Randy Yates wrote:
ruffrecords writes:


PenguiN wrote:

The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that comes

from only one source, the complex electrical waveform driving the speaker

motor. All the other anologies have two sources, one for the low frequency
motion and one for the high frequency sound, NOT a valid anology for what
happens when a speaker reproduced a complex waveform.

What if we take this to the extremes with a thought experiment:

Picture the largest loudspeaker in the universe sitting outside

somewhere. It's so big that it has a maximal excursion of several
feet. Now picture a very low bass signal played on that speaker at
almost maximal volume. The speaker cone is vibrating
in-out-in-out-in-out.
Now add to that signal a small, high pitched, low amplitude waveform.

The two waveforms are added together so that it seems like the higher
pitched wave is "riding on top of" the bass wave.


What gets added are the instantaneous pressures. The air pressure
produced is exactly the same as two separate speakers at the two
frequencies. There is no such thing as doppler distortion.


Consider this gedanken: Place a 4-inch speaker on the cone of a 14-foot
speaker. Now, the two speakers are fed different signals.

Consider this. place a 14ft speaker next to a 4inch speaker and feed
them different signals. Is there Doppler? No


The difference between receiving two such summed signals electrically
versus acoustically is that one has the physical phenomenom of the
propagation of sound through the air in one case and not in the other.

I did not mention electrical adding of the signals.



Get out a physics book and read about Doppler. The explanation of
how the observed wavelength changes when there is a relative velocity
between the source and observer should make you a believer that this
is precisely the scene in a speaker reproducing two frequencies.

get an electrical test book and read about linear superpostion.

Ian

ruffrecords writes:

Randy Yates wrote:
ruffrecords writes:


PenguiN wrote:

The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that comes

from only one source, the complex electrical waveform driving the speaker

motor. All the other anologies have two sources, one for the low frequency
motion and one for the high frequency sound, NOT a valid anology for what
happens when a speaker reproduced a complex waveform.

What if we take this to the extremes with a thought experiment:

Picture the largest loudspeaker in the universe sitting outside

somewhere. It's so big that it has a maximal excursion of several
feet. Now picture a very low bass signal played on that speaker at
almost maximal volume. The speaker cone is vibrating
in-out-in-out-in-out.
Now add to that signal a small, high pitched, low amplitude waveform.

The two waveforms are added together so that it seems like the higher
pitched wave is "riding on top of" the bass wave.


What gets added are the instantaneous pressures. The air pressure
produced is exactly the same as two separate speakers at the two
frequencies. There is no such thing as doppler distortion.
Consider this gedanken: Place a 4-inch speaker on the cone of a
14-foot

speaker. Now, the two speakers are fed different signals.

Consider this. place a 14ft speaker next to a 4inch speaker and feed
them different signals. Is there Doppler? No

Hey man, stay stupid - see if I give a ****.

The difference between receiving two such summed signals electrically

versus acoustically is that one has the physical phenomenom of the
propagation of sound through the air in one case and not in the other.

I did not mention electrical adding of the signals.


Get out a physics book and read about Doppler. The explanation of

how the observed wavelength changes when there is a relative velocity
between the source and observer should make you a believer that this
is precisely the scene in a speaker reproducing two frequencies.


get an electrical test book and read about linear superpostion.

You mean a text on linear system theory and/or basic circuit analysis?
Like Oppenheim and Willsky's "Signals and Systems"? Or Sedra and
Smith's "Microelectronic Circuits"? Or how about the old standard,
Boylestad's "Circuit Analysis"? I've read those books over the course
of 20 years and two degrees in electrical engineering.

I've also read about the migratory behavior of sperm whales, but
neither one have anything to do with the Doppler effect in
speakers. So forget this argument and go buy another eighth of
sensamilla at your local pot store.
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
, 919-472-1124

Porky wrote:

So, anyone want to describe a test procedure that can be done with
equipment that at least some of us are likely to have access to, and see if
everyone will agree that it's valid and that it will measure Doppler
distortion while excluding any other form of distortion that could be
mistaken for Doppler?

