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PURIFI finally did a fully purified passive speaker design! The SPK 16 prototype is here - with a PTT tweeter

Buckchester said:
if it provides an actual improvement, why isn't anyone else doing it?
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Probably the patent has something to do with it.

I am not sure if it makes a big audible improvement, but (unlike some supposedly better products) there is a pretty clear tangible mechanism that would drive the change in sound quality, and the drivers measure better than pretty much all of their direct competition AFAIK, and subjective reviews I have seen are all good.
 
kemmler3D said:
Probably the patent has something to do with it.

I am not sure if it makes a big audible improvement, but (unlike some supposedly better products) there is a pretty clear tangible mechanism that would drive the change in sound quality, and the drivers measure better than pretty much all of their direct competition AFAIK, and subjective reviews I have seen are all good.
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Interesting, thanks. Now all we need are some blind listening tests to see if this design is actually audible.
 
I've heard people mention there isn't some of that "cupped" sound you sometimes get. But then again it may also depend on the speaker
 
Buckchester said:
Now all we need are some blind listening tests to see if this design is actually audible.
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I'm not sure if it's been done, since you'd have to construct the same speaker, but with a different style of surround, which would demand adjustments in other parts of the speaker...

Purifi claims a certain amount of reduction in IMD, a first approximation of a blind test would be to see if you can hear the difference they claim to make using a processed + recorded sample.
 
IPunchCholla said:
While it does seem that could provide some improvements, graphs with no axis info automatically make me think of marketing BS.
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If you click through to the product detail pages, they give a lot of measurements, and with labeled axes, even.

e.g. https://ptt.purifi-audio.com/document/share/31/dd7edead-c63b-49ef-bfc2-b99f8e02eb19

They claim IMD about 50dB below signal... unfortunately I don't know of any other manufacturers who bother to publish IMD... must be because they don't want to indulge in marketing BS ;)

In all seriousness there has been at least one independent test: https://www.diyaudio.com/community/...ootout-purifi-anarchy-plus-maybe-more.371979/ - however, subjective reports are not there, from what I can tell.

I guess you could use these tests to construct a distortion effect and see if you can A/B a proportionate difference in IMD on headphones.
 
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Buckchester said:
Cool, thanks. But it does beg the question, if it provides an actual improvement, why isn't anyone else doing it? Is it actually practical, or simply marketing?
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I'm looking at my Neuman KH310 woofers and they have some "molded in indented lines" on the surrounds. Unlike the Purfi they are nice and neat and symmetrical but I believe they serve the same purpose so there are others that have been doing something similar for quite some time.
 
kemmler3D said:
If you click through to the product detail pages, they give a lot of measurements, and with labeled axes, even.

e.g. https://ptt.purifi-audio.com/document/share/31/dd7edead-c63b-49ef-bfc2-b99f8e02eb19

They claim IMD about 50dB below signal... unfortunately I don't know of any other manufacturers who bother to publish IMD... must be because they don't want to indulge in marketing BS ;)

In all seriousness there has been at least one independent test: https://www.diyaudio.com/community/...ootout-purifi-anarchy-plus-maybe-more.371979/ - however, subjective reports are not there, from what I can tell.

I guess you could use these tests to construct a distortion effect and see if you can A/B a proportionate difference in IMD on headphones.
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Thanks for the links. I didn’t mean to imply Purifi is doing BS. I just hate graphs without labels. Given my performance on the Klippel distortion test (about -15dB with music) I doubt IMD distortion on speakers is going to be a huge issue for me, but I really like how purifi is pushing the state of the art.
 
levimax said:
believe they serve the same purpose so there are others that have been doing something similar for quite some time.
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Textured or other shapes for surrounds to allow expansion have been common for a long time, but I am sure that if that woofer had (otherwise patented) tech that would hold Sd constant we would have heard about it in the marketing materials.
 
Buckchester said:
Cool, thanks. But it does beg the question, if it provides an actual improvement, why isn't anyone else doing it? Is it actually practical, or simply marketing?
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Some Japanese maker (maybe even more than one) made something vaguely similar in the past, they were trying to sell it to the company I worked for. But the overall package I didn't feel had the same potential for overall sound quality as the Scandinavians.

One big reason more people don't do it is tooling costs. It gets expensive in money and time to keep tooling up different shapes. Nowadays you can do decent simulation I guess but that's not free either. So a lot of stuff gets done the same old way same old way same old way.
- I'm not aware of much experimentation with cone profile/shape/cross-section. Some I guess but for instance I never read that someone's coaxial cone is following an actual waveguide profile.
- Or experimentation with the thickness. A former boss of mine tooled up something where the thickness tapered, and some others have done that, but again most stuff seems to be the same old...
 
