Talk:Rotary woofer

Needs improvement[edit]

There's far too much in here about humans and low frequency hearing than there is about this thing and what it does or how it works. It's not a good article, it needs to be expanded.

Article needs to be non-product specific[edit]

This article seems to be highly product specific. While I understand there may only be one product on the market at this time, the article title seems to be about the theory of operation regarding rotary subwoofers. Seems a clean up or move is appropriate. (I suggest a cleanup) - Davandron | Talk 19:25, 8 January 2007 (UTC)[reply]

Three concepts are at play here.

1) Human perception of sounds below 20 Hz.
2) sound generation below 20 Hz.
3) the rotary method to generate sounds below 20 Hz.

With respect to those three areas this article can be cleaned up somewhat.

The title of this article needs to reflect the rotary method as a patented technique for generating those lower subwoofer sounds much as a paper cone is used for generating most other sound frequencies.

The information about the human perception of these extremely low frequencies could be added to the article on sound. Are these frequencies produced at all during the production of music or are they more in line with natural or man-made sounds other than music? Given that there is a subwoofer capable of producing that sound range one would assume that those tones are present in music.

Finally a subsection in the subwoofer article with respect to sound generation below 20 Hz could contain a sysnopsis of this article and a link to this page.

Mike S. Nov 9-2007

—Preceding unsigned comment added by 167.1.120.20 (talk) 07:46, 9 November 2007 (UTC)[reply]

Something fundamental missing from article[edit]

... namely, how does the damned thing work?

After checking the Eminent Technology site, it appears to be kind of an overgrown fan, with variable-pitch blades that, presumably, wobble in time to the subwoofer signal. Basically a giant low-frequency air mover. Would be nice if the article gave a clue as to how this works. Right now, it pretty much reads as a piece of marketing PR from Eminent. +ILike2BeAnonymous 07:33, 15 January 2007 (UTC)[reply]

how it works Should be merged with subwoofer. — Omegatron 05:40, 6 April 2007 (UTC)[reply]

Or maybe infrasound Rubbrchikin 22:29, 5 May 2007 (UTC)[reply]

Nope; that's a general technical article, not a good place for a specialized piece of audio equipment. (Of course, there certainly could be a "See also" link or such.) Subwoofer is the place. +ILike2BeAnonymous 23:21, 5 May 2007 (UTC)[reply]

Of course, were this article mostly about the rotary woofer I would agree with you. It's not though, the bulk is about the perceptability of infrasound, which probably fits better into the infrasound article than it does in subwoofer. Rubbrchikin 04:25, 24 May 2007 (UTC)[reply]

Ok, it works as a sound transducer but not like a standard cone transducer. It works by spinning at a pre-determined RPM and then using small motors, changes the pitch of the blades rapidly back and forth which causes an oscillation of air back and forth like a standard cone transducer. What makes the rotary sub different is that the cone transducer is physically limited in it's ULF reproduction by both the maximum physical excursion of the transducer and the ridiculous power demands that would be needed for a cone transducer to even come near to competing with a rotary sub. The rotary sub's main strengths is its great efficiency at going into much lower frequencies than a standard cone transducer as well as having the ability to move a more significant amount of air compared to a cone transducer.

crackyflipside, AVSforum.com —Preceding unsigned comment added by 65.6.174.174 (talk • contribs) 03:05, 27 July 2007

I think the technology is sufficiently different from the standard cone subwoofer to warrant its own article. There are articles for many different types of loudspeaker, such as electrostatic speakers, and plasma arc speakers; why shouldn't this have its own article? I agree that some more should be said on how it works, as that is a place the article is lacking. As for it being highly product specific, as was said, this is the only product on the market at the moment that uses this technology. It's difficult to be generic about it when there's only one product in the world that performs this way.

ShokaLion 16:39, 04 Aug 2007

Conflicting information from two wikipedia articles[edit]

This article states that:

The human auditory system is sensitive to frequencies from 20 Hz to a maximum of around 20,000 Hz, although the hearing range decreases with age.

This article states:

...the lower limit of human hearing (about 16 or 17 hertz)...

However, this article (Rotary woofer) states that:

Humans could hear sounds below 20 Hz.

Seems to me like this 3rd article, the one we're discussing here, is a bit off. NIRVANA2764 (talk) 02:38, 7 January 2008 (UTC)[reply]

Rename to rotary subwoofer[edit]

How the fuck can you call this a woofer when so many speakers that play above 100 Hz and wouldn't dream of diping below 20 Hz are considered subwoofers. I know this isn't going to go over well, but if anything is a subwoofer, it's this. Daniel Christensen (talk) 06:59, 21 August 2009 (UTC)[reply]

Zero Hz?[edit]

The article currently claims that these devices can reproduce sound at 0Hz. I'm not an acoustician, but isn't that kind of a meaningless claim? Doesn't any silent object constantly produce "sound" at 0Hz? Matt Gies (talk) 19:59, 21 July 2010 (UTC)[reply]

No, it's not. A 0 Hz signal is a fixed unvarying pressure difference, and a rotary subwoofer, installed in an opening in a (mostly) sealed room, can produce exactly that. In the terms you use in your second question, any silent object produces "sound" at any frequency but with zero amplitude; we normally talk only about "producing" sound when the amplitude is non-zero. A rotary subwoofer can produce a significant amplitude at 0 Hz. (Nothing can go to a mathematically exact 0 Hz because it has a limited operational lifetime. An annual on/off cycle would be 31 nHz, while the age of the universe to date wound be 2.3 aHz. But that's a practical limit, not a theoretical one.) 71.41.210.146 (talk) 07:00, 14 September 2010 (UTC)[reply]

Noise, distortion and rotor speed[edit]

"Current models use an AC induction motor spinning at 800 RPM (13 Hz)" which means a significant source of noise that's within the band of frequencies reproduced by the device and, as mentioned at the beginning of that paragraph, distortion to frequencies it reproduces between 13 Hz and its upper cut-off frequency. How are they mitigated and why was that particular rotor speed chosen, as it looks like a compromise? 87.75.117.183 (talk) 14:36, 9 October 2019 (UTC)[reply]

Trinity church installation removed? Generic name[edit]

A more generic name for what these actually are would be Hyperbaric loudspeaker.

Trinity Church in Manhattan only had these for a brief while? B137 (talk) 19:08, 13 January 2023 (UTC)[reply]

In music, a contrabass is an instrument that produces tones an octave below the bass register. Another possible option for a generic name might be "contrasubwoofer". The name "rotary woofer" implies an alternate technology for the standard woofer, not a woofer designed for a lower register. 63.224.64.175 (talk) 20:00, 4 January 2024 (UTC)[reply]

Comparison to helicopter swashplate[edit]

A helicopter swashplate is designed for both cyclic and collective blade pitch control. A "rotary woofer" requires only collective pitch control. A much simpler comparison would be to a variable-pitch prop, or helicopter tail rotor. 63.224.64.175 (talk) 20:05, 4 January 2024 (UTC)[reply]