Purifi Audio by Bruno Putzeys and friends.

[ErnieM]

Just saw mention of this venture in VoiceCoil magazine.

Lots of impressive resumes involved in this collaboration. Main focus is improved transducer design and class D amps from the looks of it.

Transducers - Purifi

Impressive performance for a 6.5" driver.

[jan.didden]

The next AudioXpress will have a report from me about a presentation Bruno and Lars did for the NL AES section. That will have more technical details about the improvements in both the class D and the driver.

Jan

[Keith Taylor]

There are some tests on the amplifier here Articles, Reviews and Measurements of Audio Products (As an Amazon Associate I earn from qualifying purchases) | Audio Science Review (ASR) Forum


Keith

[gabdx]

that is way better than the best that are available right now....

very impressive THDs and response, I hope it sounds as good as the graph promise.

[AllenB]

Originally Posted by ErnieM

Main focus is improved transducer design

Some of this appears to be overcoming the downside to small area long stroke drivers to make them comparable with the converse. Bandwidth is gained. Efficiency and voice coil diameter are not large.

[Max Headroom]

Why is long stroke good......large cone displacement causes doppler distortions does it not ?.


Dan.

[ErnieM]

I'm glad to see them taking on speakers now. Electronics have been more than good enough for years at this point.

I like the systematic approach to design that they're doing. Focusing on problems that are the most audible in your typical 2-way bookshelf speaker system. I like my big speakers but I can appreciate the effort to get more out of a small box.

A controlled directivity design like the Kii or Dutch&Dutch using these improvements will make for even more impressive clean spl for a given size. Very attractive for the typical listening room.

[scottjoplin]

Originally Posted by Max Headroom

Why is long stroke good......large cone displacement causes doppler distortions does it not ?.

One would think. It's a type of FM or even IM distortion. There isn't much info about how it's tackled. The Jordan Eikonas are long throw and use "contraflex" cones, little info about that also and only in older papers.

[jan.didden]

Originally Posted by AllenB

Some of this appears to be overcoming the downside to small area long stroke drivers to make them comparable with the converse. Bandwidth is gained. Efficiency and voice coil diameter are not large.

That is the case, yes. Risbo's investigations into making a small, long stroke as clean as a large short stroke lead him to some magnetic issues. And Bruno's investigations into possible 'granularity' in class D lead him to - magnetic issues (output filter coil). So that's the reason an amp designer and a speaker designer teamed up on the same issues ;-)

Edit: the reason for interest in small long stroke is of course because of the trend towards more compact speakers with adequate output levels.

Jan

[Max Headroom]

Originally Posted by jan.didden

And Bruno's investigations into possible 'granularity' in class D lead him to - magnetic issues (output filter coil).

Yup, just like I have stated in the past that typical class D amplifier ferrite output inductors are noisy, I also stated that ferrite speaker magnets are noisy and I also stated that I have solution for this, ie Goop changes noise properties of such ferrites.


Dan.