Purifi SPK5 Speaker Review (Prototype)

[Xyrium]

One of these do not belong.

https://www.audioholics.com/bookshelf-speaker-reviews/rbh-pm-8-monitor/conclusion

It’s good, just not SOTA.

I believe even the Presonus Eris XT or something like that, fared better in the roundup they put together, for 20% of the price.

 

[Massimo]

Well, we could have said the same for their amp but clearly they went all out there to create the best possible performance. They should have strived for the same here.

The difference is that the amp you test was built by Purifi. As were the Purifi speakers tested by Mitchco. These speakers were not built by Purifi. They are poorly assembled which renders the test data rather meaningless.

 

[ROOSKIE]

The difference is that the amp you test was built by Purifi. As were the Purifi speakers tested by Mitchco. These speakers were not built by Purifi. They are poorly assembled which renders the test data rather meaningless.

Mitchco's in room measurements spell a similar story (but with somewhat better bass)
As a diy hobbies builder I deff want to be more impressed given the hype and new tech.
I do realize the box was damaged but a good number of these issues are likely not affeted by that.
Still excited to see Dennis Murphy use this woofer in a 3way.
That dude is the good.
Anyway I have given more than my 2 cents in this thread so I will hang back until another model uses this woofer and gets tested here.

 

[amirm]

The difference is that the amp you test was built by Purifi. As were the Purifi speakers tested by Mitchco. These speakers were not built by Purifi. They are poorly assembled which renders the test data rather meaningless.

No it does not. There is a mountain of data in the measurements not impacted by the theory of leakage. Many are supported based on other factors. That crossover is not correct (and I have checked every component for compliance with Purifi design). The resonances in the tweeter are real. Overall tonality is just wrong.

The review is also properly marked as to its origins. So there should not be any confusion.

 

[dougi]

Sounds like a trip to Home Depot. Foam insulation tape can be found in varying thicknesses...and if you could find a fairly thin product it would work well for this.

Yep. I converted some old (Proac Tablette iiis) from ported to sealed after I changed woofers. These have a removal rear panel and putting adhesive (or not) insulation foam around the lip was perfect for sealing it!

 

[The Jniac]

I have noticed that the weirdness in the impedance graph coincides with where the FRs of the port and woofer meet. Could that be the culprit?

 

[amirm]

I have noticed that the weirdness in the impedance graph coincides with where the FRs of the port and woofer meet. Could that be the culprit?

It is in that region.

 

[ctrl]

Somewhat unfortunate is the (horizontal) radiation, as you can see on the PowerDI / ERDI and normalized horizontal FR.

Because of the high crossover frequency @3.1kHz the bass-midrange driver is already clearly narrowing the sound radiation in the range of 2-3kHz.
Unfortunately, due to the interaction of the tweeter without any directivity control and the baffle in the frequency range 4-6kHz, there is a significant widening in the sound radiation.

Such "fast" changing in sound radiation patterns are very difficult to correct with a passive crossover - with a relatively linear axis frequency response up to 3kHz and a significant dip in the 4-6kHz range - maybe.
As a prototype for the 4'' Purifi woofer the combination with the AMT would probably have been a bit better (in the horizontal directivity).

But this "prototype" is a nice example of how much work goes into well-designed loudspeakers in terms of chassis selection, cabinet design, chassis placement on the baffle, crossover tuning,...

Just throw two expensive loudspeaker chassis into a cabinet can work, but it doesn't have to.

 

[moonlight rainbow dream]

There is such a thing as asymmetrical crossovers to correct for the physical offset between the tweeter and midwoofer acoustic centres. More reading here

I see though in Purifi's documentation that they targeted 2nd order acoustic slopes on both the tweeter and woofer filters so not sure what's going on there. I think it's a speaker design rule of thumb that a 2nd order crossover should utilize physically time-aligned drivers which is not the case here. This may be an institutional thing, because I have noticed a similar thing from SB Acoustics' factory kit designs (high xover freq + low order filters), maybe to show off the extended bandwidth of their flagship drivers.

 

[hardisj]

Mitchco's in room measurements spell a similar story (but with somewhat better bass)
As a diy hobbies builder I deff want to be more impressed given the hype and new tech.
I do realize the box was damaged but a good number of these issues are likely not affeted by that.
Still excited to see Dennis Murphy use this woofer in a 3way.
That dude is the good.
Anyway I have given more than my 2 cents in this thread so I will hang back until another model uses this woofer and gets tested here.

you saw my testing of the Selah Purezza, right? If not, check it out. Uses the Purifi woofer.

https://www.audiosciencereview.com/...audio-purezza-review.15850/page-6#post-563021

 

[The Jniac]

I just looked up those tweeters. Why on earth do these exist? You can get significantly better tweeters for less, unless there is something special about AMTs that I am missing.