I have suggested one that would be definitive and free of
any extraneous effects. While not cheap or generally
available, this is about the _only_ experiment that can
isolate distortion that might or might not be occuring at
the air/piston interface which is how "Doppler distortion"
is described. Put a mirror at the center of the cone and a
laser interferometer at the position of a very linear
microphone. Drive the speaker with the classic two tones
that are supposed to most simply evidence the effect.

If the signal that comes from the microphone has a spectrum
that contains things that are zero in the spectrum of the
laser interferometer then there is real experimental
evidence for "Doppler distortion."

Mackie has or once had a laser interferometer such as what
is needed that they used to find out what was happening at
various points on a tweeter dome.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Arny Krueger wrote:


Suggestion. Send the signal through a 4 kHz BPF that is wide enough
to pass the sidebands but not wide enough to pass the 50 Hz or it's
harmonics.


That's an idea.

Yeah, a really good one.



You should then be able to analyze this BP signal to see
if it is AM or FM. If it is AM, the envelope will vary at 50 Hz. If
it is FM, the envelope will be constant.


Its a mixture. Now the fun begins. There is an envelope, quite clearly at 50
Hz.

Now we're getting somewhere!


However, if we limit it heavily to forcably eliminate the envelope, there
are still 4 sidebands left.

Interpretation?


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Arny Krueger wrote:
"ruffrecords" wrote in message



PenguiN wrote:


As far as our

super-excursion speaker is concerned, the location that's generating
the high pitched sound is moving forward and backward several feet.


No it isn't. This is the flaw in all the doppler distortion
arguments.


If all the explanations for Doppler distortion are wrong, where does all of
the FM we measure come from? Why does it correlate well with the *incorrect*
theoretical predictions?



To produce FM there needs to be a non-linearity. If you detect FM there
is a good chance a non-linearity exists. But it is not due to the
doppler effect.

Ian

ruffrecords wrote:

To produce FM there needs to be a non-linearity. If you detect FM there
is a good chance a non-linearity exists. But it is not due to the
doppler effect.

Exactly, and until an experiment is done which eliminates
all other driver non-linearities an experiment hasn't been done.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Randy Yates wrote:
ruffrecords writes:


Randy Yates wrote:

ruffrecords writes:


PenguiN wrote:


The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that comes

from only one source, the complex electrical waveform driving the speaker


motor. All the other anologies have two sources, one for the low frequency
motion and one for the high frequency sound, NOT a valid anology for what
happens when a speaker reproduced a complex waveform.

What if we take this to the extremes with a thought experiment:

Picture the largest loudspeaker in the universe sitting outside

somewhere. It's so big that it has a maximal excursion of several
feet. Now picture a very low bass signal played on that speaker at
almost maximal volume. The speaker cone is vibrating
in-out-in-out-in-out.
Now add to that signal a small, high pitched, low amplitude waveform.

The two waveforms are added together so that it seems like the higher
pitched wave is "riding on top of" the bass wave.


What gets added are the instantaneous pressures. The air pressure
produced is exactly the same as two separate speakers at the two
frequencies. There is no such thing as doppler distortion.

Consider this gedanken: Place a 4-inch speaker on the cone of a
14-foot

speaker. Now, the two speakers are fed different signals.

Consider this. place a 14ft speaker next to a 4inch speaker and feed
them different signals. Is there Doppler? No



Hey man, stay stupid - see if I give a ****.

Nothing stupid about it. If both systems are linear then they will work
in an identical manner.

Ian

"ruffrecords" wrote in message

Arny Krueger wrote:
"ruffrecords" wrote in message



PenguiN wrote:


As far as our

super-excursion speaker is concerned, the location that's
generating the high pitched sound is moving forward and backward
several feet.


No it isn't. This is the flaw in all the doppler distortion
arguments.


If all the explanations for Doppler distortion are wrong, where does
all of the FM we measure come from? Why does it correlate well with
the *incorrect* theoretical predictions?



To produce FM there needs to be a non-linearity.

Not really. A nonlinearity produces AM.

FM is exactly what Doppler distortion produces.

If you detect FM there is a good chance a non-linearity exists.

