Like this one ? http://www.diyaudio.com/forums/multi-way/140190-jean-michel-lecleach-horns-16.html#post3246631
(one cap, one inductance, two resistances). One more cap and one more resistance, because we made the filter symmetrical for some reasons i don't want to discuss in such an atmosphere.
Very flat response curve without accidents (slowly descending on purpose: 1db/decade from 700 to 16 000).
It is a JBL 2426J . Resultant impedance: 6 Ohms, to match the bass speaker's one.
In a well designed MC unit, the spider should set Xmax so by definition, it will be responsible for most of the 'distortion'.
You design the spider to limit where you want it but also to compensate for other distortions. A very important one is that a long overhung voice coil wants to jump out of the gap ... ie it distorts. It's a dynamic mechanism and the simplest way to reduce distortion is to have the spider limit gradually. (There are other more expensive methods
It's non-intuitive but a spider that appears to 'distort' statically can reduce LF distortion over a very wide range of levels & frequencies.
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Gerhad, Unique Fibrous Material (paper) is almost an ideal material for cone speakers. It has the highest flexural stiffness of any sheet material. The problem is that it is inconsistent.
I've managed to replicate its properties with an engineered plastic but only up to about 90dB @ 1m 1W. Above that efficiency, UFM reigns supreme.
We used to make the 2nd best selling speaker in Europe for about 7 yrs. It used a blueish UFM cone from Kurt Mueller. The marketing dept. always wanted us to change to a black cone. Every year or so, we would get black samples (otherwise identical) and compare them in DBLT. The blue cone won every time.
If I wanted to appear clever, I could pontificate on damping of different dies bla bla but in truth, I don't know .. & neither did Kurt Mueller. 😀
But a good sounding UFM cone behaves very differently under the Scanned Laser Interferometer compared to a good sounding plastic cone.
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Maybe that's enough of speakers. Back to CFAs.
Agreed that TMC in the wrong hands can be dangerous, and that it is indeed 2-pole in nature. There is no free lunch with TMC, but it is a different lunch.
As I pointed out in my TMC/TPC article in Linear Audio, TMC and TPC are different, and are optimized differently. It is important to recognize that the best performance for each does not necessarily occur with the same ratio of C1 to C2.
Cheers,
Bob
Kgrlee and Joachim,
I agree that a paper cone can have a very complex combination of materials. Not only cellulose fibers but cotton and reticulated acrylic and god knows what other additives can be added and then the binder. They have worked for 100 years and that is reason enough for many to stick with those materials. I am working with some other materials that others wouldn't think of, not a typical plastic matrix material used by others. Plastics and composites R&D are where I made my living for over 30 years while working on speakers and waveguides at the same time.
I'll get off the speaker conversation, we have high-jacked this thread enough already.
Frank,
I don't think that stiction would be a good description for the movement of a spider. It really isn't a sliding friction.
I agree that a paper cone can have a very complex combination of materials. Not only cellulose fibers but cotton and reticulated acrylic and god knows what other additives can be added and then the binder. They have worked for 100 years and that is reason enough for many to stick with those materials. I am working with some other materials that others wouldn't think of, not a typical plastic matrix material used by others. Plastics and composites R&D are where I made my living for over 30 years while working on speakers and waveguides at the same time.
I'll get off the speaker conversation, we have high-jacked this thread enough already.
Frank,
I don't think that stiction would be a good description for the movement of a spider. It really isn't a sliding friction.
Very illuminating !
@ kgrlee
UFM 😀 Marketing types would have loved that ! Interesting observation about the blueish UFM's. I wonder why they were chosen initially, before testing ? Also why they didn't stay with blue, & choose blue for the whole range, if they were better ?
Kindhornman, this, http://www.diyaudio.com/forums/multi-way/100392-beyond-ariel-949.html#post3685833, is where one discussion of what I was thinking about starts, though Lynn has also mentioned it a few times previously ...
Frank,
I haven't read anything in that thread for awhile but I really have a different view of what I would call stiction.
