Hey all. Just some discussion here,wondering if its worth every buying one of these off ebay,or making one!
So how would you design the box for one of these?No t/s parameters,ist obviously not a spring and mass idea...
For those of you not familiar with the Phoenix Gold Cyclone, it is a discontinued "rotary motion, servo motor" type subwoofer.
it was a very unique subwoofer, to the degree that there has never been another rotary servo motor produced on the market.
This subwoofer uses a completely different technology to create a sound transducer.
Rather than a voice coil motor, which pushes a cone in and out in a linear motion, this driver uses a servo motor to twist a bisected panel back and forth via it's center shaft. The shaft has a back-and-forth rotating motion, hence the term "rotary".
Whats causing the inefficiency ? only 90db/1watt? it uses electric motors so i thought less losses would be involved.
http://www.betteraudio.com/geolemon/cycloneinside
And his DIY version
http://www.betteraudio.com/geolemon/servoproject/
So how would you design the box for one of these?No t/s parameters,ist obviously not a spring and mass idea...
For those of you not familiar with the Phoenix Gold Cyclone, it is a discontinued "rotary motion, servo motor" type subwoofer.
it was a very unique subwoofer, to the degree that there has never been another rotary servo motor produced on the market.
This subwoofer uses a completely different technology to create a sound transducer.
Rather than a voice coil motor, which pushes a cone in and out in a linear motion, this driver uses a servo motor to twist a bisected panel back and forth via it's center shaft. The shaft has a back-and-forth rotating motion, hence the term "rotary".
Whats causing the inefficiency ? only 90db/1watt? it uses electric motors so i thought less losses would be involved.
how can it have an Fs?
http://www.betteraudio.com/geolemon/cycloneinside
An externally hosted image should be here but it was not working when we last tested it.
And his DIY version
http://www.betteraudio.com/geolemon/servoproject/
It is still a spring and a mass - just rotary rather than a piston. IIRC, The devices are meant to be used free-air (into a car's trunk), or infinite baffle into a large space like your attic.... The reason you can't go higher than 60Hz is because there is too much inertia. I think the limitations of this technology are the mechanical noises made - much like the servodrive subs.
A loudspeaker motor is the same technology as a rotary motor. Neither technology is "better".
A loudspeaker motor is the same technology as a rotary motor. Neither technology is "better".
Cyclone
Hi
Maybe I can fill in some blanks, being the its inventor and having made the pre-production prototypes for PG, I am familiar with the technology.
The cyclone is a rotary motor and rotary radiator driver (where a normal Servodrive is a rotary motor and piston radiator system. My goal in this invention was to eliminate the problems, losses and non-linearity associated with the edge suspension and spider in a system where a large displacement in a small physical size was needed.
Back in the late 1980’s when I invented this, my job involved making very intense sound, mostly for scientific purposes so the Cyclone is actually the smallest rotary driver I worked on. We had built a number of units that had the displacement of 6, 18” drivers (@1”pp) that were used for active sound cancellation until the Power plant was retired due to an earthquake.
All of the rotary drivers I built had moving magnet motors I designed as well, to produce an “Fs”, a torsion rod is within the center of the shaft and supplies the “restoring force” which gives it the Fs of 10 Hz.
While eliminating all of the flexing / bending parts eliminated those problems, it turned out the torsion spring is also far more linear than spiders etc.
When Tom Nousain reviewed it for a magazine back then, he said it had the lowest distortion of any driver he had ever measured.
This was partly due to the elimination of the brushes which cause low level noise in the servodrive as well as the non linearity’s that normal drivers have.
Like any woofer, the efficiency is set by the T&S parameters and with any application there is a “best” alignment so far as efficiency vs low cutoff.
Why wasn’t this more successful?
At Intersonics, the speakers division was by far second fiddle to the NASA work, when the NASA work died off (a trickle down from the shuttle accident) the company eventually went out of business and the rotary drivers were too labor intensive to pursue in the Surviving speaker div.
PG licensed the technology and got off to a good start. They had good luck molding everything out of plastic and made the Cyclone that way.
Note; do not mold a motor housing out of plastic when the motor has strong Neo magnets inside. Unfortunately, over time, too many of the Cyclone began to rub internally.
While one could usually re-adjust the tension bolts to fix it, it was a rubber glove to fix a leaking pen.
I may resurrect the technology now that I am on my own but there are several other “full range” and “bass horn” things I have to focus on for the time being.
Hope that helps,
Tom Danley
Hi
Maybe I can fill in some blanks, being the its inventor and having made the pre-production prototypes for PG, I am familiar with the technology.
