Not a power DAC. "This amplifier is a straight self-oscillating fully analogue design like all my prior work of the past 15-some years. We decided to call our technology Eigentakt, an obscure German term for self-clocking or self-oscillating. Peter Lyngdorf on our team was of course historically involved in open-loop 'PWM power DACs' as developed by Lars Risbo, my twin brother in this new venture. It's thus important to reiterate that Eigentakt is not such a power DAC.
"Wat's new in it? One thing is that I developed a sampled domain model for self-oscillating loops which remains valid for all duty cycles so it can predict closed-loop response exactly under all conditions. This then allows finding a loop design with very high loop gain (about 75dB at 20kHz, 20dB better than my previous designs) without running into stability problems near clip. Then there is the loop structure that allows better control of the closed-loop frequency response. My previous amp had approximately a 1st-order roll-off. Since the output filter naturally has a 2nd-order roll-off, this amp could be overdriven with out-of-band noise from e.g. DSD recordings but in fairness, only if you cranked a quiet recording high. Also, a 1st-order response already droops noticeably by 20kHz. Eigentakt has a well-defined 2nd-order response which stays dead flat in the audio band and rolls off in a fully controlled manner with a sensible -3dB point of 60kHz. The loop structure used to get this behaviour is subject to a patent application. From a practical perspective, the enormous loop gain is partly used to allow more relaxed timing of the power stage without paying for that in distortion performance. As a result, the 400-watt power stage only has an idle loss of 1.7 watts or so. From dire experience I learned that people don't perceive an amplifier as 'cool running' if the idle losses aren't super low. It seemed sensible to get that sorted once and for all. In other words, the measurements are those of a power stage actually optimized for idle loss, hence efficiency under real listening conditions."
Then this preliminary fact sheet—for a forthcoming 8 x 400w multi-channel amp under the Lyngdorf brand based on Eigentakt—provided more generalized descriptions. Finally, this interview gets even more technical for those who, unlike me, can truly follow.
By June 6th, "Bruno reminded me that there was some earlier discussion about submitting an Eigentakt demo unit for testing? We currently have a limited number of loaner units. Should be able to send one quite soon if you are still interested?" That was Claus Neesgaard. My obvious reply was "indeed, yes and yes."
By then, Mivera Audio had received demonstrator boards to evaluate against Ncore 500 and latest-gen ICEpower. Their findings were very favorable. My own comparators would be £1'775/pr NC500-based Nord Acoustics monos with Hypex SMPS and their own Rev D input buffer [previous buffer on the right on the lid]. Unlike Bruno's own Kaluga monos, these represent Ncore tuning by Colin North's designer.
