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"Invisible" Speakers 141

Posted by CmdrTaco from the isn't-that-nifty dept.
Maurice Boughton sent us a link to an interesting bit about speakers that you can mount to your wall to let it resonate as a speaker. You read more. They're only like $60 so it might be worth it, although I'm curious how they sound. Oh, and as for the 6 billion of you who emailed me to wish me birthday greetings, thanks, now stop!
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"Invisible" Speakers More

"Invisible" Speakers

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  • With these following not far behind the "zero thickness" computer speakers, I see a trend strating: every lousy (but peculiar) notion that has ever been turned into a noise-producing loudspeaker - and there have been lots, and far weirder ones than these two - will shortly be making yet another appearance in this new market category.

    I can't wait to hear lousy under-sampled or mangled by compression PC audio played back through a latter-day "walsh" system. Those things were bad enough with analog sources that usually had some HF rolloff...

    I wonder how much a plasma driver would interfere with one's monitor?

    (signed) too lazy to login for this

  • Their claims don't make sense. (Score:1)

    by Anonymous Coward
    Let's see...they claim that they can create large volumes of sound without creating high sound pressure levels. Yeah, right. They're the same thing, Sparky! Then they claim that they get the room to vibrate sympathetically and contradict this in the next sentence by claiming that there are no standing waves in the room!

    I think these people are bozos.

  • I may be wrong but... (Score:1)

    by Anonymous Coward
    I quote:

    "DO NOT series two individual transducers together to obtain a 16
    ohm load. The amp won't put out as much power, neccesitating even higher volume
    setting. Also the first T/D in the series could receive a disportionate amount of the
    power before it passes onto the next one in line. Because Amplifiers must, as a rule be
    turned up higher than nomally, it is wisest to design a system that plays comfortably
    at the lowest possible Impeadence level    "

    Surely the power is equal between the two T/Ds (which are essentially just voice coils from a speaker rather than any kind of bizarre electrostatic things with funny resistance behaviour) so why would one distort first?

    And who came up with the idea that amplifiers are more stable with a smaller load? Why is there no mention of damping factors needed to drive these "hifi" devices? Why is there this fixation on the angle of the volume knob? Perhaps this guy should get a job in a PA company for a bit and _work_ with some amplifiers for a bit :-(

  • Cool (Score:1)

    by drwiii ( 434 )
    You know it's a good product when they use bright green tables to sell it :-)
  • Posted by Invisible1:

    Have you? If your nails pop out, then your work is pretty poor. And any good installer checks back to see if the wall has been secured properly. he has to...most Sheetrock hangers could care less.
    If you have a bad case of loose sheetrock, all it takes is a few more screws and that's history. But in any case, in over 5000 installations I've overseen personally, and a bunch more elsewhere, not on recorded instance of any wall damage, reguardless of content/volume, has ever been recorded. And nails pop out if you slam a door if they are not sank into studs. Plaster walls, Wood paneling, Cultured Marble, (How do ya like that?) even R-Wall(Styrofoam overlaid by Plaster) has been used to great effect.

    As for being a crock, how do you know for sure. Are you the authority on the subject. I think not. Keep an open mind. The days of the Inqusition are long gone. Most people don't trash what they don't understand these days. (Do they?)
  • Posted by Invisible1:

    Thanks for the small vote of confidence. Many is the time I've removed existing In-wall speakers, installed the 'ducers, and refinished the old hole back to the original condition of the wall. And beleive me, more people bite on the idea of our cutting a small hole in a wall and then making it dissappear than settling for a Grill. That is if they know of our product. I'm suprised that there are so many narrow minded people out there in who feel it's neccessary to dis something they really don't have a understanding about. The few that have some audio experience I can forgive, for the whole concept seems just too alien for thier minds to accept. That fact keeps many from enjoying our systems. Too bad. But for anybody to flat out state that such a thing CAN'T sound good, or CAN'T possibly work, and that the appearence of the Web Site has anything to do with the validity of the product, smacks of small minds and ignorance.

    For the record, I posted my 'artical' as a response to someone, not as an advertisement.
    And anyone who has a bone to pick, or a comment to make, good or bad, just call me up for free, the 800 number is on my site. I've spent 22 + years satisfing customers while defending my product from all the 'High End' stores whose business I took away. The harsh comments I've read usually only come from those whose business was lost to Invisible Stereo because they looked down upon the customer, instead of treating him like a Human Being and trying to make them happy instead of poorer. And any who want a raft of refferences, and who are willing to run up thier phone bill, can get them from me. Take your pick...USA, Canada, Britain, Mexico, Austrailia, Denmark, Italy, South Africa, Saudia Arabia, Dealers or Customers, it makes no difference; they all say the same thing, "I didn't belive it until I heard it, and it sounded good enough for me."
  • Posted by Invisible1:

    Meditation chamber, eh? Many Flotation tanks use the Rolen Star. Usually, about 8 of them. Nothing else lasts more than a few weeks, and Pink Floyed sounds pretty good inside one of those things.
  • Posted by Invisible1:

