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PURIFI finally did a fully purified passive speaker design! The SPK 16 prototype is here - with a PTT tweeter
- Thread starter DTTOM37
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I meant Purifi drivers and Purifi electronics, Hypex / Mola-Mola.
Keith
Keith
Well, aren't all those tests done with tweeters whose dispersion narrows significantly? Therefore to not have excess direct energy too bright, the room response has to slope downward. The result could be different with a tweeter of truly constant dispersion.
(Then again all music is pretty much mixed with narrowing dispersion tweeters so we have a different version of Floyd Toole's "circle of confusion" where if your speaker is much better than some inferior thing the music was mixed on, the music may not sound good. Like Heart from 1985 which sounded great on my best friend's boom box in her flat, but not great on a much better system.)
Do you mean like the what is it LaVoce or something?
Heck, is there even a non-DIY large waveguide tweeter available? Without 3D printing, without grinding or routering some existing waveguide to fit?
I'm serious-I haven't looked at every product out there but I'd think a 1" dome with waveguide should not be so much more expensive. OK, after a little searching I see various items from even $20 so maybe I should say
- That can go down to like maybe ≤2 kHz crossover to match 10" or 12"
- What I see available the "waveguide" is hardly any bigger diameter than a flat-flange version of the tweeter would be, so I by "large" I mean oh 6-8" (150-200 mm). Like a Buchardt A500 or something. Large for a tweeter, not of course as huge as a mid/treble horn.
- Any waveguides or horns with truly constant dispersion? Yes that would mean a falling high frequency response, to be equalized either in passive or active crossover. It seems most designs are made to be flat on-axis and thus the dispersion narrows.
A 7" or 8" waveguide for a coax with a 4" midrange and a 1" tweeter would be a very good selling products. The main function of such a waveguide is to assure a fitting di transition from the tweeter to the midrange with low or no unwanted diffraction.
The idea is the same like in the upper line KEF coax or the Genelec one line. A 3" or 4" midrange driver is easy to build and a dome tweeter in a waveguide can provide a very good di. Therefore combining both makes a lot of sense.
The idea to provide a fitting bigger waveguide which also narrows the di of the midrange significantly is also interesting but even if executed well won't sell that much due to its bigger size of 10" and more. You also add the problem of a bigger distance between the coax and bass driver which might become to large to avoid a significant angle dependent phase shift of the midrange and bass...
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AES E-Library » The Subjective and Objective Evaluation of Room Correction Products
A panel of eight trained listeners gave comparative ratings for five different room correction products based on overall preference and spectral balance. The room corrections were applied to a single loudspeaker/subwoofer in a typical semi-reflective listening room, and evaluated using three...www.aes.org
Well, this is more about the final in-room curve, and nothing really stops a constant directivity speaker from achieving the "correct" downward slope, but it's harder than with a speaker that naturally narrows as frequency increases.
I think there's a lot of misinterpretation of that paper. Remember what's being compared there. Not different speakers, but automated EQ on one loudspeaker with notable fidelity issues.
IMO the main actionable knowledge gained from that study for a listener is, neutering room gain is a perceptually bad thing to do. That’s why Audyssey was rated worse than no EQ and and an early version ARC was about the same as no EQ. So don’t neuter your natural room gain!
Also, it’s trivial easy to get a downwards-sloping real room curve with constant directivity - change the direct field! Whether that’s a good approach or not is up for debate. Dr. Geddes endorses an HF rolloff for constant directivity speakers with high DI, if memory serves.
N.B. it would be interesting to see a blind comparison between a good speaker and a bad speaker equalized to the same in-room response as the good speaker. We all think we know the answer, but I don't think the test has actually been done.
Another thing to consider is, due to air absorption and reflections, the predicted in room response may be off in the top octave. For example, here’s the PIR for a JBL 708P, which has basically flat DI to 20kHz.
And measured average response over a 3-seat sofa from two 708i’s* in a real family room. This room has no dedicated "acoustic treatments." One sidewall is 2/3 glass with thin curtains. The floor is hardwood with an area rug, and the back wall is a built in bookshelf loaded with books and such of varying depth. Room correction (Dirac Live Bass Control) is used up to 500Hz.
Interestingly (and admittedly not what I expected when I went to look) the DI of M2 and Salon2 are basically identical from 10-20 kHz. I knew both had rising top octave DI (and Salon2 had lower and consistent rather than constant midrange DI generally) but did not realize they were quite so close up top. In that respect, this Purifi tweeter (as well as JBL 705/708 tweeter+horn) are a step ahead IMO.
