B&W CM1 Review

[gene]

Sneak Peek.

http://www.audioholics.com/productreviews/loudspeakers/BWCM1p1.php

 

[Sheep]

That has to be the biggest Sneak Peak I have ever seen.

Looks like a nice speaker.

SheepStar

 

[Tomorrow]

Was this review written a year ago or is the date incorrect?

I appreciate that the reviewer owns up to the inevitability that all speakers color sound. And while he hints at it, I think he's hedging just a bit on the ultimate truth that it is the least offensive type of coloration, not the absolute least degree of coloration, that makes one speaker more presentable to our ears than some other speaker. More lifelike/accurate? No such thing.

(Tell 'em your Hollywood Bowl story, AverageJoe.)

 

[jaxvon]

Excellent review, David. I have no criticism. I am, however, somewhat counfounded by the spectral decay plot. Assuming that it is correct, there seems to be a lot of 'garbage' throughout the measured spectrum compared to measurements of B&W products by Stereophile. I understand that the scales differ, but it seems that there is a lot more 'garbage' on your measurements. I am not accusing you of inaccuracy in measurement, but rather inquiring as to why you think such a perceived discrepancy exists.

This brings me to a general suggestion for Audioholics. I think that AH should be working on standardized measurements that are performed in a controlled environment. Ideally, AH would have a dedicated measurement facility where all of the products reviewed are tested. This would allow readers to accurately compare measured data on products. In addition, it would enhance the publication's credibility. If you are already working on such an endeavor, then I apologize. If not, get to work!

Oh, I would also like to see accelerometer measurements to show the levels of cabinet resonances.

 

[AverageJoe]

Was this review written a year ago or is the date incorrect?

I appreciate that the reviewer owns up to the inevitability that all speakers color sound. And while he hints at it, I think he's hedging just a bit on the ultimate truth that it is the least offensive type of coloration, not the absolute least degree of coloration, that makes one speaker more presentable to our ears than some other speaker. More lifelike/accurate? No such thing.

(Tell 'em your Hollywood Bowl story, AverageJoe.)

I haven't read the review, so I'm not sure how relevant this story is, but I figure RJ must have a reason (I trust him a little bit ), so here goes:

A long, long time ago (no, not in a galaxy far, far away - but it was Southern California, so it may seem like another galaxy), a friend of mine participated in a review of some "incredibly innovative audio equipment that sets new highs in hi-fidelity" or some such jargon. I'm not sure when all this took place, but I met him in the mid 70's when he owned a small recording studio so it had to be before that. He had already been a musician, music producer, and was involved in the recording industry for years.

In any case, the organizers of the event had access to Hollywood Bowl for an afternoon, and set up a demonstration of the equipment for 25 or 30 local studio engineers, musicians, audio enthusiasts, hi-fi reviewers, etc. The type of equipment was not revealed and was set up behind a large curtain. The participants were told the music was previously unheard live rehearsals, and were encouraged to write down all impressions and observations - both pro and con.

Unfortunately, the "incredibly innovative audio equipment" was not very well received. The cons far outweighed the pros: "lifeless and flat", "overly exaggerated high freq.", "sounds like a low-end stereo". Some of the kinder reviewers thought it might sound better inside a room instead of outdoors - "You can't expect any equipment to perform well under these conditions".

Anyway, to make a long story short, after gathering up the reviews of the equipment, the organizers dropped the curtain to reveal a live orchestra.

At least two of the reviewers had guessed what was going on because it was written on their notes, but most were quite surprised.

I'm told this type of thing has happened a few times, but this was the only one I heard specifics about.

 

[Tomorrow]

Anyway, to make a long story short, after gathering up the reviews of the equipment, the organizers dropped the curtain to reveal a live orchestra.

At least two of the reviewers had guessed what was going on because it was written on their notes, but most were quite surprised.

Psychoacoustic effects at their finest.

 

[gene]

Was this review written a year ago or is the date incorrect?

The date in the headers on the top of each page is wrong. Always go by the date on the main review table summary on page 1.

This brings me to a general suggestion for Audioholics. I think that AH should be working on standardized measurements that are performed in a controlled environment. Ideally, AH would have a dedicated measurement facility where all of the products reviewed are tested.

Its a great idea. Then I can fly each of our reviews from all around the world to our facility each time they wish to conduct a review. What you propose is impractical, expensive and unproductive. Mark is already working on a new measurement standard for us to produce very accurate results using in room measurements. Its not an easy task, but will be well worth the efforts when completed. In the meantime you will have to live with our 5000+ word reviews with pretty darn good measurements

 

[jaxvon]

Its a great idea. Then I can fly each of our reviews from all around the world to our facility each time they wish to conduct a review. What you propose is impractical, expensive and unproductive. Mark is already working on a new measurement standard for us to produce very accurate results using in room measurements. Its not an easy task, but will be well worth the efforts when completed. In the meantime you will have to live with our 5000+ word reviews with pretty darn good measurements

I never said you had to conduct the review at the facility, just have the review sample shipped to your lab before it goes to the person reviewing it. And since most of your reviewers are in FL, it shouldn't be that much more in shipping costs. The lab would of course cost some cash, but I don't think that it would be impractical.

