Purifi class-D amplifiers

[JonMarsh]

I'm thinking an MTM with a large wave-guide loaded tweeter designed for a low crossover point.,..

These specs are somewhat different from what earlier blurbs implied. But it's an interesting looking driver- I like the impedance curve, too, pretty well controlled inductive rise.

Might be great for a mini- Ardent. I'm in agreement that three way applications seem more reasonable.

Bottom line is the price and availability.

[Zvu]

Regardless of what they say, that smells to me like very good pure woofer driver, not midwoofer. Really looks a lot like Denovo Anarchy 704 (costs 66$) but Denovo being a little more potent with +/-12.5mm Xmax.

https://www.diysoundgroup.com/anarchy7-4ohm.html

Measurements available at John Krutke's blog.

http://www.zaphaudio.com/temp/EX-Anarchy-HD.gif

http://www.zaphaudio.com/temp/EX-Anarchy-FR.gif

http://www.zaphaudio.com/temp/EX-Anarchy-CSD.gif

https://i.postimg.cc/7hPgkQrj/Ex-Anarchy3.jpg

https://i.postimg.cc/xC2vs1xf/Ex-Anarchy2.jpg

[ergo]

And some more news from Puriti

A new speaker driver data here
Whitepaper here

Very unique looking surround on that driver. The 2nd harmonic THD has a rise at 2k, but I guess there need to be some tradeoffs as the Xmax in turn is very big and some other parameters look very good.

[JonMarsh]

And more good news

[ATTACH=CONFIG]29267[/ATTACH]

Hmm, as a moderator, am I allowed to say, "Hot Damn!!"

:T

I saw the NAD announcement yesterday and forwarded it to a few friends...

[ergo]

And more good news

[ergo]

https://www.purifi-audio.com/press/

"May 8th, 2019

NAD Electronics and PURIFI Announce Cooperation Agreement

NAD will license PURIFI’s patent-pending amplification technology to create next generation amplifier platform..."

[Evil Twin]

They are using this design concept in a new Lyngdorf 8 channel amplifier, but the physical realization is not in modules as shown in the PuriFi data sheet.

Looking at the module render, I think the physical construction is not very different from nCore. Note that the output level is somewhat lower, even compared with the nCore NC500 module; I think they are most likely using pre-clipping/limiting like the class D modules from Merus audio, who was bought last year by the company I work for in my day job. Unusual compared with Hypex modules, the power spec is essentially at clipping, like many other Class D modules, approaching 1% distortion.

The performance should give them an opportunity to charge more, but on the surface it doesn't look like they'll be significantly more expensive to manufacture than nCore modules. Same RM core inductor concept, same 6x WIMA caps in parallel for the output filter. The secret sauces is in the gain structure and feedback loop, I think.

I did advise our own teams about this development, as we have been developing GaN HEMTs focused on the Class D market.

[kimmosto]

Many speakers need different gain for tweeter, mid and woofer. This kind of modules should have switch which affects to both gain and noise voltage at the output. It would be useful with sensitive (115 dB/2.83V/1m) drivers without requirement of passive components for noise reduction. For example 14 dB and 26 dB would be quite adequate gain options. Hypex FA for 3-way has different nCore module for tweeter. That is usually okay. At least more okay than e.g. fixed 26 dB gain such as with Pascal Audio S-PRO (which I really like but output noise is way too high for compression drivers and PA mids).

[5th element]

They have comparable gain to my TI post filter feedback tpa3250s. One of the design benefits of that is lower noise.

These seem like amazing amplifiers it does bring up implications of cost mind you.

[ergo]

As for gain - indeed. At least I would need to either mod by Bruno Putzey's Balanced Preamp or then go for some other design that could pull that much pre-gain off.

[ergo]

The AudioXpress news also gives a hint
"At the company's first presentation they will be unveiling the PTT19-W02-03 ultra-low distortion 6.5" long-stroke woofer (Xmax +/- 14.7 mm), rated for 4 Ω nominal impedance. Purifi says this new driver is optimized for excellent transient behavior and is able to reach high SPL without distortion, thanks in great part to moving parts designed with low internal damping."

That'll be interesting too. I'm wondering if the long goal would be some amp/speaker driver combo. Lars Risbo has bee working with TI SmartAmp technologies with real time 'IV Sense' that can keep small woofers from overdrive etc. It does not say anywhere thought that such interaction would be in between these two new products, but as Evil Twin says 'Force is strong with these guys'

[JonMarsh]

Very interesting.

Two observations-

• Notice the gain level, and the implications for the input necessary to achive rated output. This only makes sense in order to achieve THD+N at this level, N must be very low- and level must be higher at the input. This is a pro audio input/output gain structure setup. My Benchmark preamp wouldn't have any problem with this.
• THD is now falling into a level I have only seen approached with amplifiers like my Halcro DM68's. "Triple oh two" is getting down there, and you need a unit like the APx555 to measure reliably at that point.

[Evil Twin]

Impressive... most impressive.

Unquestionably these tiny technological terrors could have an outsized impact in some sectors...

The Force is strong with Bruno and others on this team... I think we will see for the first time that Bruno is truly collaborating with peers now...

[ergo]

Not sure if we'll be so lucky and this comes available as DIY module also, but it sure is interesting and from people with great track record.

https://www.audioxpress.com/news/purifi-audio-promises-to-reduce-distortion-in-speakers-and-amplifiers

https://6moons.com/audioreview_articles/purifi/

https://6moons.com/wp-content/uploads/audioreviews/purifi/1.pdf

https://www.monoandstereo.com/2019/02/new-lyngdorf-class-d-amplifier.html