask_ if they're on solid legal ground. Maybe the Sumo/Museatex concepts failed patenting under prior art or something...
Magnepans aren't electrostatic, they're planar magnetic, and don't require the extra power supply that electrostatic speakers do. (And they're definitely not made of styrofoam; I'm not sure what the "poly-planar" speaker Bruce talks of was.) Planar magnetic speakers work with a diaphragm suspended between two magnets; either the diaphram itself is conducive, or there are conducive strips connected to it.
As someone else pointed out, the frequency response on these flat panel speakers isn't that impressive. The satellite speakers only go down to 300 Hz, and the subwoofer only to 70 Hz, meaning that it's not going to have much better response than my (subwooferless) Roland monitor speakers. (Ugly and not magnetically shielded, but they sound great, and they were about $80 for the pair.) Also, subwoofers rely on the principle that you can't localize low-frequency sound, but "low frequency" means "under 100 Hz." A crossover frequency of 300 Hz is silly.
Quadrophonic, incidentally, isn't really the predecessor of Dolby Surround except in a spiritual sense. The quad LP formats used distinct tracks for front, side left, side right, and rear, with the idea that the speakers would be 90 degrees apart from one another. Analog home theatre sound really just uses the two standard front left and front right tracks, and mathematically encodes a limited-frequency rear 'effects' channel and center dialogue channel. (Dolby Digital makes all of the channels full frequency separate tracks, separates the rear effects channel into left rear and right rear and adds a limited-frequency separate subwoofer channel.)
These aren't electrostatic...I recall reading about the development of the "exciter" that they mention on the web site several months ago. In the press release, they claimed that they could make speakers of almost any size, so long as the transmitting medium was stiff enough.
I see a couple of problems with planar speakers, although they are more personal in nature than objective.
1. They are not a point source, so they are very poor performers in creating a spatial sound field, such as that generated by 3-D sound cards. Since the sound is radiated 360 degrees in a horizontal plane (or nearly so...there are "dead" areas at the sides of the speakers), there is no "focal point" or discernable origin of the sound.
2. Frequency response from planar speakers has always been problematical at best. Infinity probably made the best use of the characteristics of planar elements in their ribbon tweeters of 20 years ago or so. These speakers produce great mide and high range sound, but they are simply too large in area to move coherently over large distances to create any kind of substantial bass frequencies. You'll see that most fans of planar speakers are also fans of subwoofers for this very reason. That's also why these speakers come with a subwoofer.
As far as speaker tech goes, these are really more of a curiosity than anything else, I think. But there are other uses for the technology, such as panels built into walls or ceilings that can produce sound without the physical intrusiveness of a speaker box.
I suppose that a case can be made for the smaller footprint that these speakers have. And they do look very cool...and that's certainly worth something!
The new technology is very interesting indeed. New ideas come along in the speaker world maybe once a decade or less, and this is one.
But this is hardly ready for prime time.
I'm intrigued by the flat panel approach because it makes the idea of creating a "mini sound stage" more feasible.
At the moment I have two Crown CE1000s, two JBL 15s and a Cerwin Vega 18 sub. Compared to that, these flat panel things are toys -- can't handle real power and produce serious SPLs, don't have the frequency response.
In a few more years, this may develop into an interesting submarket though.
signed,
/The Beat That Goes BOOM/
-------
Bill Gates Is My Evil Twin.
Depends on what you are claiming is nothing new...
Magneplanar/Electrostatics, no...
NXT's flat panel? Yes.
Instead of driving the surface of the panel which drives the air to create the sound, you 'inject' the panel with energy in such a way as to create the panel to vibrate, and these vibrations help to create the sound...
So instead of a driver pushing the entire plane, or a ribbon or a strip across the panel, molecular clumps of atoms become drivers. The interplay and interaction of the fundamental vibrational modes of the panel(which is required to be rigid and inflexible, for these purposes) with the air cause the sound...
Perhaps an inverse example might make more sense. A panel of glass will vibrate when any sound impacts on it. Laser mics use this property to capture sound off a flat rigid purpose. The glass itself isn't moving, like a speaker driver and cone moves, but rather vibrations across the surface of the glass can be detected on a laser beam reflected off the surface, and these vibrations can be used to reconstruct the original source sound.
Reverse this technique, and create sound from the vibrations off a rigid flat panel. It can be 1/4 of an inch thick, rigid and transparent(Like an LCD screen on a notebook!), is very frequency independent, which means no more need for the tweeters and midrange, at least, and because it isn't drive by a 'point' source, the sound isn't directional; it's a flat plane of sound energy!
That's why it's new tech...
AS
-AS
*Pikachu*
Several comments thus far on this being old-tech.
This is new stuff, but you are right in saying it's an old form...
Not only is it flat, it's thin; the company who designed and owns the patent is working on making a thin acrylic or plastic sheet an active speaker device, and thus make LCD screens in notebooks or even a sheet layered upon a conventional CRT active speaker elements.
