Sony PCM-7030/50 Synchronization Issues Part I of II

Sony PCM-7030/50 Synchronization Issues
(Part I of II)

by
Evan T. Chen
April 17, 1995

In order to help clarify the whole 0.1% pull-up/down business with our Sony PCM-7030 and 7050 timecode DAT machines, I did a preliminary test. A balanced analog sine wave was sent from the Avid AudioStation to the dub room, measured at 10038Hz, and then sent into the left "Analog In" of the Sony PCM-7050. A pilot tone generated from the internal clock of a Timeline MicroLynx was sent from the Avid Room into the "REF VIDEO" input of the PCM-7050. The DAT player was then configured to record from its analog inputs at a sampling rate of 48kHz referenced to 60r FiL rEF-tcF with the "Sync nrr" option set to off. The following chart summarizes my findings.

Sync nrr: oFF
rEF-tcF: 60r FiL
Sine wave: 10038Hz
Signal fed into "REF VIDEO"
connector during recording:
59.94 Hz pilot60.00 Hz pilot
Signal fed into "REF VIDEO"
connector during playback:
59.94 Hz pilot10038 Hz10028 Hz
60.00 Hz pilot10048 Hz10038 Hz

Some comments are in order. Setting the rEF-tcF to 60r FiL and inputting a 59.94Hz pilot signal causes the "Variable Speed" display to automatically show "-0.1%", even though the "Vari-Speed" parameter was not adjusted throughout the test. The PCM-7050 also has a 60r ndF rEF-tcF which was not used for this test. The same test can be repeated at a rEF-tcF of 50r Ebu or 50r FiL and using 50Hz and 49.95Hz pilot tones.

From the results of the test, a +0.1% pull-up can be achieved by recording at 60r FiL rEF-tcF with a 59.94Hz pilot input signal and then playing back using a 60Hz pilot. Similarly, a -0.1% pull-down is achieved by recording at 60r FiL rEF-tcF with a 60Hz pilot input signal and then playing back using a 59.94Hz pilot.

[Note: The successor to the now unmanufactured Sony PCM-7030 and 7050 is the Sony PCM-7040 Timecode DAT Recorder, and although this test has not been verified on this newer deck, chances are the results would remain the same. Special thanks to the staff at Soundtrack, New York for their assistance and initial inspiration for this test. - Evan 4/22/00].

Click here for Part II of II.

Copyright © 2010 by Evan T. Chen. All rights reserved.