Celuaris SPK5 Purifi Review (speaker)

[Selah Audio]

I wonder if @Rick Sykora 's experiment with a passive radiator with provide some interesting results that would deal with that port cancellation.

It's already been done by myself and a few others.

 

[Rick Sykora]

I wondered what happened for SPK5? The SPK4 I had in my room just smoked my KEF LS50's in every way possible, lower distortion, much higher SPL and absolute clean bass response down to 32 Hz. I am just speaking to the Purifi driver. See post https://www.audiosciencereview.com/...ker-review-prototype.17806/page-2#post-578454 for some in room measurements.

From my modeling, not clear why SPK5 was done. SPK4 has lower bass extension, does not have the 400 Hz port resonance and allows more excursion at lower frequency. Also, the port tube is a whole lot simpler than the SPK5 one. Will check with Purifi designer when I get a chance.

This may explain why your SPK4 experience was better.

 

[Rick Sykora]

It's already been done by myself and a few others.

Hi Rick! Yes, and I acknowledged before this review went up. See here...

https://www.audiosciencereview.com/...ved-with-a-passive-radiator.20068/post-660852

 

[ctbarker32]

I am extremely interested in Purifi and this woofer in particular. I know shipping is hard/risky but how hard is if for Purifi to ship a properly assembled version of this speaker to Amir? I would think for Purifi's reputation, they would want to get the best available version for definitive testing. We are on at least version 2 now of testing and still no closer to knowing if this thing has legs or is a dead end. I know Bruno has posted here so why can't he get a "blessed" version to Amir for testing?

 

[Ericglo]

I am extremely interested in Purifi and this woofer in particular. I know shipping is hard/risky but how hard is if for Purifi to ship a properly assembled version of this speaker to Amir? I would think for Purifi's reputation, they would want to get the best available version for definitive testing. We are on at least version 2 now of testing and still no closer to knowing if this thing has legs or is a dead end. I know Bruno has posted here so why can't he get a "blessed" version to Amir for testing?

Not to beat a dead horse, but the Purifi woofer has been tested by Erin. He has not only tested the 6.5", but the new 4" as well. He also tested the Purezza by Selah Audio. There is a thread around here about the test with comments from Rick.

Erin even has a two hour interview with Purifi's Lars Risbo.

https://www.erinsaudiocorner.com
https://www.youtube.com/c/ErinsAudioCorner/videos

 

[Selah Audio]

The enclosure doesn't have any effect on the efficiency / sensitivity. That's determined by the woofer and the passive crossover.

 

[tktran303]

I am extremely interested in Purifi and this woofer in particular. I know shipping is hard/risky but how hard is if for Purifi to ship a properly assembled version of this speaker to Amir? I would think for Purifi's reputation, they would want to get the best available version for definitive testing. We are on at least version 2 now of testing and still no closer to knowing if this thing has legs or is a dead end. I know Bruno has posted here so why can't he get a "blessed" version to Amir for testing?

Because it’s not a Reference design or anything of that nature for consumers (audiophiles/listeners)

It’s a Evaluation sample to get manufacturers a quick and dirty way to evaluate the woofer in a 2 way, which is the typical use case of this midwoofer.

 

[amirm]

I am extremely interested in Purifi and this woofer in particular. I know shipping is hard/risky but how hard is if for Purifi to ship a properly assembled version of this speaker to Amir? I would think for Purifi's reputation, they would want to get the best available version for definitive testing. We are on at least version 2 now of testing and still no closer to knowing if this thing has legs or is a dead end. I know Bruno has posted here so why can't he get a "blessed" version to Amir for testing?

Beyond this, where are commercial speakers based on this driver? It has been out for a long time. If there is no market adoption, then there are more serious issues than me testing the reference design.

On that topic, I have heard through the grapevine that they are unhappy with me testing these samples which then begs the question you asked: why not send me one they have built? They know me. They know where to find me. I have gone though great effort and expense to test these samples (you have seen two but I also tested a third sample). There is only so much I can do here with what is available to me.

