Eminent Tech TRW 17 Part 2

Bookmark and Share

by Josh Ray on October 31 '05

 Images Eminenttechtrw17

Welcome everyone who read our article over at OhGizmo! If you're not familiar with Sonic Flare, we provide daily updates on the wide world of high-end audio and shine a light on awesome gear from small companies who get overshadowed by the electronic giants (and, no, not all of it is insanely priced. We're also on a quest for killer budget gear).

Our post on the Eminent TRW 17 is traveling rapidly across the internet so we did some digging and found even more information on this beast to send your way. Read the rest of this article for pictures of installations, reviewers running for their lives and links where you can find out more.

[UPDATE: part 3 is now up]

Alright, so here's how Ultimate AV describes the TRW 17 experience:

"The big fan—er, sub—with a blade diameter I'd estimate at 17-inches was operational, and clearly produced audible, high level output to at least 17Hz. Below that its action was more obvious in the way it shook everything in the rooms and, below 10Hz, caused the rooms' walls to literally flutter back and forth like a sheet in the wind. Scary, but impressive."

And the chaps over at Stereo Times had this to say:

"The photo right shows the demo unit was in an adjacent room with a enclosure built around it leading to the room where I, along with maybe a half-dozen others, sat and listened in total amazement. The room's walls, pictures and window literally shook for as long as test tones played. I'm not talking of the type tones that sounded boomy, distorted or even fake..."

And here is the photo Stereo Times is talking about:


From the Eminent Technologies website, here is a picture of the TRW 17 installed in an attic and firing down into some lucky dude's listening room:

  Graphics Rwimage3

That's it for now. We'll keep you updated as even more information surfaces.


