Dig Down Deep... Devilishly Deep... Behold Other Subterranean Subwoofers Out There...

[risabet]

This is the only woofer with true response to DC, yeah, that's right, DC. The Eminent Technology Thigpen rotary woofer TRW-17. This must be installed in a basement or attic that acts as an infinite baffle and the amp must be able to generate maximum output between 1 and 3 Hz.

Check out the ET homepage

http://www.rotarywoofer.com/index.htm

 

[JonFo]

Well since Risabet beat me to the punch posting the ultimate sub, the Thigpen rotary, I'll just have to direct your attention to other subs.

In my book, no box sub, and none of the ones listed so far can compete with a well designed Infinite Baffle sub. Yes, not everyone can host one, but if you can, do not waste your money on commercial subs.

See the IB gallery for cools pics of awesome subs. No, they don’t look pretty, most of them are invisible in their installs.

I innovated the concept of the ‘in room manifold’ with this beauty featuring 4 15” drivers.

It replaced two highly tuned (using ETF measured EQ) Velodyne ULD-18’s. No contest, the IB is way, way better than any Velodyne. A perfect match for the Martin Logans with its extremely low distortion and high SPL ability.

Actually, it now looks a lot more like this:

Turns out an in-room IB's makes a handy stand for a big custom center speaker

 

[Robin]

Brilliant!

Robert,

Facinating advancement is subwoofer technology with the Interesting article and information regarding the DC powered - The Eminent Technology Thigpen rotary woofer TRW-17. At $22K - $26K it provides infinate bass you would feel all around the HT and house for that matter, really amazing advancement in subwoofer engineering... :wow:

Jonathan,

The Ifinate Baffle (IB) subwoofer system actually seems more affordable somehow, if the proper home conditions exsist to utilize a large unused attic or crawl space, as an extention of the subwoofer it-self. Your website was fascinating to read how you accomplished this subwoofer feat, Jonathan. I was especailly pleased with your results after all that DIY work on your IB system and just what your cabinent maker friend and yourself accomplished together, so interesting... What was particularly interesting was you were taking an educated risk that your IB subwoofer system would actually really improve the sound. You didn't rally know if all your planning and hard work, would all work out until you were finished and actually auditioned your IB system subwoofer. I am glade it did work out, even better than your original expectationsl... Just an outstanding review of the DIY process you went through. I loved it... Thanks for sharing. :cheers:

 

[Robin]

The Eminent Technology Thigpen rotary woofer TRW-17...

I was researching this a little further and found this website with a practical application of The Eminent Technology Thigpen rotary woofer TRW-17.



http://images.google.com/imgres?imgurl=http://www.dagogo.com/images/Eminent-Technology-01.jpg&imgrefurl=http://www.dagogo.com/Events/RMAF05/GalleryThree.html&h=575&w=600&sz=56&hl=en&start=5&tbnid=O3CIllQoHJH4XM:&tbnh=129&tbnw=135&prev=/images%3Fq%3DSubwoofer%2BTechnology%2B%2B%26svnum%3D10%26hl%3Den


Thrilling subwoofer technology...

 

[MiTT]

Robin,

I think that may have been the same set up I had seen at T.H.E. Show here in Denver last fall.

Here is a link to my post on it...

http://www.martinloganowners.com/~tdacquis/forum/showthread.php?p=24897#post24897

The way this thing energized the room was amazing. It was way beyond hearing the lower registers, it was visceral, like a punch in the gut with the right material. Very impressive technology.

 

[Robin]

Thigpen Rotary Woofer TRW-17....

Robin,

I think that may have been the same set up I had seen at T.H.E. Show here in Denver last fall.

The way this thing energized the room was amazing. It was way beyond hearing the lower registers, it was visceral, like a punch in the gut with the right material. Very impressive technology.

Tim,

The DC powered - The Eminent Technology Thigpen rotary woofer TRW-17, must have been amazing to experience live and in person. I look forward to all the future cutting edge audio electronics, which are coming in the not too distant future...

 

[JonFo]

Those Rotary's are the Ultimate Sub, but they will sure add complexity.

They really only operate up to about 40Hz, so you need to cross over to a 'regular' sub at 30Hz or so, then crossover yet again to your mains.

Not a problem for me, as I have spare crossover capacity, but boy, it will take extra effort to tune and EQ something that complex.

I'm still trying to figure out how to host 2 IB drivers (my current IB + a rotary) off the same backwave space. But I'm concerned the current IB drivers would become 'passive radiators' for the Rotary. That thing can push some air!

BTW- on any subwoofer, one of the most relevant metrics is liters (or cubic inches) of air displacement by the cone as installed in the box. At low frequencies, that’s what generates the sound at loud volumes.
For example, my IB produces 15.24 liters of cone motion displacement. That’s 6.5 times what a Velodyne 18 (2.15 liters) can deliver, and almost 10 times as much as a Descent (90 cu in vs 870 cu in).

Not sure for the Thigpen Rotary, but it sure is not constrained by its diameter, as the variable speed ‘fan’ enables it to be able to increase the volumetric displacement to insane levels (for audio).

 

[JohnA]

...For example, my IB produces 15.24 liters of cone motion displacement. That’s 6.5 times what a Velodyne 18 (2.15 liters) can deliver, ...

Jon, do your 4 drivers have maximum excursion double that of the Velodyne?