    Meditation chamber, eh? Many Flotation tanks use the Rolen Star. Usually, about 8 of them. Nothing else lasts more than a few weeks, due to the saline environment, and Pink Floyd sounds pretty good inside one of those things. Subliminal Tapes take on a whole new effect. And waterbeds? You betchca!
  • Posted by Invisible1:

    Thanks for the support. But there is very little bleedthrough into the next room; less than any unbaffled In-wall spkr. And Town Homes are a regular type of installation for us. Most have Firewalls so sound transfer is not a problem.
    As for retrofitting, only a 12" wide x 6" tall hole between the studs is needed, not the "tearing down" of walls. Usually, only people who have heard the RSAT in action say that because they cannot comprehend how a small device can create such a big sound. Until they see the unit itself, they think it must be a HUGE device.
  • Posted by Invisible1:

    Let's take these as they come

    "DO NOT series two individual transducers together to obtain a 16 ohm load. The first T/D in the series could receive a disportionate amount
    of the power before it passes onto the next one in line.


    Because Amplifiers must, as a rule be turned up higher than nomally, it is wisest to design a system that plays comfortably at the lowest possible Impeadence level"


    Surely the power is equal between the two T/Ds ( so why would one distort first? )

    ...most speakers that do not require much power seldom experience the headroom potential of a amp; or not for very long! The RSAT thrives on headroom, but because of this, what would be a subtle difference in effecient speakers becomes a much more dynamic one @ 100 watts continious power. Anyway, by parralleling before you series, you always create a beefier circuit. Two units in tandem have twice the power handling potential. In a series, they only have thier original power handling cababilities.

    And who came up with the idea that amplifiers are more stable with a smaller load? Why is there no mention of damping factors needed to drive these "hifi" devices? Why is there this fixation on the angle of the volume knob?



    Perhaps this guy should get a job in a PA company for a bit and _work_ with some amplifiers for a bit :-(

    I was building PAs for Night Clubs, Arenas, and Bands, and doing Live and Studio mixdowns in 1972. Where were you then, A crib? The RSAT does so many things differently than conventional speakers, someone such as yourself would have to throw out all your old concepts and beleifs to accept what 1000s have already embraced.
  • Posted by Invisible1:

    Let's take these as they come

    "DO NOT series two individual transducers together to obtain a 16 ohm load. The first T/D in the series could receive a disportionate amount
    of the power before it passes onto the next one in line.

    *******
    The initial surge into ANY type of series circuit will ALWAYS affect the leading device more strongly if both devices are of the same impedence.
    *******

    Because Amplifiers must, as a rule be turned up higher than nomally, it is wisest to design a system that plays comfortably at the lowest possible Impedence level"

    *******
    All this means is that you must pick your amp to meet your "worst case" load.
    *******

    Surely the power is equal between the two T/Ds ( so why would one distort first? )

    *******
    See above......most speakers that do not require much power seldom experience the headroom potential of a amp; or not for very long! The RSAT thrives on headroom, but because of this, what would be a subtle difference in effecient speakers becomes a much more dynamic one @ 100 watts continious power. Anyway, by parralleling before you series, you always create a beefier circuit. Two units in tandem have twice the power handling potential. In a series, they only have thier original power handling cababilities.
    *******

    And who came up with the idea that amplifiers are more stable with a smaller load? Why is there this fixation on the angle of the volume knob?

    *******
    The Web Site was designed for common folk who don't live and breathe Audio. To them, you have to talk at thier level, and use terms they relate to.
    *******

    Perhaps this guy should get a job in a PA company for a bit and _work_ with some amplifiers for a bit :-(

    *******
    I was building PAs for Night Clubs, Arenas, and Bands, and doing Live and Studio mixdowns in 1972. Where were you then, A crib? The RSAT does so many things differently than conventional speakers, someone such as yourself would have to throw out all your old concepts and beleifs to accept what many 1000s have already embraced. Can you still learn/unlearn anything?
    ********
  • Posted by Invisible1:

    I'm sure you'll never know if they work or not because you'll be happy with the thought that money buys quality. Too bad it can't buy more of that intellegence you seem to set such great store in. Those who would condemn without understanding it are worse than idiots. And the Web Site will be updated soon....I've been too busy making money and satisfying customers since it was published in Jan.95.
  • Posted by Invisible1:

    Your biggest problem is that everything you stated in your reply was either wrong,missguided, or just a obnoxious opinion. Which, of course your entitled to. The RSAT has found it's place in Multi-million dollar homes all the way down to Starter Homes, and out of thousands of customers over 22 years, some who bought thier systems on refferal only without ever hearing it, I can think of only 2, maybe 3 that were dissatisfied. And NONE have requested a refund. Even most High End speakers cannot match that claim.
  • Posted by Invisible1:

    As far as your past experience, I stand corrected. I found it hard to beleive a lerned individual could stray so far off base. But with your reply, you've gone and done it again!
    You say that I.S.is more expensive.
    But you don't know this, do you? You dead wrong. A 10 room Invisible Stereo system costs $3990.00 ($399.00 per Room, installed w/volume control) and a 20 transducer Home Theater is $1995,installed. Most In-wall speakers that are worth considering START at $400.00 UNINSTALLED, and any good matched SS speakers including Rear Chan. Dipole/Tripole radiator designs will average $6-800.00 ea. And I hardly EVER use crossovers, the units have such a smooth response that in multible arrays, I can attenuate/accentuate the frequency response by varying the thickness of the Mounting board and just send the Full range signal to them.