Killer. I don't have a basement, so I guess it's a no go for me, though. I wonder if movie theatres will start using these in their digital cinemas for better effect?
Will it rattle your house to pieces?
this is a joke. dumbasses!
No joke, I heard this thing at the Rocky Mountain Audio Fest in Denver last month. It is astounding.
Well, I would have to say we have a competitor in the world, however with the Bag End Subwoofer systems that are much more affordable, much smaller in footprint and will effectively go down to 8Hz we would have to say welcome to the low bass world. Anyone interested in discussing our extended low frequency products, feel free to go on line to: or call us at 847-382-4550 to discuss. Nothing in the world sounds better than a Bag End speaker, other speakers maybe louder but the box is soooo much bigger and no where near as tight. Have a great day! John
For most audiofiles, as the company rep noted here, other systems will meet their needs. What this system has is range, down to 1Hz. This is the kind of system for home theaters, earthquake simulators, and haunted houses.
Geez ... what a cheap shot the Bag End guy took! They might have good subs, but please ... this fan-sub is a whole new way of looking at reproducing low frequencies. Give credit, dude! It took a genius to think of this thing! What a wanker! Anyone interested in discussing John from Bag End being a wanker, feel free to go to or call him at 847-382-4550 to discuss the extent of his wanker-ness. "Have a great day!"
There is only one thing that I am finding hard to understand about this sub.... Bass from a sub is generally created by "compressing" the same air to a desired frequency. This would mean that this fan had the capability of compressing the air in an attire basement???? At what speed does the fan oscillate at? Something doesn't seem to add up here.
I don't work for Bag End, but they are phenom like speakers @ a great price -- I had planned on buying this new unit, but john reminded me about the bag end 8 hz at a great cost. Thanks for reminding me John. You saved my marriage!!
Anyone who has stood near an aircraft and a desktop fan will know those blades are too small. Clever idea though.
This technology break-through is amazing. And I thought the Intrasonix ContraBass was the shit..
This is not a joke - I had the pre runner of this for some 9 years now.. It produced a great sound and, was a little more compact see picture
It's like a helicopter tail rotor. A helicopter tail rotor spins at a constant speed. The pitch of the blade can be change almost instantly causing a blast of air in one direction or the other. This sounds like a good subwoofer design to me.
I would love to see the specs on the drive unit, the design is (pun) sound; rotational speed for the fan is most likely constant but I would love to know how fast its running; wondering how you would isolate the motor noise and how much overhead has built in torque wise, shifting the pitch (funny) of the blades will effectively shift the pitch of the audio effect but it will also generate a large amount of resistance and quite possibly some time shift on response on the heavier notes. making sense at all?
This defines a whole new meaning to the term "Nose tickling bass"
The concept is essentially correct in that sound is nothing more than the movement of air particles. I would think a fan the most obvious tool to implement this action, though to reproduce a 1 hertz tone requires moving a lot of air a long distance. A standing 20Hz wave is about 60 feet long, so a 1Hz would be several hundred. And it's not just a matter of installing the "sub" itself, you'd really need to calibrate the room itself with proper acoustics to prevent that even more extreme low end from going haywire. But then again, this is considering current traditional speaker technology. This thing might just be a whole different beast.
Hi guys! This idea is not really new, some years ago I read that some freaks were experimenting with creating low frequencies using ultrasonic interference (you know, when two very near audible frequencies are sounded, the whole sound "wobbles" with varying frequency, depending on the closeness of the frequency of the two component sounds). The same goes for ultrasonics, but you don't hear the components, just the wobbling, which is considerably slower tha the original sounds'frequency. It seems that this "ventillator fan" does the same job, but simpler: there is no need for high power ultrasonic tweeters. However, I would like to strongly dissuade anyone to experiment with very loud (high energy) infrasonics. Audible is OK, but the blood vessels resonate somewhere between 6-8 Hz, and you wouldn't want to get your arteries ruptured because of a very good audio experience... :-) the infrasonics can aslo cause depression, headache and other maladies. (in the second Warld War there was some secret experimenting with infrasonics, they constructed a concrete tube some 25 meters across, in which such infrasonic waves could be generated that they could kill a man from as far as 8-10 kilometres away). capt. Nemo
Wow, how'd you find out about those secret experiemnts, Neo? Were you there, or did some super secret spy come to your house to tell you?
It's like collective pitch on a helo. The blades turn around the motor axis as expected but they also rotate their angle reletive the the plane of rotation. This changes the way the fan compresses the air passing through it. How they keep this focused into a cone is what I don't get. 2na
