Another cause of intermodulation distortion happens as a driver isn’t equally good in moving in a linear fashion at all cone positions. For example, if you play music with a powerful bass signal at 30Hz making your woofer cone move to near the extremes where the magnetic field and rubber surround are at the edge of their operating range, other higher frequencies added will experience more distortion as the cone can’t move well relative to all the near peak cone positions of the 30Hz signal.
I’ve been thinking just this question, without knowing how to formulate it into words, excellent, banged the nail on the head with the question and answer. Thank you!
Back in the 90s i had 4 10" kicker solobaric subwoofers running over 1000 watts in the hatch of my 1986 corvette...with the windows up and when the bass would hit the smaller drivers would be driven backwards in their baskets. So yes they distorted immensely when there's 140db pushing against them. Lol. That's the sledgehammer type bass that makes your hair dance, and makes you hold your breath even when you dont want to. Quite painful.
The sound of the doppler in a large full range speaker when listening to a voice with a strong deep bass tone is similar sonically to singing into a fan. ;-)
Great video (as always),sounds very confusing to be honest to a basic car audio spl guy such as my self. There is a rebassed version of a song call "my sub" by Big Kritt. This i would think is a perfect example of what "the caller" is describing with the 2 freqs playing over the top of another.
I once had a pair of speakers that sounded fantastic when the music was simple, a single horn or voice or piano. The sound deteriorated as more instruments were added. I assumed that this was IM distortion. My current speakers retain the clarity of each instrument even when a whole band or orchestra is playing.
The IM distortion in loudspeakers is not by the Doppler effect. As Rod Elliott (sound.whsites.net/doppler.htm) pointed out. When Doppler was the cause of the distortion, then the distortion should be at its greatest when crossing zero, when the speed is at its maximum. But, it is not. The IM distortion is at its greatest at the maxima of the excursion, when the speed is zero! So, it is not the Doppler effect, but change in position of sound source for the higher tone. Another (and bigger) sources of IM distortion are non linearities in the force factor and the suspension of the driver.
Man, that’s an EKG at the first frame! Maybe it was on purpose... a good heart may exert influence on another heart.... or even distort it... hehe. Music for our hearts...
A strong, steady low tone can actually modulate your hearing, i.e., create intermodulation distortion within your ears. There are no mods you can make to the speakers, to correct that.
I would think the speaker would vibrate on the resulting combined frequency, and not try to play each frequency independently of each other. Does that make sense?
I understand how this IM distortion can occur with a single driver, but would not a 200 Hz tone be passed through the crossover to the woofer and the 5,000 Hz tone be passed to the upper mid range or tweeter depending on the drivers? Another question is can this occur in amps? I think so because I have an IM distortion analyzer that is used to measure this in the amplifier. How is IM distortion addressed in amplifier design?
Swinde crossovers of any type don’t spit the frequencies cleanly. They get attenuated gradually (a number of dB per octave) this vids question was somewhat philosophical... but for example if you have a xover at 5000htz and play a 4999htz and 5001 htz note: the xover will have little influence what the speakers do
That is true, but a 200 Hz tone should be attenuated to the tweeter that is reproducing the 5,000 Hz tone which will reduce any IM that would occur in this case.
Hey Paul, I think you’re wrong about blaming the Doppler effect as a source of distortion... (Not that it matters) That is how frequencies naturally mix.. more interesting though: I wonder if your amplifier engineers have taken a simple amplifier design and purposely tried to increase harmonic distortion for learning purposes??
"How is IM distortion addressed in amplifier design? " Back in the Dark Ages around 1970 amplifier designers were competing to achieve the lowest possible THD. Then Jim Sugden introduced his A21 amplifier with an order of magnitude or more THD than his rivals, but it sounded much better. This was eventually identified as due to the A21 having much lower IM distortion. The extremely low THD in rival amplifiers was achieved through using gain stages with a large "excess" gain that was used to provide a high level of negative feedback. Reducing the gain and thus the amount of negative feedback reduced IM distortion. Individual stages in the amplifier chain were also designed with a very high bandwidth of 50 KHz or more. The input was limited to 20 KHz, but available bandwidth after that is often 100 KHz. Keeping global NFB low also appears beneficial. Hope that helps.
I still can't get my head around how a speaker can play two different frequencies at the same time. The speaker cone is been driven by effectively a push pull motor. If one note is asking for 2000Hz and another note is calling for 5000Hz why doesn't it average it and play a 3500Hz frequency? I am envisioning this to be like asking a car engine to do 2000rpm and 5000rpm at the same time. Can someone explain in simple terms how this is possible please.
