What i basically want to say is, if one aims for improvement on a "fine level"
of a speaker (especially one made up from fullrangers) to be built and also
wants to match a speaker pair, i would rather go for selection and pair
matching of drivers.
But to adress problems in modal behaviour that come with the design of a
certain driver, significant modifications to the design are needed.
Regards
of a speaker (especially one made up from fullrangers) to be built and also
wants to match a speaker pair, i would rather go for selection and pair
matching of drivers.
But to adress problems in modal behaviour that come with the design of a
certain driver, significant modifications to the design are needed.
Regards
For a more detailed article on the design of this driver, as well as the rest of the Nautilus 801, have a look at this article: (PDF)
http://www.google.co.uk/url?sa=t&so...FRk_SJsMA&sig2=x6OqqlkwoqtiZAN8vwfP1A&cad=rjahttp://www.hifiportal.co.uk/Articles/Article0026-Development of the Nautilus 801.pdf
Very good, albeit long reading 🙂
Gene, tensile strength is not really relevant to speaker cones (it very much is for drumheads). Flexural modulus very much is, as is loss factor. Ever wonder why PET is not a good speaker cone material?
I am curious, if fiber rubbing is used to damp cone resonance, how do we know how much noise the rubbing action will generate?
I doubt there is much if any frictional rubbing between individual bundles of fibres in the weave to generate spurious noise in the B&W driver, as they use a lot of resin for both damping and binding the woven structure together.
Other Kevlar drivers, who knows, although I doubt Kevlar is a material that can be used satisfactorily without significant added damping from resins etc...
Thanks for the link. I'd lost some of pdf files I used to have, I think that this was one. Those interested in diaphragm movement should pay particular attention to Appendix I, pages 34, 35 and 36. The key to the Kevlar drivers is largely in the randomness of the distances to weave "joints", so-to-speak. The other interesting point is their analysis that shows that the midrange unit performs much better with no surround. The surround mass seems to have been a significant contributor to adverse effects on the major wave component, the compression wave that, as they describe, moves much faster than the bending wave and and that the latter is very much smaller in the Kevlar cone vs. a plastic cone.
They also confirm the reduction in effective radiating surface as frequency increases, roughly maintaining it's directivity. B&W uses research, not speculation, about diaphragm movements. Were there anything other than mass/compliance/damping involved, you can bet that they'd know it and show it.
Dave
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I don't believe that it has much at all to do with rubbing. It's based on the randomness of reflections. The shape makes the driver output resemble that of a rectangular diaphragm, even though it's round.
Dave
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Polyester sheet
tensile
Yes but hardly a comparison. Mylar doesn't come in thicknesses of a speaker cone as far as I know.
Oops, now I'm stepping into SY's realm. 🙂
Step back before you hurt yourself. 😀 Mylar comes in whatever thickness you want. For really thick or complex sections, you can even injection mold it.
Thickest I know about is the 12 mil (0.012") stuff we used on windows for bomb protection. Is there thicker than that?
How thick would your average 15" polypropylene woofer cone be?
How thick would your average 15" polypropylene woofer cone be?
Oh, you can make it much thicker. Half an inch, easy.
Remember, polyprop cones are heavily mineral loaded, which drastically changes the mechanical properties compared to straight polypropylene. I haven't torn apart any 15" drivers to check thickness, but I'd guess something like 30-40 mils?
Remember, polyprop cones are heavily mineral loaded, which drastically changes the mechanical properties compared to straight polypropylene. I haven't torn apart any 15" drivers to check thickness, but I'd guess something like 30-40 mils?
LineArray
Would you expect to find what MigeO found here? Enable Tests Be sure you move your mouse pointer completely off of the page to see the blink comparison, beginning with the untreated driver.
If you go here and read http://www.diyaudio.com/forums/multi-way/119677-enabl-technical-discussion-88.html#post2349611 you will find that Michael also found that the more usual portrayal methods for finding differences between EnABL'd and clean cones are just barely different, if at all, from what you would expect to find across a production run of drivers. Look further to find all of the test sets laid out in blink comparison to see what I mean. Do stop and think about what the elimination of reflections echoing up off of the cone might mean in terms of information, to an intelligent microphone as opposed to one without any form of discrimination.
Bud
Would you expect to find what MigeO found here? Enable Tests Be sure you move your mouse pointer completely off of the page to see the blink comparison, beginning with the untreated driver.
