Fan is a subwoofer

**toecheese** · **08-09-06, 01:00 PM**

http://www.rotarywoofer.com/

I thought this was a hoax at first, but it seems to be pretty for real. Very interesting how using variable-pitch fan blades with a CV motor can greatly increase the swept area for LFE.

**Darren** · **08-09-06, 01:46 PM**

Yes, it is for real. I was following a thread over at the cult on that. I believe it is $15,000 for one presently

**toecheese** · **08-09-06, 03:24 PM**

Well, when I think IB/DIY, I don't think $15k! It is a really cool concept though; I've been working through the math on it today in the patent for it.

**Darren** · **08-09-06, 04:07 PM**

You got farther than I did

That stuff is over my head, I heard the price would be substantially less if it ever went to market but I have a feeling the demand wouldn't be that high so the price would probably remain well above "reasonable". I'd LOVE to hear one though.

**toecheese** · **08-09-06, 07:43 PM**

Do some googling- there are some videos of it at work (a helicopter sound was cool)- though they can't do it justice for the low frequencies unless you're there in person, I suspect.

**Danny** · **08-10-06, 06:49 PM**

Sounds good but can you use it as a fan as well?

**JimPeitersen** · **09-01-06, 12:40 AM**

I believe that they are "marketing" them now, as I think I saw an ad in the latest Stereophile (don't think it mentioned a price).
JP

**Ayreonaut** · **09-01-06, 08:26 AM**

Kingjamez at CotIB says he's building a DIY rotary sub!

Quote:

kingjamez wrote:

Yea, Bruce Thigpen is the reason I need the amp. I'm trying to build a DIY rotary sub and have got all the parts on order. I just needed an amp that can actually drive it. I'll use Speaker Workshop to test the amp (and my sound card) and see if it will actually produce subsonic frequencies.

**alan monro** · **10-15-06, 05:43 AM**

If one realy wants to be buffered by lots of moving air ,stick your head out of a car window while moving. A very unpleasant feeling unless one happen to be a bikie...........It is a lot cheeper than buying a glorified fan Kind regards alan

**tzucc** · **10-17-06, 04:40 PM**

Quote:

alan monro wrote:

If one realy wants to be buffered by lots of moving air ,stick your head out of a car window while moving. A very unpleasant feeling unless one happen to be a bikie...........It is a lot cheeper than buying a glorified fan Kind regards alan

not even close to the rotary woofer. There is no net displacement of air, unless, truly, there is a DC signal or offset. You also won't feel ill or nauseous at all... the SPLs to get there are achievable, I suspect, by the TRW, but my room would be destroyed far before I got there.

**alan monro** · **10-18-06, 03:47 AM**

Tzuzz I agree,My eardrums would be wrecked before the room was. I know of a bloke that ignored a "do not enter this area " warning on the top parts of a cruise ship ,This area was reserved for the ship FOG HORN.So it happened that day was foggy , the results,he is now permantly deaf as a lamppost.Kind regards Tzuzz,alan.

**ThomasW** · **10-23-06, 12:53 PM**

I removed the remainder of this post since a moderator or admin deleted sections of it and failed to post to that effect

**Jerm357** · **10-24-06, 10:41 PM**

Quote:

alan monro wrote:

Tzuzz I agree,My eardrums would be wrecked before the room was. I know of a bloke that ignored a "do not enter this area " warning on the top parts of a cruise ship ,This area was reserved for the ship FOG HORN.So it happened that day was foggy , the results,he is now permantly deaf as a lamppost.Kind regards Tzuzz,alan.

WOW how loud do you think the fog horns were to cause him to go instantly deaf?

**Danny** · **10-24-06, 11:12 PM**

I think (from memory) that at 150Db your eardrums will burst

**Sonnie** · **10-24-06, 11:36 PM**

Hey guys... let's try to keep this on topic... thanks!

**Chrisbee** · **10-28-06, 04:32 PM**

alan

You don't need to stick your head out of the window.

Very high levels of VLF (flutter) are possible when driving reasonably quickly with one window partly open. Presumably the car becomes a Helmholtz resonator excited by the turbulent airflow across the open window. Like blowing over the top of a very large bottle.

I haven't tried adjusting window height to see if the frequency changes noticeably as it might with variations of reflex port area. I prefer to concentrate on my driving.

I think you are much too dismissive of a clever technology with this fan subwoofer. Who knows where further development might lead? The first example of every successful invention is rarely the final evolution. I wonder what Alexander Graham Bell would think of a G4 mobile phone?

