CurtPalme.com Home Theater Forum

**AnalogRocks** · Posted: Mon Nov 17, 2008 12:45 am Post subject: Worlds most powerfull subwoofer

http://www.ohgizmo.com/2005/10/31/worlds-most-powerful-subwoofer/

greg_mitch · Joined: 03 May 2006 Posts: 5321

They would be interesting to see and hear in real life.

Many threads over at AVS on them. I believe it is spanky ham that has first hand experience with it?

Very specialized room design though.

**AnalogRocks** · Posted: Mon Nov 17, 2008 1:14 am Post subject:

Looks like a 1940's fan to me.

greg_mitch · Joined: 03 May 2006 Posts: 5321

True. Come up with a bigger motor and figure out how to coordinate the variable fan blade pitch with low frequencies and you could start selling those!

lostmandan · Posted: Mon Nov 17, 2008 5:21 am Post subject:

Hmmm.. $12,000?

If only I could find someone who was actually selling one of the Clark Synthesis Tactile transducers at a price I could afford. Heck used would be fine even. Unforunately the TST329 looks to be $315 everywhere and that is a bit more than I can justify.

I've never heard one in action but I have read that bolting one to the bottom side of a deck can avoid the need for outdoor speakers - it can reproduce the audio spectrum fairly well.

nomadII · Joined: 16 Jun 2006 Posts: 252

Apparently a whale can hear that Eminent Technologies sub from 3 miles!
Now that is not neighbor or structure friendly!!

**AnalogRocks** · Posted: Tue Dec 09, 2008 2:54 pm Post subject:

jask · Joined: 17 Mar 2006 Posts: 10165 Location: kamloops BC

**Curt Palme** · Posted: Fri Jan 16, 2009 6:09 am Post subject:

I dunno, I'm still skeptical, and followed all of the avs posts in the high end forum a year or two ago.

Tom.W · Joined: 09 Mar 2006 Posts: 6637

Interesting concept though...

http://www.eminent-tech.com/RWbrochure.htm

Domminigan · Joined: 08 Oct 2008 Posts: 30

So what, this thing starts moving air and then the blades of the fan move in and out like a sub cone, or does it control the speed of the fan blades?

jask · Joined: 17 Mar 2006 Posts: 10165 Location: kamloops BC

the blades pitch or angle of attack can be controlled (tilted) while at speed and this sets up the frequency- as the frequency gets lower the angle of the blades "lays back" more, moves more air and changes the frequency. If you have ever been around big prop planes when they are taking off you have experienced a similar effect.

ecrabb · Posted: Sun Jan 25, 2009 3:42 pm Post subject:

It might be what you meant, Jask, but I wasn't clear... So here's my version:
The motor is driven at a constant speed. The blades' angle of attack is modulated just like a normal subwoofer cone is. Amplitude is controlled by the angle of attack (steeper angle, more air movement, more amplitude, louder), while the frequency is simply the frequency of the oscillation of the blades' movement. The power is in the spinning motor-driven fan. That makes it efficient from an amplifier perspective because all the amplifier is doing is rotating the fan blades themselves... It's the motor itself that's the "power" behind the process.

Here's their page on it:
http://www.rotarywoofer.com/howitworks.htm

Very cool piece of technology, and I'd LOVE to hear (feel?) one. It would be kick-ass for two or three grand, but $12,000 makes it a non-starter for 90% of people into home theater. Of course, 90% of auto enthusiasts can't afford a Ferrari, either.

SC

DrKnow65 · Posted: Sun Jan 25, 2009 4:18 pm Post subject:

I believe you are correct ecrabb, fan blades only push/pull air with the +/- sine wave just like a diaphragm while the rotation is constant...

Clever for low frequency, suppose at to high of a frequency you would start to get velocity noise of the edges of the blade though?

We used to use servo drive 36" woofers for live PA work that were impressive and cost around $3000~ but you had to use a $10000 amp/processor to push them and the transient was a little lacking. I think Pink Floyd ran them too in the later years.

jask · Joined: 17 Mar 2006 Posts: 10165 Location: kamloops BC

SC/ DK65 that is what I was trying to say,... you just said it more clearly! - the pitch oscillates at the frequency desired to create the increasing/decreasing pressure that becomes the sound wave. I know a fellow that had a chance to play with one of these and he said the "impulse" he felt standing in front of it was physically painful!! He was in to competition car audio and said this was unlike anything he had ever experienced in or out of a car.

SC that link is great, do you think the fan blades in the animation are meant to be spinning counterclockwise?

DrKnow65 · Posted: Sun Jan 25, 2009 9:30 pm Post subject:

Being a pressure wave (sound) it would require a baffle. Just standing in front would not be the full effect.

**AnalogRocks** · Posted: Sun Jan 25, 2009 9:37 pm Post subject:

Cool link.

ecrabb · Posted: Sun Jan 25, 2009 10:14 pm Post subject:

jask · Joined: 17 Mar 2006 Posts: 10165 Location: kamloops BC

**AnalogRocks** · Posted: Sun Jan 25, 2009 11:24 pm Post subject:

http://www.youtube.com/watch?v=E7Bkrypxzs4&feature=related