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In Reply to: Great post...especially item 1)...also... posted by DPC on July 24, 2002 at 04:20:21:
I think some listeners actually do object to the distinctive "sound" of the kevlar coned drivers (the constant in many B&W models) and to a lesser degree the "sound" of B&W tweeters. After living with a B&W design for many years (and auditioning all the rest), I can say that the kevlar cone driver is probably the speaker's weakest ingredient. These drivers just don't sound smooth at the top of their passband (where they flex and break-up). Most manufacturers try to keep the driver motion pistonic, but B&W seem wedded to the kevlar driver; touting the in-band break-up behavior as a "benefit." It may be a benefit to the speaker's measurements. They measure well (at least from some axis), but they don't "sound" that good between 2 - 4 kHz (the top of their passband and the band of frequencies where the human ear is most sensitive).B&W engineer a beautifully dry and neutral bass into every model. So, why can't they perfect the mid-range response (which would mean dumping the kevlar drivers) and the treble (use less beamy and resonant tweeters)?
Follow Ups:
your opinion since of all the big names out there like Paradigm etc use their typical off the shelf drivers and NONE of them have midrange neutrality that approach the level of B&W. In fact the midrange is where I find the B&W strength to be. All the reviews seem to back that up, all the people I know agree, and you seem to be saying the measuerments(which I admit I never even look at)are supporting that as well.It sounds like you call them bright drivers...which is fine I find ALL speakers using metal tweeters to have serious problems of some sort...most ring(Studio series, PMC to a lesser degree)etc. B&W gets around that with their inverted tube...but it is a little on the bright side. It's obviously bright enough to annoy you, but not everyone.
As for Kevlar it's another driver that has its pluses light and tough and even. Though I'm not sure about the overall durability.
And I own the only speaker that doesn't have Kevlar or the metal tweeter the DM 302 - and I liked it better than the 601 that I was going to buy...for some of the reasons I think that you hear. So I don't disagree necessarily with what you're saying but I don't think the problem is with the driver, since to me their speaker lines all sound quite different. The 600 series is a bit bright, but so is almost everything for the money...except maybe Castle and Mission.
Actually I don't find B&W speakers particularly bright. The company seems to voice for a hot or peaky on-axis balance in the high treble to compensate for the lack of wide-dispersion in this passband. If you sit just a little off axis of a B&W tweeter you get a fairly dry (ruler-flat) result. Unfortunately though, the treble seems too dry and as you move off-axis, high treble response falls off quickly. This puts less power into the room at the very highest frequencies resulting in a lack of air and high frequency "wetness." Whether or not this is noticeable, depends on how much of your high frequency hearing you still retain. Some manufacturers use additional "ambience" tweeters to compensate for lack of high frequency dispersion (but not B&W).What I think is more audible and objectionable are the power flares that occur in the lower treble. Specifically, these metal domes show wide dispersion in the bottom of their passband, which drops off steadily with higher frequency. You might see 180 degree dispersion in the 4-8 kHz passband, which narrows to 90 degree dispersion at 10 kHz and narrows to less than 20 degree dispersion at 15 kHz and so on. Consider that the kevlar cone produces 90 degree dispersion at 1 kHz and very rapid changes of dispersion through the actual crossover, you end up with some pretty drastic changes of dispersion through the upper mid/lower treble. This will not load the room evenly, resulting in too much energy in the lower treble passband and too little above. The human ear is ten times more sensitive to lower treble frequencies than to high treble frequencies. This uneven power response will irritate.
Yet, I don't have a problem as much with the quantity of the treble produced by these metal domes as its quality. The domes need better damping. I am sure loading the dome with a column of air (the Nautilus transmission line) is helping to lower the resonant behavior of these domes, but I still hear a residual chromium plated edge in the lower treble (which coincides with the domes peak power). The domes are ringing ever so slightly at the bottom of their passband around 4 kHz (visible in time domain graphs). The domes need to be damped better. Perhaps they need to be lighter to resist ringing better. It can be done. Focal have succeeded in producing high quality metal domes that resist this low treble ringing (probably by careful use of damping compounds applied to the dome), resulting in a less fatiguing low treble sound.
Getting back to the kevlar cones…they seem to be fine up to around 1-2 kHz…then they go into break-up. B&W run them all the way up to 3 or 4 kHz, but the cones are not behaving in a linear fashion in this crucial passband. This is far, far more audible than any problem occurring in the treble (due to the extreme sensitivity of human hearing at these frequencies – the nails on a chalk board passband). As a result (depending on your listening angle) violins can screech unnaturally or sound unnaturally dull. The lack of linearity in the presence passband creates colorations of the human voice…the pinched or nasal coloration that we are somewhat used to from loudspeakers. Presence band instruments like trumpets and trombones can sound very synthetic and unconvincing due to power anomalies in this passband (even though technically the speakers might measure flat on-axis). The results…the sound…speaks for itself.
A speaker designer absolutely MUST get the upper crossover right for the speaker to sound coherent. Otherwise the music will separate into treble and mid-range. It's a delicate balancing act. Ideally you DO NOT want to stick a crossover between 2-4 kHz, but if you MUST…you will need to spend all your time and effort getting the drivers to work together in phase over a useful range of vertical and horizontal angles. B&W solved this problem (and many others) in the original Nautilus by dividing the audible spectrum into four bands (using four drivers); all of which behaved as true pistons in their operational passbands (no in-band break-up modes a la kevlar). If I were designing "Nautilus" speakers, they would follow the original design much more closely.
As you can see, the designer in me causes me to think, "how could I improve the sound of these speakers?" Before starting, I would need to identify those areas that needed help. If I listen to a loudspeaker long enough, I am usually ready to re-engineer it. I often think, "if I could combine that speaker's treble, with this speaker's mid-range, with that speaker's bass…and avoid crossover irregularities, I'd have a really good product." It can be done; especially when you don't have to design by committee or design based on what sells or the latest trend. In my world-view, speakers need to be accurate…period.
Hello,
Your argument is interesting. I admit I know diddley about tests frequency responses and the like. But I just wonder what baseline measurments are....such as listening distance, room size, and decibel levels.I have a suspicion that a lot of times the bigger nautilus speaks like n803-n800 are probably played at volumes well below what they were designed for. I don't have a big room for my 801's. But I notice that with better recordings I can turn up the volume higher than usual and the system kicks into another gear.
Remember I talked about human hearing being non-linear? We perceive sounds at 3-4 kHz as louder than at other frequencies. Since the speakers put less energy into the room in this passband, its easier to raise the volume significantly without pain. If you position your head just so (and keep it there) you can get the response to flatten out more or less (around the crossover point), but the lack of a smooth power response will always be a handicap.I don't want to give the impression that I am picking on B&W designs. I analyze every speaker this way. I have heard much worse. The (difficult) trick is make the design coherent at the crossover. Using a kevlar driver (or any non-rigid driver subject to flexing) makes this much more difficult.
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