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In Reply to: Re: Disagree posted by JeffMO on July 23, 2002 at 13:19:35:
Take any of the Nautilus series. They have been engineered to produce ruler-flat on-axis response (as are all B&W speakers). On-axis they do sound "honest" to the source material (painfully honest as far as some are concerned). Unfortunately, most listeners listen in the far field, a little bit off the reference axis. The off-axis response of the N-series suffers, particularly around the upper crossover point. This creates gross tonal balance differences between the on-axis response and off-axis response (i.e. phasiness). This is not good (and not what you would expect in a "top of the line" product). Some individuals are more sensitive to phasiness than others, but its difficult (for anyone) to avoid big changes in tonal balance with position (with this series). You only get ideal tonal balance in one position - so be prepared to lock your head in a vise for the duration of your listening session.Getting the upper crossover right (flat response - drivers working in phase, wide dispersion or at least dispersion matching adjacent frequency bands i.e. even power response) is fundamental to the success of any loudspeaker. It's the starting point for every design - step 1 in the design. For B&W to deviate from this standard recipe indicates design by a (very) different set of standards.
Also look at that kevlar driver (used in most B&W models). It allegedly shrinks as it works higher in frequency (avoiding the break-up modes and cancellations of traditional drivers). Yet, it only approximates this ideal behavior on the reference axis. Off-axis, these drivers are displaying problems with break-up modes leading to uneven response around the crossover point. Their response becomes more and more chaotic, the farther you move off-axis. Usually, you get response cancellations in the off-axis break-up zones which the ear would perceive as "politeness." Yet, move your head just an inch, and your ear could be zapped by a response peak. Ouch! This is what many B&W haters report (without really knowing what the phenomenon is). This chaotic off-axis behavior is not good.
A company this sophisticated could abandon the kevlar gimmick and chose better behaving drivers and engineer better designs overall. The reference should be live music, but right now it seems B&W are engineering speakers that will sound impressive to the most people (to non-audiophiles); speakers that are voiced to sell (but not necessarily measure or sound accurate). I think B&W can do better, and I don't think it will hurt their bottom line to voice speakers for accuracy. Then again, with a large volume company (a mass marketer) that may not be entirely true. So, B&W have an identity crisis. Do they go the way of the consumer mass marketers (like JBL) or do they stick to their specialist, audiophile roots? The choice would be easy if I were running the company. I would stick to my roots, but I definitely see that as these companies get larger and larger, the pressures to go mass-market increase dramatically. In my opinion, there are enough mass marketers to go around. B&W should perfect what they do best (providing a quality product to audiophiles).
Follow Ups:
Have you actually measured their off-axis response? The reason I ask is that both Audio Magazine and Hi-Fi News reviewed the speakers and measured their off-axis response with identical results. At 15 degrees off axis they both found the response commendably flat and essentially identical to the on-axis response. Even at 45 degrees off axis, they both found the response to be quite good. I understand that we are all appropriately skeptical of magazine reviews, but their lab tests are are accurate.
Some tests are more exhaustive than others. I have the Hi-fi News tests reports by the way. Off-axis problems in the upper crossover of the N801 are noted (this was not the case with the N802). Each model must be slightly different in terms of implementation of the upper crossover. Yet, the problem seems to be a consistent theme in every N800 speaker with the exception of the N802. Sometimes reviewers spot it (especially if they conduct extensive off-axis testing). Sometimes not.The problem afflicts both horizontal and vertical dispersion, but seems most severe in the vertical plane. The vertical dispersion of these designs seems unusually narrow (or at least the arc of coherent frequency response seems unusually narrow). Note Stereophile's published measurements of the N801; particularly figure 6 (horizontal dispersion) and figure 7 (vertical dispersion). Figure 6 shows deep cancellation notches centered at 3 kHz as you move off the reference axis, followed by a power "flare" at 6 kHz, followed by deep cancellation notches at 13 kHz as you move off the reference axis.