If you do the math, nonlinearities can't produce FM distoriton. You need
something that operates in the time domain, not the amplitude domain.

But it is not due to the Doppler effect.

"Bob Cain" wrote in message

Arny Krueger wrote:


Suggestion. Send the signal through a 4 kHz BPF that is wide enough
to pass the sidebands but not wide enough to pass the 50 Hz or it's
harmonics.


That's an idea.

Yeah, a really good one.



You should then be able to analyze this BP signal to see
if it is AM or FM. If it is AM, the envelope will vary at 50 Hz. If it
is FM, the envelope will be constant.


Its a mixture. Now the fun begins. There is an envelope, quite
clearly at 50 Hz.

Now we're getting somewhere!


However, if we limit it heavily to forcably eliminate the envelope,
there are still 4 sidebands left.

Interpretation?

Mixture of AM &FM

ruffrecords writes:
If both systems are linear then they will
work in an identical manner.

That statement is absolutely correct, just as "If I am pregnant,
then I am a female." is absolutely correct.
--
% Randy Yates % "Maybe one day I'll feel her cold embrace,
%% Fuquay-Varina, NC % and kiss her interface,
%%% 919-577-9882 % til then, I'll leave her alone."
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr

Bob Cain writes:

ruffrecords wrote:

To produce FM there needs to be a non-linearity. If you detect FM
there is a good chance a non-linearity exists. But it is not due to
the doppler effect.

Exactly,

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.
--
% Randy Yates % "Though you ride on the wheels of tomorrow,
%% Fuquay-Varina, NC % you still wander the fields of your
%%% 919-577-9882 % sorrow."
%%%% % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr

"ruffrecords"

What gets added are the instantaneous pressures. The air pressure
produced is exactly the same as two separate speakers at the two
frequencies. There is no such thing as doppler distortion.

Ian



** Ian is another who cannot walk and chew gum at the same time.





.......... Phil

"Phil Allison" wrote in message
...

"Porky"

The sound produced by the speaker happens because the speaker is
driven
by a single complex waveform, thus there is a single source for the
sound.
The sound that comes from a train whistle is generated by the whistle,
and
the motion imparted to the whistle comes from the train's motion, two
separate sources.


** WRONG !!!

There is only one source of sound in both cases.

Case 1 = the cone.

Case 2 = the whistle.



If you move the whistle back and forth in a manner
approximating that of a speaker cone, you still have two sources, the
whistle's sound and the mechanical vibration of the whistle, if you
mount
the whistle on the speaker cone, you have two sources, that driving the
cone
and that coming from the whistle.


** I told you to lay off that damn weed !!


None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that
comes
from only one source, the complex electrical waveform driving the
speaker
motor.


** The SOURCE source of any sound is the vibrating object or air column.


All the other anologies have two sources, one for the low frequency
motion and one for the high frequency sound,


** Simply not relevant.


NOT a valid anology for what
happens when a speaker reproduced a complex waveform. If you don't get
that,
then perhaps it is you who should "lay off the weed".


** There is nothing rational anywhere in your posts to get.


You aren't going to
get it until you can differentiate that which comes from two or more
separate simple driving sources and that which comes from a single
complex
driving source


** Totally false distinction.

It exists only in the words.


BTW, I never said anything about a cone's motion being prodiuced by
sound.
I said "a speaker reproducing a complex waveform".


** Quote:

" Even moving the whistle back and forth in approximation of a
moving speaker cone is not a valid anology, because the whistle's back
and forth motion is not generated by the sound coming from the whistle,
as
it would be in a speaker reproducing a complex waveform. "


** Yes you did, then deceitfully snipped it.

In the first place, I don't go drugs of any kind, including weed and
alcohol, and in the second place if you don't see the difference between
providing all forms of motion involved (whether they produce sound or not)
with one complex source, and providing the different forms of motion
(whether they produce sound or not) with multiple simple sources, then any
conclusion you may come to is going to be fundamentally flawed, and all your
flippant answers aren't going to change that.

