Picture of Rotary sub controller
Built by Marchand Electronics for the Eminent Technology TRW-17 Rotary Subwoofer
Built by Marchand Electronics for the Eminent Technology TRW-17 Rotary Subwoofer
Fan noise
The fan noise is muffled by the the large enclosure that
is lined on all inside surfaces with 6" fiberglass. From
the listening seats the rotating fan is just barely audible
with no music playing.
The fan noise is muffled by the the large enclosure that
is lined on all inside surfaces with 6" fiberglass. From
the listening seats the rotating fan is just barely audible
with no music playing.
6" fiberglass = an acoustic low pass filter.
How far is the fan from the listening seats in your instalation?
OK, I am wowed and horrified at the same time:
WOW: this is seriously interesting technology. What other sub can generate a DC signal?????
HORRIFIED: Let's see, I could get me a new car, or I could install a somewhat audible fan cum subwoofer... 😱
Did you know that you can get in room response down to DC using a low Q sealed woofer??? Sure, it needs to be the typical 18" monster, but it's 1/10th the cost. The room response (e.g. boost) at low frequencies plus the sealed driver can lead to essentially flat in room response to very low frequencies.
So why did you choose the fan thingy?
-Charlie
You are going to need a lot more than one. 😉 They won't do DC either. Should cost ~1/3-1/4 the amount of a comercial TRW.
There is a DIY rotary woofer version coming. Waiting on Fi Audio to come back with some motor options. It will cost less than a hand full of woofers, and amps.
Well, that would depend on the SPL you want to achieve.
OK, but there is not much content to play down there, since pretty much everything in the signal chain will crap out by 5 Hz or so.
I'd say the cost would be around $500-$750, depending on the driver you want. This is less than 1/10th the cost.
Hmmm, OK, I'd be interested in that. As long as it doesn't cost more than $1k.
Honestly, if you model the combined response of a sealed box woofer and the room response, you will find that there is a huge (e.g. 20+ dB) boost at "low" frequencies, e.g. below 20-30Hz. The boost increases the room response at about 12dB/octave, and this will mirror the sealed box's 12dB/octave falling response. You can model the room response using Jeff Bagby's Baffle Edge Diffraction Simulator. You can download it for free here:
Loudspeaker Design Software
But if you want to play with expensive fans, that sounds like fun! 😛
OTOH, the arrangement I mention will give you flat response but the human hearing system is losing sensitivity below 20 or 30Hz, so maybe the extra SPL from the fan based subs would be worth it. I would certainly be curious to find out...
-Charlie
CharlieLaub,
As one of the nuts to have played with eight 18" drivers in a small room before, (and everything in between) I can tell you that one 18" or 21" sub will not do infrasound. You could do 15-16Hz, but that is about it, and it would still work better with two.
Room gain won't get you there.
As one of the nuts to have played with eight 18" drivers in a small room before, (and everything in between) I can tell you that one 18" or 21" sub will not do infrasound. You could do 15-16Hz, but that is about it, and it would still work better with two.
Room gain won't get you there.
Distance from rotary sub
The distance from the vent opening, for the rotary sub,
to the listening seats is 13'.
The distance from the vent opening, for the rotary sub,
to the listening seats is 13'.
Having done some very low frequency horn design as in close to 10 hz low frequency I have this little observation.
Although I applaud the ideas and techniques behind this type of generation of sound. For the volumes required for the manifolds and the related work I could quite easily produce a folded horn that could perform in the same manner down to 10 hz at a very reduced cost. The efficiency factor would be very high as well. One of the models showed 108db/watt.
To go to this level of performance requires a great love for the reproduced effects. My hat goes off to the gentlemen that pursue this level of realism!
The laws of physics apply
In order to hear 10 hz you need sound pressure levels above 100db. To hear 5 hz you need sound levels above 110db. Existing subwoofer systems cannot do that. To create an audible 5 hz with cones
you would need between 8 and 20 woofers 15 inches
in diameter or greater with several thousand watts of
amplifier power. With a single rotary woofer a couple
hundred watts will do. The hearing threshold curve
suggest that even the most expensive cone subwoofers available would have barely usable output between 14
and 20 hz. This rotary subwoofer produces very low bass with very low distortion, transient response that is essentially perfect, and just plain realistic sounding.