What enormously bad form it is to advertise your product in a comment to an article about a competing product. I don't care how good Bag End products are, bad form is bad form.
He read it somewhere on the internet Doubter.
No, Nemo's correct, the Germans did develop a sound weapon in WW1. It's well documented in the classic 80s film "Biggles". I quote: "It's a sound weapon! They've developed a bally sound weapon!" Fortunately Biggles foils them by stealing a police helicopter with a PA system from mid-80s London, flying it in front of the sound weapon, and destroying it with feedback. (Yeah, there's some time travel involved there too.)
mmmm, I can see how it's do, and could be done differently. Thinking outside the box (pun)
The effect of 2 frequencies playing, only a few Hz appart is called 'beating'. People in the Middle East have used it for ages to communicate great distances by varyig the differed frequency. It somehow allows the sound to travel much further.
It might be bad form -- but it got them a sale! And saved my ($13,000 almost gone bad) marriage!
hmmm...Griz L has an interesting point about the length of the waves, but i think that the length of the wave has more to do with resonance than it does with the production of sounds. To produce a 1Hz tone, you would have to compress and decompress the air in a room once a second, and it would be far easier to do with a fan then a large diaphram. (Unless that's one REALLY large diaphram) Sure, it can reliably repoduce simple waves, but i would be interested to see how well it produces even semi complex waves (a square wave, etc.) I think this has applications for science and experimentation, but i doubt it will find it's way into many home theatres.
Is this an audio forum or a forum for recovering morons? "Anyone who has stood near an aircraft and a desktop fan will know those blades are too small." This is Moron#1, to make a realistic comparison, you would need to place the aircraft and the fan in the same room. This beauty is from capt. Nemo: "...(in the second Warld War there was some secret experimenting with infrasonics, they constructed a concrete tube some 25 meters across, in which such infrasonic waves could be generated that they could kill a man from as far as 8-10 kilometres away)." Nice try fish man. The sound pressure level required to "kill a man" at 10 km would blow apart the concrete tube killing all the "men" close to the device, and it would probably kill a few fish too! They may have tried this in WWII but they failed, yes they had morons in WWII also. Making any intelligent comment about this method of producing low frequency, high spl is impossible without either being given some technical data (re: measurements) or building one and generating the data independantly. For example: what is the frequency response above 20 Hz? Don't try to tell me harmonics won't have a role to play. How would you apply a filter to remove these unwanted harmonics? The answer is: you can't, unless you apply a sound cancelling technique which would require a separate loudspeaker, which, in turn would have to be quite large... even a moron should be starting to get the message now. This method of producing high spl at low frequencies probably works. Oh. one more suspected problem. Blowing air into your listening room from the basement or attic will play havoc with the rest of your system. Besides the fact that intermodulation distortion would be massive at all frequencies produced by your system, the un-conditioned air entering the room will cause discomfort and pain when paying your utility bill. Not to mention the fact that air density changes from unconditioned spaces will also adversly affect the sound produced by the rest of your system. What about the noise produced by the fan motor? How do they filter the back EMF so that your system power supply does not induce interference? Does the motor use capacitors to start? If so, bad news for your system... Does the motor turn off during quite passages or do you just have to sit there listening to the motor hum and fan blade noise? Starting to get the message? The message posted by Paul stating that "There is only one thing that I am finding hard to understand about this sub...." is not correct, Paul obviously misunderstands many things about this sub. First, you do not compress air to a frequency. Compressing the air in an 'attire' [entire?] basement is easy, partial compression is more difficult. Oh yes, the fan does not oscillate, its the blades that move, not the fan. In order to create more than one frequency the blades would have to rotate at different speeds relative to each other, otherwise only one frequency can be created, but this would cause the frequencies to be different in spl. This is impossible given the current design. You would need two fans running at different speeds to create the 'beating' effect. This device probably creates some kind of infrasonic effect, but is is most definitely not 'high-end'. Talk to me in six months, we'll see if this has taken the audio world by storm. As for the Hobbit from Bag-End, I'll have to check out his website, see what crap he's trying to push on unsuspecting morons...