 

[Lord Victor]

Damn, was really hoping this was a build worth doing...

 

[Lord Victor]

Beyond this, where are commercial speakers based on this driver? It has been out for a long time. If there is no market adoption, then there are more serious issues than me testing the reference design.

On that topic, I have heard through the grapevine that they are unhappy with me testing these samples which then begs the question you asked: why not send me one they have built? They know me. They know where to find me. I have gone though great effort and expense to test these samples (you have seen two but I also tested a third sample). There is only so much I can do here with what is available to me.

In all honesty, speaking as an industrial designer, I'd say one reason many companies would pass on it could be the look - that melted-plastic-goop look is a hard sell anywhere outside of cheap ghetto blasters or car audio I suspect.
On the other hand I'm aware there are plenty of more esoteric makers out there who don't care about such things.

Though I would also say that their amplifiers have seen MUCH less use than I'd expect - outside of their partner NAD, its pretty much just small homebrewed things, basically DIY; I mean no offense to the makers of the various Purifi based amps that circulate, my point is simply that I think Putzeys intention of "sticking it to the man" by making products with top class performance available to the everyman, might potentially have flown too much in the face of most manufacturers who need to make a huge margin on a product to consider it, causing them to back off.

 

[FeddyLost]

that melted-plastic-goop look is a hard sell anywhere outside of cheap ghetto blasters or car audio I suspect.

I'd expect current Purifi components lineup in some very expensive soundbar or some "standing soundbar" like active Piega.
But it's a very ... niche solution.
If we calculate retail prices and see real world requirements, there's not much place for Purifi.

 

[Dennis Murphy]

Beyond this, where are commercial speakers based on this driver? It has been out for a long time. If there is no market adoption, then there are more serious issues than me testing the reference design.

Well, as mentioned, Rick Craig has a very nice kit using it. But the simple answer is it's very tricky to work with (and expensive, and ugly). Trying to find a reasonably proportioned port suitable for a .5 cu ft is a puzzle I haven't been able to solve. And the factory passive radiators have too much mass, and in any event make for a klunky and very expensive speaker if two are used on opposite sides of the cabinet. Rick resorted to a single "race track" SB Acoustics passive radiator on the back a la Buchardt S400. I haven't had any personal experience with that design. However, I have worked with two Purifi's mountd in a small tower cabinet with a port designed by Jim Salk, and that works great. The larger and taller cabinet allows more leeway in proportioning the port. That particular design uses another odd-duck driver--the AirBlade 180 degree tweeter. I tried to come up with a commercial design using a passive crossover, but the current AirBlade needs some work (which I believe is underway) to get the response up at the low end and allow a low crossover point. Jim Salk plans to offer an active version--so then there will be two commercial designs.[/QUOTE]

 

[tktran303]

Beyond this, where are commercial speakers based on this driver? It has been out for a long time

12 months is hardly a long time.
Given the circumstances of 2020...

But here: first 7... in no particular order

Joachim Gerhard - Surveyor
Wayne Jones Audio Baby Reds and Big Reds
Selah Audio- Purezza
Joseph Crow Audio - №1198
Taipuu Speakers- TBA
March Audio-TBA

 

[tktran303]

Hi Dennis,

My test box was a cabinet of 0.7cu ft, damped with felt and lined with 200gsm Dacron (all walls except front baffle)- My port was fixed at 2.5” x 8.5”
- the software model predicted a Fb of 42Hz.

But after taking an impedance trace it was 39Hz!

So your required port length might be shorter than what you expect.

Though it’s only taken me a decade is discover this- Troels Gravesen conducted a small study in 2005:
http://www.troelsgravesen.dk/vent_tuning.htm

In a 1/2cu ft cabinet tuned to 42Hz you don’t a need a port any longer than what a, say, L18RNX/P would need.