It's like the car engine's vibrations at the power stroke frequency, which add to the basic crankshaft rotation. They need to be suppressed by a flywheel so they don't cause parts to loosen and fall off while driving. Or try this visualization: You're sitting on a swing, swaying back and forth at perhaps 0.3 Hz. Now hold your hand up in front of you and move it forward and backwards at 1-2Hz. Then wiggle a finger at 3-4Hz. If a string was attached to your finger, do you see that it would experience motion that includes all of those frequencies, but nothing in between?
Put two speakers at the opposite ends of a see-saw, then spin the see-saw. That'll give you plenty of doppler distortion. But the Leslie rotating speaker only rotates a deflector or duct that sits in front of the speaker, and the speaker itself doesn't move. So I think the primary audible effect is using the sound's directivity to modulate the frequency response. Some doppler shift would occur, but only from the sound reflecting off of the interior walls of the moving duct, that is only a fraction of the sound is affected.
What causes distortion when all the members of a band go crazy. High frequencies in a band sounds like shi. Bands should try to make low tone recordings.
I just learned a little more about the inter-relationships between the second third or fifth and beyond harmonics in how they affect sound thank you for the analogy and clarification
I would've thought that someone with a username including "tube" might appreciate modest levels of even-harmonic distortion. That is a large part of the "tube sound" that some listeners enjoy.
The Doppler effect in speakers just hadn't occurred to me. Thanks for splainin it.
Another cause of intermodulation distortion happens as a driver isn’t equally good in moving in a linear fashion at all cone positions. For example, if you play music with a powerful bass signal at 30Hz making your woofer cone move to near the extremes where the magnetic field and rubber surround are at the edge of their operating range, other higher frequencies added will experience more distortion as the cone can’t move well relative to all the near peak cone positions of the 30Hz signal.
That's probably the best question yet. Good show! I learned something new today.
I’ve been thinking just this question, without knowing how to formulate it into words, excellent, banged the nail on the head with the question and answer. Thank you!
Back in the 90s i had 4 10" kicker solobaric subwoofers running over 1000 watts in the hatch of my 1986 corvette...with the windows up and when the bass would hit the smaller drivers would be driven backwards in their baskets. So yes they distorted immensely when there's 140db pushing against them. Lol. That's the sledgehammer type bass that makes your hair dance, and makes you hold your breath even when you dont want to. Quite painful.
Humans do strange things.
I will never understand them.
Oh, wait . . .
I'm amazed that you know so much in so many different areas when it comes to stereos. "Thumbs Up"
Great explanation Paul. I have visualized this in my minds’ eye, and enjoyed your discussion. Thank you.
The sound of the doppler in a large full range speaker when listening to a voice with a strong deep bass tone is similar sonically to singing into a fan. ;-)
Good video
Great video (as always),sounds very confusing to be honest to a basic car audio spl guy such as my self. There is a rebassed version of a song call "my sub" by Big Kritt. This i would think is a perfect example of what "the caller" is describing with the 2 freqs playing over the top of another.
Great question!
I once had a pair of speakers that sounded fantastic when the music was simple, a single horn or voice or piano. The sound deteriorated as more instruments were added. I assumed that this was IM distortion. My current speakers retain the clarity of each instrument even when a whole band or orchestra is playing.
Sod the distortion , play some HAPPY HARDCORE !! lol
Thanks. This was an interesting one.
Very clear, thanks.
Wow...great video👍
Doppler Effect...Compression & Rarefaction...High Frequency Traversing in Relation to a Low Frequency Wavefront.
The IM distortion in loudspeakers is not by the Doppler effect. As Rod Elliott (sound.whsites.net/doppler.htm) pointed out.
When Doppler was the cause of the distortion, then the distortion should be at its greatest when crossing zero, when the speed is at its maximum. But, it is not.
The IM distortion is at its greatest at the maxima of the excursion, when the speed is zero! So, it is not the Doppler effect, but change in position of sound source for the higher tone.
Another (and bigger) sources of IM distortion are non linearities in the force factor and the suspension of the driver.
sound.whsites.net/doppler.htm is the right link (without the ')' ), sorry.
Man, that’s an EKG at the first frame! Maybe it was on purpose... a good heart may exert influence on another heart.... or even distort it... hehe. Music for our hearts...
Few days back i was purposely playing 30 hz tone on my subwoofer while listings the song the sound was coming from sub was not good
A strong, steady low tone can actually modulate your hearing, i.e., create intermodulation distortion within your ears. There are no mods you can make to the speakers, to correct that.