"PenguiN" wrote in message
om...
The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that
comes
from only one source, the complex electrical waveform driving the
speaker
motor. All the other anologies have two sources, one for the low
frequency
motion and one for the high frequency sound, NOT a valid anology for
what
happens when a speaker reproduced a complex waveform.

What if we take this to the extremes with a thought experiment:

Picture the largest loudspeaker in the universe sitting outside
somewhere. It's so big that it has a maximal excursion of several
feet. Now picture a very low bass signal played on that speaker at
almost maximal volume. The speaker cone is vibrating
in-out-in-out-in-out.

Now add to that signal a small, high pitched, low amplitude waveform.
The two waveforms are added together so that it seems like the higher
pitched wave is "riding on top of" the bass wave. As far as our
super-excursion speaker is concerned, the location that's generating
the high pitched sound is moving forward and backward several feet.

Fundamental flaw in the logic, the higher pitched signal is not "riding on"
the lower pitched signal, they are combined to produce a complex waveform
driving the speaker.

If you still don't believe that this scenario validates the
train-whistle analogy, why not make the bass waveform move at the
speed of, oh say a train, and have the high pitched signal on top of
it be, oh say the sound of a whistle.

Doesn't apply, the train and whistle are supplied by two separate sources of
energy.

The scenario described in this thought experiment would *certainly*
produce doppler shift in the higher signals. If you made the bass
carrier sound low enough frequency and loud enough, you would even be
able to hear the weeeooohhweeeoooh modulation of the higher frequency
as the source of that sound (the surface of the speaker cone) is
moving towards and away from you. It follows reasonably that this also
happens with regular speakers, but to a lesser extent.

Once again, comparing two separate sources of motion (the train and the
whistle) provided by two separate sources of energy, to one complex motion
source provided by one single complex source of energy (the signal driving
the speaker motor) is comparing apples to oranges.

The question of whether it's a relevant, measurable, or hearable
distortion is a separate issue from whether it physically exists.

Agreed, but in order to reach any valid conclusions, one must stop comparing
apples to oranges!

"Porky"
"Phil Allison"


** Yes you did, then deceitfully snipped it.

In the first place, I don't go drugs of any kind, including weed and
alcohol, and in the second place if you don't see the difference between
providing all forms of motion involved (whether they produce sound or not)
with one complex source, and providing the different forms of motion
(whether they produce sound or not) with multiple simple sources, then any
conclusion you may come to is going to be fundamentally flawed, and all
your
flippant answers aren't going to change that.



** This little piggy cannot trot and chew gum at the same time.




............ Phil

"Porky"


Agreed, but in order to reach any valid conclusions, one must stop
comparing
apples to oranges!




** This litle piggy cannot trot and chew rotten fruit at the same time.




............... Phil

"Randy Yates" wrote in message
...
Bob Cain writes:

ruffrecords wrote:

To produce FM there needs to be a non-linearity. If you detect FM
there is a good chance a non-linearity exists. But it is not due to
the doppler effect.

Exactly,

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

This whole argument is based on the wrong assumption that the high
frequency source is "riding on" the low frequency source like a whistle on a
train. It is NOT! Both sounds are being produced simultaneously by the
complex electrical waveform driving the speaker cone which moves in
accordance. Assuming that the speaker is being driven within its linear
limits, the cone's motion accurately follows the driving signal, and it is a
linear system.
Forget the train/whistle anology, it is not an accurate representation for
what goes on with a speaker, period!

"Bob Cain" wrote in message
...


Porky wrote:

So, anyone want to describe a test procedure that can be done with
equipment that at least some of us are likely to have access to, and see
if
everyone will agree that it's valid and that it will measure Doppler
distortion while excluding any other form of distortion that could be
mistaken for Doppler?

I have suggested one that would be definitive and free of
any extraneous effects. While not cheap or generally
available, this is about the _only_ experiment that can
isolate distortion that might or might not be occuring at
the air/piston interface which is how "Doppler distortion"
is described. Put a mirror at the center of the cone and a
laser interferometer at the position of a very linear
microphone. Drive the speaker with the classic two tones
that are supposed to most simply evidence the effect.

