Check out Mr. Knight's UK patent # 2445695 for a detailed explanation. I found the patent as written was dissapointing. How can one make a claim on a decades old method of calculating the mH valued on a woofer coil? How can an examiner award a patent when no utility is demonstrated? The only novelty (and that's a stretch) I found was a modified formula for calculating a tweeter's uF value included "CM" - a factor for adjusting the spread of the xover slopes.
I had a few spare minutes, so I looked through the UK & US patent / applications. So, correct me if I'm wrong here, but essentially what we're dealing with is an extension of what Solen-popularised. Regular 1st order Butterworth has the XO at -3dB. Solen's 1st order variation (presumably also done by other people before them too, but a convenient handle) crosses at -6dB. And this one is at -12dB.
Quite easily re the patent grant etc. I've seen things that are a far greater stretch being patented. US Patents No. 6486750 and 6025810 for e.g. Or any patent produced by a hifi wire company come to think of it.
I can't say the design philosophy advoctated here of deliberately creating an enormous hole in the midband frequency / power / amplitude / whatever response appeals to me, but live & let live.
Quite easily re the patent grant etc. I've seen things that are a far greater stretch being patented. US Patents No. 6486750 and 6025810 for e.g. Or any patent produced by a hifi wire company come to think of it.
I can't say the design philosophy advoctated here of deliberately creating an enormous hole in the midband frequency / power / amplitude / whatever response appeals to me, but live & let live.Ahh, but Mr. Knight's contention is the dip counteracts the rise in our normal hearing profile shown to increase in the 1-3 kHz (typical 2-way xo) range by Flethcher and Munson. Other claims of lower distortion in the xo region caused by the Basilar 'beating' effect go unproven other than subjective assertions. The problem is - where's the test data to proove any of his claims of sonic improvements? No doubt the method claims to produce the dip are defensible, but the rest..... not so much!
Sort-of someone has. Have you ever heard (or heard of) a Danley Synergy horn? Acts like a single-driver point source, but with constant directivity and high SPL capability. Can even be made to have linear phase (wavecom accurate) over wide range of frequencies. There are commercial ultra high SPL models and number of more tamed-down DIY versions around. Rather an ear-opener.
I know what the contention is regarding the hole in the FR / whatever you want to call it; I don't agree with it, but as I say, I take the live & let live view. As for the Basilar business, YMMV. Can't say I've ever had a problem along those lines myself, but I'll wait & see what data emerges.
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If the goal of a speaker designer is to make a speaker that reproduces recorded music accurately, the last thing one would want to do is put a 12 dB response dip at the ear's most sensitive frequency.
It will be interesting to see how Ian defends his assertion that flat frequency response is not optimal.
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flat on axis in a semi-reverberant field is not the best. I read the patent too, well, there are a lot of subjective assertions there, it's dissapointing. Proofs, any? Also it says in case of a 3 way, same crossover applies. Really? Another dip in the mid-bass? I guess people who have active crossover facilities can try and report.. but I am far from being convinced!
Yes, you are right. But that's a speaker, not a driver, even if it behaves as a single driver. I'd love to check one sometimes.
The patent's text starts with an IMHO completely wrong assumption: They suggest that one should have a hole in the frequency response in the area where the ear has increased sensitivity due ear canal resonance.
Well - we are used to hear like that ! We hear all unamplified and natural sounds including this hump in the ear's response. It is nothing more than natural. It simply doesn't make sense to "iron it out" in an artificial reproduction.
One of the most important things regarding the often cited Fletcher and Munson curves is the fact that every recording has to be reproduced by a linear speaker at the correct SPL level.
Regards
Charles
Well - we are used to hear like that ! We hear all unamplified and natural sounds including this hump in the ear's response. It is nothing more than natural. It simply doesn't make sense to "iron it out" in an artificial reproduction.
One of the most important things regarding the often cited Fletcher and Munson curves is the fact that every recording has to be reproduced by a linear speaker at the correct SPL level.
Regards
Charles
Maybe only 6 if the phase is just right
There was a BBC reference that showed that a continuous treble rolloff was preferable to flat response with a hole at the crossover. A large dip at crossover magnifies the impression of a divide betweeen the elements.
Absolutely true that we are used to the resonance peak in our normal hearing and must not try to EQ it out with our speakers (its also different frequencies for different people; big ears, small ears).
And, did we ever hear how this was related to the Basilar membrane?
David S.
that's not true Charles, our hearing was not originally built for reverberant spaces, we can only adapt to them. Why our ears are shaped and spread as they are is mainly a cause of hunting/hunted situations that you and I, obviously never met! It's a survival thing .
have a look:
http://www.2pi-online.de/diffuse_attenuation_color.png
I believe it also depends on the polar of the source, omni, dipole, horn.. CD or not, so there isn't a clear, unique answer.
That's where this concept I believe fails. A gap, ok, why not. But for any speaker, really? Independant of the radiation pattern?
Mr Knight seems to have dissapeared!
.have a look:
http://www.2pi-online.de/diffuse_attenuation_color.png
I believe it also depends on the polar of the source, omni, dipole, horn.. CD or not, so there isn't a clear, unique answer.
That's where this concept I believe fails. A gap, ok, why not. But for any speaker, really? Independant of the radiation pattern?
Mr Knight seems to have dissapeared!
I think he got much more than he bargained for.
I suspect he was 'testing the waters' to see what reaction he'd get to his marketing approach and design philosophy. He's done this at 3 defferent speaker DIY forums!
David,Maybe only 6 if the phase is just right
There was a BBC reference that showed that a continuous treble rolloff was preferable to flat response with a hole at the crossover. A large dip at crossover magnifies the impression of a divide betweeen the elements.
Absolutely true that we are used to the resonance peak in our normal hearing and must not try to EQ it out with our speakers (its also different frequencies for different people; big ears, small ears).
And, did we ever hear how this was related to the Basilar membrane?
David S.
I fished the patent out of my trash so others won't have to bother down loading Ian Knight's masterwork.
"With the Basilar Membrane not having to deal with the two-tone noise generation...."
It is a good laugh, don't drink anything while you read it
.Art
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It does sound a little like an English public school.
"Well Jenkins, what are you doing here?"
"I've just popped in for a quick beating sir."
David,
I fished the patent out of my trash so others won't have to bother down loading Ian Knight's masterwork.
"With the Basilar Membrane not having to deal with the two-tone noise generation...."
It is a good laugh, don't drink anything while you read it
Art
Thanks for that Art. Pure BS to think that crossover impacts beating. As long as the frequencies are preserved (of course they would be) gain is equal for both tones (brought into question with his design) then the beating rate and depth can not change. Even phase shift will only shift the "phase" of the generated beat.
Still no connection to the Basilar membrane that I can see. A good example of technical obfuscation, it sounds plausible and tech-ish.
David S.
Evidently just enough Dave to get a patent and launch a marketing campaign.
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