 

[ROOSKIE]

you saw my testing of the Selah Purezza, right? If not, check it out. Uses the Purifi woofer.

https://www.audiosciencereview.com/...audio-purezza-review.15850/page-6#post-563021

Just did, I missed it before tonight.
Heroic review, seriously comprehensive. (all of yours are)
Thank you.
The speaker looks pretty good.

 

[The Jniac]

Just did, I missed it before tonight.
Heroic review, seriously comprehensive. (all of yours are)
Thank you.
The speaker looks pretty good.

Yeah, Mr. Craig is quite the wizard. I sometimes wonder what he could come up with if he had access to Harman-level R&D resources.

 

[Cahudson42]

Hmmm. Let's take the woofer and AMT from a B652 Air, directly replace the two current drivers, 'leave everything else exactly as-is' - and see how it comparatively measures...

 

[Francis Vaughan]

There is clearly some sort of issue in the bass alignment. The impedance plot in the low frequencies doesn't match the Purify design document in the bass, but is almost exactly the same in the higher frequencies. Tellingly the resonances have shifted up in frequency and the impedance at resonance has dropped quite a lot too. That does suggest a leak. Which is annoying at best. The wobbles in impedance suggest something very odd is going on. Even a ham-fisted design won't manifest this unless something else is wrong.

OTOH, like many DIYers, I was enthused when this bass driver was announced, but when the final product and its parameters came out I was rather deflated. This is a driver that struggles to find a use case. The extraordinary excursion, one that is claimed to put it on par with drivers of significantly greater diameter is something of a significant handicap. In order to build a viable bass reflex enclosure the port is forced to be extraordinarily large. So much so that it starts to dominate ones thoughts on design. Purify sell passive radiators, but these are just the same driver without a motor, and cost half the price of the full driver. Because of the nature of bass reflex, you need two. So suddenly you are looking at double the price in drivers, from what is already a pricey driver. The alternative of using a third party passive - and one sees the SB 5x8" passive pressed into service yet again, and it seems the more sensible. But even here, it isn't clear that that radiator has enough excursion.
If Purify put their minds to a pure high end mid-range I think they would find many more friends. Not all of us live in tiny European apartments.

The Purify reference design SPK5 is a little odd. It adds a lot more damping material than is typical for a normal bass reflex, and the clearance for the port inside the cabinet is very tight, so much so that the effective length of the port must be affected.

And I'll echo the thoughts. Who the heck thinks that using this tweeter is a good idea? It just snatches defeat from the jaws of potential victory.
The silly expensive crossover components is also a turn off. There is little to no science to any of them.

 

[w1000i]

Puri Bliss could be a better implementation than purifi it self.
Puri Bliss - BeWg | HiFiCompass

 

[March Audio]

OTOH, like many DIYers, I was enthused when this bass driver was announced, but when the final product and its parameters came out I was rather deflated. This is a driver that struggles to find a use case. The extraordinary excursion, one that is claimed to put it on par with drivers of significantly greater diameter is something of a significant handicap. In order to build a viable bass reflex enclosure the port is forced to be extraordinarily large. So much so that it starts to dominate ones thoughts on design. Purify sell passive radiators, but these are just the same driver without a motor, and cost half the price of the full driver. Because of the nature of bass reflex, you need two. So suddenly you are looking at double the price in drivers, from what is already a pricey driver. The alternative of using a third party passive - and one sees the SB 5x8" passive pressed into service yet again, and it seems the more sensible. But even here, it isn't clear that that radiator has enough excursion.
If Purify put their minds to a pure high end mid-range I think they would find many more friends. Not all of us live in tiny European apartments.

The Purify reference design SPK5 is a little odd. It adds a lot more damping material than is typical for a normal bass reflex, and the clearance for the port inside the cabinet is very tight, so much so that the effective length of the port must be affected.

And I'll echo the thoughts. Who the heck thinks that using this tweeter is a good idea? It just snatches defeat from the jaws of potential victory.
The silly expensive crossover components is also a turn off. There is little to no science to any of them.

The use case (when implemented correctly) is very good bass extension in a small box with very low distortion. However, yes its not cheap when you add PRs.

 

[March Audio]

Not final measurements but just for info (specifically the low frequencies). This box is 24cm x 21cm x 45 cm. Flat to 65Hz, f3 is around 44Hz

 

[Francis Vaughan]

Puri Bliss could be a better implementation than purifi it self.
Puri Bliss - BeWg | HiFiCompass

Yeah, I had briefly glanced at that design. It costs well over twice the design being tested here. Neat if you absolutely must have a speaker that small. But for the money, not my idea of value.

 

[March Audio]

Yeah, I had briefly glanced at that design. It costs well over twice the design being tested here. Neat if you absolutely must have a speaker that small. But for the money, not my idea of value.

Not sure I would call it small - its depth!