Sample Rate Conversion

A digital bitstream is a combination of a master clock signal and a data signal (see below). In an ideal digital world, the master clock signal would always be perfectly shaped and the digital data signal transmitted without errors and well-defined in time. In the real world, unfortunately, this is hardly ever the case, as fierce price competition encourages CD/DVD player manufacturers to use simplified design principles and inferior cable. Unfortunately, HDMI™, selected for simplicity’s sake as the standard format for transferring digital audio and video, is also a notoriously poor interface for handling that task. HDMI™ compromises the audio stream, as it is embedded in the video signal and transferred at a very high frequency.

In other words, the signal is extremely dependent on the quality of the cable or consequently, cable impedance and possible influence from external noise causes an uncertainty of the re-generated master clock, as illustrated in the drawing below (by the red vertical part of the curve). The bitstream transmission then fights a losing battle to maintain proper timing – resulting in degraded sound. Jitter is a source of disharmonic distortion to which the human ear is acutely sensitive.

In the P1, the audio signal is extracted from the active input e.g. a HDMI™ input. From the bitstream signal, the master clock rate is determined and cleaned or regenerated to minimize jitter in the re-clocking circuit before the signal is passed on in the system as secure data, relative to the clean master clock. Unique in home theater processors, this can be performed in Model P1 for an HDMI™ input, enabling high quality playback of uncompressed PCM audio over HDMI™ as well as S/PDIF and TOSLINK.
When the input signal is regenerated relative to the internal master clock, it is kept safe and clean throughout the audio chain, with no loss of dynamics all the way to the output stages of the amplifiers.