IPunchCholla said:
While it does seem that could provide some improvements, graphs with no axis info automatically make me think of marketing BS.
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Perhaps it's a mix of marketing and genuine (measurable) advantages.

I don’t think I’m out of my depth in suggesting there’s a strong chance its' advantages are completely inaudible.
When you consider how often these questions and debates arise about the design of the surrounds on these drivers, it becomes clearer why they took this approach. It might be that they initially had pure intentions, genuinely researched and found measurable improvements, but marketing seized the opportunity -and suddenly, everyone has an opinion on their surrounds. People talk about it, and they remember the name.

That’s my theory, and I’m sticking to it.
 
levimax said:
I'm looking at my Neuman KH310 woofers and they have some "molded in indented lines" on the surrounds. Unlike the Purfi they are nice and neat and symmetrical but I believe they serve the same purpose so there are others that have been doing something similar for quite some time.
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That is to break up the resonance of the surround to shift the resonance in higher frequencies. This or similar techniques where used longer time ago. E.g. the fancy looking FW168HR.


The idea to keep the area constant is first published by purifi and is something different compared to the break up of the resonances.

However if you have a closer look at the surround of the fostex or some double or triple bended surrounds you will find that keeping the area of the surround more constant was applied longer time ago without explicitly mention it or understanding it.
 
Buckchester said:
Cool, thanks. But it does beg the question, if it provides an actual improvement, why isn't anyone else doing it? Is it actually practical, or simply marketing?
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Well there's a couple reasons immediately jump to mind:

1) Patents
2) More expensive to manufacture

In addition, while Purifi obviously has motive to present their proprietary technologies as the greatest thing since sliced bread, not everyone may be so convinced that it's solving a problem worth the additional expense.

There's no question that Purifi drivers are generally regarded as excellent, but we certainly had excellent speakers before Purifi became a thing.

Edit: Dang, didn't realize I was missing a lot of posts in this thread until after I'd posted, so a bit late to the punch here.
 
Old_School_Brad said:
Perhaps it's a mix of marketing and genuine (measurable) advantages.

I don’t think I’m out of my depth in suggesting there’s a strong chance its' advantages are completely inaudible.
When you consider how often these questions and debates arise about the design of the surrounds on these drivers, it becomes clearer why they took this approach. It might be that they initially had pure intentions, genuinely researched and found measurable improvements, but marketing seized the opportunity -and suddenly, everyone has an opinion on their surrounds. People talk about it, and they remember the name.

That’s my theory, and I’m sticking to it.
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I'd agree it's pretty good product marketing either way. No mistaking these drivers even from a distance.
 
IPunchCholla said:
While it does seem that could provide some improvements, graphs with no axis info automatically make me think of marketing BS.
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Axis info? Do you mean off axis? On axis is provided, but the tech here related to the surround is mostly for managing distortion. If you want off axis data head to erins audio corner, he reviewed some of their drivers and dispersion is just fine for them.

Purifi and marketing bs are not really two terms that make sense together to me. They're very transparent about their products and development behind them, they have articles in their blog section that go into detail on various loudspeaker and audio reproduction fundamentals. None of it is marketing BS, it's all well represented and executed science. I beieve

If you want an example of marketing BS Focal has you covered. They constantly come out with new cone materials touting all sorts of things, only to end up delivering pretty sub par performance a lot of the time. I could understand criticism against purifi if they were doing the same, but they're not. Their products are offering very good performance and the data clearly shows their engineering is sound.
 
boXem said:
2 or 3 years ago Purifi was demoing their speakers with a slow (around 0.5 Hz) high amplitude sine wave superimposed with music.
Seeing the cone high amplitude movements while the sound didn't seem to be affected was quite impressive.
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That’s a cool demo but doesn’t their surround design address a different issue? IMD due to linear movement of a cone is not something you can fix. As far as I understand their surround addresses distortion cause by the cone surface area changing as it moves.
 
Ktacos said:
Axis info? Do you mean off axis? On axis is provided, but the tech here related to the surround is mostly for managing distortion.
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He's referring to the lack of labels on the graphs' axes on the linked webpage. Graphs without labelled axes are indeed pure marketing fluff, since the lines can be doing whatever they want depending on how the axes are scaled and what exactly you're plotting. That doesn't mean Purifi doesn't have real engineering behind their drivers, they obviously do. But they definitely have a marketing team doing their usual marketing stuff.
 
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