Stereophile comment on the vertical dispersion in fig. 7, "Fig.7, which shows the changes in the B&W's response in the vertical plane, normalized to the tweeter-axis curve, reveals that as long as the listener sits with his or her ears between the tweeter axis and the midrange axis, the perceived balance will not change too much. But if you sit so you can see the top of the speaker, or---horrors---stand up, a deep suckout appears at the upper crossover frequency (indicated in this graph by the cursor). This lack of vertically off-axis energy in the presence region might also lead to the speaker's reverberant energy being too politely balanced."
It's my contention that these "changes" in response relative to the reference axis create the synthetic sound (lacking natural timbre) of the Nautilus speakers. The suckouts and peaks are not devastating problems in and off themselves, as long as the tonal balance of the off-axis sound remains the same as that of the on-axis sound. The N800 series speakers do not, however, achieve this kind of even power response. The "changes" in tonal balance with listening angle destroy the illusion of accurate timbre.
By the way, I "measured" all of these problems just by listening to the speakers. At first it registered as a general, "something is not right about the sound," but over time it's easy to pin-point that the problem occurs at the upper crossover point. Furthermore, looking at the published measurements of the N805 and N800, it's possible to spot the same kinds of problems (differing only in degree). B&W need to address these problems in order to banish the synthetic, boxy quality that afflicts the N800 speakers.
PS: Look at Soundstage's measurements of the inexpensive B&W Model DM303. The on-axis frequency response is not flat but note how the off-axis response tracks the on-axis reponse to 75 degrees (there are no big timber changes). This speaker will sound a lot more coherent as a result of its smooth power response (the ratio of on and off axis response). If B&W can engineer this into their most inexpensive model, they could do the same with the top of the line N800 series.
Soundstage Measurements of DM303
http://www.soundstagemagazine.com/measurements/bw_dm303/Stereophile Measurements of N801
http://www.stereophile.com/showarchives.cgi?207:9Stereophile Measurements of N805:
http://www.stereophile.com/showarchives.cgi?168:7Stereophile Measurements of N800:
http://www.stereophile.com/showarchives.cgi?600:7
I should have been clearer. The lab tests I referenced were for the N802, and its off-axis response was very good as measured by both Audio and Hi-Fi News. Audio's lab tests were clearly the most exhaustive of any hi fi magazines. My personal experience is with the N802 and N804 (both of which I own along with a pair of CDM-7NTs). I have never seen a lab test faulting their off-axis response, and I have never experienced the off-axis tonal imbalance that you refer to in listening to the speakers I own. (I spent some time last night specifically trying it out by moving vertically and horizontally off-axis and found the overall tonal balance to remain remarkably constant. I also frequently listen to music while doing other things in the house in other rooms, and I have found the sound to be excellent).
I think that I am beginning to understand...this thread is really ticking off owners. I had not anticipated that (perhaps because I also own a set of these speakers). I sometimes forget...that I have an extreme love of music that overides brand loyalties and loyalty to any one idea, set of ideas, or design techniques. Not everyone loves music to this degree. I sometimes overlook the fact that accurate instrumental timbre, the accurate timbre of the human voice...these things may not be as important to others as they are to me. I almost regret having started the discussion (or having joined it). Almost.If its any consolation, very few speakers produce accurate timbre. Most speakers are designed pretty much the same way and they all struggle with the kind of issues that I have highlighted with these B&W designs. I do believe that speakers in general can be better, but I accept that the majority are good enough for most people. Perhaps...this extreme concern on my part for accurate timbre and accuracy period...sets me apart. I am not an equipment-phile, so much as a music-phile. I accept that I am probably a small minority. To each his own.
What a truly special and unique individual you are! How wonderful and exalted a position you occupy among an otherwise unrefined and unsophisticated populace! If only I could (for but a brief instant) be able to discern, appreciate, and love music with the purity and passion that you do. Ah, but I am a mere mortal. I will never be able to love as you do. My spirit will never soar to the dizzying heights that yours does. My weak and coarsely tuned senses will never be able to accurately measure timbre with the scientific precision that comes so naturally and easily to someone of your nearly superhuman abilities. I stand in awe and admiration of you and your wonderful abilities.
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