Wow.... would love to measure this thing, only problem is my guess, huge distortion as is typical of nearly any of these types of devices trying to generate something resembling sine wave. I guess we are all very comfortable with double digit distortion at low freq in any case as this is very typical of nearly any conventional form of large cone mass bass generators. Keep your eyes open for a very cool press release on 14th or the 15th of November for a new infrasonic generator relevent to the aerospace industry (-; CLAS (Cascaded Linear Aray Subwoofer) is the name of the patent pending technology and it will change infra-bass as we know it... Sonicguru
Doubter, I am an officer (Captain, to be specific) of the Hungarian Army, and I did some research on the topic of electronic and other technological warfare and reconnaissance, this being my speciality...
Slimylimey, you wrote: "sound pressure level required to "kill a man" at 10 km would blow apart the concrete tube killing all the "men" close to the device, and it would probably kill a few fish too!" No, it wouldn't. How much energy do you need for a high-pitched sound to fracture a wine glass? Infrasounds travel much farther than audible ones, that's how elephants call to each other when not in sight range. And however strange it may seem to you, sound can be directed... furthermore, not the pressure kills the man, but the resonance effect in the blood vessels. (My nickname came not from the fish movie, but from my real life rank and my real name and is a lot older than these modern computerised cartoons :-))
This reminds me of the Leslie system on electric and electronic organs, intended to produce a subsonic volume variation, a tremulo (not a vibrato, which varies pitch). This device tries to do both volume and pitch, apparently. The Leslie is a rotating disk in front of a speaker, blocking part of its output part of the time. If you live in an Edison house (poured concrete) or something similar, this might not destroy it.
Ummm, I think there are a number of people getting the wrong idea of how this thing should work (or atleast one). IT IS NOT A FAN. If all this thing did was spin in one direction, you would get no sound, just good ventilation from one room to another...LOL. If this thing is real, then it would use a baffle.. from application suggestions, probably a wall between two rooms. Also, this thing would not function like any kind of conventional fan, it would have to function more like a speaker. A speaker causes sound by changing compression in a room. It does this by pulling and pushing air in a room. Did you get that? Pulling and pushing, not just blowing air in one direction at different speeds. At 1 Hz, for example, it would need to spend 1/2 second pushing air forward, and 1/2 second pulling air back out of the room, then the next 1/2 second pushing the air forward again, and so forth. This is to simulate sound wave, that has positive & negative compressions. Instead of seeing those "fan" blades spinning like a "fan", they would be vibrating very quickly back and forth in clockwise/counterclockwise positions, in order to cause the compression/decompression effect. For 20 Hz, it would need to change direction of motion 20 times in one second, for 100 Hz, 100 times a second. It really is a fairly simple concept. Instead of pushing/pulling air with a paper cone, it is using blades instead. The question in my mind, is the ability to create a motor that can change directions that lightning fast, over a large frequency range (1 Hz to maybe 250 Hz?). If they can and have created such a motor though, then in theory, it should work. Oh, and as far as only being able to produce one frequency at a time, it should be able to handle multiple frequencies just like any other subwoofer (providing that motor can deal with those lightning fast changes in direction mentioned before). As far as how good it really is in the real world? Geez, I don't know. I wouldn't have thought such a thing was possible, and I have no idea as to what the efficiency difference between a very fast switching motor and a standard cone woofer would be. If these people are telling the truth, then it must work pretty good.
Okay, before anyone really burns me on here, I just read the write up. So this thing somehow works by changing the pitch of the blades?? I'm not sure which would be more mechanically difficult, to produce a strong electromagnetic motor with a very light weight, but strong shaft & blade, able to deal with the stresses of changing direction at that kind of speed, or trying to wire in tiny motors inside the blade hub, so the blades can swivel to either suck or push air, at different amounts & frequencies, at lightning fast speeds. If it works, I'd love to see a demo of the thing.
The intertia is the devil in the case of reversing rotation... We used the pacific scientific low inertia motors in many different designs and they were also used in the aformentioned Contrabass and the horn loaded tech7 bass cabinets by Danley's Servodrive company but the limit as was determined was the mass at space distance from the center of the shaft which Tom Danley engineered past in the pancake piston design as used in the two models above but was stricken with in the case of the vane servo designs AKA : phoenix gold Cyclone product. the vane area and loading actually works OK up to 45-50hz but these units were plagued with in-efficiency and worse (uncoated Neo Magnets in the armature) which decomposed and grew hair faster than your average Viking Woman. I think the arangment has merit but not 13k worth of merit... If they are interested I would be happy to Do a third party TEF measurment session with one of the devices to get to the real performance criteria. My guess is the units would be far from linear across it's useable bandwidth based upon the the mechanics of the beta capable mechanism which has to be similar to the turbo-prop style actuation or that of the aformentioned tail rotor from your favorite Bell/Sikorsky product... I say we Horn load it (-; Sonicguru