I would think the speaker would vibrate on the resulting combined frequency, and not try to play each frequency independently of each other. Does that make sense?
Yes, that is called music, or "Complex Waveform."
It does both. The degree of the "combined frequency" is proportional to the level of nonlinearity (distortion) from the speaker.
I understand how this IM distortion can occur with a single driver, but would not a 200 Hz tone be passed through the crossover to the woofer and the 5,000 Hz tone be passed to the upper mid range or tweeter depending on the drivers? Another question is can this occur in amps? I think so because I have an IM distortion analyzer that is used to measure this in the amplifier. How is IM distortion addressed in amplifier design?
Swinde crossovers of any type don’t spit the frequencies cleanly. They get attenuated gradually (a number of dB per octave) this vids question was somewhat philosophical... but for example if you have a xover at 5000htz and play a 4999htz and 5001 htz note: the xover will have little influence what the speakers do
That is true, but a 200 Hz tone should be attenuated to the tweeter that is reproducing the 5,000 Hz tone which will reduce any IM that would occur in this case.
Hey Paul, I think you’re wrong about blaming the Doppler effect as a source of distortion... (Not that it matters) That is how frequencies naturally mix.. more interesting though: I wonder if your amplifier engineers have taken a simple amplifier design and purposely tried to increase harmonic distortion for learning purposes??
"How is IM distortion addressed in amplifier design?
"
Back in the Dark Ages around 1970 amplifier designers were competing to achieve the lowest possible THD. Then Jim Sugden introduced his A21 amplifier with an order of magnitude or more THD than his rivals, but it sounded much better. This was eventually identified as due to the A21 having much lower IM distortion. The extremely low THD in rival amplifiers was achieved through using gain stages with a large "excess" gain that was used to provide a high level of negative feedback. Reducing the gain and thus the amount of negative feedback reduced IM distortion. Individual stages in the amplifier chain were also designed with a very high bandwidth of 50 KHz or more. The input was limited to 20 KHz, but available bandwidth after that is often 100 KHz. Keeping global NFB low also appears beneficial.
Hope that helps.
Jonathan Strum ... Thank you for this. I have both Harmonic distortion analyzer and IM distortion analyzer. I had wondered how the IM was addressed.
Simple answer is yes.
I still can't get my head around how a speaker can play two different frequencies at the same time. The speaker cone is been driven by effectively a push pull motor. If one note is asking for 2000Hz and another note is calling for 5000Hz why doesn't it average it and play a 3500Hz frequency? I am envisioning this to be like asking a car engine to do 2000rpm and 5000rpm at the same time. Can someone explain in simple terms how this is possible please.
It's like the car engine's vibrations at the power stroke frequency, which add to the basic crankshaft rotation. They need to be suppressed by a flywheel so they don't cause parts to loosen and fall off while driving.
Or try this visualization: You're sitting on a swing, swaying back and forth at perhaps 0.3 Hz. Now hold your hand up in front of you and move it forward and backwards at 1-2Hz. Then wiggle a finger at 3-4Hz. If a string was attached to your finger, do you see that it would experience motion that includes all of those frequencies, but nothing in between?
@@marianneoelund2940 good examples, I get it.
I know nothing about this is related but thinking about Doppler and a speaker makes me think of my churches' Leslie rotating speaker.
That is the Doppler effect exaggerated. The original Leslie speaker was amplitude modulated, but later versions were frequency modulated.
Put two speakers at the opposite ends of a see-saw, then spin the see-saw. That'll give you plenty of doppler distortion.
But the Leslie rotating speaker only rotates a deflector or duct that sits in front of the speaker, and the speaker itself doesn't move. So I think the primary audible effect is using the sound's directivity to modulate the frequency response. Some doppler shift would occur, but only from the sound reflecting off of the interior walls of the moving duct, that is only a fraction of the sound is affected.
I shall start on my 19,980 driver speaker. 1 driver for each frequency,Haha!!
Why not? That's how our ears work.
It's seems as this video has some distortion
Additionally...
Dopelar Effect: (n.) The tendency of stupid ideas to seem smarter when they come at you rapidly.😳😂😂😂
Similar to the Dream Effect.
What causes distortion when all the members of a band go crazy. High frequencies in a band sounds like shi. Bands should try to make low tone recordings.
I just learned a little more about the inter-relationships between the second third or fifth and beyond harmonics in how they affect sound thank you for the analogy and clarification
All distortion is bad. But thats just me.
I would've thought that someone with a username including "tube" might appreciate modest levels of even-harmonic distortion. That is a large part of the "tube sound" that some listeners enjoy.