The concept is much different than traditional flat speakers, and an issue with these speakers is the loss of the 'sweet spot' traditionally seen in directional speakers. These flat speakers project sound in a flat plane, and the interaction of the two speakers will not produce a cone of good sound quality, but rather a uniform zone of sound that should not change as one moves around in it. This doesn't bar reflective or destructive interference and interaction between the sound source, walls, and other obstructions, of course.
Succinctly, these speakers work by setting up vibrational modes across the surface of a sheet of plastic material, forcing the entire sheet to act as a speaker. They have effectively enabled each atom and molecule on the surface of a sheet to act as a driver unit, as opposed to a coil behind a cone. This design also removes the frequency limitations that were traditionaly dealt with by having a tweeter, midrange, and bass, though a bass unit is provided for more volume and kick, I believe.
There's more information at their site
flat panel technology
Because there is no directionality or frequency distributed speakers, I almost think that the technology is inherently incompatible with 3d sound algorithms, though it is still possible to create 3d sound by being surrounded by these speakers and sending different signals to each speaker. It would be equivalent to trying to create a true 3d image out of a 2d surface like a CRT of LCD.
AS
-AS
*Pikachu*
If people are interested in flat panel multimedia speakers, they should check out Monsoon Power's MM-1000. More pricey (around $200) but great reviews.
http://www.colorcase.com/products/speaker/DA9000.h tml Are still the best, cheap for what you get, awesome if you have the space, best computer speakers I've seen. Matt
I bought a pair of these from PcMall. They aren't worth $100.. perhaps $40 (which is what I paid for my ACS-40's, which sound just as good).
Well, to be more accurate, the panels sound fine.. clear, untroubled highs with a large sweet spot. Tight high end response. For a vibrating quarter stuck to a piece of silvery styrofoam, they sound pretty decent. However, in the case of the Benewin models, they are mated with a small combo sub-midrange speaker, that has all the controls on it. Which means you can't put it on the floor like a conventional sub. You wouldn't want to -- it produces nothing close to sub-like wavelengths.. mostly muddy midrange, which is very bright. Apparently Benewin thought the mids were not being represented well, or perhaps they bought the world's cheapest crossover, but the sub, IMHO, bites.
The panels would sound good if they were a bit bigger, (to handle more of the midrange), with more power and a decent floor-sitting sub.
As for the technology of the flat panels, it's COOL.. you can make a speaker out of a ceiling tile, a picture, mouse pad, wrist rest or whatever.. but the price you pay for versatility is a clean smooth ramp from high end to mid.
Keep an eye out for several other manufacturers coming out with NXT's technology -- I believe the URL for them is http://www.nxtsound.com (may be slashdotted right now).
But recycling of audio trends is nothing new. Remember Quadraphonic? (4-channels instead of 2 as in stereo). It's now "Theatre sound system" or some such, and is used mainly with video.
Bruce
Bruce Perens.
Anyone given to the idea of a single strip speaker, using NXT flat panel technology, one foot high, 1/2 inch think, and surrounding an entire room?
Or a theatre placing large flat panels as the projector screen and along the walls for even sround sound?
AS
-AS
*Pikachu*
I think I forgot to explain something...
I was wondering if one speaker using NXT's flat panel technology was capable of 3d sound =)
If one could encode phase variation to be played by the speakers, perhaps the speakers could produce truly directional sound, like the way phase array radar works; a grid/array of radar units can actually scan directionally despite being immobile and stationary, by some sort of differential phase calculations.
Likewise NXT panels, since they may be thought as an array of millions of speakers, can you encode delay into the sound and play directionally delayed sound from one panel?
The left edge producing a different direction than the right edge? The middle?
Because it's a panel, you can conceivably create a flat 1 foot tall curved speaker wrapping around an entire room!
AS
-AS
*Pikachu*
These speakers use a different vibrational technique than that of magneplanars or electrostatic speakers. The goal is still to produce massless driverless speakers, and towards that goal the NXT technology has shrunked the speaker elements towards the size of molecular clumps.
Magneplanars and electrostatics use smaller distributed drivers, and in this sense are similar to NXT's speakers, but they still use larger elements with more mass and more frequency distortion issues. However, since the technique has been done previously by Magenplanars and electrostatics, they can be drawn from...
One thing I can see as a disadvantage is that NXT speakers might not be able to deal with 3d sound other than multiple speakers arranged in an enclosing formation. Perhaps with more computational power and advanced encoding of sound, a single sheet speaker can produce phase varying sound, and multiple speakers can produce delay varying sound, for a better 3d sound experience.
Can a magneplanar speaker be used in this sense, since it is an array of many small speakers? Has anyone tried to create a simple/single 3d sound solution out of a magneplanar speaker?
AS
-AS
*Pikachu*