Dear @dave_b : "" Try psychotherapy... ", you can go on insulting me in all the ways you intent/intented.
What you need is to learn and understand the IMD meaning that obviously that as you several other persons in this thread just can’t understand it or have a severe misunderstood for a very low knowledge levels in that speacific IMD regards.
Here " something " that could help to fix your misunderstood.
You say I need psycotherapy because you are sticked as one stupid here with the very old " fashion " ( same as REL people. ) to use a subs as only a low bass speaker reinforcement even with true full range speaker designs.
That old and wrong way to use subs to listen MUSIC in stereo home systems changed several years ago in favor to lower the IMD levels to achieve true improvements in the room/system quality sound reproduction.
Next some high-lihgts and links to understand about:
this comes from white papers by Putzeys.
""" Read any discussion about loudspeakers and you get the impression that distortion as a topic is eagerly avoided. If it is mentioned, it is done sotto voce, implicitly. For instance: “you can’t get good bass out of a small long-stroke driver. There’s no substitute for cone area when you want to move air”. Doesn’t sound like it is about distortion at all, does it? Let’s unpick the statement a bit: there is no substitute for cone area. Of course there is: displacement. If you want to move 100 cc of air, you could move a 500 cm 2 cone by 2 mm or you can move a 200 cm2 cone by 5 mm. At the wavelengths we’re talking about, there’s no difference between the two. So if the bigger driver sounds better, it must be because it’s managing that 2 mm movement much more precisely than the smaller driver is managing its 5mm. And that is a statement about distortion. If we can crack the question why a short-stroke driver is more accurate over short strokes than a long-stroke one over long strokes, it should enable us to build a long-stroke driver that’s just as accurate as a long stroke one for the same acoustical output. More accurate in fact, because once you understand the problem, there’s no reason why you couldn’t reduce distortion even further.
A HD measurement done on a complete driver tends to show a complicated jumble of frequency and amplitude dependent distortion products. An IMD measurement shows another jumble.
When we talk about distortion, there’s often a distinction made between Harmonic Distortion (HD) and Intermodulation Distortion (IMD). These aren’t two different types of distortion per se, but different ways in which the same distortion mechanism can manifest itself more or less saliently. Take for instance a woofer whose BL curve droops progressively with excursion. Tested with a single 30 Hz sine wave, this will only manifest itself as a form of soft limiting. This sounds like a change in tonal quality, but little more. The effect of the suspension progressively stiffening (Kms increases) with excursion would sound more or less the same in a single sine wave test. A HD measurement is not helpful in telling you which of the two effects is happening. By contrast, imagine what happens if you add a 1kHz tone to the bass tone. The added excursion caused by the 1kHz component itself is negligible. But now the two distortion mechanisms show very different signatures. As BL rises and falls throughout the 30 Hz cycle, so does the sensitivity of the motor. The 1 kHz tone gets amplitude modulated. You can hear the 1 kHz tone wobble. BL droop manifests itself not only as harmonic distortion, but also as intermodulation. The variable stiffness of the suspension however has no such effect. The 1 kHz tone will not be modulated by suspension stiffness. Why should it? 1 kHz is well above the resonance frequency, so there the mass of the cone completely dominates how the 1kHz component makes the cone move. The difference between the two distortion mechanisms is plainly audible on any genre of music that has both bass and midrange content. And as a distortion mechanism, the droop of the BL curve is much more audible than the progressive stiffening of the suspension. This is rather important. One often encounters drivers where two different distortion mechanisms are precisely orchestrated to make their harmonic distortions cancel. Such drivers look great on paper but this sleight of hand actually worsens IMD.
The distortion takes the form of the signal being multiplied with a filtered version of itself, so it is predominantly second order in nature. Now, there is a common misconception that second order distortion is innocuous. This may be largely true of harmonic distortion where a second harmonic is easily masked by the fundamental, but in the case of intermodulation distortion it is patently false. Second order IMD generates difference frequencies which are below the signal frequency and don’t get masked at all. They audibly clog up the bass region in a manner which becomes extremely obvious once you remove the distortion. Also, amplitude modulation of mid frequency signals by the bass is very audible as burbling. """
http://www.klippel.de/know-how/measurements/nonlinear-distortion/intermodulation-distortion.html
In next link read critical issues and you will see IMD:
http://www.klippel.de/test-objects/low-frequency-drive-units.html
http://www.klippel.de/fileadmin/klippel/Files/Know_How/Application_Notes/AN_08_3D_Intermodulation_Di...
https://www.audioholics.com/loudspeaker-design/audibility-of-distortion-at-bass/intermodulation-dist...
In next link you can read:
"" Another well known type of distortion is Intermodulation Distortion (IM) where a higher frequency is amplitude modulated by a lower frequency, causing new frequencies above and below the highest frequency at a frequency“distance” equal to the lowest frequency (mirrored side-bands). ""
https://www.rmsacoustics.nl/papers/whitepaperdistortion.pdf
Joe D’Appolito:
"" We can tolerate relatively high levels of harmonic distortion in program material because, as their name implies, the spurious components added to the program are harmonically related to the original program. Intermodulation distortion (IMD) produces output frequencies that are not harmonically related to the input. These frequencies are much more audible and annoying than harmonic distortion. ""
In 1967 a gentleman who cares about IMD made it his patent:
https://patents.google.com/patent/US3327043
Now, the CW woofer handled a wide frequency band where exist very high IMD levels and that only can be lower if part of the bass frequencies goes out of that woofer and for this we need subs and a high-pass filter that liberates the CW woofer of that bass frequency short band.
I respect that you prefer the CW or any other speaker in full range status. So that means that you are not even aware of that IMD developed by those woofers in all the speakers you own or owned.
Stay where you are and follow sticked to that old and wrong " fashion ". It’s your privilege and no one can disagree with.
