The Andrew Jones paper clearly shows that this is not true. He puts an accelerometer on the woofer magnet and compares decoupled to rigidly coupled. In the rigidly coupled case you have some nasty resonances from the cabinet impacting the magnet acceleration (and therefore coupling into cone motion). In the case of the decoupled driver the magnet acceleration profile is smooth and resonance free.
This is a case of people having a hypothetical objection without taking the measurements.
David
I agree with the quoted bit. The experimental evidence i have supports. Experiments we did with removing the isolation in early KEF 105 yeilded better DDR and a less constipated speaker. Speakerdave says the FR might not be as flat after.
dave
"Decoupling the transducer from the cabinet is an undesirable approach because it prevents the transducer from utilizing the overall mass of the loudspeaker cabinet to minimize unwanted motion of the transducer frame. If the transducer is decoupled from the cabinet, there will be relative movement between the transducer frame and the cabinet"
Planet10 dave, will you elaborate more?
Planet10 dave, will you elaborate more?
I agree with speaker dave ;-)
All data shows a better result with isolating the drive unit from the evils of the cabinet vibration. Cabinet vibration is reduced, as is driver vibration.
In the testing I have ever done almost the listeners prefer the decoupled result, hearing much better precision and clarity, if the isolation is done properly
Best results are obtained in a three way system, with the bass driver tightly coupled to a box that is resonant free in the driver passband, and with a midrange that is isolated. This is what I do with the TAD Reference 1 and Compact Reference.
This is not to say all people will prefer isolation. Some people like the sound of cabinet coloration, or the change in the resulting tonality of the speaker makes up for some deficiency in the engineered response. But is it more accurate to have cabinet coloration? I would venture no.
AJ
All data shows a better result with isolating the drive unit from the evils of the cabinet vibration. Cabinet vibration is reduced, as is driver vibration.
In the testing I have ever done almost the listeners prefer the decoupled result, hearing much better precision and clarity, if the isolation is done properly
Best results are obtained in a three way system, with the bass driver tightly coupled to a box that is resonant free in the driver passband, and with a midrange that is isolated. This is what I do with the TAD Reference 1 and Compact Reference.
This is not to say all people will prefer isolation. Some people like the sound of cabinet coloration, or the change in the resulting tonality of the speaker makes up for some deficiency in the engineered response. But is it more accurate to have cabinet coloration? I would venture no.
AJ
I'll stick with decoupling and or force cancellation, thank you. 
The problem I have with claims of better DDR is that this is a subjective term without measurement. Not that I don't believe or understand the significance of such. There are a meriad of ways to decouple a driver, how effective it is and or how done is the question. Seeing little analytical research done comparing the same drivers vs. different dampening methods and materials in the same enclosure leaves my mouth rather dry.
Dampening materials can be anything from modeling clay, butyl rubber, neoprene, latex caulk, tar paper, bitumin, etc and then you have a plethora of commercial products.
Dave you are right, to much hypothesis and not enough lab time.
The problem I have with claims of better DDR is that this is a subjective term without measurement. Not that I don't believe or understand the significance of such. There are a meriad of ways to decouple a driver, how effective it is and or how done is the question. Seeing little analytical research done comparing the same drivers vs. different dampening methods and materials in the same enclosure leaves my mouth rather dry.
Dampening materials can be anything from modeling clay, butyl rubber, neoprene, latex caulk, tar paper, bitumin, etc and then you have a plethora of commercial products.
Dave you are right, to much hypothesis and not enough lab time.
Hi very interesting and i see a very popular solution.
Actually i see many 3 ways with a bass box under a mid-high satellite
But what about a 2 ways ? a solution like B&W maybe ?
An externally hosted image should be here but it was not working when we last tested it.
My feeling is that B&W speakers are very well designed.
But that kevlar woofer ... maybe it is just the color ... but i would like to listen a B&W with a Scanspeak for instance ... a huge curiosity (sorry this is OT clearly).
