Ok, then as a last resort to make you see doppler happens at speakers maybe read the article I posted?
Sometimes it’s nice to have an old textbook handy to fact check the internet speculations :
[”Finally, there is one myth about loudspeaker performance which should be laid to rest. Occasionally in technical and hi-fi magazines the phrase
”Doppler distortion” is used…
.. In fact, Villchur and Allison (1980) have shown , both by listening tests and by theoretical analysis, that Doppler distortion is completely inaudible for any practical cone velocity”]
From:
An Introduction to the Psychology of Hearing
Fifth Edition , page 347 1st para.
Brian C.J. Moore
Department of Experimental Psychology
University of Cambridge.
Please note that the posted article is , despite it’s scienterrific content, entirely speculative, commercially driven and unproven in practice. As far as I am concerned the Villchur et.al. research still stands unless someone can point me to newer findings.
[”Finally, there is one myth about loudspeaker performance which should be laid to rest. Occasionally in technical and hi-fi magazines the phrase
”Doppler distortion” is used…
.. In fact, Villchur and Allison (1980) have shown , both by listening tests and by theoretical analysis, that Doppler distortion is completely inaudible for any practical cone velocity”]
From:
An Introduction to the Psychology of Hearing
Fifth Edition , page 347 1st para.
Brian C.J. Moore
Department of Experimental Psychology
University of Cambridge.
Please note that the posted article is , despite it’s scienterrific content, entirely speculative, commercially driven and unproven in practice. As far as I am concerned the Villchur et.al. research still stands unless someone can point me to newer findings.
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Ok, this quite different from Arthur Jackson's
reasoning that speaker doppler does not happen at all.
This basically states its there but inaudible.
I assume my pointer to the article of Reinhold Lutz?
Not sure he would agree with you..
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Whether or not doppler distortion is audible, I feel that removing huge bass excursions from a small-ish driver which is simultaneously trying to reproduce midrange has to be a good thing.
Non-linear distortion becomes higher with excursion, and by relieving the poor little midrange-sized driver of trying - and failing - to reproduce worthwhile bass we should expect improvements.
The Satellite-Sub concept has much going for it but still seems to have some kind of stigma attached to it.
Non-linear distortion becomes higher with excursion, and by relieving the poor little midrange-sized driver of trying - and failing - to reproduce worthwhile bass we should expect improvements.
The Satellite-Sub concept has much going for it but still seems to have some kind of stigma attached to it.
Please note that Dr. Lutz has done absolutely nothing to disprove Professor Moore or the research of Villchur & Adams. If he had done so he would have disrupted some of the basic research in audio. Instead he has published an article in an industry publication that serves to sell products. A publication which, as anyone can see, posts these “breakthroughs” in every other issue. Most of us never see them going anywhere either in the industry or in academia.
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I mean on the remark of calling it "internet speculation", not about disproving the work of the others you mention (cant find much online btw, I need to go to an actual library it seems)
Do you have the text somewhere?
Do you have the text somewhere?
The maths is flawed:
p(t)=(ρSD/2πr) x a(t)
p is pressure. ρ is air density. SD is cone area. r is measuring distance.
a(t) is acceleration, which is proportional to drive voltage to the speaker motor coil.
This is a linear expression, so two different drive frequencies added produce a sum pressure waveform, no intermodulation or phase modulation.
Intermodulation happens in reality due to a(t) being a non linear function of voltage as the coil hits the end stops and the cone surround limits travel.
But I am not trying to sell a product
A related one:
A few weeks ago I met a guy who restored a Leslie speaker, a specialist speaker o complement organs. I never heard of it before. As I understand it uses Doppler effect to add vibrato effect to the sound of organ. Driver mechanically rotates inside the speaker box to produce Doppler effect. Rotation speed can be changed. Amazing!
A few weeks ago I met a guy who restored a Leslie speaker, a specialist speaker o complement organs. I never heard of it before. As I understand it uses Doppler effect to add vibrato effect to the sound of organ. Driver mechanically rotates inside the speaker box to produce Doppler effect. Rotation speed can be changed. Amazing!
if this p(t) was coming from a stationary position you would be right.
But its moving.
Maybe because I wrote Adams when it should have been Allison..🫣
https://pubs.aip.org/asa/jasa/artic...Doppler-distortion-in?redirectedFrom=fulltext
ISBN 0-12-505628-1
Use multiple drivers (line array) to reduce Doppler Effect (DE) which means individual drivers don't move as much. This minimizes DE and adds other speaker related benefits. I will never publish this but if I did it would be known as Doppler Effect Array Drivers.
Removing something that doesn’t exist or is simply imagined (’DE’) makes very little sense to me. Whatever…
Yes!
