new subwoofer design with 1hz-30hz +/-4db

[anotherid2lose]

Has anybody ever seen this before?

http://www.rotarywoofer.com/

Specifications:

Amplifier Requirement: 200 watts @ 8 ohms

Impedance: 8 ohms 0Hz - 40Hz

Frequency Response: 1Hz – 30Hz +/- 4dB

Suggested Crossover: 20Hz @ 18dB/octave

Sensitivity 90dB 1 watt 1 meter @10Hz

Maximum Acoustic Output: >110dB between 1 and 30Hz.

Distortion: Typically 3% or less between 1 and 30Hz @90dB

Warranty – 3 years parts and labor

 

[ptalar]

Looks like something dangerous to have around the house with kids. I think it is a niche toy for some who really need to hear at low frequencies (below 20Hz). If it does what it claims it does.

Too much too fast for design evolution. I am not sure it is ahead of its time. It looks like it could use some design refinement.

PT

 

[j_garcia]

This has been discussed here more than once already.

 

[billnchristy]

anyone remember this:

http://www.phoenixgold.com/webfaq/cyclone.htm

The instructor at my audio school had 15" servos in his accord, that puppy played clean to 10hz...good enough for me.

They say the space shuttle makes 1/4hz tones, until they reach that they can keep their finger choppin' death fan...

 

[Sheep]

Looks like something dangerous to have around the house with kids. I think it is a niche toy for some who really need to hear at low frequencies (below 20Hz). If it does what it claims it does.

Too much too fast for design evolution. I am not sure it is ahead of its time. It looks like it could use some design refinement.

PT

You don't exactly just stick it in a corner, it has to be build into the walls and have its own enclosed space. Otherwise its just a fan.

SheepStar

 

[JAD2]

I think it is a niche toy for some who really need to hear at low frequencies (below 20Hz). If it does what it claims it does.



PT

Nobody can hear below 20, 30-35 would be pushing it. All your ears can do is feel the pressure waves or your body and its vibrations into things!!

 

[Buckeyefan 1]

You don't exactly just stick it in a corner, it has to be build into the walls and have its own enclosed space. Otherwise its just a fan.

SheepStar

Well, it's a pulsating fan (oversized voice coil and magnet) with pitching blades and a massive motor. It's a neat design, adding extreme air pressure to a moving "blade" driver.

Check out this design.
http://www.betteraudio.com/geolemon/servoproject/

Here's how to get the rotary sub to work:

 

[billnchristy]

That enclosure is HUGE!

You could solve the homeless problem building a few of them and putting them in parks.

 

[ptalar]

Buckeye,

Is that your project? Do you have a wife? I would be out on my a_ _ if I had that big thing in the house. Its bad enough the ragging I took when I snuck the SVS PB12-plus/2 in the home theater room.

If the rotary subs need housings that big they don't seem too practical. I understand they are ususally installed in compartments in the ceiling or wall but that is not WAF friendly. My wife does not want her walls carved up with HT equipment.

I learn something new every day on this board.

Phil

 

[Buckeyefan 1]

Phil,

LOL... That's not me. I got that off the net. Never would I (even if the wife allowed me) put that obstruction in my living room. Now a Plus/2 - absolutely. They make great end tables.

 

[billnchristy]

You know, the more I look at that, the more it looks like a hotel room.

Scary...I wonder if they know he took the door off!

 

[bandit]

I thought I'd seen it all... has anyone actually heard this thing work? It isn't clicking with me.

 

[Mark Seaton]

Seen it, measured it, heard it, experienced it. It works. It has install and cost complications.

There was a long thread at AVS about the test/demo install that a friend in N California asked Bruce Thigpen to set up in his quite impressive, dedicated home theater. At minimum it made an undeniable arguement for the added value of extending a system's response into the single digits with significant output.

 

[j_garcia]

Nobody can hear below 20, 30-35 would be pushing it. All your ears can do is feel the pressure waves or your body and its vibrations into things!!

About 22Hz it starts to reach the point where it is more vibration, but 18Hz still has a sound that is fairly audible (to me anyway). Hearing is not the only aspect of sound; vibriation is a big part of it, so I don't get where you're going with that.

 

[billnchristy]

There is no doubt that feeling it is cool. My instructor said another set of 15" servos in his car and you could cause internal bleeding...neat.

haha.

The pressure wave at those low frequencies is something else.

That thing just seems impractical...now if I rezoned a church and had the HT in the main room...maybe.