    Need anymore real facts, or would you prefer to go on making up false ones?
  • Posted by Invisible1:

    This "technological innovation" rears its ugly head every fifteen-odd years.

    ////Maybe you were the one that had to raise your u__y head to see what was happening around you. The RSAT has been utilized in a big way by many industries for over 40 years. And in the largest of Custom Homes for over 20 years throughout the nation. The Mfg. 'DID' ignore Retail for OEM and Custom Installation, but only because....

    A.)More units per customer are sold that way.
    B.)Quality installations are more likely with trained installers.
    C.)A low profile meant less chance of a 'clone' being developed by another concern. Popularity breeds envy.


    The first time I saw them was about '65 in "Popular Science" or "Popular Mechanics".

    ////...and reveiwed by no less than Julian Hirsch in DB magazine.////

    Originally, they were designed for car doors [because 8-track music speakers were losing the battle against the overall volume of SSs, GTOs,
    SuperBirds, Mules with blowers, Cudas, and such].


    ///Thats just a plain, false statement. The Cardboard kick panels prevailent in Automobiles of that period was wholey inadaquate for the task, and never ever a consideration by anyone who was remotely familiar with the product. I know of NO instance where ANY product was installed in a car application prior to the Mid-70s. And then, Front & Rear windows were the accepted medium, and power was supplied most often by the first Fosgate 50 wpc Amp around '76'////

    The fundamental problems for dwelling installation WERE power and media. How much power does it take to vibrate sheetrock at 20 or 22,000 Hertz? LOTS! And, how can you get ACCURATE sound reproduction [20-20,000Hz] from an amorphous, wall-melange of sheetrock, brick, wood, paint, fiberglass, asbestos, dried pizza, pipes, nails, SuperModel posters, bookcases, conduit cables, cola-stains, electric cables, telephone cables, computer cables, poorly-framed diplomas, circuit boards, and, [insert personal collection here]? YOU CAN'T!

    ////I included all the above tripe just so everyone could witness a juvenile attempt to make a humorous point with NO knowledge to back it up. Any well made Home is a good prospect for the RSAT. And usually, a new home is just a little better suited than you clame too. As for power, 50 wpc minimum for a multi-room system circa 1968 thru 1975 was NOT out of hand, just not the type of gear that the 35 to 65 year old market who built those Homes had on hand. And Retail prices of such equipment were disproportionatly high. Though we worked with MacIntosh, Fisher, SAE, Marantz, and almost all the early overseas 'Big Boys' from Pioneer, Sansui, and such, thier prices limited the RSAT to a very select market. But around 1975, the introduction of 100 wpc Receivers by the several of the afforementioned that retailed for less than $600.00 broke open new markets for the everyday human who could be talked into spending those lessor sums. In fact, we placed equipment with customers that would NEVER have considered anything but a 8 Track/TV Console. Such is the influence and warm & fuzzy feeling our customers got when antacipating thier systems.////

    Note: When you go testdrive Bose 901 speakers, the room is EMPTY, and, the reflecting wall is covered with plexiglass.

    ////I love it! Bose 901s, and the current 'Lifestyles' designs are next to worthless if they cannot take FULL advantage of the 'Direct/Reflecting' aspect of thier design. And you better be positioned 'just so' to get the full benefit. In the real world, people do not have perfect cubes or rectangles for rooms, nor are the walls covered with Pexi-glass to enhance reflection. Any fool would pick up on such a biased way of demo-ing a product. But the there were a lot of fools back then, and still are, Mr. 901 owner. One aspect we can be thankful for. Bose's piss poor Bass response did help make the term 'Sub Woofer' a reconized phrase in the late 70s. (Though few could afford a $1500 Velodyne the size of a coffee table back then) Magnaplane and similar Electrostatic speakers also need assitance, but atleast thier dispersion characteristics were cabable of filling thier rooms on thier own merit. The RSAT produces such a wide dispersion,(up to 8' for each unit) and creates so few standing waveforms from of it's affected surface that reflection, reverberation, or unwanted absorbsion cease to be anywhere near the concern the conventional speakers have to deal with. These characteristics are what made esoteric designs like the Magnaplanr's so desirable...and so expensive.////

    Is YOUR room empty, and, the reflecting wall covered with plexiglass?

    ////see above/////

    [My 901s, on the top of a bookcase, delivered all their power into the wall, up the main apartment complex load-bearing beams, and, into an apartment three floors up and one apartment over ... ]

    ////Which is why the 901s were not that popular among those really in the know. Now the old 301s; there was a product that knew it's place....on the stage!////

    Unless the developers have some wonderful technical innovation [for $60?], this sounds very much like Silicon Valley snake-oil.