 

[gene]

I never said you had to conduct the review at the facility, just have the review sample shipped to your lab before it goes to the person reviewing it. And since most of your reviewers are in FL, it shouldn't be that much more in shipping costs. The lab would of course cost some cash, but I don't think that it would be impractical.

As I stated before its not feasible to have all products come to my facility for testing and we have many reviewers that are NOT Florida based. I don't have the time or desire to have every product we review come to my facility for measurements. We are working on training some of our key reviewers with better methods of making meaningful inroom measurements - this hasn't been done in the industry to date - but is part of our pending measurement standard.

Now lets get the thread back on topic - the CM1 review. If you have any additional criticisms or suggestions regarding our review procedure, send them via PM as per our forum policy. thanks.

 

[gene]

<P><FONT face="Arial, Helvetica, sans-serif" size=2><A href="http://www.audioholics.com/productreviews/loudspeakers/BWCM1p1.php"><IMG style="WIDTH: 125px; HEIGHT: 94px" alt=[bw] hspace=10 src="http://www.audioholics.com/news/thumbs/bw_th.jpg" align=left border=0></A>The B&amp;W CM1 loudspeakers may definitely be considered a successful design that can suit a number of different usage goals.&nbsp; The build quality of the CM1’s is excellent: the construction is solid and the finishes are of high quality.&nbsp; The sound quality is notable with a character that is at ease and warm, yet still detailed.&nbsp; The CM1’s will fare well against similarly price competitors.</FONT></P>
<P><FONT face=Arial size=2>[Read the Review]&nbsp;&nbsp;&nbsp;&nbsp; [Measurements &amp; Analysis]</FONT></P>

 

[Tumara Baap]

The reviewer is upfront when whats being put forth is merely an opinion or hypothesis. That said, I think things are really being stretched when the psycoacoustics of the precedence effect are used to explain the perceived enhancement by a kevlar cone (if there really is an enhancement). The precedence or Haas effect manifests as a tonally matched reflection of the original sound, within a given time span, and usually from lateral angles. Phase shifts taking place at the source in the same driver would be coloration of timbre. One may enjoy the coloration. But it is misleading to invoke the precedence effect to explain it.

Tumara Baap

 

[DavidW]

I appreciate all the comments, but at this point I would like to interject a few points to note.

Some have mentioned the nature of the measurements and plots, citing some general differences with another source. I went to this source to see what may or may not have been different; the reader can follow this link to the source as well:

http://www.stereophile.com/budgetcomponents/805bw/index3.html

Upon review of this similarly priced model from the very same manufacturer, I noticed several things that give rise to differences.

1. The dB floor of the spectral decay plot is set higher, truncating results, and hiding what is occurring beyond that threshold.
2. Various measurement plots indicate 0.1 octave smoothing which I chose not to use. Smoothing can mask irregularities in measurements and technique, but it can also mask real results as well. Typically smoothing is justified on the premise of limits in the ears ability to hear discrepancies.

Other than the above, the measurements were done using maximum length sequence hardware/software for digital data acquisition and the frequency response plots were constructed from quasi-anechoic far field/near field measurements, not likely taken in any sort of special chamber, as it were.

Others have mentioned the invocation of the ‘Precedence Effect’, otherwise known as the ‘Haas Effect’. For a clearer understanding of what exactly the effect is, I invite all to follow the convenient link to this publicly available source:

http://en.wikipedia.org/wiki/Haas_effect

While the Haas Effect is commonly spoken of in reference to lateral reflections, it really has no intrinsic tie to reflections, only delayed (phase shifted) sound and how the human ear processes the sound. The Haas Effect also applies to multiple sound sources and how to use them for sound reinforcement rather than interference.

What I am hypothesizing is, based on a fair amount of literature review of composite material mechanics and wave propagation, that the cone itself will act as the multiple source. Wide discrepancies in cone stiffness, due to anisotropic behavior of Kevlar weaves verses more commonly used isotropic materials, will cause different portions of the cone to radiate at slightly different times circumferentially. The time discrepancies are small and fall well within the time range of the Haas Effect meaning they will enhance and reinforce the perception of sound rather than obfuscate it.

For more on wave propagation/radiation, please see my forthcoming bit on driver mechanics.

Thanks for reading the review and I hope this makes some things clearer.

David

 

[Tomorrow]

David, that was an excellent and concise comment which followed an equally pleasant review. I'd like to see you do more reviews....not butt kissing here...but your references and hinting at universal speaker coloration is rare and refreshingly admirable.

 

[DavidW]

Glad to be of service.

David