Wadia 27ix & Wadia 270 transport Measurements part 4
Fig.12 Wadia 27ix, balanced outputs, HF intermodulation spectrum, DC-24kHz, 19+20kHz at 0dBFS, 100k ohm load. (Linear frequency scale, 20dB/vertical div.)
Fig.13 Wadia 27ix, balanced outputs, HF intermodulation spectrum, DC-24kHz, 19+20kHz at 0dBFS, 600 ohm load. (Linear frequency scale, 20dB/vertical div.)
Using the Miller Audio Research Jitter Analyzer, I tested the Wadia components' jitter performance both as connected with the ST-optical links and with the D/A processor driven by a PS Lambda transport. (The Miller rig is a combination of proprietary software written for a National Instruments PC card-based measurement system and a low-jitter CD-R carrying a special test signal.)
I first investigated the effect of the clock link. The 270's clock error was just 3 parts per million, which indicates superb accuracy. Without the clock link, and with the Wadia 270 and 27ix connected by an ST-optical datalink, the measured jitter level was 248 picoseconds peak-peak—somewhat higher than I have measured with other great-sounding CD playback systems. The dCS Elgar, for example, driven by a Meridian 500 transport, achieved an astoundingly low 142ps. When I added the clock-link connection, which meant that the 270 transport now derived its reference clock from the crystal controlling the 27ix's D/A converters, the measured jitter dropped only slightly, to 234ps.