The cyclone is a rotary motor and rotary radiator driver (where a normal Servodrive is a rotary motor and piston radiator system. My goal in this invention was to eliminate the problems, losses and non-linearity associated with the edge suspension and spider in a system where a large displacement in a small physical size was needed.
Back in the late 1980’s when I invented this, my job involved making very intense sound, mostly for scientific purposes so the Cyclone is actually the smallest rotary driver I worked on. We had built a number of units that had the displacement of 6, 18” drivers (@1”pp) that were used for active sound cancellation until the Power plant was retired due to an earthquake.
All of the rotary drivers I built had moving magnet motors I designed as well, to produce an “Fs”, a torsion rod is within the center of the shaft and supplies the “restoring force” which gives it the Fs of 10 Hz.
While eliminating all of the flexing / bending parts eliminated those problems, it turned out the torsion spring is also far more linear than spiders etc.
When Tom Nousain reviewed it for a magazine back then, he said it had the lowest distortion of any driver he had ever measured.
This was partly due to the elimination of the brushes which cause low level noise in the servodrive as well as the non linearity’s that normal drivers have.
Like any woofer, the efficiency is set by the T&S parameters and with any application there is a “best” alignment so far as efficiency vs low cutoff.
Why wasn’t this more successful?
At Intersonics, the speakers division was by far second fiddle to the NASA work, when the NASA work died off (a trickle down from the shuttle accident) the company eventually went out of business and the rotary drivers were too labor intensive to pursue in the Surviving speaker div.
PG licensed the technology and got off to a good start. They had good luck molding everything out of plastic and made the Cyclone that way.
Note; do not mold a motor housing out of plastic when the motor has strong Neo magnets inside. Unfortunately, over time, too many of the Cyclone began to rub internally.
While one could usually re-adjust the tension bolts to fix it, it was a rubber glove to fix a leaking pen.
I may resurrect the technology now that I am on my own but there are several other “full range” and “bass horn” things I have to focus on for the time being.
Hope that helps,
Tom Danley
Hi all
Answers to a few questions, the rotary drivers we produced at Intersonics in the late 80’s (the 6X15) was only a commercial industrial device unlike the Servodrive speakers which were for concert / special effects use.
The power plant (in Redondo Beach Cal) was taken off line by the earth quake, not the speakers and in fact nearly all (ideally all of it) of the sound each of the 6 drivers at the perimeter of each fan was “canceled” by the sound the 20 foot diameter fan made.
Unlike a home or “music” application, this had to run 24 hrs a day at full level, part of what made this particular driver a pain in the rear to make.
Perhaps the coolest aspect of the moving magnet motor in general as with this driver and the Cyclone (its huge peak power capacity) was entirely wasted in this application with an “zero head room” signal. Funny, I remember I wanted to set the stinky epoxy the winding was encapsulated in, so I plugged it in to an outlet for a half hour until it was nice and toasty. In operation it was driven by a 3200Watt PWM amplifier and the motor supplied with forced air cooling.
I followed the link one of the fellows had in this thread to the diy rotary driver and thought hey I have been there, pretty cool.
An important thing to keep in mind if playing with rotary “things” is that the obey a different set of relationships so far as how a given force or mass impacts the system.
In the normal “in and out” speakers, the relationship is simple and direct, with a rotary system, force applied at a radius produces torque which is equal to force times radius.
Mass on the other hand is reflected as the radius squared.
For example, in the case of the PG Cyclone, if one used a solid steel center shaft, ¾ inch dia, it would only have a reflected mass on the radiator of a few tens of grams (if I remember off the top of my head). Hence in both of these drivers, I was able to have a considerable amount (mass) of magnet but have a manageable impact on the moving mass. Anyway that different rotary relationship will make these more understandable when you keep it in mind.
What am I doing now?
I had been working at Servodrive / Sound Physics Labs where I have been focused nearly entirely on horn design for the last 6 years or so.
At Servodrive I developed the Unity Horn design which allows multiple frequency ranges to drive a single constant directivity horn. These have the radiation pattern and phase response of a single source even though some of them have as many as 7 drivers on one horn. Also the Bdeap which is a 32Hz horn when placed in the proper location near a corner or can be stacked in multiples of 2 or 4 for as much as 10 dB or more of forward directivity in the bass range (although with a higher low cutoff than in a room).
The 2 on 2 configuration is humorous, it has a measured sensitivity of 97 dB 1 W at 10 Meters (10 meters being –20 dB from 1 Meter) outdoors, halfspace. Add 8 KW of amplifiers and one can “make bass” for several friends.
