Meeting the Purifi'sts: A quick report from DuckToller
During final preparations for the Munich High End the audiophile universe has born a new star, Purifi ApS and audiophilestyle.com received an invitation to preview its pre-production units in a private setting close to the official expositions.
What is Purifi?
This new star, Purifi ApS in Roskilde, Denmark, which in reality was founded as early as 2014 by Peter Lyngdorf, Lars Risbo and Bruno Putzeys, is a patent holding audio company that brought together some of the brightest minds (and patent holders) in the European audio industry with high hopes:
"With a focus on developing and verifying accurate mathematical models to solve problems in analogue and digital sound reproduction, PURIFI aims to remove all technical limitations in the enjoyment of reproduced music." (1)
The company is led by Co-owner Claus Neesgaard as CEO, and a team of highly talented, qualified and experienced professionals in CLASS D & transducer development. More about Purifi
What Was Up?
Purifi invited us to an apartment 10 uber-minutes away from the High End exposition for a private preview of its forthcoming products, the class D amplifier board 1ET400A, called "Eigentakt" and the newly developed transducer PTT6-5W04-01A. The specific name "Eigentakt" is the type of German language that can't be found in the standard dictionaries. It translates in self-oscillating, which in turn exactly describes the characteristics of that very Class D amplifier. Or what DJ's are doing, especially the ones that use this name for their Techno releases .(2)
Who Did We Meet?
While Chris' agenda in Munich could not match the available time slot, I made my way to the premises alone and met with Claus, Lars and Bruno in particular, while all Purifi'sts were present in full manpower towards the end of that rendezvous.
I felt somehow like that guy, who once had an assist for a first-half buzzer-beater, now meeting with The Claw and his NBA All Stars.
Main Talking Points:
Technical specifications , An extreme pool of exciting figures on key specs, like:
THD+N <0.00017% (-116dB) @ 100W, 4Ω, 20-20kHz
Dynamic Range ~ 131dB(A)
Efficiency > 94% for more specs please see here (PDF)
About the correct use (mathematically and practically) of "feedback" in Class D
In essence, Bruno P. explained, people have done experiments where they thought they increased feedback and then correctly found that the sound got worse. Reviewing those experiments reveals that in fact they did not increase feedback. So, distortion got worse and so indeed did sound. They heard right, but drew the wrong conclusion from the experiment.
Why isn't it necessary to use an expensive Linear Power unit with this amplifier module?
In short: The amplifier module is very insensitive to power supply noise. The effect of an LPS is negligible.
How did the developer of the TACT module (Lars) and the designer of the nCore module (Bruno) got together in this partnership:
Nothing short of a bromance, based on math and the love of music. Just ask Lars' wife.
Who are the customers Purifi aims for:
Audio companies searching licensing deals and the DIY audio segment. Purifi does not aim (at the moment) to compete with any of the companies that the various partners are involved in besides Purifi (my short list: Lyngdorf, Mola Mola, Grimm, Kii)
Mola Mola Tambaqui (networked DAC, approx. 7k Euro), the Red Box, sporting the new amplifier modules (price schedule tbd, said to be “competitive in serious quantities”) and a 2 way speaker system with a passive crossover (around 200 Euro in parts), containing the PTT6-5W04-01A long stroke driver (still to be determined, but expected to be “very competitive with other high end units”) and Mundorf AMT ribbon tweeters (appr. 500 Euro/pair).
A non-treated apartment room, sofa in the sweet spot, fully balanced.
Real Life Conditions:
Construction noise from the next building, covered by a big blanket in front of the window.
What's inside the Red Box?
According to the information I have received from Mr. Putzeys:
- I/O board (visible in the photo above in Bruno's hand, with one amp unit attached. He confirmed, "The I/O board is a very simple board we designed and built to make it easy to connect two 1ET400 amplifier boards to a stereo source and speakers. It is much simpler than the input buffer of the Kaluga. We supply the I/O board to clients who want to quickly test and audition the amplifiers. The same I/O board will also be supplied to hobbyists."
- 1ET400 boards and 1 SMPS (from another source, the Purifi SMPS is still in development) + cabling
Specs and Details:
How much will it cost?
Both products are between technology readiness level 6 and 8, therefore pricing was not discussed during the meeting. Purifi verified to me its plans to make an announcement on the 1ET400A amplifier in Q3 this year.
We know from the announcement from NAD that it will soon use these new amplifier modules, presumably for its Master series that has used the NC400 from Hypex. The M22 Stereo amplifier sells close to 3k USD and we have a fascinating quote from Bruno Putzeys, stating:
“Customers will find out that ultra high end amplifier performance doesn’t need to cost an "effing" 40 grand. That sort of number is completely unjustifiable for even the best imaginable amplifier, it’s got at least one digit too many.”
Until then, under reference to Bruno's quote and the 2019 pricing of the NAD m22 stereo amplifier using licensed nCore NC400 technology, the trickle down case is up to the interested reader.
How does it sound?
We listened to some of Bruno Putzeys' personal favorites: on the video snippet you will hear " Kokob / Mètché Dershé” (DR11) from the French ethio-jazz group Akalé Wubè, ethio stands for Ethiopian, not to be confused as one of my usual spelling faults!
The second track was "Seeya" from Canadian DJ Deadmau5 (DR8), a funky track, that allowed everyone in the room to show visible traces of PRAT to underline the quality of the reproduction. Played on augmented output levels due to the construction work noise from the next building, I felt the sound was extremely clear, crisp and neutral, and especially the excellent French Dub track was convincingly reproduced with this physical presence of vibes and notes, that usually divides good from mediocre systems.
I made a specific request to listen to the system on low volumes, that's my way to determine quality reproduction. Unfortunately, that attempt was precisely torpedoed by the drill hammer next door with no chance to reproduce, as we were already a quarter overdue. From what I heard, I can report it was nothing short of ok'ish under that circumstances.
Without having a critical listening, I feel that there will be a great opportunity for manufacturers and DIY'ers to create excellent sounding amplifiers or active speakers. Oh, that was so easy to predict ...
What comes next?
We have arranged with Purifi that Audiophile Style will conduct a community-generated interview with Lars Risbo and Bruno Putzeys, about their products and the underlying technologies. This move allows them to precisely answer according to the interest of our users.
Chris will announce this opportunity in the different threads, which have already started to discuss the newest developments in Class D.
Edit: Please see this topic to post your questions for Bruno and Lars of Purifi! (-CC)