(What a neat tool, @pierre!)
My impression was this tweeter was designed as a system with phase plug and waveguide. Which puts Purifi five steps ahead of the rest of the OEM tweeter vendors. Really this type of integration should be the norm, not the exception. The work that people such as Brandon are doing on DIY waveguides for 3D printing is pushing the art forward, but why should that kind of thing have to happen when the vendor themselves are best placed to design and manufacture a appropriate waveguides?
In other words, the midrange cone itself is a kind of shallow, not very constricting waveguide for the 1" tweeter. Which would then mount into waveguide continuing the profile of the midrange cone? Like what Genelec seems to be doing with their coaxials? That is an interesting product idea, since offhand it seems simpler and less expensive than a full-on horn-type coaxial. Maybe we could persuade Parts Express or someone to make such.
Yes the midrange cone and the waveguide both act as a waveguide for the tweeter. Genelec and some other companies built speakers this way.
It would be nice but I don't have much hope. There aren't even many fitting tweeter waveguide combinations which you can buy and there aren't many good coaxial cone speakers also.
I don't know why there is a lack of waveguide tweeters since a tweeter with a good waveguide like the seas with DXT waveguide is very popular. Some companies might not have a developer who can engineer a good waveguide but the companies which also develop PA horns definitely have such a competence and there are also some guys which can be hired to develop a good waveguide.
A good coaxial speaker is difficult to develop on its own and since there aren't many good ones these mediocre ones also don't sell that well...
If a company manages to develop a coax with waveguide which measures and sound well I guess it would be very popular and used by many smaller speaker companies and diy enthusiasts.
The Visaton WG 148 R is a commercial off the shelf wave-guide option for DIYers. It's designed to be used with 25mm tweeters, and a few Visaton models are listed on the company website product page. Other tweeters have been used with it in DIY designs, where mechanical (and acoustic) fit worked out.
www.visaton.de
And of course, Augerpro (Brandon) has multiple designs that can be 3D printed - a great resource for DIYers who would like to use waveguides in their builds.
Waveguide WG 148 R | Visaton
14,8 cm Waveguide of high-quality plastic for 25 mm tweeters. The exponential enlargement provides a high sound pressure level gain in the lower high frequency range, which discharges the tweeter. In addition, the focus and the coupling to a woofer are improved, because the sound generation...
And of course, Augerpro (Brandon) has multiple designs that can be 3D printed - a great resource for DIYers who would like to use waveguides in their builds.
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are there any updates on how/if this speaker will be made available for purchase? Will it be in kit/plan form like the previous Purifi speaker designs or perhaps a finished product?
OP
DTTOM37
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The update is about the color of that
As it is a
The parts, however, may be made availiable to the DIY community.
And then there is Troels Gravensen (http://www.troelsgravesen.dk/), who already did a couple of PuRiFi builds.
Lyngdorf may have an interest in the design, too. But that's all speculation ...
edit: Thanks @boXem
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I perfectly get your intention, but I fear that calling this a prototype causes more confusion than clarification: in the industry, prototyping is part of the steps preceding the production. If a company has no intent to produce a thing, they call it a demonstrator or a reference design. Indeed Purifi call the SPK16 a reference design.
Not sure about EU or elsewhere, but previous Purifi reference designs were not sold in US.
The SPK5s I have came from UK.
The SPK5s I have came from UK.
Already in progress. See Audio Shows forum section.If anyone happens to visit the Munich High End Show (Hall 1, A8 - Munich, May 18-21, 2023), I hope they will report back here - Maybe even make a new Munich High End Show Thread
I was at their Open House in Munich. Words cannot describe how spectacular the sound was.
Da cynics
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Acoustic Horn Design – The Easy Way (Ath4)
I tried it in the same WG as the T25A above. This kind of tweeter would need a different approach... Agreed, top octave very similar behaviour to what I've seen in my various simulations and actual measurements in one of augerpro's waveguides. I've been working on a theoretical mitigation...
Exploring Purifi Woofer Speaker Builds
I was fortunate to hear the SPK16 at the Time House gathering and hear Bruno briefly explain the research Purifi conducted. Stunning small speakers but even more amazing were the SPK16. Amazing like there was no speaker at all but an orchestra in the room even though I was not in the sweet...
Is phase plug /coherer really necessary? ・・・・