 

[mike c]

Seen it, measured it, heard it, experienced it. It works. It has install and cost complications.

There was a long thread at AVS about the test/demo install that a friend in N California asked Bruce Thigpen to set up in his quite impressive, dedicated home theater. At minimum it made an undeniable arguement for the added value of extending a system's response into the single digits with significant output.

question is ... was it worth it? (was the feeling of single digit freqs. worth installing something like that)

 

[greenjeens]

It's a pleasure to see something new, must have been like this when there was still so many fundemental properties to discover and a well educated man could stay on top of all the new discoveries, if not participate actively in them!

Forgot who said "audio should be fun".

A Sub-Subwoofer!

What horsepower rating is that motor?
How fast is that thing turning? Looks about twice the size of the 1HPs in my spa!

The explanation indicates a vari speed controller.
Must be for adjusting frequency range or would that be the volume?

Anyone have an idea as to what the general principle being used here is, to create, transfer and modulate LF sound waves?
Does it work by transfering the sound vibrations to the spinning rotors and then the small waves, started in the blades, are amplified in the box/through the air?
Is the fan pressurizing the box??


Not so strange... when a wire coil with a magnet inside, with a silk cone glued to the end, placed inside a box, has been the only analog sound "motor" to survive for 75 years as the sound reproduction device of choice, in the digital age... now that's really wierd


I'd like to see the demo song playlist first, the one with all that hidden LF info. That's got to be one strange playlist!


This device certainly looks capable of "unveiling the sound"...and blowing it far away or tearing it off in tragic accident...

Imagine picking up a whole new bunch of information, hidden within our ordinary recordings? Akin perhaps, to leaving magnetic tape recorders on and recording, those "Voices", too faint for normal hearing... from the "other side"?

But at 10hz wouldn't it be more of a wave touching you, than a sound?
Could potentially cause any low frequency acute, zoo Elephants, to prick up their ears, someone should keep an eye out


Are we having fun yet?


-
Dave

 

[arnar]

Anyone have an idea as to what the general principle being used here is, to create, transfer and modulate LF sound waves?
Does it work by transfering the sound vibrations to the spinning rotors and then the small waves, started in the blades, are amplified in the box/through the air?
Is the fan pressurizing the box??

The fan turns at constant-speed. The pressure wave is created by changing the pitch of the blades, so they alternate between blowing air in and out of the box so that the air-pressure in front of the fan oscillates. See the explanation at http://www.rotarywoofer.com/ and http://www.eminent-tech.com/howitworks.htm

Changing the fan-speed would (presumably) change the volume, the faster the fan moves, the more air is moved by a given pitch of the blades.

I'd like to see the demo song playlist first, the one with all that hidden LF info. That's got to be one strange playlist!

As noted on the page I linked above, currently used microphones capture those low frequencies so chances are that your DVDs already containt that LF info. Examples mentioned are the pulses of a helicopter blade (4-5 Hz), rumble of wind etc.

Arnar

 

[Mark Seaton]

question is ... was it worth it? (was the feeling of single digit freqs. worth installing something like that)

The benefit to the listening experience was significant and something I think is worth persuing. Heck, the experience spurred me to go back to an idea I had sketched up before but not gotten around to building up yet. I personally think there are other ways to get a good likeness to this device in closed rooms without spending >$10k. We'll see soon enough.

Being "worth it" is a matter of perspective. If you had a crawl space, basement or attic adjacent to a theater, this would have no intrusion to your space and be simple enough to install or have Bruce's team install for you. The big boxes shown in the pictures above were used to convert a hotel doorway (of connecting rooms) to a baffle/manifold for a demo at an audio show. The manifold is needed with ~3 bends and a bunch of fiberglass to attenuate the self noise of the motor and the blades.

Master & Commander and SpiderMan 2 were quite something to experience with this device.

 

[JAD2]

About 22Hz it starts to reach the point where it is more vibration, but 18Hz still has a sound that is fairly audible (to me anyway). Hearing is not the only aspect of sound; vibriation is a big part of it, so I don't get where you're going with that.

All sound creates some sort of vibration.
Good child ears can actually audibly hear down to just under 20hz at adulthood and older it begins to rise rapidly depending on what things ones does thats noisy.
What I was getting at, is why all this fuss about getting AUDIBLY lower??? First allmost all music will never ever get anywhere close to this low, secondly, for the majority, you CANT HEAR IT, only feel it. 20-30hz audibly is more than far enough, but then you would really get away from audibly creating the sound then going force air movement and vibration creation.