Pre/Power Amplifiers

I discuss the implementation of the Asahi Kasei AK4137 SRC and AK4493 DAC (one stereo DAC per channel) in our boxout, but this is otherwise the only DAC to rival ESS's Sabre solutions when it comes to jitter suppression. The figures obtained from the Musicbook Source are spectacular – less than 7psec with any sample rate – while the A-wtd S/N ratio is a wide 111dB provided the 'DAC Mode' setting is switched to 'PCM'. Maximum output, with the volume set to '99', is a full 4.8V (balanced) from a usefully low 23ohm source impedance while distortion is as low as 0.0003-0.0011% from 20Hz-20kHz over the top 20dB of its dynamic range [see Graph 2, below].

Wisely, in my view, Lindemann has chosen Hypex's Ncore NC502MP Class D module for the beating heart of its 'Power 1000'. Lindemann rates it at 2x250W/8ohm and 2x500W/4ohm, according well with the module's 2x350W/8ohm and 2x500W/ 4ohm specification, and the 2x365W/8ohm and 2x650W/4ohm measured on the lab bench here. The PWM module, and SMPS, necessarily has limited headroom but the 365W, 725W, 850W and 455W achieved under dynamic conditions into 8, 4, 2 and 1ohm loads [see Graph 1] is still sufficiently powerful for most installations. The 81dB A-wtd S/N ratio (re. 0dBW) is also good for this technology – the noise is 'white' rather than hum – while the response is both very extended at ±1dB from 1Hz-25kHz and also extremely stable into varying load impedances. This is a key feature of the Hypex Class D solution. Distortion, too, is a very low ~0.003% through bass and midrange frequencies right up to 275W/8ohm and only increases, quite steeply, above 10kHz reaching 0.18%/20kHz/10W. All in all, this is a very solid amp. PM