A bit more productive response would be that I would rather suggest that, in the case of the line array , a larger diaphragm area couples better to the air, primarily due to enhanced efficiency in energy transfer and impedance matching.
Increased Volume Velocity:
Volume velocity (\(Q\)), the product of diaphragm area (\(A\)) and velocity (\(v\)), directly influences sound pressure (\(p \propto \rho_0 c A v\)). A larger diaphragm displaces more air molecules for the same velocity, generating higher sound pressure levels (SPL) and greater acoustic output. This makes the energy transfer more efficient.
Impedance Matching:
Air has low acoustic impedance
(\(Z = \rho_0 c\)), and a larger diaphragm area reduces mechanical impedance, improving impedance matching. Better matching minimizes energy reflection at the air-diaphragm interface, enhancing coupling.
Radiation Resistance:
Radiation resistance (\(R_r\)), which governs power radiated as sound, scales with the square of frequency (\(f\)) and diaphragm area. Larger diaphragms increase \(R_r\), especially at lower frequencies, ensuring more energy is converted into sound rather than stored or dissipated.
Low-Frequency Efficiency:
At lower frequencies (long wavelengths), larger diaphragms maintain effective radiation resistance, allowing efficient coupling. Smaller diaphragms struggle here, as their radiation resistance drops, leading to poor bass
This results in higher efficiency, greater SPL, and better energy transfer, even if high-frequency performance involves other design considerations.
A bit more productive response would be that I would rather suggest that, in the case of the line array , a larger diaphragm area couples better to the air, primarily due to enhanced efficiency in energy transfer and impedance matching.
Increased Volume Velocity:
Volume velocity (\(Q\)), the product of diaphragm area (\(A\)) and velocity (\(v\)), directly influences sound pressure (\(p \propto \rho_0 c A v\)). A larger diaphragm displaces more air molecules for the same velocity, generating higher sound pressure levels (SPL) and greater acoustic output. This makes the energy transfer more efficient.
Impedance Matching:
Air has low acoustic impedance
(\(Z = \rho_0 c\)), and a larger diaphragm area reduces mechanical impedance, improving impedance matching. Better matching minimizes energy reflection at the air-diaphragm interface, enhancing coupling.
Radiation Resistance:
Radiation resistance (\(R_r\)), which governs power radiated as sound, scales with the square of frequency (\(f\)) and diaphragm area. Larger diaphragms increase \(R_r\), especially at lower frequencies, ensuring more energy is converted into sound rather than stored or dissipated.
Low-Frequency Efficiency:
At lower frequencies (long wavelengths), larger diaphragms maintain effective radiation resistance, allowing efficient coupling. Smaller diaphragms struggle here, as their radiation resistance drops, leading to poor bass
This results in higher efficiency, greater SPL, and better energy transfer, even if high-frequency performance involves other design considerations.
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FM distortion does exist. No doubt about that. The question remains whether it is audible or not.
According to Martin Colloms it is an issue with wideband drivers when they have to do more than 6 mm of peak excursion. I haven't done any formal test of that but have encountered "gargling midrange" on a small active two-way with bass EQ.
I myself think that a speaker whose midrange has regularly more than 3 mm peak excursion is seriously underdimensioned. Therefore one has to either use a three- or more-way system or a two way with large midwoofers if this happens too often.
The type if distortion caused by FM modulation is indeed a form of IMD due to the sidebands caused by the involved Bessel function. But since its source is different from the other sources of IMD the remedies against the latter do not always help as remedy against FM distortion ( Multi-way helps, copper in the airgap doesn't .....).
The idea of modulating the point of acousic origin is not new and is used for a few years now by Silbersand in a small active two-way speaker:
https://www.silbersand.de/delphi_en.html
Regards
Charles
According to Martin Colloms it is an issue with wideband drivers when they have to do more than 6 mm of peak excursion. I haven't done any formal test of that but have encountered "gargling midrange" on a small active two-way with bass EQ.
I myself think that a speaker whose midrange has regularly more than 3 mm peak excursion is seriously underdimensioned. Therefore one has to either use a three- or more-way system or a two way with large midwoofers if this happens too often.
The type if distortion caused by FM modulation is indeed a form of IMD due to the sidebands caused by the involved Bessel function. But since its source is different from the other sources of IMD the remedies against the latter do not always help as remedy against FM distortion ( Multi-way helps, copper in the airgap doesn't .....).
The idea of modulating the point of acousic origin is not new and is used for a few years now by Silbersand in a small active two-way speaker:
https://www.silbersand.de/delphi_en.html
Regards
Charles
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Why i am a fan of WAW. First experienced what HPing the midTop when we added woofers to a pair of LS3/5A in the late 70s.
dave