I resigned from Servodrive in October and have since established a new company called Danley Sound Labs.
That is in its infancy but one can see “what there is so far” at Danleysoundlabs.com
The “Tapped Horn” at the web site is a new horn invention, which allows the size of a bass horn to be reduced significantly for a given cutoff frequency without depending on external loading.
It is to a conventional horn what a vented box is to a sealed box, more or less.
I will be able to describe its operation in detail shortly.
There are some other things coming along too but not enough to talk about.
The companies focus is on commercial sound / installed sound, not the home so I figure indulging my DIY urge every so often is ok. Hey, besides, no one can tell me I can’t anymore come to think of it.
So far as the commutated VC driver, I built a few so I know it can work but at Intersonics there was no interest in pursuing it and no one has approached me about it since.
The patent ought to expire soon if it hasn’t already (I don’t remember when it is) so it may resurface who knows.
Best Regards,
Tom Danley
Answers to a few questions, the rotary drivers we produced at Intersonics in the late 80’s (the 6X15) was only a commercial industrial device unlike the Servodrive speakers which were for concert / special effects use.
The power plant (in Redondo Beach Cal) was taken off line by the earth quake, not the speakers and in fact nearly all (ideally all of it) of the sound each of the 6 drivers at the perimeter of each fan was “canceled” by the sound the 20 foot diameter fan made.
Unlike a home or “music” application, this had to run 24 hrs a day at full level, part of what made this particular driver a pain in the rear to make.
Perhaps the coolest aspect of the moving magnet motor in general as with this driver and the Cyclone (its huge peak power capacity) was entirely wasted in this application with an “zero head room” signal. Funny, I remember I wanted to set the stinky epoxy the winding was encapsulated in, so I plugged it in to an outlet for a half hour until it was nice and toasty. In operation it was driven by a 3200Watt PWM amplifier and the motor supplied with forced air cooling.
I followed the link one of the fellows had in this thread to the diy rotary driver and thought hey I have been there, pretty cool.
An important thing to keep in mind if playing with rotary “things” is that the obey a different set of relationships so far as how a given force or mass impacts the system.
In the normal “in and out” speakers, the relationship is simple and direct, with a rotary system, force applied at a radius produces torque which is equal to force times radius.
Mass on the other hand is reflected as the radius squared.
For example, in the case of the PG Cyclone, if one used a solid steel center shaft, ¾ inch dia, it would only have a reflected mass on the radiator of a few tens of grams (if I remember off the top of my head). Hence in both of these drivers, I was able to have a considerable amount (mass) of magnet but have a manageable impact on the moving mass. Anyway that different rotary relationship will make these more understandable when you keep it in mind.
What am I doing now?
I had been working at Servodrive / Sound Physics Labs where I have been focused nearly entirely on horn design for the last 6 years or so.
At Servodrive I developed the Unity Horn design which allows multiple frequency ranges to drive a single constant directivity horn. These have the radiation pattern and phase response of a single source even though some of them have as many as 7 drivers on one horn. Also the Bdeap which is a 32Hz horn when placed in the proper location near a corner or can be stacked in multiples of 2 or 4 for as much as 10 dB or more of forward directivity in the bass range (although with a higher low cutoff than in a room).
The 2 on 2 configuration is humorous, it has a measured sensitivity of 97 dB 1 W at 10 Meters (10 meters being –20 dB from 1 Meter) outdoors, halfspace. Add 8 KW of amplifiers and one can “make bass” for several friends.
I resigned from Servodrive in October and have since established a new company called Danley Sound Labs.
That is in its infancy but one can see “what there is so far” at Danleysoundlabs.com
The “Tapped Horn” at the web site is a new horn invention, which allows the size of a bass horn to be reduced significantly for a given cutoff frequency without depending on external loading.
It is to a conventional horn what a vented box is to a sealed box, more or less.
I will be able to describe its operation in detail shortly.
There are some other things coming along too but not enough to talk about.
The companies focus is on commercial sound / installed sound, not the home so I figure indulging my DIY urge every so often is ok. Hey, besides, no one can tell me I can’t anymore come to think of it.
So far as the commutated VC driver, I built a few so I know it can work but at Intersonics there was no interest in pursuing it and no one has approached me about it since.
The patent ought to expire soon if it hasn’t already (I don’t remember when it is) so it may resurface who knows.