The question is not whether the fan subwoofer works but whether the world needs or wants it it. Is the average HT nut willing to buy it in sufficient quantities to warrant manufacture on a much larger scale? And if he did, would civilisation survive high level infrasonics in every home that could afford it?

**Bob in St. Louis** · **10-25-07, 12:08 PM**

Sorry to revive a one year old thread, but is there any new news?

Bob

**toecheese** · **10-27-07, 05:43 PM**

The last I heard, a bunch of people were making some version of the rotary fan woofer to varying degrees.

Personally, after sREWing around a bunch and setting up my dual 18 IB, I don't think the ultra-low frequencies are necessary anyway.

What I mean is that, I can't hear or feel these very-low effects under 25 Hz or so. Maybe it was the series of Van Halen (I'm talking pre-sammy, pre-1984, *real* rock) concerts.

In any case, I'm thinking if I want true LFE, it'll have to be with buttkickers, or somesuch. Doing it through the air is just too inefficient.

Since the old comparison I used to do with theaters was "is my sound better that what I'd get at a theater", I passed the "absolutely, yes" mark a while ago. I don't think any theater has such a contraption, so I'm wondering who is using this stuff anyway?

**Scuba Diver** · **10-27-07, 06:00 PM**

umm ok. It might be great in a hot room. I wonder if it will work with my centeral air conditioner. All kidding aside, the real question is why. Is that price for real?

**Chrisbee** · **10-28-07, 01:57 PM**

Quote:

toecheese wrote:

The last I heard, a bunch of people were making some version of the rotary fan woofer to varying degrees.

Personally, after sREWing around a bunch and setting up my dual 18 IB, I don't think the ultra-low frequencies are necessary anyway.

What I mean is that, I can't hear or feel these very-low effects under 25 Hz or so. Maybe it was the series of Van Halen (I'm talking pre-sammy, pre-1984, *real* rock) concerts.

In any case, I'm thinking if I want true LFE, it'll have to be with buttkickers, or somesuch. Doing it through the air is just too inefficient.

Since the old comparison I used to do with theaters was "is my sound better that what I'd get at a theater", I passed the "absolutely, yes" mark a while ago. I don't think any theater has such a contraption, so I'm wondering who is using this stuff anyway?

I can only suggest that you are rolling off too early due to a rumble filter somewhere or you haven't enough displacement. Even my humble PCI can play infrasonic fireworks completely silently. My 4 x 15" IB can produce much more of the same. If you get 100dB @ 10Hz (uncorrected SPL meter) from your IB doesn't your hair shake if you go close enough? At around 15Hz doesn't the air in the room seem to go thick? Slightly lower again doesn't it feel as if your head is pumped up with air? Mine does all of this with hardly a sign of cone movement. Are your speakers in phase? Perhaps you need a house curve?

**toecheese** · **10-28-07, 03:37 PM**

Yeah, when it is in the low 20s, I can 'feel' a vibration in the air- and in certain movies, it really adds to it.

The new IB is new, and I really haven't put it through the paces yet. I have power and xmax to spare, so I can really turn it up, but yes, I do have a housecurve, and could make it a scary one, but not sure how high I need to go...

**Chrisbee** · **10-28-07, 04:38 PM**

Perhaps your IB simply needs to be a little bit hotter compared with your speakers?
SPLs are vital for maximum effect at such low frequencies.

The fan sub story seems to have gone quiet again.
There were rumours of a much more affordable model in the pipeline.
The Fan Sub website is still claiming that cone subs cannot compete.
That may be true below 5Hz but a few good 18" cones in an IB would go a very long way down without costing the earth.
Place them in a manifold under the floor and you need never know they existed.
Until, that is, the monster is called forth from its dark lair.

**Bob in St. Louis** · **10-31-07, 04:17 PM**

Thanks for the reply toecheese. I was hoping to find some fellow that's DIY'd one of these. I think they could be a viable piece of equipment, but not at current prices.

Chrisbee, you wouldn't happen to have a link to the fan club guys would you? When Google searching, all I find is Thigpens unit.

Thanks guys!
Bob

**Chrisbee** · **10-31-07, 06:42 PM**

Sorry, Bob. I'm not sure what you mean by "fan club guys"?

I only know of the Thigpen as a successful project.

There was some input from Bruce Thigpen on the Cult of the Infinite Baffle forum under general topics on Page3. The thread is called "One amazing subwoofer".

There are lots of links on this page: http://www.rotarywoofer.com/

(Scroll down to further links on the right for another page of links)

The owner of the first installed pair had a construction blog and posted on a number of forums I think. Very patient chap. He answered a lot of questions.

**Bob in St. Louis** · **11-01-07, 05:54 AM**

Quote:

Chrisbee wrote:

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