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In Reply to: SF Guarneri Memento's terrible measurements posted by Pinkus on May 7, 2007 at 19:18:55:
I'd be curious for a Stereophile review, too. Those measurements weren't very detailed. Nevertheless, putting a 1st order x'over on a metal cone driver -- that's gotta be a first. It must have some serious proprietary damping ...
Follow Ups:
As I'm sure everyone has figured out by now, these mid-bass drivers are sourced from Audio Technology, and they are poly cones. Here is a nice link to a faq from their site: http://www.audiotechnology.dk/iz.asp?id=4|q|195|||
So, I wonder how much time KH actually spent with the speaker to mistake what is very obviously a poly cone for an aluminum unit.As for the crossover, Sonus faber has not used a pure 1st order in many, many years, but rather what they refer to as a "1st order attenuated"
If you check out the response curve of the SEAS Ll5RLYP metal cone you'll see it starts to drop off naturally around 2Khz and then has a sharp peak around 7Khz if I remember correctly.
One can get a 2nd order slope out of this with just a coil in series and a notch filter. It's essentially a first order topology for the woofer but ends up with a second order slope on the woofer.I think Joseph audio uses a similar and larger metal cone in at least one of their speakers. Hopefully I will be corrected if I am wrong. They approach it differently and use their "infinite slope" which is something like a 60db/octave slope on the woofer. This squelches any need for a notch filter in the first place.
Don't equate 1st order phase/time coherent with small number of parts crossover. Be it first or 48db a crossover can have supporting circuits (phase correction, notch filters, impedance compensation).
yes but Thiel does an enormous amount of passive equalization first to control the metal resonances which is why their crossovers are so complex which you wouldn't expect with 1st order crossovers.
The acoustic order does not equal simple xover.
I'm not so sure that it does have a metal cone. That would be a *huge* shift for Sonus Faber, who have always used polypropylene or paper cones for their woofers. In the main text, Ken Kessler talks about the woofer quite a lot but doesn't mention an aluminum cone. The only place it is mentioned is in Keith Howard's measurements sidebar.But when you look at the picture of the driver, it looks more like the old poly cone Dynaudio drivers. You know, where the dust cap attaches to the cone there is a series of circumferential slots. So I'm thinking that KH just made a mistake and that it really is just a poly cone.
I am pretty sure you are right, Charles. The vents around the dust cap are very reminiscent of Dynaudio or Skanning.
Taking another look, you’re right. I bet they’re poly made by Skaaning (who founded Dynaudio originally). True, they could use a trap for the break-up mode but I assumed they didn’t since the reviewer mentioned a minimalist crossover.I’ve never seen a truly minimalist (or null) crossover on any midbass other than a poly cone (since they typically lack any break up mode unlike paper and everything else).
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