Focal Polykevlar cones

Interesting topic to investigate further: Sd modulation due to cone flexing @LF.
That will result in tons of distortion, since the cone doesn't act like a proper piston anymore.
There might be a Klippel paper devoted on this.

I have seen alu cones from MarkAudio that were permanently damaged because of the stresses in the cone, while not being stiff enough.

Obviously this only happens for mid-woofers who need to be able to handle a lot of cone-excursion as well as being able to do proper mid-range as well.(talking about studio/home hifi)
Or are just very poorly made.

Which is a inherent huge compromise and limitation of that approach in general for a single woofer, because we might as well split the audio range into two speakers that are far better optimized for the audio band they have to perform in.
Splitting the audio band across woofers will also reduce IMD significantly for the same reason.

Plus having a HUGE advantage to go multi-sub.
Which is in my opinion a very extremely important but totally overlooked disadvantage of a woofer that does it all.

With some serious DSP trickery things can be done, but that is far from straightforward.
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Then you need to think through the harmonics and sweep through the frequency range with your stroboscope. Your camera frame rate managed to catch it. That is proof it is possible to do with a strobe. In fact if you get the periodicity correct it can look like a real time movie. I have a Stroboscope considerably older than I from the 50's that works fine. And I have a new one that uses LED's The old one with the analog dial is actually easier to find your frequency with. Nice large dial and you turn up and down. Or you set you strobe frequency and sweep your driver frequency. Again thinking through harmonics and sub-harmonics. Even partials it quickly becomes intuitive. I'm pretty sure than like me many on this thread are musicians. Or at least were. That helps think through the harmonic progressions.
The issue with a stroboscope is that you have to match the frequency of interest.

Which is a little difficult with music.
Since it's not about one particular frequency, but sudden high peak transients.

With a high speeds camera it's just sampling and playing it backwards at a slower speed.

It has been a while, but we couldn't really get the same results with just playing a single sine wave a bumping the gain up all of a sudden.

Theoretical simulations tell extremely little how speakers practically perform that are made for sound reinforcement purposes.
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Aside from being brittle, the pioneer HPM Cone material may never be exceeded.
Extremely stiff and very lightweight.
There was a multitude of drivers used, most with a polymer coated paper pulp diaphragm.

I assume you are referring to the "PG" polymer graphite cones, like my TAD TM-1201's have.
Has it's positive and negative sides just as with any material.
You will find some info in the published document, and Pioneer has some AES publications retaining to it.


  • 050_Cone_Diaphragm_Mtls (1).pdf
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kravchenko_audio, what are those appendages from the spider all about?
Huh, well I'm not buying it!
I think they are part of an intermodulatory resonance suppresson. Doped with a polysaturated quasidistortinated fluid that distributes the destructive waves into oblivion. Hence reducing all harmonic motion and creating a subnewtonian waveguided resonance destroyer.
Sorry buddy, your secret is out!!
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Loving it. So do you want to see how you do this? Design a motor?

Cones I design sometimes, if a client has an unusual request. We take an existing frame and rework it to make a larger cone and surround.
If possible what gets done is open tooling. Much more economical. And many times it make little real difference. I just did 4 prototype woofers coated paper and Aluminum cones and the mass difference was 0.5 grams. They will be tested well soon.

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