In order to hear 10 hz you need sound pressure levels above 100db. To hear 5 hz you need sound levels above 110db. Existing subwoofer systems cannot do that. To create an audible 5 hz with cones
you would need between 8 and 20 woofers 15 inches
in diameter or greater with several thousand watts of
amplifier power. With a single rotary woofer a couple
hundred watts will do. The hearing threshold curve
suggest that even the most expensive cone subwoofers available would have barely usable output between 14
and 20 hz. This rotary subwoofer produces very low bass with very low distortion, transient response that is essentially perfect, and just plain realistic sounding.
Diy rotary sub
Many people have been working on a diy of the rotary
subwoofer, and as yet, no has been successful. Check out the AVS Forum, under diy rotary subwoofers, and you will see what I am talking about. It took Eminent
Technology 5 years to get the rotary subwoofer to operate with low distortion and reliability. This is a custom made product, and as such, the cost would be very expensive. I have been involved with audio for 50 years and this is the most
exciting product that I have ever owned. There is quite a lot of recordings and movie content that is available that benefit greatly from the rotary subwoofer. Also getting the right electronics with the necessary low frequency bandwidth is very important. PS Audio's Perfectwave system is dc coupled and provides the best low bass I have ever heard. Oppo's BD-83 SE blueray player does a wonderful job with movies that have very low bass content. Listening and watching "War of the Worlds" with the rotary woofer is extremely exciting and realistic. Please read Peter Moncrieffs review of the rotary subwoofer in International Audio Review, titled "The Only Subwoofer". In this long and complete review, he explains the benefits of the rotary subwoofer for music recordings and movie content.
Many people have been working on a diy of the rotary
subwoofer, and as yet, no has been successful. Check out the AVS Forum, under diy rotary subwoofers, and you will see what I am talking about. It took Eminent
Technology 5 years to get the rotary subwoofer to operate with low distortion and reliability. This is a custom made product, and as such, the cost would be very expensive. I have been involved with audio for 50 years and this is the most
exciting product that I have ever owned. There is quite a lot of recordings and movie content that is available that benefit greatly from the rotary subwoofer. Also getting the right electronics with the necessary low frequency bandwidth is very important. PS Audio's Perfectwave system is dc coupled and provides the best low bass I have ever heard. Oppo's BD-83 SE blueray player does a wonderful job with movies that have very low bass content. Listening and watching "War of the Worlds" with the rotary woofer is extremely exciting and realistic. Please read Peter Moncrieffs review of the rotary subwoofer in International Audio Review, titled "The Only Subwoofer". In this long and complete review, he explains the benefits of the rotary subwoofer for music recordings and movie content.
The largest horn sub in the world
Check out this world's largest horn enclosure "The Royal Device Audio Room on the web. This is what is needed to get down to 10 hz efficiently. Even with this huge horn enclosure the response is limited to 10 hz. The Rotary subwoofer is capable of response to below 1 hz, with a measly 200 watts of power.
Check out this world's largest horn enclosure "The Royal Device Audio Room on the web. This is what is needed to get down to 10 hz efficiently. Even with this huge horn enclosure the response is limited to 10 hz. The Rotary subwoofer is capable of response to below 1 hz, with a measly 200 watts of power.
Not exactly. That is but one way to go down that low. There are other methods.
I design loudspeaker enclosures for a good percentage of my income. 3200 liters will get you almost flat to ten hertz. And that is is two Pi space not cheating corner loading. The efficiency I quoted is also worked out in two Pi space. Throw in the room gain and a properly sized rear volume for the woofers and you will get very strong response down room six hertz. Power input will be under one hundred watts most of the time and generally loaf around ten watts. Yes it is a very large box. But just as you have your fan and coupling manifold tucked out of sight and out of mind in like manner a horn subwoofer can be implemented.
I design loudspeaker enclosures for a good percentage of my income. 3200 liters will get you almost flat to ten hertz. And that is is two Pi space not cheating corner loading. The efficiency I quoted is also worked out in two Pi space. Throw in the room gain and a properly sized rear volume for the woofers and you will get very strong response down room six hertz. Power input will be under one hundred watts most of the time and generally loaf around ten watts. Yes it is a very large box. But just as you have your fan and coupling manifold tucked out of sight and out of mind in like manner a horn subwoofer can be implemented.
Pictures
Sounds like a very interesting approach to producing very low bass. Do you have any pictures of these horn enclosures and systems that you have installed.
