Another import point is that the inventor is extremely touchy and ill tempered on the subject of patents. Some of that is understandable, of course, but a few of the posts have been extreme. Blowing your top when someone is offering good advice and help does not take you far on a public forum.
I really don't understand why an inventor who is so nervous about his I.P. would even post to a forum like this.
I really don't understand why an inventor who is so nervous about his I.P. would even post to a forum like this.
The acoustic power of a source, at frequencies for which the wavelength is larger than the dimensions of the loudspeaker diaphragm, is a function of NEITHER the shape NOR the motion of this radiator.
As stated elsewhere by T. Danley, the acoustic power is defined by the displacement volume and the excitation frequency, period. The fan-like solutions aren't appropriate, but a rotary diaphragm will then behave mechanically different than a piston-like diaphragm. Applying the force to the apex of the cone, along its axis, will result in cone breakup, then you can rather use a single-vane or, better, a dual-vane system centered on a shaft, equivalent to a 10" piston with more than 4" peak-to-peak excursion. I have several ideas to improve the design of this driver.
As far as the behaviour of this driver, it's clear that the polarity of the signal determines the direction of rotation, then the torque is proportional to the input signal and the back emf is dependent of the velocity of the conductor coil. Since there are rotating elements, the contribution to the TS parameters depend on these distances and, for example, the radius of the diaphragm will participate at its squared value...
For low frequency, "Servodrive subwoofers" using rotary voice coils will be able to deliver much more power than any voice coil cone driver. They will behave much better regarding "power compression" (rise of the coil resistance with the temperature).
Well I don't know why you tell us all this, I'm sure you have thought it out very well.
Is this in response to my post on acoustic shorting?
Is there a point to your post?
Edit: I don't want to get involved in a discussion about all kinds of speaker principles. My original point was that the view that you can only judge a design by building a prototype is shortsighted and not optimal, and that criticism to people who analyse a design and give a reasoned judgment is in principle unfounded. I tried to make something clear, not to start a fight. I want to leave it at that.
jan
Is this in response to my post on acoustic shorting?
Is there a point to your post?
Edit: I don't want to get involved in a discussion about all kinds of speaker principles. My original point was that the view that you can only judge a design by building a prototype is shortsighted and not optimal, and that criticism to people who analyse a design and give a reasoned judgment is in principle unfounded. I tried to make something clear, not to start a fight. I want to leave it at that.
jan
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For high frequencies, the major drawback of any coil driver is its inductance and the inductance depends on the square of the number turns of the coil... This is the reason why the impedance rises rapidly with the frequency, since the impedance is also proportional to Lw, as a consequence, the frequency response of the driver collapses !... The important parameter for the voice-coil driver is then the ratio (Bl)/(R^1/2), with the usual values for each term (B field, L lenght and R the DC resistance).
Then, as stated in one of my previous posts, this design will have a cut-off frequency. The cross-section of the conductor used for the coil will command largely this cut-off : explicitely, the smaller the cross-section of the coil windings, the higher the cut-off frequency !... The mechanical constraints will also have an incidence on this cut-off.
With some caution, it's now quasi sure that an almost full-range driver can be derived from this previous design. Moreover, a very well phase-behaviour will be awaited. The same for the amplitude response. Some other results concerning the good sounding for music are also probable but some measurements on the harmonic distorsion must be made before...
OK, these 2 posts are just to explain to you, and to some others, that their comments are erroneous. Then, you are free to believe what you want and/or to build or not this driver. I neither want to start any fight here or elsewhere, but I want just to recall that some of the posts will scare the author of this design and we'll loose a very interesting source of info...
Then, as stated in one of my previous posts, this design will have a cut-off frequency. The cross-section of the conductor used for the coil will command largely this cut-off : explicitely, the smaller the cross-section of the coil windings, the higher the cut-off frequency !... The mechanical constraints will also have an incidence on this cut-off.
With some caution, it's now quasi sure that an almost full-range driver can be derived from this previous design. Moreover, a very well phase-behaviour will be awaited. The same for the amplitude response. Some other results concerning the good sounding for music are also probable but some measurements on the harmonic distorsion must be made before...
OK, these 2 posts are just to explain to you, and to some others, that their comments are erroneous. Then, you are free to believe what you want and/or to build or not this driver. I neither want to start any fight here or elsewhere, but I want just to recall that some of the posts will scare the author of this design and we'll loose a very interesting source of info...
