The TRW Rotary Subwoofer revisited.... - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 26 Old 06-14-2011, 10:27 PM - Thread Starter
 
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I checked Bruce Thigpens website to check what goings on as of lately...

Here his subwoofer replicates a volcano eruption in Kona and is registered 3 miles away!



Here twin TRW's attached to a Church door...Lol!


and here they drilled trough the concrete slab to install 6 trw's to recreate you gessed it...Niagara Falls.


Here Winston recreating the TITAN ROCKET IGNITION:


Then to add to the NEWSWORTHINESS he has compiled a list of BD's/dvd's which are recorded with 0-20hz relevant signals (he missed SHOOT EM UP):

You may remember Helene:


Aeon Flux
Alice in Wonderland
Alone in the Dark
Avatar
Ballistic
Battlefield Earth
Black Hawk Down
Blade Trinity
Boogie Man
Bourne Ultimatum
Basic
Casino Royal
Catwoman
Children of Men
Cloverfield
Confessions of a Dangerous Mind
Constantine
Confidence
Curse of the Golden Flower
Daredevil
Dawn of the Dead
Daybreakers
Die Another Day
District 9
Day After Tomorrow
The Dark Night
Exit Wounds
Exit WOunds
Final Destination 2
Fantastic 4
Finding Nemo
Freddy vs Jason
From Hell
The Fog
Ghost Dog
Golden Eye
The Golden Compass
Gothika
The Grudge
The Grudge II
The Good Shepard
Harry Potter and the Prisoner of Azkaban
Hellboy
Hellboy II
Hitchhikers Guide to the Galaxy
Hulk
The Hurt Locker
Idiocracy
Inception
Incredibles
Inglorius Bastards
Iron Man
Iron Man 2
Italian Job
Jurassic Park III
Kick Ass
Lost in Space
Matrix Revolutions
Mirror Mask
Mulholland Drive
Mummy
Munich
Open Range
Master and Commander
Minority Report
The Mangler
Oxygen
Panic Room
Pans Labryinth
Pirates of the Carribean - Dead Mans Chest
Quicksand
Revenge of the Sith
Sahara
Sea Biscuit
Shrek the Third
Spider Man Two
Scary Movie 3
Scott Pilgrim vs. The World
Sum of All Fears
The Italian Job (2003)
They
3:10 to Yuma
Terminator Salvation
Today you Die
Transporter 2
U-571
Unstoppable
The Village
V for Vendetta
Walk the Line
War of the Worlds

FANTASTIC LIST!!!!! SOLD!

I think it's time to put the TRW back on the Moon Of Saturn Menu.
LL
LL
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post #2 of 26 Old 06-15-2011, 09:16 PM
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I'm definitely a fan of those subwoofers and anything capable of such reproduction!
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post #3 of 26 Old 06-16-2011, 05:37 AM
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I'll be downsizing my house in a few years and I have to have one of those in my new theater!!!! Very, very cool!!!

Goodbye to a great audio and video genius and writer... JOHN GANNON. I enjoyed your friendship, wit and a nice long run we took around Indianapolis at CEDIA years back... and for buying my Runco 980 Ultra years back... you saved my ass! Rest in peace.
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post #4 of 26 Old 07-03-2011, 08:18 AM
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I have had the TRW-17 Rotary Woofer for almost
3 years and it is truly an amazing subwoofer that
provides realistic very low bass and is worth the
cost and time to build the enclosure.
LL
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post #5 of 26 Old 07-03-2011, 09:13 PM
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RWA,
That is really nice looking. Did you do it yourself? Did you demo the rotary before buying?