    ////Wonderful close. You sound like someone confused, scared, and uncertain about what is real and what is not, but compelled to rattle on about the subject anyway. I hope you got a little insight with all this and wish you well dispite it all. I have the feeling you and your dog need well wishing. ;-) /////
  • Posted by Invisible1:

    First, it's obvious that you don't understand that the RSATs mount on the inside of the sheetrock wall surface, not the outside. Either it's installed at the building stage or retrofitted.
    People who are interested in NOT SEEING ANY speakers are instantly in love with I.S., and people who own/build houses do not have the same mindthink as apartment dwellers/renters. A House wide a/v system, either zoned or a composite grouping of rooms, (even 16 in some big homes) is looked upon as an asset, a selling feature, and something that is used everyday, everywehere, throughout the house. I can't beleve that you totally ignorant of the Market out there for Distributed audio, and if your own tastes and budget scream,"I'd never want that many rooms!" at least acknowledge that not everyone shares your views. Like the last 3000 clients I've had, virtually all of which had Home Theater rooms, an average of 7 rooms in Audio, and EVERY ONE OF THEM HAD TRANSDUCERS IN THIER SHOWERS...For FREE! That's a perk that I've always offered any client that did at least 5 rooms in Audio that included the master Bathroom. NO other In-wall speaker can claim such 'per home' averages, and certainly not going back 22 years. It's all in the targeted market and your marketing skills.

    I Have two different offers so far from legitimate Magazines to reveiw Invisible Stereo. In extensive multi-room appa w/Home Theaters. Do you think that you could install them and hear them in thier best light, when installations in existing homes are so much more representitive of thier potential and capabilities? I have never touted the RSAT as a do-it-yourselfer product, but just as well I have not denied access to the product to those with an open mind. It so happens I'm in the process of acquiring a Dealer in K.S. MO Shold that result, I'll be there personally to train thier Installer/s and then you can check out I.S at your conveinence, which seems to be the only way it will happen. Or the invitation is open to spend $60 or so on gas, 9 hours on the road, and come see as many REAL installations as you can stomach, talk to real customers, some of which are 2 and 3 time repeaters, (they don't mind leaving it behind because they alway go a little more crazy with the next house they build.) and those who have had the system for over 10 years without a failure, and are still just as snthusiastic about telling newbees about it now as they were 10 years ago. can you think of ANY other speaker system that can hold such loyalty? It may not be for everyone, but it is a real option for the MAJORITY of people who belive in owning thier own homw and who do not want visable speakers. Is that clear enough?

    I'll email you @ your private address an perhaps this will get rectified. and for the record, I can't recall ever calling you dishonest, just someone who is too free with speculative claims of malfeasence and unwarrented and biased criticisims without even knowing the real facts or the product at all.

    Maurice
  • Note that he said, "Put a crossover in front of it to make sure you don't break the window"

    Still, even then, I wouldn't do it...

    This seems like something really shitty for high frequencies but great for bass.
  • I've always been interested in speaker design in general, do you know where I might be able to find information on design and construction of electrostats? (Or speaker systems in general, for that matter.)

    An open-source speaker design program would make for an interesting project...

  • Yeah, but think of the possibilities of quieting your room by producing white noise. Especially in the low frequency ranges that the wall board doesn't already dampen.
    ^~~^~^^~~^~^~^~^^~^^~^~^~~^^^~^^~~^~~~^~~ ^~
  • There are so many reasons why this is a bad idea. Most people I know live in rooms with parallel walls, so the resulting standing wave (depending on the resonant frequency of the room) would probably be even worse than with traditional speakers, not to mention aging plaster or sheetrock crumbling. Also, most people like to hang stuff on their walls, and I would imagine those little adhesive picture hangers or tiny nails many use would be woefully inadequate when the needle drops on that new Spice Girls re-mix. And then there's neighbors, if you have any, although I would have liked to use them in retaliation against the country music-loving "look, it goes to eleven!" sisters who lived upstairs & drove me nuts for months. Did I mention they will almost certainly sound like garbage?

    I can think of at least one album that would sound good though, and it's by Pink Floyd... (ducking)
  • Most audiophiles are over 30 and can't hear the full range that their speakers are capable of reproducing anyhow.

    Of course, there are exceptions to the rule. Like a prof I had at the UofC. Back in the early days of CD's, he could actually hear the frequency modulations in cheaper players. To fix it, he would encase the quartz crystal in many pounds of lead (I think) and bee's wax. He pretty much built his own CD players and converted many of his audiophile friends to them, at a time when audiophiles just snickered at CD players for their lack of decent sound.

    For those from the UofC, yes, I'm talking about Chris "Mr. Tangent" Walpole.


  • Why not just get some normal-ass every-day run-of-the-mill speakers?!? Is there NO GOD?!
  • I don't trust anything that has as badly designed a web site as that one. It hurt my soul to look at it.
  • A friend of mine made a "meditation chamber" with these sometime back in the 70's. I don't know anything about the older ones, though.
  • Audiophiles have been known to love old and outdated technology?

    I doubt that. If you look at the specs on that "old" technology so many high end audiophiles like (phonographs, tube amps) -- the specs on them are *nothing* like what was available in the respective technology's heyday. They are ultramodern versions of outdated technology. :) Kinda like souping up your 1.5 mhz Atari 800 to run at 500mhz.