If the signal that comes from the microphone has a spectrum
that contains things that are zero in the spectrum of the
laser interferometer then there is real experimental
evidence for "Doppler distortion."

Mackie has or once had a laser interferometer such as what
is needed that they used to find out what was happening at
various points on a tweeter dome.



Which brings up another point, at frequencies whose wavelengths are
relatively small compared to the driver's diameter, the sound is emitted
from radiational nodes on the surface of the driver. I think Doppler
distortion might be a possibility in this special case, but not when the
whole driver is acting as a rigid piston and the whole driver is uniformly
producing both sounds. It seems to me that, assuming that crossover points
are chosen so that radiational nodes don't form on the woofer, Doppler can
be dismissed.
My personal view allows for the possibility that Doppler distortion might
exist under certain circumstances in a speaker, but if it does, it is
generally so low in amplitude in any properly designed speaker that it will
be masked by other forms of distortion.

"Phil Allison" wrote in message
...
In the first place, I don't go drugs of any kind, including weed and
alcohol, and in the second place if you don't see the difference between
providing all forms of motion involved (whether they produce sound or
not)
with one complex source, and providing the different forms of motion
(whether they produce sound or not) with multiple simple sources, then
any
conclusion you may come to is going to be fundamentally flawed, and all
your
flippant answers aren't going to change that.



** This little piggy cannot trot and chew gum at the same time.

Are you kidding? I can drive a racecar while chewing gum and
simultaneously contemplating the possibility that a speaker can generate
Doppler distortion while producing multiple tones when driven by a single
complex waveform, and at the same calculating the probibility (approx
83.762%) that you are the one who is smoking weed.:-)

"Phil Allison" wrote in message
...

"Porky"


Agreed, but in order to reach any valid conclusions, one must stop
comparing
apples to oranges!




** This litle piggy cannot trot and chew rotten fruit at the same time.


Ah, yes, but Phil can, in fact, he does it all the time. Unfortunately the
rotten fruit has fermented and contains a high level of alcohol, which has
severely unbalanced Phil's mental process.:-)

"Porky" writes:

"Randy Yates" wrote in message
...
Bob Cain writes:

ruffrecords wrote:

To produce FM there needs to be a non-linearity. If you detect FM
there is a good chance a non-linearity exists. But it is not due to
the doppler effect.

Exactly,

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

This whole argument is based on the wrong assumption that the high
frequency source is "riding on" the low frequency source like a whistle on a
train. It is NOT!

Oh, but it is. That is precisely what is happening.

Both sounds are being produced simultaneously by the
complex electrical waveform driving the speaker cone which moves in
accordance.

True, and how does that refute that there is no Doppler? Before it
ever gets to a speaker, such an electrical signal will have the
characteristic of the high frequency wave "riding" on top of
the low frequency wave. You will see it on a scope. Input that to
a speaker and you will see precisely the same thing if you observed
a plot of speaker cone displacement versus time.

Assuming that the speaker is being driven within its linear
limits, the cone's motion accurately follows the driving signal,

True.

and it is a
linear system.

FALSE! Well, at least if you define "it" to be the entire composite system
from the speaker's electrical input to the acoustic receiver's input. In
that case, it ain't linear. That's the whole point. The physics of what
happens between the speaker cone and the acoustic observer are such that
Doppler will take effect. Now how *much* Dopper is another question, but
the effect will be there for sure, just as two masses will experience an attraction
based on the inverse square law (m1*m2/r^2).

Forget the train/whistle anology, it is not an accurate representation for
what goes on with a speaker, period!

Proof by assertion?
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

On Mon, 16 Aug 2004 21:57:16 -0500, "Porky" wrote:


"PenguiN" wrote in message
. com...

If you still don't believe that this scenario validates the
train-whistle analogy, why not make the bass waveform move at the
speed of, oh say a train, and have the high pitched signal on top of
it be, oh say the sound of a whistle.

Doesn't apply, the train and whistle are supplied by two separate sources of
energy.

Have two amplifiers, one for the low frequency connected to the
speaker through an inductor, another amp outputting the high frequency
connected to the speaker through a capacitor. Thus the low and the
high are supplied by two separate sources of energy.

