Is Purifi audio a game changer?

[Wes]

or...


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[ctbarker32]

My latest video related to Purifi.

 

[Savi]

Nevertheless, it would be somewhat wasted in use as a midrange driver only. There are smaller and/or cheaper drivers on the market with similar midrange nonlinear distortion performance, and which offer other advantages to manufacturers (lower cost, closer C2C spacing, better off-axis performance at higher frequencies, etc).

I really have trouble seeing the 6.5" Purifi earning its keep in any configuration other than a passive-radiator two-way (or perhaps a sealed two-way if the design is an active one); in that particular context, though, it obviously excels.

I have the same feeling about the 6.5".
What are your thoughts about the 4" ? Impressive performances but I see no easy way to use it: small active two ways with PR or as a midrange in an active 3 way (10" + 4" + 1") ?
In the future, I really want to try a 3 way active project with hypex fusion, I see a lot of nice woofer and tweeter but the midrange choice seems more difficult, any suggestions ?

 

[diyhobby]

How about a Peerless STW 350 15" woofer and Purifi 6.5"for midrange or 4" woofer and a Great Tweeter

 

[KSTR]

The Purifi drivers are IMHO excellent for midrange duty as those are one of the few small drivers than can be crossed over 2nd order (acoustic) to a woofer (one or two 15 inchers) at 300Hz and below and still can play loud. 2nd order means constant excursion in the slope, so no excursion relief. Will need a beefy amp, 400Watts is not too much, nor would be 1kW++

In a two-way, these drivers have low enough IMD that Doppler distortion becomes dominant (and then it makes sense to correct for that).

 

[KSTR]

I really have trouble seeing the 6.5" Purifi earning its keep in any configuration other than a passive-radiator two-way (or perhaps a sealed two-way if the design is an active one); in that particular context, though, it obviously excels.

In an active system T/S-parameters are mostly irrelevant (and Qes can be arbitrarily changed), so the drivers will work in any alignment, be it CB, PR, BR, TML, Dipole, ...

 

[pma]

Somewhere I read, the 1ET400A amplifier is an evolution of the designs made by Bruno Putzeys before Purifi, but the Purifi transducers are a revolution in transducer design.
And I think that is correct, the search for imperfections in the design of a transducer and the solutions to solve these imperfections are astonishing.

So in fact, is it really a great leap forward compared to NC400? Could you bring facts and literature citations? And I mean real facts, not the youtube company videos. I am asking for hard and independent data.

 

[KSTR]

Pavel, @Bruno Putzeys is a member here, so he might take any questions directly. And he (as the whole Purifi team) is a hell of an engineer, their data and specs are reliable and correct, I have no doubts about that.

 

[pma]

Pavel, @Bruno Putzeys is a member here, so he might take any questions directly. And he (as the whole Purifi team) is a hell of an engineer, their data and specs are reliable and correct, I have no doubts about that.

I know and I have had some communication with Bruno in direct e-mails, however based on published measurements here I do not see much difference to call it a "game changer".

You may compare by yourself

https://www.audiosciencereview.com/...and-measurements-of-hypex-nc400-diy-amp.5907/

https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/

it is +/- the same, nothing to indicate possible audible difference.

 

[Mnyb]

Wait and see perhaps ? Purify has to date only produced very few drivers and those with a very specific application target.
To be a driver manufacturer you must offer all kinds of drivers with parameters suiting more different projects.
And doing oem for others.
They could start by doing a dedicated bass woofer and a true midrange ? the very interesting video talks about a tweeter ?
I think they have a future if they introduce more products.

 

[mSpot]

So in fact, is it really a great leap forward compared to NC400?

That isn't what he said. The post you quoted was referring to the Purifi speaker drivers, not amplifier.

 

[Vasr]

A game changer? I was for me. I have VTV's version of the Purifi with VTV's own buffer and a Sparkos SS3602.

If I could talk about sound differences without incurring ridicule, I would say that the Purifi is significantly superior to my previous Hypex NC252MP in transparency, resolutions, and dynamics. But I suppose that is just my imagination, right?

The OP was about the Purifi transducers (speaker drivers) not their amplifiers. The evaluations of the two relative to any predecessors aren't related.

Just to avoid this thread derailing into the amp discussion.

 

[NYfan2]

The OP was about the Purifi transducers (speaker drivers) not their amplifiers. The evaluations of the two relative to any predecessors aren't related.

Just to avoid this thread derailing into the amp discussion.

That's correct.

I was impressed after I saw the interview that Erin of Erin's audio corner had with Lars Risbo about the development of the Purifi transducers.
And it is a question not a statement.

 

[EB1000]

It's an experimental amp. I'd wait for a rev 2 module. The way I see it, a truly digital class-D should be the real game changer. I mean a power-DAC where you input a PCM signal, which is upscaled to 24bits 768kHz and then converter into PWM in digital domain. using GaN FETs you could reach a 768kHz switching frequency on a full-bridge topology, and eliminate the need for both closed loop feedback and output filter...

 

[dougi]

It's an experimental amp. I'd wait for a rev 2 module. The way I see it, a truly digital class-D should be the real game changer. I mean a power-DAC where you input a PCM signal, which is upscaled to 24bits 768kHz and then converter into PWM in digital domain. using GaN FETs you could reach a 768kHz switching frequency on a full-bridge topology, and eliminate the need for both closed loop feedback and output filter...

Didn't Bruno P go through the difficulties of a true digital amp in an interview to do with Purifi? I think the conclusion was that it was not worth the effort. Lyngdorf is still persisting AFAIK, although no GaN FET based ones yet. Sounds like one of these ideas that is conceptually superb but other topologies are still more practical.

 

[KSTR]

It's an experimental amp. I'd wait for a rev 2 module. The way I see it, a truly digital class-D should be the real game changer. I mean a power-DAC where you input a PCM signal, which is upscaled to 24bits 768kHz and then converter into PWM in digital domain. using GaN FETs you could reach a 768kHz switching frequency on a full-bridge topology, and eliminate the need for both closed loop feedback and output filter...

You'll always need a feedback loop, otherwise you will have:
- zero PSRR !
- zero correction of switching dead time uncertainity (the higher the frequency the worse this gets), the power stage output PWM is not the same as the input PWM.
The PWM feed also needs to be high resolution, almost infinite, much better realized in analog.
And how would you get around an output filter, you sure don't want a 768kHz full power square wave on your speaker wires (EMC disaster).

Axign, NL, has a nice chip that incorporates a very fast ADC so the feedback loop can be realized in the digital domain, very convenient for higher order loop feedback.

The future of class D is multilevel topologies (like MERUS/Infinion) IMHO, which may get away without filter at lower powers