I've done some quick calculations here, and area-wise 4x15" drivers are a bit less than three times the area of a 18" driver. Therefore yours have to be travelling at least twice as far in order to shift over 6 times the air volume.

...or am I missing something here?

 

[Joey_V]

I still say, give me two Gothams and I'm done forever.

 

[Beat_Dominator]

Everytime I click this link and see that Avalon sub at the top of the page..... I cry

 

[Robin]

Gotham g213 Subwoofer...

I still say, give me two Gothams and I'm done forever.

Joey,

The Gotham g213 sure looks impressive.

 

[JonFo]

Jon, do your 4 drivers have maximum excursion double that of the Velodyne?

I've done some quick calculations here, and area-wise 4x15" drivers are a bit less than three times the area of a 18" driver. Therefore yours have to be travelling at least twice as far in order to shift over 6 times the air volume.

...or am I missing something here?

Yep, they have an xmax of +/- 23mm.

A velo ULD-18 has +/- 12mm.

So almost twice as far. The displaced area for an AV 15 is 3.818 liters (each)

Here's a link to a supplier in the UK:
http://www.mcaudio.co.uk/audio-bass.htm

Although I believe the AV15 was discontinued as of mid-2006, when a small final batch was made. They are legendary in IB circles. I was lucky to get my set when I did.

 

[Peter Hogan]

Yep, they have an xmax of +/- 23mm.

A velo ULD-18 has +/- 12mm.

So almost twice as far. The displaced area for an AV 15 is 3.818 liters (each)

Here's a link to a supplier in the UK:
http://www.mcaudio.co.uk/audio-bass.htm

Although I believe the AV15 was discontinued as of mid-2006, when a small final batch was made. They are legendary in IB circles. I was lucky to get my set when I did.

Hi,
The ULD series from Velodyne is ancient, a current series is the DD series. According to a Stereophile review here:
http://stereophile.com/subwoofers/604velodyne/
They say:
"the DD-18 can reach 1.75" on transients."

Converted to metric, this is 1.75" = 68.89mm. You claim the ULD has +/- 12mm or 24mm total, the new Velodyne nearly triples that. This would reduce the volume advantage factor you have to just over double what the new Velodyne can do. With a pair of them, you'd be in the same ballpark. Although there is no denying what a good IB can do, a standard sub can also do quite well.

Some of us do not have the option of cutting a huge hole in the floor, wall, or ceiling to mount an IB, so we have to 'make do' with a normal sub. (I don't think my landlord would be too pleased if I installed an IB sub, especially as he lives below me...)

Just my .02 worth,
Peter

 

[Beat_Dominator]

That 68mm number is peak-to peak I would bet

 

[IWalker]

Er... isn't it 2.54 cm in an inch? That would be

2.54x10 = 25.4 mm x 1.75" = 44.45 mm. If that's peak to peak, that's 22.2mm Xmax one way, which is not likely to all be linear (generally, depending on motor structure, your xmax is pretty far outside your linear excursion range)

The big question is here...is it peak to peak?

http://tcsounds.com/lms5400.htm

This is a monster driver. Weighs 75lbs, Costs $1000+, has 38mm linear Xmax (one-way) and has 2500 watts RMS power handling. The magnet alone is 516 oz (32+ lbs)

The DD-18 is a very nice sub, and has servo control, which is quite nice. Expensive though! And BIG!

 

[Beat_Dominator]

Look into the Digital Designs 18" Z-series woofer. Used for car audio competitions it has a huge neo-magnet and costs over $4,000.

 

[Robin]

REL Studio III ~ Marvelous Looking...

I like how the cabinet looks on the REL Studio III subwoofer...

 

[Robin]

Art Of Sound Signature ~ Subwoofer Beauty...

This amazing ~ Art Of Sound Signature Subwoofer has an even more beautiful cabinet design. Check-it-out this subwoofer features an incerdible 21 inch cabasse woofer speaker, crossover 490 watts amplifier/crossover..., all this for only $18K....

 

[Robin]

Lovely DIY Subwoofer Power...

This DIY Subwoofer project looks too cool. The cabinet has a very unique shape / style...

 

[HsvToolFool]

Look into the Digital Designs 18" Z-series woofer.

After exploring JohnFo's IB and others, I've been thinking
about building one myself. Perfect attic for it. Thing is,
I never could find a driver that would concentrate on the
reeeeeal low-end; say 5 Hz to no more than 35 Hz. I think
that range would complete the Summit's 25Hz bottom nicely.

TC Sounds LMS-5400
Cost: $1,200
Cone: Titanium !!!
Size: 18-inch
Stroke: 3-inch peak to peak!!!
Fs: 14.5 Hz !!!
Qts: 0.26

You can't hear, but just reading the specs causes me to
literally do that evil "mwuah ahh ahhhh" laugh. I didn't
think people really did that, but I guess we do.

JohnFo, if these are not the specs of an ideal IB driver,
please tell me what I should look for. Two of these 18-inch
drivers facing each other are equivalent to a single 26-inch
driver with a 6-inch peak to peak stroke. That's a HUGE amount
of air movement. I bet you could get 5 Hz with that setup.

The coolest thing is that they use a motor assembly which
detaches from the basket. You can order the basket and
cone separately while building your IB enclosure, and
then buy the motor after everything's mounted in the
attic. It makes the installation much easier by removing
the heaviest piece from the speaker.

Say 'ello to my leh-ul fren...