Rotary subwoofer? Is this for real?

[GeorgeWalk]

This guy makes a rotary subwoofer (looks more like a fan attached to a subwoofer). Some of his comments are interesting:
"This is the most useless thing I have ever built."
"I may use it only once a year to impress friends."
"Unnecessarily expensive braided cables."

 

[fpitas]

They are good if you just have to feel the chopper blades whirling past you. Commercial ones are available.

 

[voodooless]

Yes, they are real and are excellent at ultra-low frequencies and massive SPLs. I saw the video a few days ago, seems like a pretty cool DIY project

 

[egellings]

This guy makes a rotary subwoofer (looks more like a fan attached to a subwoofer). Some of his comments are interesting:
"This is the most useless thing I have ever built."
"I may use it only once a year to impress friends."
"Unnecessarily expensive braided cables."

Unless the fan is mounted so that it rotates flush with a wall that has a hole just large enough for the blades to spin in, that fan will add nothing to the bass at all in free air.

 

[fpitas]

Unless the fan is mounted so that it rotates flush with a wall that has a hole just large enough for the blades to spin in, that fan will add nothing to the bass at all in free air.

It's true the ones I've seen were mounted that way.

 

[DVDdoug]

seems like a pretty cool DIY project

It looks like a difficult DIY project!

I didn't watch the video but this is from the webpage for the commercial version:

A motor controller and electric motor rotate a set of blades at a constant speed. The rotary woofer pitch mechanism uses a conventional voice coil and magnet assembly. This is connected to your amplifier to pitch blades in proportion to the applied audio signal. As the blades pitch while rotating a pressure wave is generated, the degree of pitch controls the amplitude of the pressure wave. Air is allowed to transition through the blades. Thus oscillating the pitch of the blades creates sound while they are rotating .

So you need a mechanism that connects the voice coil to all of the blades, and that mechanism needs to be smooth, quiet, and efficient... while the blades are rotating.

And once you have it, it needs to be mounted in a wall with another room (or perhaps a large closet or garage) as a "speaker cabinet".

 

[antcollinet]

It looks like a difficult DIY project!

I didn't watch the video but this is from the webpage for the commercial version:


So you need a mechanism that connects the voice coil to all of the blades, and that mechanism needs to be smooth, quiet, and efficient... while the blades are rotating.

And once you have it, it needs to be mounted in a wall with another room (or perhaps a large closet or garage) as a "speaker cabinet".

Helicopter collective mechanism seems to be what he is using. And he uses "the outside"as the other room.

 

[Andysu]

Helicopter collective mechanism.

get some cheap hot glue a larger cone what ever woks and 18" turned into 80" and with other d , should produce larger air wave or buy a ac cooling fan , no don't need snake oil sub fan that is going to be noisy

 

[hex168]

Eminent Technology makes one:

Eminent Technology: home

 

[tknx]

I just watched this too!

Frankly I would love to see this tested with 50hz or audible audio. Do you cross it over to a regular subwoofer at some point? Also the device itself seemed quite loud.

It is a shame that Eminent has so massively overpriced this device to prevent any sort of real adoption. I have been debating between upgrading my HT subwoofers or going crazy and doing infinite baffle on the floor into the crawlspace below, but if I could justify it, I would absolutely look at a rotary subwoofer.

 

[fpitas]

I just watched this too!

Frankly I would love to see this tested with 50hz or audible audio. Do you cross it over to a regular subwoofer at some point? Also the device itself seemed quite loud.

It is a shame that Eminent has so massively overpriced this device to prevent any sort of real adoption. I have been debating between upgrading my HT subwoofers or going crazy and doing infinite baffle on the floor into the crawlspace below, but if I could justify it, I would absolutely look at a rotary subwoofer.

I get the feeling it's really for 20Hz and below.

 

[antcollinet]

I get the feeling it's really for 20Hz and below.

Me too.

I very much doubt that the mechanics will work even as high as 20Hz. The inertia will be far too high. I note that in the video he didn't go higher than 10Hz.