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PURIFI finally did a fully purified passive speaker design! The SPK 16 prototype is here - with a PTT tweeter
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This thing really moved overall speaker response up by at least an order of magnitude. Having said that, what are the limitations?
- Sensitivity is really low...I think I said before I'd hope for something with higher sensitivity and could easily give up bass presuming use of a subwoofer.
- Speaking of which, response to 37 Hz, but is the output capability enough to really hear that? Or is this kind of cool as a showoff but not practical out of twin 6.5" radiators? (i.e. per Benjamin and Fiedler, if you can't output enough SPL to tickle your ear, it's useless).
- Someone mentioned desiring less vertical dispersion. That could also apply horizontally as well though I get Lars' comment about doing axisymmetric for ease of demonstration...plus it's an amazing showoff to hit this kind of off-axis dispersion, I've only ever seen flat-panel honeycomb experiments do that.
Others?
As for a kit, are the woofer/tweeter/crossover available? I'd be interested in a shallower probably sealed version, again using a subwoofer. Maybe an 8' tall stack of this woofer ha ha, hey the Powerball lottery is up to how much now?!?
- Sensitivity is really low...I think I said before I'd hope for something with higher sensitivity and could easily give up bass presuming use of a subwoofer.
- Speaking of which, response to 37 Hz, but is the output capability enough to really hear that? Or is this kind of cool as a showoff but not practical out of twin 6.5" radiators? (i.e. per Benjamin and Fiedler, if you can't output enough SPL to tickle your ear, it's useless).
- Someone mentioned desiring less vertical dispersion. That could also apply horizontally as well though I get Lars' comment about doing axisymmetric for ease of demonstration...plus it's an amazing showoff to hit this kind of off-axis dispersion, I've only ever seen flat-panel honeycomb experiments do that.
Others?
As for a kit, are the woofer/tweeter/crossover available? I'd be interested in a shallower probably sealed version, again using a subwoofer. Maybe an 8' tall stack of this woofer ha ha, hey the Powerball lottery is up to how much now?!?
killitmore
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Any thought on purify woofer compare with jbl 4367 driver?
Waxx
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The JBL 4367 driver is the JBL 2216ND-1, and it's a very different type of woofer. It's a 15" high sensitive woofer with a neodium magnet with a heritage back to the infamous JBL D130 or the Altec Lansing 515 woofers. Those are more like pro audio woofers from B&C, Beyma and Faital. Purify are small high excursion woofers, kind of the opposite style of those pro woofers. Both can be very good in sound, but they are hard to compare.
Some advanced specs of that JBL 2216ND-1 are found here (in French): https://www.petoindominique.fr/php/mysql_thiele_seul_ref.php?ref=2216ND-1
killitmore
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Sr if this question is noob, I am wondering whether it's possible for this 2 way design with 8 inch purify driver to be full range. I am thinking that the crossover point might be too high for the woofer or two low for the tweeter 
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Bagby used the same tweeter with a SB 9.5" driver I'm a stand mount with excellent results. I'd assume looking at the Purfi drivers response there will be no issue here either with the low tweeter crossover.Sr if this question is noob, I am wondering whether it's possible for this 2 way design with 8 inch purify driver to be full range. I am thinking that the crossover point might be too high for the woofer or two low for the tweeter
Waxx
Major Contributor
The biggest difference is that sensivity and maximum volume are way higher with the JBL, because of the bigger drivers. But even a 4" can play 20 hz, on very loxw volume only, but it will. Directivity may also differ (but i have no data to support that with numbers).Sr if this question is noob, I am wondering whether it's possible for this 2 way design with 8 inch purify driver to be full range. I am thinking that the crossover point might be too high for the woofer or two low for the tweeter
That speaker you link is 85dB sensivity and rated for 350w so a theoretical estimated max volume is 110dB (probally less). The JBL Is 94dB and 300W RMS and so get to a theoretical max volume of 119dB/1m. Bandwith is more or less the same.
I suppose if it will not change the conclusion but to estimate maximum SPL at low frequency, the Xmax of the woofer must also be considered. For instance, attached is the maximum SPL of purifi driver (1m 2pi). Add baffle step compensation and it's even less, but add potential room gain and it's more (these two parameters are installation effect so in order to max comparison I believe the graph made by Lars Risbo is the good way).
Knowing woofer parameters, VituixCad (for instance), is pretty easy to estimate SPLmax.
Regarding directivity, vituixcad can also give an idea of the differences between the two woofers (8 and 15 inch) in their frequency range.
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Penelinfi
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We're still waiting for measurements for those. It's been written Soon™ on the website for a couple of monthsSr if this question is noob, I am wondering whether it's possible for this 2 way design with 8 inch purify driver to be full range. I am thinking that the crossover point might be too high for the woofer or two low for the tweeter
I guess Soon™ means When It's Ready©®™
A tweeter that gives CD over 180°?
Who really (in reality) will want to deserve this?
Would need a lot of damping of reflections, as low (but not overdamped) reflections may give best spacial illusion.
Keep in mind, what the microphone captured is not, what your room does to it.
Know well, there are different approximations (Manger did this 40 years ago and Gerhard followed with Medea same way, but did not succeed), as spacial dimensions differ a lot.
Who really (in reality) will want to deserve this?
Would need a lot of damping of reflections, as low (but not overdamped) reflections may give best spacial illusion.
Keep in mind, what the microphone captured is not, what your room does to it.
Know well, there are different approximations (Manger did this 40 years ago and Gerhard followed with Medea same way, but did not succeed), as spacial dimensions differ a lot.
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Which Manger driver are you referring to? I'm only familiar with the 6" full range bending driver. Manger asked me to design a speaker using that one, but its very narrow dispersion at the top killed the project. So I assume you're referring to a tweeter?
I think the reference is to the thing that was like a sheet of plastic driven in the middle.
ah...I think I know what you mean, which one was that? @killitmore a waveguide can really move down the usable frequency of a tweeter with matching dispersion. Until someone actually measures it's hard to know the final result however.
The Gallo CDT tweeter has more than 180 degrees...
The in room resulting sound is subjectively excellent (replacing my previous electrostatics)
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That's the only one I know of, but it certainly isn't an example of 180 degree constant radiation in the highs. Maybe I'm missing his point.
Indeed this one (MSW: MangerSchallWandler):
https://mangeraudio.com/en/discover/about/the-manger-sound-transducer/
But it's not the driver but the concept (meant like this):
https://www.hifiengine.com/manual_library/manger/zerobox-107.shtml
https://www.hifiengine.com/manual_library/audio-physic/medea.shtml
https://www.springair.de/en/audio-physic-medea-semi-active/h74638
https://mangeraudio.com/en/discover/about/the-manger-sound-transducer/
But it's not the driver but the concept (meant like this):
https://www.hifiengine.com/manual_library/manger/zerobox-107.shtml
https://www.hifiengine.com/manual_library/audio-physic/medea.shtml
https://www.springair.de/en/audio-physic-medea-semi-active/h74638
In the early days there was a lot of experimentation. Not all succeeded.
Regarding dispersion, what about auxillary speakers with delay? In engineering a simple rule is to devide and conquer. It is a complex task to have both pretty darn linear direct sound and wide dispersion--for what else than to fill the room? The room-fill, does it need to be phase correlated to the direct sound? What about the timely correlation in general? If you think about it, a de-correlated, delayed extra speaker, or a few, would do the job, whilst not interfering with the direct sound, subjectively, due to the precedence effect. Stereo is fully maintained. Simple.