cool. why can't a fan blow and suck equal amounts of air to and fro, just like a loudspeaker? looks to me like: the blades are balanced so their angle can be modulated with minimal force from their actuator. they have symmetry because they both blow and suck. in helicopter terms, this device needs 'collective' (for frequency and amplitude) and 'throttle' (for overall volume) controls only. if the designers were smart there are no rotating electrical contacts. the blade angle is controlled like a helicopter collective and the actuator is a voicecoil that moves a sleeve surrounding the motor shaft. The blades are returned to max minus by springs in the rotating hub, held at zero by a constant pressure on the 'collective' created by a constant voltage on the voicecoil (a DC offset), and modulated between max minus and max plus in the usual manner. what do y'all think? should i do some actual research first, or, as seems to be tradition here, go ahead and hit the Post button? this is totally fookin cool and i want one.
Fish-Man, You’re getting confused with low frequency sounds in water. Lesson #1: Sound is nothing more than varying pressure(s) traveling through some medium like air or water. Lesson #2: When the wavelength of a sound is greater than the width (or diameter) of the device producing the sound, the radiation pattern is omni-directional, commonly known as 4 pi radiation pattern. (Which is why low frequencies tend to be difficult to locate precisely in space). Lesson #3: If we assume that it takes 10 watts to produce 90dB spl using the concrete tube, you would need about 167,772,160 watts to generate 150dB at the distances needed, which is what it would take to kill man or fish. That’s 219,597 horsepower. The spl at the tube would be about 156dB-160dB, which would definitely kill the horses if they were providing the power! Glasses break when their resonant frequency is excited, the concrete tube you refer to does not shatter by having it’s resonant frequency excited, it is just the absolute pressure levels that would be required, that will shatter the tube, remember, 219,597 horses can do a lot of damage! Different organs in the body resonate at different frequencies so you would need to ‘target’ certain organs, but you still need sound pressure level to get the organs to start resonating. Many everyday things (cars hitting potholes, falling items, waves in water (you are probably familiar with them) generate infrasonic frequencies, but this does not seem to have killed many people as far as I know. Yes you are correct, sound can be directed, but… the device generating the sound needs to be wider than the wavelength of the frequencies being generated, otherwise the sound is omni-directional. To generate a frequency that is directional at 10Hz would require that the device be at least 112 feet across! I don’t know very much about how elephants communicate, and I am very surprised that you do, being of the sea, so I won’t comment on that. One more thing, if anyone is interested I can provide a sub-woofer just like the fan-woofer, for about $5,000. Let me know if you’re interested and I’ll remove it from my attic! $13,000 sounds like a lot of money to pay for a 1hp motor with plastic fan blades, but I suppose there’s no helping some morons. The bottom line here is: before making statements of a technical nature, gather your data and make your assumptions based on that data, not on some romantic notion that you have in your gut. Please excuse the pun.
This is good entertainment... the comments are definitely as interesting as the device. Now, I am not a physicist, nor a physician, but I did see an interesting episode of "Mythbusters" where they attempted to prove (or as it turned out) the "brown tone" theory - that is that there is a certain resonant frequency that would trigger a spontaneous bowel movement. They surrounded the subject with Meyer concert subs (supplied by Meyer and operated by audio guru Roger Schwenke). They generated some pretty stunning spl, but were only able to accomplish "mild disorientation", and not any involuntary reactions. I am always suspicious when I see a device like this with no tech specs or other supporting information, but the theory is not unsound. I found it a bit of a forehead slapper that it makes sense to move air with a fan, as really that is all we are doing with the cones of those speakers anyway, right? And the good news is that I find it hard to envision the the fan itself could be inadvertently taken out by some stray DC :-) - although I don't know about the actuators that modify the pitch of the fan blades... Using a motor to provide sub is not new (anyone remember Servo-drive subs??), but in those cases they were _great_ at providing truly astonishing low-frequency, but that astonishment fell off quickly as the audio moved into the audible range... by design they (and this, I believe) can move large amounts of air at low speeds, but most of that would be inaudible, but impressive if the _goal_ is to shake the pictures and windows... unfortunately most productions are recorded and processed without much mind given to what is happening below 20Hz, much less anything remotely "artistic" happening down there (in fact a lot of mastering facilities - especially if the person doing the mastering is "old school" - will filter below 20Hz - "saving" the energy expended by your system for something you can hear - why amlify 10Hz if you aren't going to hear it?) Then there is the whole issue of coupling the device to the environment... There seem to be a lot of theory-presented-as-fact (in both the article and the comments), but the idea itself is not outrageous, but I would find the practical implementation questionable.
