This is way different - Rotary Vane Transducer

[Filmboydoug]

At first glance I thought this was a fan to cool a subwoofer amp, but this is either the transducer, or they still have an April Fools joke page on their website.

Has anybody heard one of these?

Here is the website

http://www.eminent-tech.com/main.html

From the website: On the other hand, the rotary woofer has enough acoustic output to move a open door back and forth .5” between 1 and 5Hz! It has enough output to find resonance frequencies of walls and ceilings in a room. It requires no equalization to achieve flat response to below 1Hz.

Eminent Technology’s founder, Bruce Thigpen has invented a new type of loudspeaker, The Thigpen rotary vane transducer (patent pending).

The transducers sound originates from rotating vanes or surfaces that change pitch in response to the audio input signal. The advantages are improved impedance match with the air, high potential conversion efficiency at low frequencies, low distortion, a very high theoretical limit for acoustic output with a small transducer, and infrasonic response to DC.

 

[Filmboydoug]

Here is the fr graph.

 

[Kencat]

Man, that's what you call thinking outside of the box !!

At first look it sure does look like some kinda joke, but it is there on Eminent's web site. I'm still skeptical...sorta....I think ?

See the price ?? 12,900 $$$ That's one expensive fan. Could take HT to new realism heights though.....you get the hurricane force winds blowing in your face along with unhearable infrasonic sound and they could even hook up a water spray system so you can really get wet in the storm sequences.

Sure would be interesting to read some "independent" reviews of this.

 

[rylos]

Oh great! Now we're going to see articles about how your sound can be improved by using $2,000 premium exotic materials bearings...

 

[Filmboydoug]

Good points.

Man, that's what you call thinking outside of the box !!

... but it is there on Eminent's web site.

Thats whats freaking me out. Eminent is as legit as they come. It's not like its some anonomous DIYer's site.

See the price ?? 12,900 $$$ That's one expensive fan.

It would cost ya alot to have a capenter build an infinate baffle in your attic too!

 

[Rockmonton]

hmm, i wanna DIY this one without even seeing the device in action, anyone wanna bet i can do it?

 

[Charivari]

I wonder why someone hasn't thought of already doing this with some variable pitch propeller from an airplane. Who needs a little motor that looks like a suped up fan to do a measly 95 dB when you can get who knows how many dB with a many feet diamater propeller.

At any rate, I thought rotary subwoofers have already been available for several years and at a lower price. Though, I think those were a little less conventional in design than this Eminent driver.

- JP

 

[Charivari]

Dern it. Everytime I see something like this, I get to wondering how it works and then have to try to deduce some less expensive way to achieve the same result. :scratch2: I think I've possibly come up with a possible DIY solution.

Variable pitch props have been in use for decades (originally envisioned as early as 1871 for ship propellers) to improve thrust efficiency. All Eminent has done is figured out a way to do the same on a smaller scale with a higher rate of change than the hydraulically driven systems found on airplanes and ships.

However, model airplane ethusiasts have desired to apply this principle to their RC airplanes and have done so thanks to the zeal found in hobbyists. There're now even commercial products available to do this.

So, I would think it'd be possible to DIY this Eminent driver by adapting the principle found here to a larger, low RPM, high torque motor with stronger blades, of course. Instead of having a servo control mounted on the rear, could not a traditional, but stronger subwofer voice coil within a magnet behind the motor be utlized? The voice coil would need to rotate, of course, but if the coil were made extra long with a pir of broad terminal surfaces with associated brush contacts, as with any well-built electric motor, the whole thing could rotate and pulsate as needed. Thus, the pitch of the blades would be changed by the voice coil to match the signal.

What do you think? Could it be done? I would think so and for a whole lot less than than $12k, but the sound quality is another matter.

- JP

Edit: Ack, I messed up a bit. The motor would have a hollow shaft for the rod attached to the voice coil to run through. A bearing would be at the end of rod so the voice coil need not rotate. This is much simpler to do and probably more effective. Then, a traditional subwoofer voice coil and magnet should suffice, provided the voice coil can be mated firmly to the rod involved and have a strong enough spider to resist and loads caused by air resistance on the blades.

 

[M Jarve]

Car audio company Kicker tried this about 7-10 years ago. I remember seeing a brief snipette about it in Stereo Review (when it was still Stereo Review). Basically a novelty unless someone has use for frequencies below 5Hz.

If I recall, their version only cost about $1999.

 

[Mike Gibson]

I wonder if it hums like a Mazda RX-8?

 

[gonefishin]

That is cool!


Here's some more cool SUb stuff The most impressive description of a house breaker sub, that I've heard of, would be by Tom Danley. He describes the sub as being able to produce high DB response down to DC (0Hz). He also states that 3Hz becomes audible at levels 122db and higher. Although, I'll admit...this wouldn't be your conventional home audio product 3Hz audible at levels over 122? Youch

click here for the link to see his description at AA.

click here to read the patent on the Servo valve loudspeaker. Actually, if you want to...you can do a patent search on Danley. You'll come up with some cool reading material.

For pure spl, he also made a siren for cleaning a baghouse that would produce a 300Hz signal at 150db.