This review of the TRW-17 by International Audio Review goes so far beyond mere opinion i believe it should be recommended reading for anyone posting and asking questions here.
Note:
It is long
There are no pictures
It will change you.
Enjoy.
Page Title
Note:
It is long
There are no pictures
It will change you.
Enjoy.
Page Title
I hope they paid that reviewer well, as it is mostly marketing speak and the "dumbing down" of technology. A similar piece on a computer would get into single crystal silicon wafer production....
It doesn't take so many pages to understand that the TRW is a good idea. The problem is that the woofers cost ~$18,000 each. It also has a drawback that it needs to be built into the structure with a labyrinth to filter out the fan noise because basically it is just a variable pitch prop.
I have considered engineering my own - if it could be mass produced and sold for $1000 (true cost of <$200 per unit if sold factory direct and <$100 if sold via distribution) it would truly revolutionize the sound industry.
Tom Danley designed a rotary woofer ~20 years ago that was probably more practical, but it didn't go to DC like a variable pitch prop does, and it also had some technical difficulties (as I recall) and faded out of the marketplace.
You can get more information about Tom's "sickmaker", it did go to DC.
It was never intended for the audio marketplace.
You can see the patent description picture of Tom's device in post # 11, and some of his comments in post #29 and 45 here:
http://www.diyaudio.com/forums/subwoofers/235430-blower-compressed-air-powered-infra-sub-2.html
He never did answer my last question about the exact nature of the output
Eminent Technology: home
I have heard one of these, and they are both odd and interesting to watch in operation. They do make bass, very low bass... They are available for use in things like no holds barred HTS systems amongst other things.. I would not mind owning one.. 😀
I have heard one of these, and they are both odd and interesting to watch in operation. They do make bass, very low bass... They are available for use in things like no holds barred HTS systems amongst other things.. I would not mind owning one.. 😀
I think the device Art is thinking about was the Phoenix Gold Cyclone Rotary Subwoofer.
An externally hosted image should be here but it was not working when we last tested it.
Years and many many beers ago I read about a similar project on The Bass List called the Contra Bass. All I recall is it too had an insane bass output even well below 20hz and I believe the DIY cost was around $500.
Hi Y'all,
The Eminent Technology TRW-17 is definitely an interesting and unique product; but, as this is a DIY site, it may be reasonable to ask: "What does the TRW-17 actually do, and what could one do for US$ 24k+-2k within the range claimed by Eminent Technology?"
It might take writing a book to answer those questions while analyzing the linked write-up in Post #1, any volunteers? And it may well be that in the range below 10Hz the blower flow modulator is a hard to beat technology.
Besides numbers of multiples of some of the subs listed and documented on data-bass.com, one more example of what can be done with conventional dynamic driver technology is the SBA Fonebones links to in Post #33 here: http://www.diyaudio.com/forums/subwoofers/254251-best-subwoofer-possible-price-no-object-4.html I know, the .pdf is written in some funny language ( 🙂 ), but the graphs and pictures tell the story well enough. That kind of SBA with highly absorbent material behind the listeners might compare favorably to the TRW-17.
Regards,
The Eminent Technology TRW-17 is definitely an interesting and unique product; but, as this is a DIY site, it may be reasonable to ask: "What does the TRW-17 actually do, and what could one do for US$ 24k+-2k within the range claimed by Eminent Technology?"
It might take writing a book to answer those questions while analyzing the linked write-up in Post #1, any volunteers? And it may well be that in the range below 10Hz the blower flow modulator is a hard to beat technology.
Besides numbers of multiples of some of the subs listed and documented on data-bass.com, one more example of what can be done with conventional dynamic driver technology is the SBA Fonebones links to in Post #33 here: http://www.diyaudio.com/forums/subwoofers/254251-best-subwoofer-possible-price-no-object-4.html I know, the .pdf is written in some funny language ( 🙂 ), but the graphs and pictures tell the story well enough. That kind of SBA with highly absorbent material behind the listeners might compare favorably to the TRW-17.
Regards,
Attachments
Ron,
The Contra Bass used a pair of Servodrive 15" and two passive radiator 18", it was based on the Pachyderm 6 used for elephant communication research, the other SDL subs were horn loaded (and could not fit in the Land Rovers the Cornell University researchers used in Kenya, Africa) and had much higher cutoff frequencies (and more output). Two units of the SDL-4 had a 38 Hz cut off, two SDL-5, 31 Hz, and the SDL BT-7 dropped to 30 Hz for a pair.
The Contra Bass had a usable frequency response from 14 Hz to 125 Hz, -3 dB at 15 Hz, 114 dB at 16 Hz, with a very rapid roll off below. 18" x 22.5" x 37", power handling 200 watts RMS, 500 peak.
There are a number of standard voice coil drivers available now with far more output capability, but for the time, the Contra Bass was an outstanding achievement for the size and LF output extension capability.
Art
Yes, indeed you can build and EQ a 2x15" high excursion driver + 2x18" high excursion PR system that has similar frequency response and SPL capability. In fact I have the drivers for this just sitting up in my attic waiting. (no joke)
For instance, I can get the response shown in the attachment using two 15" drivers having about 12mm Xmax. The enclosure volume must be very large (350 liters!), and this has prevented me from building it (a lack of where to put and how to move such a thing).
-Charlie
Attachments
...and the benefit of a normal woofer system over these alternative technologies is that all of the alternatives have some sort of drivetrain noise that makes them work fine for sound effects, but need to be mitigated to use them for music.
Charlie,
You just mentioned you have an attic waiting to house an enclosure (or serve as one), why not use it, rather than just store speakers there 🙂?
I have a crawl space that could be utilized as a giant enclosure, but I find <25 Hz much over 105 dB unpleasant, so my small 2x12" sub with flat response (at the listening position) to 20 Hz is OK by me.
I recall seeing a refrigerator sized enclosure using a pair of JBL pro drivers back in the day - 2235 or 2245 (15 or 18") I believe.
Recently I have seen elephant researchers (at least for zoo work) using bass shakers coupled to a pipe driven into the ground - more than an a couple orders of magnitude improvement in size 😉
Hi,
Its load of long winded turgid crap by somebody who
doesn't understand the subject they are talking about.
It has all the hallmarks of a article by "Peter Moncrieff"
(I think his name is) who can talk voluminous quantities
of BS about what is wrong and right about equipment,
without really having a clue what he's talking about.
Read it as an education of some one spouting shedloads
and saying nothing useful, and being excessively fond of
your own opinions rather than than being well informed.
It will only change you if you know nothing. If you know
anything about the subject you will be bored rigid at the
actual lack of insight, and ludicrous arguments employed.
rgds, sreten.
He did a review of the RockPort, another very long winded
this is right and everything else is wrong, utter pile of garbage.
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Sreten,
The review was written about a system that "blows" after all, so "long winded" is appropriate 😉.
Art
"What mortal here dares to dares speak of the Wind?", said Flatus Maximus, the demigod of the organic folded horn. 🙄
If you want to hear a "report" from this audio system, just eat a burrito and wait twelve hours. While I'm still on a tangent, how come nobody has done a version of Pachelbel's Canon with 1812 style Cannon? THAT would be a good test of a sub 🙂
If you want to hear a "report" from this audio system, just eat a burrito and wait twelve hours. While I'm still on a tangent, how come nobody has done a version of Pachelbel's Canon with 1812 style Cannon? THAT would be a good test of a sub 🙂
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