    Either way these things sound like crap. Technology no one liked when it was new people will likely still not be liked now. :)

  • OLD technology (Score:3)

    by tgd ( 2822 ) on Tuesday May 11, 1999 @08:43AM (#1897649)
    21st century? What a joke. How come we keep getting essentially nothing but ads for lousy tech on here so often?

    I've heard units like these before and they sound like crap. Beyond the inherant fact that wallboard doesn't conduct sound that well and tends to be a very dampening surface, you'd have problems with resonance in the airspace behind the wallboard, problems with the point that the wallboard touches the joists in the walls.

    The only thing this sort of technology has ever been even remotely good at is providing a bit of rumble to people in their cars -- and even then, no serious auto audiophile would come near them.

    A company called Aura makes/made them for cars. Bass-only because they're at least smart enough not to claim that heavy surfaces like that can conduct and transmit cleanly the higher frequencies into the air.
  • I first heard about these 5 or 6 years ago back in the days of living with roommates. One of the two was a tremendous bullshitter and managed to acquire a demo of those type of speakers. The only reason he wanted them was to piss off the upstairs neighbor because he was a dick. Apparently they worked too well, because 7 days later, we got an eviction notice.
    But anyway, they cost a pretty penny back then, but now only $60. Definitely worth looking into now.
  • Most of you guys seem to be completely oblivious to the point that these are NOT primarily intended for multi-dwelling use. Outside walls have insulation that will baffle most of the sound coming out the back. If you look at these in detail, it is clear these are designed for single-dwelling, NEW construction.. Retrofitting involves ripping up a whole lot of sheetrock, and putting up new walls.
  • This is nothing new, they're just mainstreaming a product that has been used in shops and office buildings since the invention of the speaker.
  • One one-thousandth actually (one one-millionth is "micro")... So his computer was an 8 MHz machine. Nothing to get excited about, but it sure beats an 8 kHz clock...

    Steve 'Nephtes' Freeland | Okay, so maybe I'm a tiny itty

  • I've got a fetish for electrostatic speakers.

    You don't have to go to this extreme to get bass response from electrostats. Just take a look at Stax headphones to see this (www.headphone.com).

    Electrostats are essentially full-range speakers. However, at lower frequencies (wavelengths > 1/2 width of speaker baffle), the front wave cancels with the back wave. This is the reason that most speakers come in boxes. However, a box loads an electrostat too much, damping the motion of the diaphram.

    Basically, you simply need to isolate the back wave from the front wave. This can be done by mounting a small electrostat in a big flat panel. I've often thought about building some electrostats to mount between studs in a wall. This ought to provide enough isolation to allow electrostats to produce 20Hz sound.
  • Well, this speaker advertisement is full of feces. However, you are wrong when you say that sound pressure levels == volume.

    Check out: http://newport.pmel.noaa.gov/whales/acoustics.html #levels

    Sound intensity levels == volume, not sound pressure. If a transducer is a point source (conventional speakers simulate point sources), then sound intensity is roughly equivalent to sound pressure. However, with complex combinations of tranducers, you can have high sound intensity levels with low sound pressure levels (and vice-versa). We measure sound pressure levels only because it is easy to measure (simply measure pressure, and compare it to some reference). I believe that sound intensity levels require directional arrays of tranducers to measure, and are typically only measured when environmental regulations require them.

    If you remain unconvinced, go check out your local environmental laws regarding sound pollution. They have separate requirements for sound pressure levels and sound intensity levels.
  • Living in a small apartment in Amsterdam, I can imagine the joy of watching my neighbours in fury at the house resonating with the prodigy on a late drinking night with my friends....

    Sander

  • slashdot has been posting ads for quite some time.

    Ads for headhunter services, ads for books on Amazon.com...

    I wonder how much it costs to get a /. story-ad. :)

  • So, instead of the elephants upstairs simply pointing their speakers at the floor (no concept of bass, it seems), they can just stick these things on the wall and annoy the whole apartment block! Great!

    But seriously folks, what are the chances of these gizmos tearing the plaster from the wall? I mean, that sound has to come from somewhere = walls vibrating at high frequency. Or am I missing the point?

    Oh, nice web site too. From the "my kid can do better than that" school of design.


    (if this posts 2+ times, it's cos I got a "doc has not data" error).
  • Now you tell me! After running close to 500' of cable and knocking holes in my walls (dodging wife who wanted to knock a hole in my head!).

    This looks pretty cool, and I suppose will work in theory...Anyone want to give these a try and let us know?
  • Semi-true... The police came to reports from his neighbors...

    Hmm.. These would be perfect to duplicate that experiment, just toss a low constant 20hz tone into a beam in a building, doesn't have to be loud or anything... Hmmm...

  • Funny, I seem to see (and HEAR) LOTS of these driving through my neighborhood in the summer, usually blasting (excuse me, thumping) hip hop tunes at INCREDIBLE volume (and distortion) levels.