R.
What you need is to learn and understand the IMD meaning that obviously that as you several other persons in this thread just can’t understand it or have a severe misunderstood for a very low knowledge levels in that speacific IMD regards.
Here " something " that could help to fix your misunderstood.
You say I need psycotherapy because you are sticked as one stupid here with the very old " fashion " ( same as REL people. ) to use a subs as only a low bass speaker reinforcement even with true full range speaker designs.
That old and wrong way to use subs to listen MUSIC in stereo home systems changed several years ago in favor to lower the IMD levels to achieve true improvements in the room/system quality sound reproduction.
Next some high-lihgts and links to understand about:
this comes from white papers by Putzeys.
""" Read any discussion about loudspeakers and you get the impression that distortion as a topic is eagerly avoided. If it is mentioned, it is done sotto voce, implicitly. For instance: “you can’t get good bass out of a small long-stroke driver. There’s no substitute for cone area when you want to move air”. Doesn’t sound like it is about distortion at all, does it? Let’s unpick the statement a bit: there is no substitute for cone area. Of course there is: displacement. If you want to move 100 cc of air, you could move a 500 cm 2 cone by 2 mm or you can move a 200 cm2 cone by 5 mm. At the wavelengths we’re talking about, there’s no difference between the two. So if the bigger driver sounds better, it must be because it’s managing that 2 mm movement much more precisely than the smaller driver is managing its 5mm. And that is a statement about distortion. If we can crack the question why a short-stroke driver is more accurate over short strokes than a long-stroke one over long strokes, it should enable us to build a long-stroke driver that’s just as accurate as a long stroke one for the same acoustical output. More accurate in fact, because once you understand the problem, there’s no reason why you couldn’t reduce distortion even further.
A HD measurement done on a complete driver tends to show a complicated jumble of frequency and amplitude dependent distortion products. An IMD measurement shows another jumble.
When we talk about distortion, there’s often a distinction made between Harmonic Distortion (HD) and Intermodulation Distortion (IMD). These aren’t two different types of distortion per se, but different ways in which the same distortion mechanism can manifest itself more or less saliently. Take for instance a woofer whose BL curve droops progressively with excursion. Tested with a single 30 Hz sine wave, this will only manifest itself as a form of soft limiting. This sounds like a change in tonal quality, but little more. The effect of the suspension progressively stiffening (Kms increases) with excursion would sound more or less the same in a single sine wave test. A HD measurement is not helpful in telling you which of the two effects is happening. By contrast, imagine what happens if you add a 1kHz tone to the bass tone. The added excursion caused by the 1kHz component itself is negligible. But now the two distortion mechanisms show very different signatures. As BL rises and falls throughout the 30 Hz cycle, so does the sensitivity of the motor. The 1 kHz tone gets amplitude modulated. You can hear the 1 kHz tone wobble. BL droop manifests itself not only as harmonic distortion, but also as intermodulation. The variable stiffness of the suspension however has no such effect. The 1 kHz tone will not be modulated by suspension stiffness. Why should it? 1 kHz is well above the resonance frequency, so there the mass of the cone completely dominates how the 1kHz component makes the cone move. The difference between the two distortion mechanisms is plainly audible on any genre of music that has both bass and midrange content. And as a distortion mechanism, the droop of the BL curve is much more audible than the progressive stiffening of the suspension. This is rather important. One often encounters drivers where two different distortion mechanisms are precisely orchestrated to make their harmonic distortions cancel. Such drivers look great on paper but this sleight of hand actually worsens IMD.
The distortion takes the form of the signal being multiplied with a filtered version of itself, so it is predominantly second order in nature. Now, there is a common misconception that second order distortion is innocuous. This may be largely true of harmonic distortion where a second harmonic is easily masked by the fundamental, but in the case of intermodulation distortion it is patently false. Second order IMD generates difference frequencies which are below the signal frequency and don’t get masked at all. They audibly clog up the bass region in a manner which becomes extremely obvious once you remove the distortion. Also, amplitude modulation of mid frequency signals by the bass is very audible as burbling. """
http://www.klippel.de/know-how/measurements/nonlinear-distortion/intermodulation-distortion.html
In next link read critical issues and you will see IMD:
http://www.klippel.de/test-objects/low-frequency-drive-units.html
http://www.klippel.de/fileadmin/klippel/Files/Know_How/Application_Notes/AN_08_3D_Intermodulation_Di...
https://www.audioholics.com/loudspeaker-design/audibility-of-distortion-at-bass/intermodulation-dist...
In next link you can read:
"" Another well known type of distortion is Intermodulation Distortion (IM) where a higher frequency is amplitude modulated by a lower frequency, causing new frequencies above and below the highest frequency at a frequency“distance” equal to the lowest frequency (mirrored side-bands). ""
https://www.rmsacoustics.nl/papers/whitepaperdistortion.pdf
Joe D’Appolito:
"" We can tolerate relatively high levels of harmonic distortion in program material because, as their name implies, the spurious components added to the program are harmonically related to the original program. Intermodulation distortion (IMD) produces output frequencies that are not harmonically related to the input. These frequencies are much more audible and annoying than harmonic distortion. ""
In 1967 a gentleman who cares about IMD made it his patent:
https://patents.google.com/patent/US3327043
Now, the CW woofer handled a wide frequency band where exist very high IMD levels and that only can be lower if part of the bass frequencies goes out of that woofer and for this we need subs and a high-pass filter that liberates the CW woofer of that bass frequency short band.
I respect that you prefer the CW or any other speaker in full range status. So that means that you are not even aware of that IMD developed by those woofers in all the speakers you own or owned.
Stay where you are and follow sticked to that old and wrong " fashion ". It’s your privilege and no one can disagree with.
R.