If you go here and read http://www.diyaudio.com/forums/multi-way/119677-enabl-technical-discussion-88.html#post2349611 you will find that Michael also found that the more usual portrayal methods for finding differences between EnABL'd and clean cones are just barely different, if at all, from what you would expect to find across a production run of drivers. Look further to find all of the test sets laid out in blink comparison to see what I mean. Do stop and think about what the elimination of reflections echoing up off of the cone might mean in terms of information, to an intelligent microphone as opposed to one without any form of discrimination.
Bud
Putting anything on the cone will most likely change its characteristics to some extent. I once tried lightly putting coconut oil on some butyl surrounds to try to help preserve them, and found it altered the sound. I quickly removed it.
Putting a few pieces of scotch tape on the cone I would guess will change the sound, too.
Putting a few pieces of scotch tape on the cone I would guess will change the sound, too.
Yes, that is true. However, there are specific places to put things on any cone, dome or flat panel that are far more useful than others. This is true for the micro masses EnABL makes use of and considerably larger masses, such as those dlr is experimenting with and soongsc utilized in his dispersal of resonant nodes and the resultant patent.
Bud
Hi Bud,
to me the differences are quite well within the range i would expect.
I cannot see any clear improvement, and it seems i am not the only one too (regarding post #875):
===================
cf.
GB2005001352 ACOUSTIC DEVICE & METHOD OF MAKING ACOUSTIC DEVICE
Commercially introduced as "Balanced Mode Radiator" by New Transducers Limited, uses annular masses for "modal balancing".
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Weather conditions today have been good enough to do promised outdoor measurements (short, calm time between blasts and rain)
Resulting wavelet analysis are not exactly as I'd have expected, but have a look yourself:
Selenium 8W4P “driver A” - un-treated:
http://www.kinotechnik.edis.at/pages/diyaudio/enabl/8W4P-A_un-treated-od.wav
Selenium 8W4P “driver B” - un-treated:
http://www.kinotechnik.edis.at/pages/diyaudio/enabl/8W4P-B_un-treated-od.wav
Selenium 8W4P “driver C” - treated:
http://www.kinotechnik.edis.at/pages/diyaudio/enabl/8W4P-C_treated-od.wav
Selenium 8W4P “driver D” - treated:
http://www.kinotechnik.edis.at/pages/diyaudio/enabl/8W4P-D_treated-od.wav
Measurements were taken at roughly 1m mic distance with the nude speaker “swingin' mount”.
Again, keep aware this is not a before / after comparison !
From the listening impression with the wooden stick which, to me, sounded kinda more “snappy” for the EnABL'ed speakers, I would have expected to see overall decay changes.
This – in my eyes – does not happen.
My guesstimate regarding less CMP behaviour – based on John's measurements – does not happen the way I'd have expected, as well.
What happens – as far as I can see and especially when looking at the treated driver “C” - is that compact reflections (at roughly time slot 1.2ms) get split into many.
I do not have a really good explanation for that. We might wait until more EnABL measurements are available to compare with.
Most interesting I find that back wave diffraction around the rim seems not to be dominating results.
For comparison here is a measurement of my 180deg honker (NEO3 in round OB) where the diffraction around the rim is most obvious.
My summary on the basis of what I've measured so far:
1.a pronounced “around the rim” diffraction overlay at a discrete time interval simply may not happen with nude speakers
2.the reflections we see may be mainly cone brake up – which basically is a CMP reflection process too (modes due to standing waves)
3.EnABL seems to break down (spread out) strong break up modes into several ones
4.The EnABL pattern applied at the SELENUIM 8W4P does not seem to have a *cone dampening* effect at first hand (as IMO is seen in John's “EnABL” measurements)
But – of course - I could be totally wrong too
😀
It might be interesting to do such analysis along each step of EnABL procedure to better pin point what comes from what step of treatment 🙂
You know - wavelet analysis software is available for free too 😉
Again Bud - thanks for all the nice work you've put into this !
Michael
I know this is from 30 pages ago and I know there has been discussion on this but for me its nice to see measurements that show differences. I can no understand that there can be audible differences.
Others might consider those differences showing more smearing in the treated cones but I see the treated cones having less intense smearing which is more important then worrying about additional low level smearing (Atleast in my current state of mind when it comes too CSDs and wavelets 😀 )
Either way, the important part is that measurements show audible differences.
I think Mig had a good suggestion. Someone could measure the differences as they go through the enable process.
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At what point does a person become tall? That's not a facetious question- you're asking (if I understand you) to delineate a sharp boundary between two fuzzy concepts.