A Transport of Delight: CD Transport Jitter Page 7

Although I haven't yet auditioned it, I measured the gorgeous new $8000 Denon DP-X transport (figs.23 and 24). The DP-X had very low jitter below 200Hz, but slightly higher jitter in the treble. The 2kHz component in the top trace (made with the -90dB, 1kHz test signal) is lower in amplitude than any of the other products tested, but it had more jitter energy above 3kHz when the transport was transmitting a full-scale, 1kHz sinewave. The DP-X had a slightly higher jitter level on music than the best of the transports tested.

Fig.23 Denon DP-X, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting digital silence (solid), a 1kHz sinewave at -90dB (dashed), and a 1kHz sinewave at 0dBFS (dotted) (vertical scale, 1ps-2ns, 100µV = 1ps).

Fig.24 Denon DP-X, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting music #1 (solid) and music #2 (dashed) (vertical scale, 1ps-2ns, 100µV = 1ps).

The Pioneer CD-65, seen in figs.25 and 26, had higher jitter than the best transports, but lower jitter than the JVC XLZ-1010. We can see a jitter spike at 60Hz, no doubt due to power-supply noise. What is the subjective effect of jitter energy concentrated at 60Hz? We don't yet know.

Fig.25 Pioneer CD-65, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting digital silence (solid), a 1kHz sinewave at -90dB (dashed), and a 1kHz sinewave at 0dBFS (dotted) (vertical scale, 1ps-2ns, 100µV = 1ps).

Fig.26 Pioneer CD-65, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting music #1 (solid) and music #2 (dashed) (vertical scale, 1ps-2ns, 100µV = 1ps).

The most surprising performance was from the $695 California Audio Labs Delta transport (figs.27 and 28). The Delta had low RMS jitter (50ps average for the five signals) and a fairly clean spectrum. However, we can see jitter energy at the power-line frequency of 60Hz in all three traces. Interestingly, the Delta showed very little change in jitter level between the two musical selections.

Fig.27 CAL Delta, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting digital silence (solid), a 1kHz sinewave at -90dB (dashed), and a 1kHz sinewave at 0dBFS (dotted) (vertical scale, 1ps-2ns, 100µV = 1ps).

Fig.28 CAL Delta, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting music #1 (solid) and music #2 (dashed) (vertical scale, 1ps-2ns, 100µV = 1ps).

Next up is the Meridian Compact Disc Recorder (CDR), shown in figs.29 and 30. The silent track (solid trace) has a very low RMS level due to the inexplicable absence of any 7.35kHz subcode-induced jitter. The spectrum of the silent track does show some periodic jitter energy at 60Hz, 220Hz, 440Hz, and 700Hz. Except for the 60Hz power-line-induced jitter at 60Hz, these periodic components don't appear in the spectra when the CDR is playing music or sinewaves.

Fig.29 Meridian CDR, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting digital silence (solid), a 1kHz sinewave at -90dB (dashed), and a 1kHz sinewave at 0dBFS (dotted) (vertical scale, 1ps-2ns, 100µV = 1ps).

Fig.30 Meridian CDR, jitter in S/PDIF data signal, 20Hz-50kHz, when transmitting music #1 (solid) and music #2 (dashed) (vertical scale, 1ps-2ns, 100µV = 1ps).

Share | |
COMMENTS
p_f_m's picture

Hi, first of all thank you very much for doing this. It is very informative and I appreciate your time and efforts you spent on this. I do have a couple of questions though -

For the audibility tests, did you test the players/sources using the same outboard dac via spdif ? or were you listening to the analog outputs of the playback sources ?

Comparing the worst v/s the best is a great way of highlighting the differences and to educate users how jitter sounds like, however I feel it would have been perfect, especially after having spent the time and effort to come this far anyway, if you could have also thrown in to the listening test one or two players that had "average" or not too bad or good jitter. This would have kind of helped understand approximately whereabouts might be the threshold of audibility of jitter.

Thank you! and looking forward to hearing from you.

-PFM.

X
Enter your Stereophile.com username.
Enter the password that accompanies your username.
Loading