Network Audio Players/Servers

Custom DAC solutions, typically implemented on configurable silicon, are becoming more popular as brands look to separate themselves from the legion of ‘off-the-peg DAC chip’ streamers. In this instance the two ES9038PRO DACs used in Lumin’s X1 streamer are superseded by a ‘Lumin Discrete DAC’ coded onto a pair of Altera Cyclone IV FPGAs. These programmable ICs are also favoured for their on-chip ‘Femto’ clock support with throughput for DSD512 (22.6MHz) and PCM 768kHz/32-bit, although Lumin’s ‘Analog Audio Resampling’ is still limited to DSD256/384kHz.

Also implemented here is a user-selectable ‘Qrono’ filter, one of a series of software products developed by the engineers behind MQA (now owned by Canada’s Lenbrook). Lumin’s own ‘Discrete DAC’ shows minimum time domain distortion [black trace, above, including response with 96kHz PCM] while switching in the Qrono option brings a medium-tap minimum phase filter into play [red traces]. The ‘shape’ of the post-event ringing here is not a million miles off that seen with the original MQA filter or, indeed, the bypass ‘upsampling’ filter in the popular ES9038/9039 DACs, though its precise tap configuration and noise-shaping will be bespoke. Do note, however, that Qrono cannot be applied in conjunction with Lumin’s ‘Analog Audio Resampling’. If you want to synchronously or asynchronously upsample/downsample the incoming PCM, or format-convert between LPCM and DSD, then the Qrono filter must be disabled and Resampling enabled. The LeedH volume option works in either mode. PM