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Speaker Asylum: Re: From another posterabout the B&W 700 series design flaws... by John Ashman

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Re: From another posterabout the B&W 700 series design flaws...

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Have you ever even heard B&Ws? But besides that, did you see the scan I linked of Kevlar breakup modes on a 6.5" driver? Do you understand that Kevlar cones actually have too much tensile strength and but are too compliant? Do you understand the point of having "pistonic" behavior in a driver? Olson clearly DOES share my criticisms of Kevlar. He specifically recommends a 24dB/octave crossover (not what B&W uses) and clearly hints that a really good tweeter would be necessary so that you can cross over at a lower point, below the range of the breakup modes because you can't do much to deal with the kevlar problems. Did you miss the point that he thought only Scanspeak (I believe) had developed a good Kevlar driver? You'd think he'd mention B&W since they've been making them for over 20 years. And, what 2-way 7" bookshelf do you think he was talking about that was so bad? There's a huge chance that it was a B&W. I wish I had a laser interfermometer in back so I could measure a B&W cone for you, but I don't. But there's plenty of obvious evidence that I'm correct. In fact, I just went to HT mag's site to link the measurements of CDM9NTs, BUT, they have taken down those pages (it used to be there). Maybe because it's not current. However, you'd have seen an obvious peak at 9KHz in the tweeter, a dip ~4kHz where the crossover is, then a +3dB bright, forward range from about 500Hz to 3.5KHz, a -3dB dip in the 100-500Hz [low mid/upper bass] range, then a +3dB peak in the midbass around 75-80Hz. IOW, it's all over the map. The problems, as I mentioned earlier are 1) mediocre tweeter 2) kevlar midrange that doesn't operate in a flat, accurate manner (and is beamy), 3) undamped woofers, 4) poor choice of crossover frequencies (necessitated by the poor choice of drivers). You obviously believe OJ is innocent due to lack of proof. I could ask you to prove to me that the sun is 93 million miles away. It is, but how would YOU prove it? For that, we have to take the word of experts in the field that have the capacity to measure this. But if you think Lynn Olson would tell you that B&W's implementation of Kevlar makes sense, you're on drugs!


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Topic - Why are the B&W 700 series less used than the CDM NT series? - bluesky 20:03:00 11/30/04 ( 34)