Best Regards,
Tom Danley
Totally OT, but an interesting acoustics read about Mr. Danley's trek to and into the Great Pyramid.
http://www.livesoundint.com/archives/2000/julyaug/pyramid/pyramid.php
Very interesting as well is the Fsharp 'tuning' of the interior.
Thought I'd share.
http://www.livesoundint.com/archives/2000/julyaug/pyramid/pyramid.php
Very interesting as well is the Fsharp 'tuning' of the interior.
Thought I'd share.
Link above :
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Member
Joined 2003
Hi again Mr Danley,
I wanted to know if your famous rotary driver concept could beat this design (louder, lower distortion, higher efficiency, lower fs, etc), maybe you didn't hear about it yet so here's the link :
http://www.adireaudio.com/TextPages/ParthenonPageFrameText.htm
I wanted to know if your famous rotary driver concept could beat this design (louder, lower distortion, higher efficiency, lower fs, etc), maybe you didn't hear about it yet so here's the link :
http://www.adireaudio.com/TextPages/ParthenonPageFrameText.htm
Hi
I have not seen Dan’s big driver first hand but I have seen photo’s of it before.
So far as the rotary systems, the only time it makes sense to use something that is not off the shelf is when you need something that you can’t get conventionally.
By that I mean the only times it makes sense to use a Servodrive (rotary motor & piston radiators) or a full rotary system like the Cyclone is when you need something different that you cannot get using a VC driver.
You ask if a rotary system could be made to do what that driver does.
Sure, one can make a rotary system with any desired displacement.
That being the case, in general on can say that for a given displacement, the full rotary system would still be somewhat different in the following ways.
For a given displacement, the rotary system will be smaller physically and lighter in weight. For example, the larger rotary system used in sound cancellation in the late 80’s had a displacement of + - 350 cu/in, it measured 16 inches long, 12 inches tall and 8 inches thick with a 10 inch long, 5 inch dia motor on one end.
Compare that to the size of the 6, 18’s each driver replaced and you can see the size advantage.
Rotary motors, especially commutated ones can also be made to be FAR more powerful than a VC motor for a given weight or series inductance.
Moving magnet motors can have a thermal time constant of a half hour where a large VC has one of about 10 seconds (how fast it heats up), moving coil motors like that in the Servodrives have a TC more like 30-45 seconds.
Remember motor strength is NOT BL but rather BL / sqr root of Rdc. This formula results in a figure of merit proportional to the Newtons of force per Watt of motor dissipation.
As a point of reference, most SDL’s like the Contrabass and BT-7 have a motor which has a BL of 27 and Rdc of 2 Ohms from a motor which is 4 inches in dia and about 5 inches long.
Those motors are easy to cool with forced air too, in 1986, about the time the big mfr’s began to mention “power compression” I presented a paper at AES and ASA called “The elimination of Power Compression in Servodrive loudspeakers”.
Since then, all of the high power Servodrives have had the “power cooling” feature discussed in the presentation and we were the first company to include a “power compression” specification in the pro-sound industry.
The down side is the cost of the motors, they are expensive and the smallest motors are still make a massive driver compared to VC systems.
Again, the only time it pays to go with a more exotic approach than a VC driver is when you need parameters you can’t get in a VC driver.
While VC drivers are a world different than they were when I made the first Servodrive, the rotary systems still offer a solution when the T& S parameters your looking for are well past those that can be achieved normally.
For example, in the LAB subwoofer project, a DIY horn I designed a few years ago, I used 2, 12” inch drivers that are pretty beefy even by today’s standards.
The Servodrive BT-7 has the same throat area more or less, basically a very similar horn all the way around. The 15 year old BT-7’s Servomotor driver is enough more massive and powerful that the same horn / throat area is driven with 2, 15 inch radiators instead of 2, VC motor 12” drivers as in the LAB.
Hope that helps,
Tom Danley
I have not seen Dan’s big driver first hand but I have seen photo’s of it before.
So far as the rotary systems, the only time it makes sense to use something that is not off the shelf is when you need something that you can’t get conventionally.
By that I mean the only times it makes sense to use a Servodrive (rotary motor & piston radiators) or a full rotary system like the Cyclone is when you need something different that you cannot get using a VC driver.
You ask if a rotary system could be made to do what that driver does.
Sure, one can make a rotary system with any desired displacement.
That being the case, in general on can say that for a given displacement, the full rotary system would still be somewhat different in the following ways.
For a given displacement, the rotary system will be smaller physically and lighter in weight. For example, the larger rotary system used in sound cancellation in the late 80’s had a displacement of + - 350 cu/in, it measured 16 inches long, 12 inches tall and 8 inches thick with a 10 inch long, 5 inch dia motor on one end.