Actually, isn't the train whistle powered by steam from the same
boiler that powers the wheels, moving the train? What's up with that?

But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

If you put the speaker on a shaker table, run 1kHz and 50 Hz
through the speaker, move the shaker table at 50 Hz opposite the phase
to the speaker so the cone only moves at the 1kHz rate with respect to
the air, will it generate doppler distorion? According to my
understanding of Bob's position, it should.
-----
http://mindspring.com/~benbradley

Porky wrote:

Are you kidding? I can drive a racecar while chewing gum and
simultaneously contemplating the possibility that a speaker can generate
Doppler distortion while producing multiple tones when driven by a single
complex waveform, and at the same calculating the probibility (approx
83.762%) that you are the one who is smoking weed.:-)

ROTFLOL! :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

ruffrecords wrote:

super-excursion speaker is concerned, the location that's generating
the high pitched sound is moving forward and backward several feet.


No it isn't. This is the flaw in all the doppler distortion arguments.

What he said.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

ruffrecords wrote:

Nothing stupid about it. If both systems are linear then they will work
in an identical manner.

What he said.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Arny Krueger wrote:

If all the explanations for Doppler distortion are wrong, where does all of
the FM we measure come from? Why does it correlate well with the *incorrect*
theoretical predictions?

What theoretical prediction might that be? I've yet to see
a theory for "Doppler distortion" that predicts. Odd, that.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Randy Yates wrote:

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

Randy has spoken. Without one shread of a predictive
theory. Odd, that.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Porky wrote:


This whole argument is based on the wrong assumption that the high
frequency source is "riding on" the low frequency source like a whistle on a
train. It is NOT! Both sounds are being produced simultaneously by the
complex electrical waveform driving the speaker cone which moves in
accordance. Assuming that the speaker is being driven within its linear
limits, the cone's motion accurately follows the driving signal, and it is a
linear system.
Forget the train/whistle anology, it is not an accurate representation for
what goes on with a speaker, period!

What he said. Is this the same Porky that I've argued with
about _so_ many things?


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Ben Bradley" wrote in message
news
On Mon, 16 Aug 2004 21:57:16 -0500, "Porky" wrote:


"PenguiN" wrote in message
. com...

If you still don't believe that this scenario validates the
train-whistle analogy, why not make the bass waveform move at the
speed of, oh say a train, and have the high pitched signal on top of
it be, oh say the sound of a whistle.

Doesn't apply, the train and whistle are supplied by two separate sources
of
energy.

Have two amplifiers, one for the low frequency connected to the
speaker through an inductor, another amp outputting the high frequency
connected to the speaker through a capacitor. Thus the low and the
high are supplied by two separate sources of energy.

Actually, isn't the train whistle powered by steam from the same
boiler that powers the wheels, moving the train? What's up with that?

But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

If you put the speaker on a shaker table, run 1kHz and 50 Hz
through the speaker, move the shaker table at 50 Hz opposite the phase
to the speaker so the cone only moves at the 1kHz rate with respect to
the air, will it generate doppler distorion? According to my
understanding of Bob's position, it should.

The whole thing hinges on the single complex waveform vs multile simple
waveform idea. If the two sound signals are mixed into a single complex
signal and that signal is what drives the cone, there are not actually two
discrete signals being converted to sound, there is a single complex signal
that our ears interpret as two different sounds. This isn't an exact anology
either, but it's better than the train/whistle thing.
If you play a CD of an orchestral performance, there is not one piece of
analytic equipment man has ever designed or built that can completely
separate and isolate the individual instruments, but any human with decent
hearing and a bit of training can. This would seem to support the argument
that the speaker is producing a complex waveform as a whole, not as a bunch
of individual tones. If this is true then there can be no Doppler distortion
in a speaker that is reproducing the signal in a linear manner. Doppler
shift can only exist when one vibration is riding on another vibration or
source of motion, it cannot exist when all vibrations are being produced as
a single complex waveform.
That is as simply as I can explain it. I'll go either way with the
Doppler argument if someone can prove that the speaker isn't generating a
complex waveform, but is generating a series of simple tones.
The fact that I drove my big speakers with a 20Hz tone combined with a
500Hz tone at a level that the online proponents of Doppler distortion said
would produce audible Doppler shift, and it didn't, tends to make me think
that Doppler shift doesn't occur under those conditions.