    Heck, I can even hear em indoors with the windows and doors closed. Maybe I've just stumbled onto this same technology and didn't know it...
  • Grin - see subj.
    And the probability that the neigbours will kill you - very high ;-)

  • Actually that would be using the same principal of the PZM (Presure Zone Mic).
    No, it wouldn't. A PZM doesn't rely on the resonance or movement of the surface it's on; in fact, it's best if it doesn't resonate at all. PZM microphones just get better base response on large surfaces because the surface will intercept the longer waves (rather than them going right around) and thus create a pressure differential in the gap between the microphone and the surface.

    At least, this is as best I recall. I've not been an audio engineer for almost a decade now, and I can feel my knowledge deteriorating....

    cjs

  • Wow, how much would that set you back?
  • I bet these bad boys would be a great device for monitoring audio in a given room... all you need to do is put them on a flat surface that can resonate easily... hook it up like a microphone and 'voila'.... just slap it on the back of a dresser mirror or something.... oh wit- i meant to post this on hackernews.com.... :)
  • The web site source has spoken. Accused me of making up false facts. I'm S-O-O-O surprised. Invisible1 [mailto], you've cut me to the quick... I must NOT have done those things I said I did... that's it -- it was all a dream -- a hallucination, yeah, that's it... [Forgive the sarcasm. The accusation of dishonesty pissed me off royally.]

    I'll admit a bias here. I've never heard an in-wall speaker or system that matched the quality of a similarly priced free-standing speaker. So I would not be at all surprised if your Invisible Stereo speakers sound MUCH better than other in-wall designs. But I'd be very surprised if any in wall system is cost competitive with well-designed free standing speakers. Now then, because of the accusation of dishonesty, I'm going to do my best to shred virtually every iota of Invisible1's post. Mostly from the standpoint of price.

    1. A 10 room Invisible Stereo system costs $3990.00 ($399.00 per Room, installed w/volume control) Two questions: (A)why in the h--- would I want to install speaker systems in ten rooms? What if I move to a new house? and (B)Assuming ten rooms, how many different audio feeds are we talking here? One high fidelity system? One per room? How do you prevent crosstalk, etc.?
    2. ...
    3. and a 20 transducer Home Theater is $1995,installed. Although I'm not in a position to spend the time or money right now to do so, if I was, I'd wager that I could put together a similar sounding system for around $1995, but I'd also buy myself a new DVD player, audio CD, graphic EQ, and speakers (surround) -- everything except for the amplifier. And STILL be able to move my system any time I wanted.
    4. Most In-wall speakers that are worth considering START at $400.00 UNINSTALLED, (see my inital comment about bias)and any good matched SS speakers including Rear Chan. Dipole/Tripole radiator designs will average $600-800 ea. I assume by "matched", you mean "pair". Your costs are about right. But if I'm building a pair from transducers on up? The finest free standing speakers I've ever personally heard were built [and are owned by an true audiophile friend] -- for a net component cost of around $700. About $200 more for the surround speakers, BTW] Returning to the idea of portability -- he's moved seven times since, and taken the speakers with him.
    5. I can attenuate/accentuate the frequency response by varying the thickness of the Mounting board and just send the Full range signal to them.I'll admit being confused by the mounting part of your comment. And I can see how different mounting boards would provide a smooth response. But does that mean I have (1) a wall made up of a bunch of different types of boards, or (2) drivers mounted to boards mounted to the wall? Option 1 isn't practical as far as I can see, and option 2 (which takes care of the portability problem -- unscrew the boards and take the drivers with you) doesn't address the fact that different frequency sounds would have to travel through two layers of wallboard, etc. A clarification here would be honestly appreciated.
    6. Backing up a little, you said that "and I hardly EVER use crossovers" The best speakers I ever designed (4 way, bass reflex, BTW) only REQUIRED one per cabinet. But it wasn't an inexpensive part of the speakers, even at that. (Note, I used two per cabinet in the final design. It sounded better.) Good crossovers aren't cheap. Especially -- which will bring me to my final point -- if the crossovers and drivers are to have adequate power handling capability.
    7. The IS transducers are rated at 50 Watts RMS continuous Music. At what efficiency? This is a key question: my own speakers are rated at about about 200 watts RMS per cabinet, with mid-range efficiency (92-93 db/w/m) I don't use all of that capacity most of the time, but when I need it (usually a movie soundtrack or symphony -- some Dregs, Yes, Styx, Journey, and other '70's and '80's rock) If the end Invisible Stereo product isn't at least as capable -- unless I'm missing something here, and I could be -- how in the hell am I supposed to enjoy the full dynamic range of a DVD movie or favorite CD-ROM?

    I'll put up or shut up now. Within the next half hour, you should be receiving an e-mail with info on where I live -- you let me know where there is a system nearby, and I'll give them a listen -- and with Rob's permission, publish my honest review here on /. [Note: I don't work for any stereo companies, so this will be an unbiased, listening test only.]

    You got game? I got ears. Let's put these to the test.