So, wait, I'm confused. Can I use this fan to kill a man at 10km? Will it save my $13,000 marriage? Is John from Bag End a wanker?
I'd say this is a very interesting idea, how well it can reproduce complex tones is probably a totaly differnt thing... But, I bet this thing would be fun in a big dance club ;) People who doubt the negitive effects that 'resonance' can have should read about some of Nikola Tesla's experiments.
I don't think this is an issue of reversing the direction of rotation of the fan. Looking at the animated gif, it seems that the shaft of the fan pulses in and out, perpendicular to the blades of the fan. When the shaft suddenly jerks in, it torques the blades so they move air in one direction, when the shaft jerks back out, it torques the blades in the other way, moving air in an opposite direction. This would mean that the huge motor would be able to attain really high speeds, and the huge angle the blades are bending due to the very sudden in and out motion could generate a load of pressure. It would be like using a desktop fan with loads of power, spinning blades turned at a 45 degree angle. The angle of desktop fan blades is really small, since the motor is relatively weak. The deciding factor is how fast the blades can spin, and how much of an angle you can generate in the spinning blades when the woofers "cone" pulses.
I dont understand why people are having so much trouble beleiving in this?? With the blade area that this thing has, it would not need to spin very fast at all in order to produce significant airflow.. so say it only spins at a few hundred RPM ( or much less) the piston in the shaft that varies the blade pitch will not have much work to do other than the wind resitance trying to bring the blad back to 0 degress pitch.. inertia will not be as big of a problem as on teh servo drive and cyclone subs as only the pitch is changing directions, not the entire fan.. And the amount of air entering and leaving the enclosure will not be that miuch in the scheme of an HVAC system..
just stopping by to read and by the power of google, found some interesting links: In any case, as I have not fully read everything in these links, nor can I say these are necessarily "credible" sources but they are interesting reads none the less. I hope this will help to at least dispel some of the tension present in this forum. :)
i don't believe this shit...anyway...supose it don't need for your usual listening to music a woofer such like this...but i guess there are some people who want to see their house walls crashing without a "hearing" reason because like it is said....human hearing is rated from 20 hz not from just one...regards from Romania...see ya all
who ever says this is a joke one more time is a cvomplete idiot, yes i did say idiot, ---i thought my heart was gonna stop because the vibraationss hitting my body as amazing!!
hahahahaha this is bullshit hahahaha.$13000 for a fan hahaha i kool with my pioneer....
This is a clever simple device. A conventional cone pushes and pulls air. This rotor(not a fan) does the same thing. A 17" cone has a predetermined surface area. The functional efective surface area of the rotor can be increased or decreased by increasing or decreasing the speed of the rotor. It's a simple concept. Changing the angle of the rotor can be accomplished in the same manner as you'd push and pull any cone speaker. This rotor gives you a huge suface area to work with. We aren't trying to kill fish or people here. Kudos to the inventor.
"I don't work for Bag End, but..." Hi John.
I like kitty
If you want to see more info and specs about this rotary subwoofer go to: I wonder how it would play very loud and hard music like thunderdome. For the people who don't know thunderdome, here is their website:
Really john? A homo? You know, 70% of people incarcerated for crimes against a homo, were sexually aroused when shown nude pics of people of the same sex. Could this mean that your a self hating homo? Perhaps. But i just recommend going and killing yourself if that’s the most productive comeback that you can think of, i mean at least try to be original, unless that’s out of the scope of comprehension for you. Have a nice day. And this seems cool, if its real or not i don’t care, its a neat idea.
Can one of these be hooked up to a 1,600W bass amp head and not harm anyone at extreme volume? That is all I want to know. I play extreme metal which may put me down already but, i have an interest in pushing the boundaries and you are the only firm who have got my frequencies right. We also have a very high rated guitar amp. We just need our bassist to match it. Can you help us? Cheers.
Has anyone tried the concept out with a centrifugal blower? Fans aren't too good at creating pressure drops...they're a good deal open area so the air can backtrack between the blades if it sees flow resistance.