Thanks a lot and kind regards, gino
This seems sensible on the face of it, but the cabinet is not a simple mass. It is a complex resonant structure. Like any electrical circuit it has a a driving point impedance that is inductive (mass like) at some frequencies and capacitive (spring like) at other frequencies. You aren't tying an inertial mass to the driver if you are at or above any of the many cabinet frequencies.
I understand there is a whole group of audiophiles with the firm belief that rigid coupling is mandatory and compliant coupling infers "loss of information". However, the measurements are very clear. Magnet motion is much cleaner in the decoupled case.
David
The three articles below discuss some properties and specific materials used for midrange driver decoupling. The 39 page article from B&W on the development of the 800 series is surprisingly informative. PDF pages 18 & 19 (article pages 32 - 35) discuss decoupling of the midrange.
http://www.fransvaneeckhout.be/bw/bw_images/800_Development_Paper.pdf
http://claudionegro.com/download/articoli/axpress 02-2008 Driver induced vibrations.pdf
http://www.linkwitzlab.com/Driver Decoupling.doc
One of the companies mentioned as supplying the decoupling material:
E-A-R Specialty Composites -- noise, vibration, shock, damping, cushioning, sound, control
http://www.fransvaneeckhout.be/bw/bw_images/800_Development_Paper.pdf
http://claudionegro.com/download/articoli/axpress 02-2008 Driver induced vibrations.pdf
http://www.linkwitzlab.com/Driver Decoupling.doc
One of the companies mentioned as supplying the decoupling material:
E-A-R Specialty Composites -- noise, vibration, shock, damping, cushioning, sound, control
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Hey Dave, I didn't post the paragraph referenced in Post #270. I'm with you on this, I'm open to decoupling midranges.
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The related Kevlar midrange is actually a very good performer, with controlled brake-ups designed into the cone material itself.
http://www.zaphaudio.com/temp/B&W-FST-LF00264-FR.gif
http://www.zaphaudio.com/temp/B&W-FST-LF00264-HD.gif
http://www.zaphaudio.com/temp/B&W-FST-LF00264-CSD.gif
From the Zaph Audio site:
Zaph|Audio
Zaph|Audio
Related to wall vibrations is the discussion on midrange enclosure interior shapes.
Surprisingly, spherical or egg shapes result in significant internal resonances.
The B&W paper, pages 28 & 29
http://www.fransvaneeckhout.be/bw/bw_images/800_Development_Paper.pdf
Jim Moriyasu's published several articles in Speaker Builder & AudioXpress. He spent considerable effects on the testing.
AudioXpress, 2/2002, "Panel Damping Studies: Reducing Loudspeaker Enclosure Vibrations"
Speaker Builder, 7&8/2000 entitled, "A Study of Midrange Enclosures"
They are available on archive CD's, by annual issues at:
CD/DVDs
Surprisingly, spherical or egg shapes result in significant internal resonances.
The B&W paper, pages 28 & 29
http://www.fransvaneeckhout.be/bw/bw_images/800_Development_Paper.pdf
Jim Moriyasu's published several articles in Speaker Builder & AudioXpress. He spent considerable effects on the testing.
AudioXpress, 2/2002, "Panel Damping Studies: Reducing Loudspeaker Enclosure Vibrations"
Speaker Builder, 7&8/2000 entitled, "A Study of Midrange Enclosures"
They are available on archive CD's, by annual issues at:
CD/DVDs
I'm guessing that 2way systems have very different requirements than 3ways in this conversation. It seems that cost-no-object views come to dominate discussions amongst bottom feeders like me. I won't be buying SEAS best any time soon, or ever, because I'm a pensioner working my way through a stack of old speakers that I've saved for this rainy day. Like SpeakerDave's AR4x, there's still a lot of goodness to be derived from vintage pieces that were optimal in their time and which are not junk now.
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