  • [Note: in "audio speak" a driver is an individual sound source -- often a speaker cabinet will have three "drivers" which show on the front - a large (bass), medium (midrange), and small (high frequency) 'driver']

    I don't claim to be an audiophile, but I've got both the math background and good enough ears to know when the math works and when it "just ain't so." This can happen in one of two ways:

    1. there's no way a design can produce a high quality sound, or
    2. spending more money won't dramatically improve the sound.
    From this background, let me tell you that as proposed on this web-site, it's not only unlikely but damn near if not impossible to design a worthwhile sound system using these drivers. Here's why:
    • Multiple transducers, are required for even moderate quality sound. With more than one of these so called "invisible speakers", there is no vibrational isolation between the low (bass note) frequencies and the high frequencies. Which means that even if wall board, plywood, etc. could accurately respond to the individual driver's frequencies, the vibrations from the low frequency drivers would muddle up the other frequencies.
    • (Quoting)...speakers by design focus their energies on creating high Sound Pressure Levels within a room to provide "presence"... This might be true for stadiums, theaters, etc. (large areas) but not the typical home system. he main requirement for good sound in a home setting is the ability to tune the system to match the acoustics of the room -- thus cancelling out the effects of standing waves, absorption of sound by furnishings, etc.
    • ...audio purists seek speakers with flat frequency response, non-directionality, and and efficient db-to-watt level. Wrong again. Audio purists are not THAT interested in efficiency, because most (but not all) efficient drivers have very uneven frequency response.
    • Different size drivers are better for different frequencies. This means that there is
    • no "one size fits all driver" that can match multiple drivers through all pitch ranges. Even the high dollar audiofile "flat" speakers usually have a cone-driven sub-woofer because the "flat" speakers can't move enough low-frequency air.
    • I'd rant for a while longer but here's a more practical way to throw this idea away -- what happens if for some reason you decide to move your home theater to erk -- a different wall, or a different room?

    • Note to Rob: rather than spending any $$ on these, buy yourself a 10 band stereo equalizer. It'll save you a ton of money and make any stereo speaker or system you'll ever buy better because with it and a little patience you can tune your system to the room .

  • I don't think I would like to live next door to the clown with these things in his walls. Can you imagine living in an apartment complex with people on either side of you playing different stations/cds. Seems like it would be worse than someone carrying a boom box down the street.
  • More junk science.

    Soundwaves in the lower frequencies are on the order of several FEET in wavelength. For the wall movement to have a measureable impact on standing waves it would have to be on the order of FEET!

    Even the highest audible frequencies have wavelengts on the order of fractions of an inch. For the wall movement to cancel potential standing waves at ANY audible frequency it would have to be moving 0.1 inches or more! And, the WHOLE WALL SURFACE would have to be undulating by at least this much, not a tiny area. Don't think it's gonna happen!

  • I'm bloody skeptical (Score:5)

    by Fish Man ( 20098 ) on Tuesday May 11, 1999 @09:44AM (#1897692) Homepage
    Having dabbled in speaker cabinet design, and designed a few PA systems, been a sound guy for bands, etc., I have a few serious reservations about how well these things would work.

    The biggest ones:

    1) Aren't the characteristics of the sound going to have huge dependencies on the construction of the walls, the size, stud spacing, wallboard thickness etc. If the wallboard is a little loose wouldn't it "buzz" against the studs? Would pictures vibrate? Wouldn't things like stud spacing, wallboard thickness, wood hardness (of the studs) and other factors affect the flatness of the frequency response. What about metal studs? What about lath and plaster walls vs. paneling vs. sheetrock etc. ...infinitely more construction based variables of course.

    2) There are several evidences in the advertising copy of junk science and BS double-talk. For example, the site claims that this technology eliminates standing waves.

    Standing waves are (almost) 100% a function of room geometry (primarily dimensions of the room vs. multiples of wavelengths, absorbancies of various surfaces in the room also come into play) and (almost) 0% a function of speaker design. This claim (and some others on the site) dump its credibility into the toilet IMHO.

    Bottom line, IMHO this system is likely to not sound very good at all in the majority of installations.
  • While on the topic of high tech speakers, have a look at these [209.84.43.137]. If I ever saved up a couple of bucks I'd get a pair, but since they are designed for music and not home theater, perhaps, I'd need 2 pairs, but what to do for the center channel?

    Anyway, anyone have a fetish for electrostatic speakers? I really like the idea, but too bad you have to go to this much overkill just to get them to have proper bass responce.
  • Comment removed based on user account deletion
  • Hey....what's wrong with doing a site in notepad? You can do anything ther eyou can do in any of yer newfangled composer programs, and the html is cleaner.

    ever seen the source of a page done on Adobe or Netscrape? it goes something like this on many a line:



    that won't happen in notepad (or vi or....)


    -Andy Martin
  • tags didn't show. oops. anyway, it basicall set center, bold, font size then turned them all off with no text in between.

    sorry.
    -Andy Martin
  • I'm gonna call BS on this one....


    -Andy Martin

  • And it caused an earthquake!!!
  • If you must have this, please allow me to highly recommend that you punch slightly larger holes in your walls (wife will persue only slightly more vigorously), and insert standard drivers. The advantage of having the vibrating surface not touch the wall, vibrate the air and thus the wall will reduce the gain, but give you the general idea. What I'm certain you'll find is that at 40hz and down it's just peachy. If I had to have this, I'd choose a new style of wall paper and replace the drywall between two studs with heavy mylar or some resilient plastic. Then the transducers might be just peachy, and the wife would get new wall paper in return for her patience.

    artpopp@gte.net

    --Windows NT and the Brontosaurus, what do they have in common?
  • Attached a coil to a column in his lab,
    the police station next door started to
    crumble.