Having fun playing the new mobile game Volley Village
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post #6 of 26 Old 07-04-2011, 07:55 AM
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I did all the construction and it took about 6 weeks
to complete. The enclosure is 8' long by 4' wide
x 4' high using 3/4" plywood and braced inside
with 2" x 2" s with all the surfaces lined with 6"
fiberglass insulation. The opening in the floor
is 4' x 4' and required modification. The legs of
the enclosure are 4" x 4" and large bolts are used
for a very strong and rigid enclosure. The enclosure
is also utilized for storage of lumber and is very
useful for my work shop.
It took many months of research and reading about
the Rotary Woofer (A great report by Peter Moncrieff
of IAR) and talking to Bruce Thigpen of Eminent
Technology before I made the decision to purchase the
Rotary Subwoofer.
From pipe organs, synthesizers and all the many sound
effects this subwoofer handles them all with very real
and powerful (transients are frightening). The best
is the Apollo rocket launch with energy between 3 and 5 hz
that moves my doors back and forth 1/2".
LL
LL
LL
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post #7 of 26 Old 07-05-2011, 09:41 PM - Thread Starter
 
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Very cool thanks for sharing.

I am planning to put 2 or 4 under the plat in this cinema venting forward into the front row or each one of the 4 venting individually into each row:
Bombelman likes this.
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post #8 of 26 Old 07-08-2011, 05:50 PM
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Ive been meaning to come visit rwaaudio as he is incredibly close to me, but life has truly got in the way.
I am still interested if the invite still stands my friend...

CINERAMAX, I'm sure you are quite aware they don't reach all that high - less then 30hz range.... what were you intending on picking up the midbass region... 2 x TRW's would require some impressive midbass modules... expecially something that would keep up with those bad boys... What will bridge the gap to your mains ?
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post #9 of 26 Old 07-21-2011, 10:39 AM - Thread Starter
 
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Quote:
Originally Posted by Warpdrv View Post

Ive been meaning to come visit rwaaudio as he is incredibly close to me, but life has truly got in the way.
I am still interested if the invite still stands my friend...

CINERAMAX, I'm sure you are quite aware they don't reach all that high - less then 30hz range.... what were you intending on picking up the midbass region... 2 x TRW's would require some impressive midbass modules... expecially something that would keep up with those bad boys... What will bridge the gap to your mains ?

Some series of 14 or 18" ME Gethain woofers.
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post #10 of 26 Old 07-29-2011, 05:59 AM - Thread Starter
 
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By the way Bruce is slammed with work for Nasa, Mit, JPL, Imax theater in Hawaii.

Here is the proposed manifold scheme for system Europa (one of our first 2 Moons of Jupiter projects)(Dual Projector 3D setups get named after the the larger moon ).


LL
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post #11 of 26 Old 08-08-2011, 10:17 AM
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Quote:
Originally Posted by CINERAMAX View Post

By the way Bruce is slammed with work for Nasa, Mit, JPL, Imax theater in Hawaii.

Here is the proposed manifold scheme for system Europa (one of our first 2 Moons of Jupiter projects)(Dual Projector 3D setups get named after the the larger moon ).


Obviously, Bruce is an extremely bright individual, especially with regard to the physics of reproducing low frequencies. However, as I look at the cut of the theater seating, I immediately see what appears to me to be a problematic cancellation issue.

An attendee, seated in the front row, experiences a coherent LF wavefront from the Rotary emanating thru all three vents. Additionally, an attendee seated in row 3, experiences the Rotary energy emanating thru the vent directly behind them, however, the energy from the other two vents creates problems. The LF energy vent exiting the front row vent, must travel enough additional distance to become problematic once it travels the length all the way to the front vent, then back toward the row 3 seat.

Even as low as 20hz, this could be a significant nulling/cancellation issue. The lower in frequency the energy, the less cancellation occurs. Help me out here, what am I not seeing?