Compare that to the size of the 6, 18’s each driver replaced and you can see the size advantage.
Rotary motors, especially commutated ones can also be made to be FAR more powerful than a VC motor for a given weight or series inductance.
Moving magnet motors can have a thermal time constant of a half hour where a large VC has one of about 10 seconds (how fast it heats up), moving coil motors like that in the Servodrives have a TC more like 30-45 seconds.
Remember motor strength is NOT BL but rather BL / sqr root of Rdc. This formula results in a figure of merit proportional to the Newtons of force per Watt of motor dissipation.
As a point of reference, most SDL’s like the Contrabass and BT-7 have a motor which has a BL of 27 and Rdc of 2 Ohms from a motor which is 4 inches in dia and about 5 inches long.
Those motors are easy to cool with forced air too, in 1986, about the time the big mfr’s began to mention “power compression” I presented a paper at AES and ASA called “The elimination of Power Compression in Servodrive loudspeakers”.
Since then, all of the high power Servodrives have had the “power cooling” feature discussed in the presentation and we were the first company to include a “power compression” specification in the pro-sound industry.
The down side is the cost of the motors, they are expensive and the smallest motors are still make a massive driver compared to VC systems.
Again, the only time it pays to go with a more exotic approach than a VC driver is when you need parameters you can’t get in a VC driver.
While VC drivers are a world different than they were when I made the first Servodrive, the rotary systems still offer a solution when the T& S parameters your looking for are well past those that can be achieved normally.
For example, in the LAB subwoofer project, a DIY horn I designed a few years ago, I used 2, 12” inch drivers that are pretty beefy even by today’s standards.
The Servodrive BT-7 has the same throat area more or less, basically a very similar horn all the way around. The 15 year old BT-7’s Servomotor driver is enough more massive and powerful that the same horn / throat area is driven with 2, 15 inch radiators instead of 2, VC motor 12” drivers as in the LAB.
Hope that helps,
Tom Danley
Hi,
I think they will charge over 8000$ for the 16 cu.ft displacement version (Around 27500 cu/in). I'm not even sure if they could build a surround to go with this version... It would cost more or less than that if someone use a full rotary system like the Cyclone to do 16 cu.ft?
If you don't know how much it would cost, could you do an estimation based on the HE18 supposed to be coming out this year (43mm Xmax for a 18 incher and I'll estimate the Sd at 1180 cm^2) for less than 750$, so around 600 cu/in.
I'm very interested in your technology. I think you should promote it before the patent expires forever, or improve it to be able to patent it again!
Thank you very much.
I think they will charge over 8000$ for the 16 cu.ft displacement version (Around 27500 cu/in). I'm not even sure if they could build a surround to go with this version... It would cost more or less than that if someone use a full rotary system like the Cyclone to do 16 cu.ft?
If you don't know how much it would cost, could you do an estimation based on the HE18 supposed to be coming out this year (43mm Xmax for a 18 incher and I'll estimate the Sd at 1180 cm^2) for less than 750$, so around 600 cu/in.
I'm very interested in your technology. I think you should promote it before the patent expires forever, or improve it to be able to patent it again!
Thank you very much.
Dare I say it.....
Perhaps superconductive motors might have good application in rotary servodrive type transducers. Considering that superconductive motors can be 70% more efficient in size and power it probably wouldnt be hard to make something that could blast out 10hz tones at 130db+
Perhaps the high frequency bandwidth would be increased also if motor inductances were lowered?
Why does the cyclone only go up to 60hz again?
Perhaps superconductive motors might have good application in rotary servodrive type transducers. Considering that superconductive motors can be 70% more efficient in size and power it probably wouldnt be hard to make something that could blast out 10hz tones at 130db+
Perhaps the high frequency bandwidth would be increased also if motor inductances were lowered?
Why does the cyclone only go up to 60hz again?
i have a piece of pvc pipe that is about two feet long with an inner diameter of seven and a half inches. I think this would be good material for building one of those cool subs.
Questions:
for a vane two feet by seven inches, what motor would be suitable, where should i buy it and about how much will it cost?
How do you decide its max excursion, i guess in degrees?
Would this be a good choice for an open baffle?
thanks
Questions:
for a vane two feet by seven inches, what motor would be suitable, where should i buy it and about how much will it cost?
How do you decide its max excursion, i guess in degrees?
Would this be a good choice for an open baffle?
thanks
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