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I think you guys are talking orthogonally. Perhaps if you propose a rotary driver, but with no baffle and a short open-backed tube...? And forget about treble for the moment and fixate on bass?
Agreed, analysis can short-circuit the prototyping necessity, but just in case there's a flaw in the analysis, a prototype nicely demonstrates that either the analysis is correct (Julian's prototype measurements showed exactly the bass rolloff, low output, and severely irregular frequency response predicted) or that it's incorrect- the latter is John's claim, but no actual data or demonstration to support it, and he is trying his hardest to convince people that they can't experiment with his concept.
Voice coil inductance is rarely the limiting factor in high frequency response of a driver even in a full range driver, its almost always the mechanical properties of the driver particularly the cone itself (breakup, beaming etc) which set the useful upper frequency limit.
The "lossy" inductance of a voice coil in a magnetic gap typically produces a smooth gradual high frequency roll off of less than 6dB/octave starting at a fairly high frequency, a roll off that can easily be compensated for in the network if necessary.
It's not usually necessary though, as in many drivers the gradual rolloff in power response due to voice coil inductance helps to compensate for on axis beaming, such drivers can often show a fairly flat on axis response with voltage drive that actually tilts upwards towards the treble or peaks before cut off if the voice coil inductance is dramatically lowered with an added shorting ring or the driver is driven with a current source.
Unless we're talking about several mH from a large woofer (which won't be operating above a few hundred Hz anyway) its just not an issue, certainly in 8" or smaller drivers where the voice coil is typically 0.5mH or less...and a shorting ring can cut that inductance down to completely insignificant levels.
Voice coil inductance on a small or medium size driver is the last thing I would be worrying about when thinking about its high frequency performance.
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Well, despite the fact that several reasons as stated above are in favor of this design, I'm definitely persuaded that several points need caution when adressed. The diaphragm and the motor itself are the major. But, I think plenty of details can definitely improve the audio results as a full-range. Even if you have to help it in the low end... Why not with a 100 Hz low-pass similar concept ?...
If you think so, try to build one yourself using the improvements you think will solve the inherent problems and do what John has been unable so far to do.
Attachments
Hi,
Its patently obvious (excuse the pun) what the thing
can and cannot do without building it and testing it.
What it can't do is what the patent claims, but the
patent only covers the implementation of the claim.
I could patent and trademark my "Acme Roadrunner"
1 metre diameter parachute, developed by simply
ignoring all physics that say it won't work and
claiming a revolutionary open cell structure that
massively increases the effective drag through air.
I would get the patent for the cell implementation.*
Would you make it according to my exact (current)
specification (which is under development) and jump
off a building with it to see if it worked ?
Not likely .... You test it more sensibly and find out
unsurprisingly it doesn't work, and say so. Ah well
I say, that's because you haven't built it to the now
current specification (still under development) and
have missed out some critical technical details.
Your version sort of worked (though the claimed
specification at the time said it worked) in that
it sort of slows you down a bit (much like a 1m
parachute would) but you don't have the latest
version which is of course immensely better.
I can imagine your reply to that .......
rgds, sreten.
The device has been built and tested and does do
what you moreorless expect (see a previous post).
However it is claimed that the lack of a couple of
technical details prevented it doing the impossible.
* As long as the patent clerk wasn't diligent enough
to spot some serious lifting from the EnABL patent
regarding the control of air flow over surfaces.
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And , you're definitely wrong ! But you can think what you want... Definitely !
Have a good look at the gallery of photos of this ''PLANOT'' loudspeaker : as a whole speaker in the living room, and all the separate parts (in particular the motor and housing/base).
You will find that the use of hard drive like components is a dead giveaway to how the speaker may possibly work. Then comes the white nylon cooking/ cutting board used to dampen the vibration(distributed modes?)around and underneath the motor housing.
Next is the ''ROD''..............two versions of it in fact : one is depicted as a triangle in the drawings and another, in a photograph, looks very much like a white ''square''(??) section of tubing.
So what is the ''rod'?........square or triangular? Was the triangular version replaced with a square one? If so, why?
I have no doubt that Julian's prototype is what the Planot loudspeaker is. Perhaps to be fair, the Planot is far better in it's design due to professional machining and a more efficient coupling of the rod to the bearing/voice coil/motor assembly.