Thanks

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post #12 of 26 Old 08-08-2011, 10:45 AM
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One thing missing in all these pictures and text has me wondering what kind of power is needed to drive one of these things efficiently. Do you need a direct line from the pole or will a simple $50 Radio shack PA amplifier suffice
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post #13 of 26 Old 08-08-2011, 10:58 AM
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It's not demanding of power. It needs enough to swivel the blades. 300 watts should be plenty.
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post #14 of 26 Old 08-08-2011, 01:05 PM
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That is more efficient then I was expecting. The $ to kilowatt ratio might actually be cheaper to run this monster verses the conventional powered subwoofer in a box.
FOH I like your signature: Flat, Deep, Clean, Linear, and Loud
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post #15 of 26 Old 08-08-2011, 11:02 PM
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Quote:
Originally Posted by FOH View Post

Even as low as 20hz, this could be a significant nulling/cancellation issue.

A 20 Hz wavelength is 57' long.

Up to 1/4 wavelength difference is considered in phase, so the distance between the vents would need to be more than 14'; doesn't look like it is.

Noah
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post #16 of 26 Old 08-09-2011, 07:26 AM
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Attachment 219616Two hundred watts is what is recommended, which is what
I use. This amp and xover unit is for pitching the fan blades.
The real power is provided by a separate 20 amp ac circuit
that the fan motor requires.
LL
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post #17 of 26 Old 08-09-2011, 12:42 PM
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Quote:
Originally Posted by noah katz View Post

A 20 Hz wavelength is 57' long.

Up to 1/4 wavelength difference is considered in phase, so the distance between the vents would need to be more than 14'; doesn't look like it is.

Noah,

Generally speaking, before we get into the specifics of this situation, the idea that one could get away with multiple path lengths such as these, for any LF system, is fundamentally flawed.

Now more specific to your post, I certainly don't agree that a quarter wavelength is considered in phase. A quarter wavelength is 90 degrees out. Quarter wavelength offsets easily have catastrophic nulling consequences. The row two vent will lessen the impact, however the energy would be a phasey, skewed mess,....even at 20hz.

Look at the cut. I make the analogy like a delay system for a huge outdoor stadium concert. Delay towers with speaker hangs are commonplace, when covering long distances. From right to left, the entire image looks like a point source emulation including a source, and two delay sources...right-to-left. This works as long as the flow is one directional and pattern controlled. However, LF is omni-directional, folding back onto itself creates a mess.

A quarter wavelength off, nulls half the magnitude.

If Thigpen created this, I implicitly and without reservation trust that I'm missing something. If otherwise, all bets are off. I welcome any input in this regard. I do see an interesting modal breakup side effect to this, but the only coherent location for the Rotary energy is if all vents were linear with respect to distance back the the source..ie., row one.

Maybe I'm wrong,..help me out
Thank you

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post #18 of 26 Old 08-09-2011, 12:46 PM
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Can these be built with a single vent on one side of a room with a good outcome ?

Art
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post #19 of 26 Old 08-09-2011, 05:32 PM
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Quote:
Originally Posted by Art Sonneborn View Post

Can these be built with a single vent on one side of a room with a good outcome ?

Art

Absolutely

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post #20 of 26 Old 08-09-2011, 09:52 PM
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Quote:
Originally Posted by FOH View Post

Now more specific to your post, I certainly don't agree that a quarter wavelength is considered in phase....

A quarter wavelength off, nulls half the magnitude.

If you add two waves 90 deg apart the waveform sums to a magnitude greater than either, though not double.

Tom Danley frequently cites this rule of thumb.

Noah
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post #21 of 26 Old 08-10-2011, 05:53 AM
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Quote:
Originally Posted by noah katz View Post

If you add two waves 90 deg apart the waveform sums to a magnitude greater than either, though not double.

Tom Danley frequently cites this rule of thumb.

All due respect to you and TD, ...just sayin'...

Given; A leading source, and a lagging source (by 90 degrees).
If the first leading source is at peak compression (top of the first peak), then the second source is at 0. That said, how can they sum to a magnitude greater than either?

Again, if the first source has already crossed zero, halfway to the rarefaction peak then it's at 45 degrees below the zero crossing point. So the places the lagging source at 45 degrees above the zero crossing point. Likewise, how can they sum to a magnitude greater than either?

