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Old 18th September 2012, 01:15 AM   #471
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Originally Posted by Stefanoo View Post
Am I right or you use the same FST for your own developments?
Well one of the variants yes. It's the same one that Zaph measured. These have the underhung motor system with the neo magnet that the 800 series switched to with the D series I believe.
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Old 18th September 2012, 01:20 AM   #472
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Click the image to open in full size.

Wrinkle at 3.5kHz, no surprise there.

Click the image to open in full size.

Frequency response + phase without the crossover.

I don't really see why the phase angles through the impedance are important though. I didn't make any impedance measurements of the driver myself because the entire system is active, so I have no absolute need for them.

Yeah that's a pretty nasty wrinkle , is that in cabinet or free standing ...?
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Old 18th September 2012, 01:21 AM   #473
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Projecting 5th ...?

pretty Poor anology ( who is Zaph ?) I have done the test both ways , others have said the same , you on the other hand have not , yet you condemn what is being said ..

Condemnation without investigation ..?
I'm surprised you don't know who John Krutke is. The analogy isn't what's important. I am sure he has done design work both in and out of anechoic chambers.

It's not that I haven't done the comparisons, is that you've not explained the science behind why the gated measurements aren't to be believed. Now as far as I am aware, I understand why gated measurements work and I also understand why they lose accuracy at low frequencies, what I don't understand is why you think they lose accuracy far above what the theory would predict.
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Old 18th September 2012, 01:23 AM   #474
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Yeah that's a pretty nasty wrinkle , is that in cabinet or free standing ...?
That's John Krutke's measurement so it's without a cabinet behind it and mounted on a very large baffle.
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Old 18th September 2012, 08:37 PM   #475
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5th,

I found this researching. I am not sure the middle driver is the same as the one on the lower series including the 801.
Check it out:

"In the midrange, the Signature 800 retains the familiar, spherical head enclosure crafted of B&W's proprietary, acoustically optimized Marlanô man-made material, housing an improved version of its trademark 6-inch FST Kevlarô driver. However, the Signature's evolution now exploits a more powerful Neodymium-Iron-Boron magnet structure - combined with a thicker top-plate, this high-tech magnet's smaller diameter both lowers harmonic distortion and reduces time-domain ""smearing"" distortions, for still clearer, more defined vocal and instrumental timbres.
The acclaimed Nautilus high-frequency driver also came in for incremental development, raising its useful top-end limit to an unprecedented 50 kHz.
The Signature 800's cabinet redesign provided an opportunity for more than just an aesthetic makeover. Supporting the new model both physically and electro-acoustically is a massive, non-resonant aluminum ""plinth"" base. This also houses improved crossover circuitry where it is entirely free from the signal-modulating influences of large ferrous metal masses and moving magnetic fields. The Signature 800's crossover exploits prodigious, custom-engineered polypropylene capacitors and air-core inductors throughout, and makes its connections via all-new, WBT type 0702 palladium-plated terminals for ultimate signal transfer and longevity"


Take it as is as I wasn't involved in the design of th speaker so don't know how much is true...but certainly sonical performance of the S800 is far beyond the lower series starting from 801s and down the road.
I thought you would have enjoyed the writing.
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Old 18th September 2012, 10:12 PM   #476
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5th,


I thought you would have enjoyed the writing.
Yes thank you for that, it helps clarify which driver was used in the signature.

The original 801 used a standard ferrite magnet, with the thin top plate and long coil, giving it an over hung geometry. At some point B&W changed over to the neo magnet, which, due to it's far greater magnet strength, allowed them to swap over to a much thicker top plate and use an under hung geometry. Under hung motors are praised as often having lower distortion, but usually at the expense of absolute excursion. This as you can imagine isn't a problem in a midrange driver and how much lower the distortion went with the change to the neo magnet we will never know.The level of the distortion in the neo FST is certainly as good as it gets though, so going for the neo motor was certainly the right choice when it comes to absolute performance.

It's nice to see that those buying the 800 sig did get something extra for their pennies besides the premium veneer!
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Old 18th September 2012, 11:32 PM   #477
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yeah I thought it was interesting.
I think the sonic differene from the regular 800 is not so significant though, maybe just a little better.
I have no knowledge about motors and drivers and scuh, I was amazed at how much you know about speakers!
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