However, that's where the buck stops. There may indeed be a greater spl from the Planot, but not by much. There will also be a lack of low frequencies which correlate to my own experiments and prototype.
On top of all this is the problem of rod resonance which renders it unusable for audio. You can tame some of these resonances with damping along the rod material but this comes at a price in regards to efficiency which is lousy anyway.
To me there is no secret to this loudspeaker patent.
You will find that the use of hard drive like components is a dead giveaway to how the speaker may possibly work. Then comes the white nylon cooking/ cutting board used to dampen the vibration(distributed modes?)around and underneath the motor housing.
Next is the ''ROD''..............two versions of it in fact : one is depicted as a triangle in the drawings and another, in a photograph, looks very much like a white ''square''(??) section of tubing.
So what is the ''rod'?........square or triangular? Was the triangular version replaced with a square one? If so, why?
I have no doubt that Julian's prototype is what the Planot loudspeaker is. Perhaps to be fair, the Planot is far better in it's design due to professional machining and a more efficient coupling of the rod to the bearing/voice coil/motor assembly.
However, that's where the buck stops. There may indeed be a greater spl from the Planot, but not by much. There will also be a lack of low frequencies which correlate to my own experiments and prototype.
On top of all this is the problem of rod resonance which renders it unusable for audio. You can tame some of these resonances with damping along the rod material but this comes at a price in regards to efficiency which is lousy anyway.
To me there is no secret to this loudspeaker patent.
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See, that's the cheap shots I protest against. DBMandrake took the trouble to explain the interrelationships of inductance, hf roll-off, the opposite effect of increased directionality with freq, and the now standard use of shorting rings on the voice coil. Something that gives you increased understanding. A reasoned explanation leading to a conclusion.
You otoh just tell us 'you're definitely wrong'.
Why don't you do us the courtesy of explaining why it is wrong?
jan
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There's two particularly telling comments in this thread, assuming I interpret them correctly:
I "know" the theory is good because I studiously ignore any evidence to the contrary.
I got a flat frequency response by applying whatever equalization was needed to get a flat frequency response.
Roughly translated:
I "know" the theory is good because I studiously ignore any evidence to the contrary.
Roughly translated:
I got a flat frequency response by applying whatever equalization was needed to get a flat frequency response.
Meaningful measurements that don't look fake would go some way towards convincing people that maybe there is something to your idea, reluctance to publish them suggests that there is nothing to publish.
1/3rd octave smoothing is not a "small" amount of smoothing, that is a LOT of smoothing.
So much in fact as to make the measurement completely worthless even if it is a real acoustic measurement, which it doesn't appear to be.I wouldn't even accept a 1/3rd octave smoothed measurement of a conventional cone driver as meaningful proof of its performance, let alone a device of unproven operation.
One of the key indicators of sound quality of a high frequency driver is its narrow band frequency response smoothness, as seen in a high resolution unsmoothed frequency response - a 1/3rd octave plot will at most give a rough idea of overall tonal balance, but no indication of response smoothness and therefore actual sound quality.
When measuring drivers or speakers I always look at the narrow band unsmoothed response - anything else is just throwing away data and fooling yourself. An unsmoothed warts and all response of your driver would be a lot more informative than what you have posted.
As to the measurement technique itself, are we looking at a single measurement or a near field / gated far field splice ? If it's a single measurement taken as you say a bit less than a metre (how much less ?) then we should see room modes and a floor bounce cancellation dominating the low frequency response. If its near field you should see large peaks and dips in the high frequency response due to being closer than 3x the radiators longest dimension. You can't have it both ways...you're not going to get a valid measurement of both high and low end response in a single non-spliced measurement unless you have access to a perfect anechoic chamber...
Without an unsmoothed measurement and complete disclosure on the specific measurement conditions all your measurement does is fuel the fires of debate against you, and is probably best removed as "evidence" of the devices functioning until such time as you can present meaningful measurements.
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gentlemen!
"Gentlemen. You can't fight in here. This is the War Room!" - YouTube
I love this thread........
now shall we argue about which end of the egg we should crack and eat from...
"Gentlemen. You can't fight in here. This is the War Room!" - YouTube
I love this thread........
now shall we argue about which end of the egg we should crack and eat from...
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