Noah, the delay tower analogy illustrates it well. One can't sit in the front row of a concert, and have any benefit from the delay towers,...they'd be terribly destructive. That's why they're bandwidth limited, and possess a measure of pattern control.

Now, any energy less than 90 degrees out, could be additive, but by definition, 90 degrees out=problematic.

Thanks

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post #22 of 26 Old 08-10-2011, 08:51 AM
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Addition of 2 sinewaves, one of which is 90 degrees shifted yields addition of Sin and Cos waves. Result shown below.

Note magnitude is identical to that of the vector addition -- Sqrt (2)
LL

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post #23 of 26 Old 08-10-2011, 08:56 AM - Thread Starter
 
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There was no way that I was going to put a giant sewer grille on the most visible wall of the room.

This is what he proposed initially.



If you see the grille then you lose half the effect that is to feel not see.


LL
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post #24 of 26 Old 08-11-2011, 06:52 AM
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Quote:
Originally Posted by jamin View Post

Addition of 2 sinewaves, one of which is 90 degrees shifted yields addition of Sin and Cos waves. Result shown below.

Note magnitude is identical to that of the vector addition -- Sqrt (2)

Thanks jamin, I stand corrected on my math

However, I stand by my contention that the vent behind the third row, combined with the vent serving the front row, would be destructive to an attendee seated in row 3. My quarter wavelength destructive angle was miss-used. Living in the live sound arena for years, I was mistakenly bringing my PA set-up, quarter wavelength rules of thumb to this application. Just like a box sub, for HT or live sound, if it's a quarter wavelength off a boundary, destructive issues ensue.

However here, in this application, unless all the listeners are forward of the row one vent, problems may arise. For anyone off the forward axis, the energy becomes skewed wrt time. The example I initially put forth, for a listener in row 3, the energy emanating from the vents is destructive. Attempting to crudely scale it, I approximated 4.5 feet from row three listener, through the adjacent vent to the Rotary transducer. From the listener to the transducer via the row one vent, I estimated 22.5 feet. This results in about an 18 feet difference, which even at 20hz, would fall about 115 degrees out (18'/56.5'= .318, so (.318)360=114.69 degrees).

As I first saw the three vents, staggered right to left from the source, it's the perfect example of how in live sound one could employ cardioid sub system, or LF steering. You line them up in a row of three in the direction of the intended effect. The back sub is not delayed, time delay each subsequent sub to fire at the time in which the energy sums in the forward axis. You keep energy off the stage (out of the mics), and hit the seating area with a nice cardioid pattern of LF.

This works fine as long as the listener is in the forward axis. Any deviation from the forward axis, as is the case for a listener in row three in the Rotary theater, results in problems. The phase problems can range from total nulling associated with complete polarity reversal, to tonality and spectral changes with only small phase differences. Acoustic signals don't sum as nicely as the example shown in the vector addition graph.

All this aside, this appears to be a superb theater, one which I'd kill to hear a properly implemented Rotary, mated with a conventional coned LF system covering the octaves above the Rotary's range.

Very interesting and I apologize for the verbose post. And again, correct my math if I'm wrong,...it's been a while as I'm a retired dude

------------------------------------
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------------------------------------
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post #25 of 26 Old 05-14-2014, 09:02 AM
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This *thing* looks amazing!

I, dabotsonline / Nicholas Polydor, am part of Panasonic UK's 'VIERA VIP Club': a group of six bloggers and forum posters receiving special access to information and events for the TV product range. Costs for activities are covered by Panasonic (no cash is involved). However, I can assure that this will never compromise my integrity or objectivity as an ethical conscience is something I have always and will forever hold very dear to my heart.
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post #26 of 26 Old 12-01-2019, 01:58 PM
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Where's the best place to hear one of these? Ideally near Minneapolis if someone would like to show one off, or anything else they think could compare.


I know of Niagara and Oregon. Which of those is louder, if I must get on a plane?
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