I haven't read anything in that thread for awhile but I really have a different view of what I would call stiction.
If I was into audiophoolery, I'd claim BLUE is the most musical colour 😀 [*]
That cone goes back to the early 70's. KM (UK) were starting to develop their own paper pulps instead of using pulps from their German parent. We were early users and used that cone for more than 2 decades. The colour was from the early samples and as I said, we tried different colours without success.
But there's more to a cone than the pulp (or colour). It was THAT particular cone that was special. It was used in one of the 3 best small speakers in the world (at that time).
I've spent a lot of time using Scanned Laser Interferometry to try and figure out why this sounds good. A good UFM cone behaves very differently c/f to a good plastic cone. I have some .. but not all the answers.
[*] Actually I HAVE done DBLTs on the influence of colour on auditory perception. The most musical colour is GREEN. Search Mirauer on the Inst. of Acoustics website. Alas, there isn't a pre-print.
I really believe in stiff low Q cones. The ceramic cone we use at Raidho is really a laminate, Oxide-aluminum-Oxide. 50% of the cone is Oxide (not to be confused with the oxide produced in anodizing, as that does not add to the rigidity of the cone). on the 102 mm membrane (4")the first fundamental is more than 12.5 Khz, and on measurements it's merely a 3 dB bump rather than the High Q peaks seen on most rigid cone drivers.
We use the driver to app 3Khz. With a diamond layer the resonance moves up an additional octave.
Membranes with so called controlled mechanical breakups are all over the place and sound very different with different SPLs. To me is not a feasible path.
I think we should bring the thread back in the direction of CFA.
We use the driver to app 3Khz. With a diamond layer the resonance moves up an additional octave.
Membranes with so called controlled mechanical breakups are all over the place and sound very different with different SPLs. To me is not a feasible path.
I think we should bring the thread back in the direction of CFA.
Lets get back to CFA amps guys.
Should I open a thread on speaker interaction with amplifiers? (seriously - if it has merit, lets discuss it)
Should I open a thread on speaker interaction with amplifiers? (seriously - if it has merit, lets discuss it)
It was the speaker i made for Euvl. Maybe you already have the paper about that project.
If not i can send you the latest version.
By the way a discussion about distortion in speakers does not high jack this thread in my opinion. The amp drives the speaker. I see that as a combination.
I know what stiction is but discussing this goes really too far here.
If not i can send you the latest version.
By the way a discussion about distortion in speakers does not high jack this thread in my opinion. The amp drives the speaker. I see that as a combination.
I know what stiction is but discussing this goes really too far here.
would it at least start with Self's, Cordell's audio amplifier books treatment as a baseline level of knowledge? - they both mention loudspeaker loads, reactive currents, current peaking with special drive waveforms
maybe read the Cordell article I linked, look up Cherry's JAES work, mention Blackman's theorem
how about a review of the Carver Stereophile Challenge - since trimming output Z of his SS amp was one of the presumed methods to get the deep null that flummoxed the professional Golden Ears - in their own room, their own choice of speaker, STOA tube amp...
Indeed, the Carver challenge was a great thing, but much of its results remained conveniently overlooked by many in the hi-end audio field. This is NOT to say that high end is needless, but rather it puts the spotlight on frequency response/damping effects that most reviewers overlook when evaluating an amplifier or a speaker.
I have always said that, at minimum, a reviewer should publish the frequency response of the amplifier/speaker cable/louspeaker SYSTEM, as seen at the speaker terminals in any review. This would give some idea of how much influence there is on frequency response by the interactions amoung these elements.
This is not to say that different components don't make an audible difference apart from frequency response, but is to say that sometimes frequency response can be a big elephant in the room affecting the listener's perception of sound quality.
I believe that it is true that, in the absence of clipping, the difference in damping factor and frequency response between an SS amp and a tube amp is often responsible for a lot of the differences heard. I think that the Carver challenge makes this point.
Cheers,
Bob
Well said Bob!
You don't have to 'believe' (take this on faith). It has been demonstrated many time in DBLTs including some of mine.