    Or did I dream that?
  • Regardless of the sound quality produced by such as system, have any of you ever tried to hang shi^Heetrock? I can't see a wall lasting through more than a few day of heavy base before the nails start popping through. And how do they account for the various thicknesses of the board. This whole thing is a crock.
  • what?

    In regards to your "Audiophile grade speakers"
    1) one speaker can not duplicate the full range of sound heard by the ear at any sort of volume and without alot of distortion
    2) duh it costs to much.....so do Corvetts, hence only the rich and anal own them
    3) this post is a grate example...so is car audio ie MTX/Rockford Fosgate/insert big name here
    4) if your going to shell out 4 grand for a stereo, shouldnt it look like 4 grand?
    5) ports are more efficent than sealed enclosures
    6) Resonance is a very bad thing...its not music, and the musicians didnt want you to hear your speaker rattling.
  • First: boy does this site suck. Looks like a retarded 4 year old chimp on methamphetamines designeded this in the midst of a particularly violent flashback. In notepad.

    Second: The premise is silly. All of a sudden, they are able to turn my house into a finely tuned resonating cavity for the entire ferquency range? You must be kidding. Sheet rock doesn't resonate for just about anything. Well designed and well constructed speakers are expensive cause... they're well designed and well constructed.

    These thing an an affront to my own intelligence.
  • Well, as long as you like to listen to "mrf wrfn brpn mmm" ...
  • great. They tend to loose high frequencies and overall sound like they are covered with a thick blanket.

    The drywall in most homes absorbs most of the vibrations causing the tone. If you had sheetmetal lining your room, then yes, they might work better.

    But, it is a start.

    RB

    They don't look invisible to me :)
  • I got a set under my seats in the car. Unless you mount them into the floor, they just vibrate. They do work well and at least Aura says that they are for bass reproduction only.

    RB
  • The windows will shatter because they are pretty brittle. Once the frequency hits the resonance of the glass for a second, it will shatter. The walls are so anchored and screwed down, the resonance will affect a small area and then dissipate. The glass cannot do that.
  • The person that sent the link sells the stuff. Now I can see how these could be considered news for nerds or stuff that matters... But it is an AD!

    RB
  • Hmm? Glass On Golf Courses? The "glass" in the carts are usually lexan that absorbs nearly everything. The glass on the proshops is similar to auto glass, that is, it has a coating on it that will prevent it from going to pieces everywhere. It still suffers from the same harmonic resonance shatter. It just won't go all over the carpet when it breaks. But it will if the speakers keep sending energy into the pieces.

    RB
  • Ahh, if only they worked in cubeland..
    Then I could get this 200watt sub out from under my desk :)
  • The Golden Rule of buying stuff on the web: never buy anything off a webpage that looks like the HTML equivalent of a Home Shopping Channel ('Mike, I can't see those speakers AT ALL! It's AMAZING!').
  • Tube amps, point by point - I couldn't resist ::heh heh::

    Tube amps are:
    1. Heavy - yeah and? Are you in the habit of moving your system around all the time?
    2. Produce a lot of heat - so?
    3. Energy hogs - the overall power consumption of a modern-day tube amp only slightly greater than that of a high-end solid state amp.
    4. Never sound the same from the first turn on - neither do transistor amps, my friend. Though I'll concede you that tube amps change their sound characteristics to a greater degree than solid state amps over a given time period.
    5. Replacing tubes each year can cost a lot - can't argue that point.
    6. High levels of harmonic distortion - ahh, but the distortion that tubes produce is *even order* harmonic distortion, which is not nearly as harsh-sounding as the odd order distortion that is produced by transistors. In fact, even large amounts of even order distortion (1%-2%), do not add significant dissonance to an audio signal.

    Best possible scenario, IMO: a tube preamp used with a high-power transistor power amp driving a nice pair of floor-standing, full range, acoustic-suspension speakers = a little slice of audio nirvana...

    Another $0.02 tossed in.

    - STUMBO
    - It might look like I'm doing nothing, but at the cellular level I'm really quite busy.
  • Wow, did I just see you make a "Walsh" reference?! Holy crap! You must really be an old audio-geek!

    Takes one to know one ;)

    - STUMBO
    - It might look like I'm doing nothing, but at the cellular level I'm really quite busy.

  • Oh, and as for the 6 billion of you who emailed me to wish me birthday greetings, thanks, now stop!

    I guess Rob got /.ed. Kinda ironic. Anyone know if there is a mirror of Rob up?
    -NG


    +--
    Given infinite time, 100 monkeys could type out the complete works of Shakespeare.
  • Most personal home pages I've seen are better than that. That's pretty cheezy. I wouldn't buy anything from anyone with a page that cheezy.
  • I wish i had a pair of bill gates. So i could just listen to his BS all the time...

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