Also have you ever heard the rotary subwoofer and experienced the awesome power and near perfect transient response. How large is the opening into ones room with this horn system and the location that is needed for alignment with the mid and high frequency transducers. Is your system horn loaded
for midrange and highs as well, and time aligned. In my experience, I have found that getting the entire range of frequencies aligned (very low bass, mid bass, etc. is paramount for excellent transient response.
The rotary subwoofer has enough acoustical output to move a open door back and forth .5" between 1 and 5 hz!!! I demonstrated this to a
experienced audiophile while playing a recording of the Apollo rocket
launch, which had a lot of content in this range, and said it was the most realistic reproduced sound he has ever heard. Thanks
Sounds like a very interesting approach to producing very low bass. Do you have any pictures of these horn enclosures and systems that you have installed.
Also have you ever heard the rotary subwoofer and experienced the awesome power and near perfect transient response. How large is the opening into ones room with this horn system and the location that is needed for alignment with the mid and high frequency transducers. Is your system horn loaded
for midrange and highs as well, and time aligned. In my experience, I have found that getting the entire range of frequencies aligned (very low bass, mid bass, etc. is paramount for excellent transient response.
The rotary subwoofer has enough acoustical output to move a open door back and forth .5" between 1 and 5 hz!!! I demonstrated this to a
experienced audiophile while playing a recording of the Apollo rocket
launch, which had a lot of content in this range, and said it was the most realistic reproduced sound he has ever heard. Thanks
I post design ideas from time to time.
So here are a couple of them:
This is very recent.
Front Loaded Horn January 2011 pictures by mwmkravchenko - Photobucket
Some personal responses from the presentations are here:
http://www.diyaudio.com/forums/clubs-events/176350-winter-diy-ottawa-meet-3.html#post2444365
A larger version I did last year useful to about 14 hz is here:
Horn Subwoofer pictures by mwmkravchenko - Photobucket
Discussed here:
http://www.diyaudio.com/forums/subwoofers/168697-trio-12-front-loaded-horn-subwoofer.html
Comments about the design here:
http://www.diyaudio.com/forums/club...ttawa-diy-audio-get-together.html#post2222280
Porting to a room is as about a simple as it gets. Pick a spot that makes sense. We determine that by using a conventional sub, then we create a proper connection to the cabinet and the room.
I have been in and around both carpentry and cabinetmaking for over 30 years. And in audio professionally since 1989. I have done driver design and manufacture and everything else in the audio chain. If it is possible to do I can get it done.
I mentioned part of my living comes from audio. The other part is still carpentry, cabinetmaking and renovations. So here are some more interesting pics of stuff I have done. Some more interesting than others of course!
https://picasaweb.google.com/mwmkravchenko
As for home system I'm currently working on a concept design that should be very interesting. But that will require another thread to explain.
And I'm way off topic as it is in this thread.
So here are a couple of them:
This is very recent.
Front Loaded Horn January 2011 pictures by mwmkravchenko - Photobucket
Some personal responses from the presentations are here:
http://www.diyaudio.com/forums/clubs-events/176350-winter-diy-ottawa-meet-3.html#post2444365
A larger version I did last year useful to about 14 hz is here:
Horn Subwoofer pictures by mwmkravchenko - Photobucket
Discussed here:
http://www.diyaudio.com/forums/subwoofers/168697-trio-12-front-loaded-horn-subwoofer.html
Comments about the design here:
http://www.diyaudio.com/forums/club...ttawa-diy-audio-get-together.html#post2222280
Porting to a room is as about a simple as it gets. Pick a spot that makes sense. We determine that by using a conventional sub, then we create a proper connection to the cabinet and the room.
I have been in and around both carpentry and cabinetmaking for over 30 years. And in audio professionally since 1989. I have done driver design and manufacture and everything else in the audio chain. If it is possible to do I can get it done.
I mentioned part of my living comes from audio. The other part is still carpentry, cabinetmaking and renovations. So here are some more interesting pics of stuff I have done. Some more interesting than others of course!
https://picasaweb.google.com/mwmkravchenko
As for home system I'm currently working on a concept design that should be very interesting. But that will require another thread to explain.
And I'm way off topic as it is in this thread.
Phoenix Gold Cyclone Subwoofer
Here is a picture of the enclosure I built for the Cyclone
subwoofer. It is too bad that this sub is no longer
available as it worked quite well.
Here is a picture of the enclosure I built for the Cyclone
subwoofer. It is too bad that this sub is no longer
available as it worked quite well.
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