But if you want to tune lower, I think you might be surprised by the outcome- my guesstimate is that you can an get close to 35Hz +/-1 Hz in 1/2cu ft
with 2” x 9-10” or 1.6” x 6-7” port

Of course going with a Fb of 30Hz needs a ridiculously long port. With such a high F3 I’m not sure I see the advantages of tuning so low...

 

[PeteL]

In all honesty, speaking as an industrial designer, I'd say one reason many companies would pass on it could be the look - that melted-plastic-goop look is a hard sell anywhere outside of cheap ghetto blasters or car audio I suspect.
On the other hand I'm aware there are plenty of more esoteric makers out there who don't care about such things.

Though I would also say that their amplifiers have seen MUCH less use than I'd expect - outside of their partner NAD, its pretty much just small homebrewed things, basically DIY; I mean no offense to the makers of the various Purifi based amps that circulate, my point is simply that I think Putzeys intention of "sticking it to the man" by making products with top class performance available to the everyman, might potentially have flown too much in the face of most manufacturers who need to make a huge margin on a product to consider it, causing them to back off.

I agree, but above all, the price is quite prohibitive, even scanspeak's Flagships don't really make it in many commercial design. Manufacturer's that could justify using such a pricy driver are in uber expensive very very niche territory, and most of the big guns rely on their own drivers.
That said, the premiss is valid, the fact that mechanical limitations is the bottleneck in getting higher fidelity, by a few order of magnitude. Market adoption on such R&D focused ventures can only be assessed in the long run. All considered Purifi is very very young in driver making, this is almost more of a research project than anything else, and despite some bumps on the road trying to make it into a successful finished speaker, what they seem to have achieved is not all smoke and mirrors. That's a first step already. These types of projects needs years if not decades to achieve commercial success, but they are important, if you want to make money fast you use available IP but it doesn't advance the state of the art. Eventually if they can afford to last, they'll be able to take some of it and make it reasonably priced, and more market friendly in term of design and usability. This is embryo stage.

 

[tktran303]

ScanSpeak's Revelator drivers series- introduced 1997

Sony SS-AR1 with Revelator drivers- introduced 2010

Wait awhile...

 

[capslock]

In addition to having excellent nonlinear distortion performance, FR and CSD are also something else, as confirmed by the review in HobbyHifi 02/2021.

If I ever buy a pair of these, I will put them in an open baffle. I wonder about the new higher sensitivity model. It's just 1 dB in sensitity, maybe a tad more in efficiency as the resistance also went up from 6 to 6.9 R. The price of this was the nominal excursion being reduced to less than 60% of its original value. Still adequate for my potential appication, but sacrificing this much excursion, I would have expected more of a boost in sensitivity.

As for the Mundorf tweeter, their AMTs usually test extremely well in distortion. What happened here?

 

[Selah Audio]

In addition to having excellent nonlinear distortion performance, FR and CSD are also something else, as confirmed by the review in HobbyHifi 02/2021.

If I ever buy a pair of these, I will put them in an open baffle. I wonder about the new higher sensitivity model. It's just 1 dB in sensitity, maybe a tad more in efficiency as the resistance also went up from 6 to 6.9 R. The price of this was the nominal excursion being reduced to less than 60% of its original value. Still adequate for my potential appication, but sacrificing this much excursion, I would have expected more of a boost in sensitivity.

As for the Mundorf tweeter, their AMTs usually test extremely well in distortion. What happened here?

The woofer won't work well in a dipole / open baffle.

 

[capslock]

The woofer won't work well in a dipole / open baffle.

Well, it can probably not be used without a sub. But crossed over at 100 Hz or higher, it would deliver the xlin that many other popular dipole midbasses just can't offer. So what is it you have in mind that makes it unsuitable?

 

[Selah Audio]

Well, it can probably not be used without a sub. But crossed over at 100 Hz or higher, it would deliver the xlin that many other popular dipole midbasses just can't offer. So what is it you have in mind that makes it unsuitable?

The Qts is too low. Adding a sub won't work well either because a higher crossover point will be required.