Randy Yates wrote:


Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be
incumbent on those that observe that no predictive theory
exists to prove why it doesn't, although I've been trying,
it should be incumbent on those claiming that it exists to
produce the predictive theory. Have at it. This isn't
string theory. If it's there, a precise model should almost
fall out by inspection.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Arny Krueger wrote:


If you do the math, nonlinearities can't produce FM distoriton. You need
something that operates in the time domain, not the amplitude domain.

If you do the math, FM distortion and linearity are mutually
exclusive. This is not debatable. Find a rigorous
definition of linearity. I've presented it but it doesn't
seem to have taken hold despite it being the bedrock of
linear systems theory.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Bob Cain writes:

Randy Yates wrote:

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

Randy has spoken. Without one shread of a predictive theory. Odd,
that.

Have you ever been to Ethiopia, Bob? We might as well be debating whether
or not gravity exists there. I've never been - you've never been - so
we can't say experientially, so it's open for doubt, right?
--
% Randy Yates % "The dreamer, the unwoken fool -
%% Fuquay-Varina, NC % in dreams, no pain will kiss the brow..."
%%% 919-577-9882 %
%%%% % 'Eldorado Overture', *Eldorado*, ELO
http://home.earthlink.net/~yatescr

"Porky"

"Phil Allison"


** This little piggy cannot trot and chew gum at the same time.

Are you kidding?



** Not one bit - you are clearly an utter imbecile.




................. Phil

"Bob Cain"


** The original non ambulatory gum chewer.





........... Phil

Bob Cain writes:

Randy Yates wrote:

Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be incumbent on
those that observe that no predictive theory exists to prove why it
doesn't, although I've been trying, it should be incumbent on those
claiming that it exists to produce the predictive theory. Have at it.
This isn't string theory. If it's there, a precise model should
almost fall out by inspection.

If by "predictive theory" you mean a theory by which this phenomenom
can be predicted, then I must ask if you are blind. I have stated it
several times in several different ways. I have cited a reference for
it (Halliday and Resnick). I am assuming you are familiar with the
theory. Is that assumption invalid? Do you want a rehashing of the
theory of the Doppler effect? Do you want me to transcribe my Physics
text into a usenet news article for you so you don't have to go to the
library and check one out?
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

Bob Cain writes:

Randy Yates wrote:

Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be incumbent on
those that observe that no predictive theory exists to prove why it
doesn't, although I've been trying, it should be incumbent on those
claiming that it exists to produce the predictive theory. Have at it.
This isn't string theory. If it's there, a precise model should
almost fall out by inspection.

I dunno Bob, are you SURE that current will flow when you place the
220 VAC electrodes across your temples? Why don't you try it. You
never know - you may be in a reference frame in which Maxwell's
equations no longer hold.
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

"Bob Cain"


Randy Yates wrote:


Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion."


** Cos you are such an utter ass you refuse to see it.



It shouldn't be
incumbent on those that observe that no predictive theory
exists


** What dishonest rot, Doppler theory is ancient.



If it's there, a precise model should almost fall out by inspection.



** I posted a link with the maths of a precise model.

Shame you are too big an ass to recognise it.





............ Phil

"Bob Cain"

If you do the math, FM distortion and linearity are mutually
exclusive.

** Big lie.

This is not debatable.


** The words of an ass.

Find a rigorous
definition of linearity.


** Find a relevant one.


I've presented it but it doesn't
seem to have taken hold despite it being the bedrock of
linear systems theory.


** Another masive lie from a dangerous fool.





............... Phil

"Bob Cain"

What theoretical prediction might that be? I've yet to see
a theory for "Doppler distortion" that predicts. Odd, that.


** This imbecile has never studied physics in his life.

The kind in books OR the real world of nature.




........... Phil

"Porky"


** This little piggy cannot trot and chew rotten fruit at the same time.



.............. Phil