Buckeye PURIFI EIGENTAKT 1ET9040BA1

Back in 2016,' I documented the rise of class-D amps using the early Tripath technology. Used in the Bel Canto eVo 200.2, TriPath cracked open the door to the High End but was never admitted due to a dim and opaque treble.

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MONOBLOCK POWER AMPLIFIER

The second wave was based on B&O's ICEpower technology, again via a Bel Canto amplifier, the Ref1000M monoblock.³ ICEpower had more credibility and was accepted by many but, often, only with, ahem, due consideration for size and efficiency. There was an explosion of new class-D amps in 2016 when Stereophile featured glowing reviews of Bel Canto's e.One Ref600M monoblock, Theta's Prometheus monoblock, and NAD's Masters Series M22 stereo amp,¹ all based on Bruno Putzeys's Hypex NCore technology modules. Finally, it seemed that class-D was "in the room," though, even to this day, there remain critics and quibblers who continue to deny them as true high-fidelity products.

Well, time does not stand still and neither did Bruno Putzeys. He, along with Lars Risbo and Peter Lyngdorf, had founded Purifi in 2015, and in 2019 he unveiled the Purifi Eigentakt power amplifier modules. Eigentakt (meaning "self-clocking") is the result of years of research by Purifi into the self-oscillation behavior in class-D amplifiers with algorithms that, when applied in control loops, "improve existing designs by an order of magnitude or more.... The Eigentakt circuit is expected to outperform any audio amplifier known, regardless of technology or class, with THD and IMD quoted as below 0.00017% at all frequencies and power levels, and the frequency response in the audioband remains within ±0.01 dB under all load conditions."