The Stereophile Test CD Page 3

Peter Mitchell's organ recording had been digitized with a modified Sony PCM-F1-format processor. Rather than go back to the original master tape, I recorded the digital datastream from a Madrigal Proceed CD player directly onto the hard disk. Since Sound Tools accepts the S/PDIF output signal found on most CD players, direct digital-to-digital transfers are possible.

After about half the total program was assembled in the playlist, it was transferred, in the digital domain, through the DAT I/O back to the Nakamichi 1000. We had originally thought the Stereophile Test CD would be about 45 minutes long. Based on that assumption, I figured that 600 megabytes of storage would be plenty. Now that the program length had grown to over 70 minutes (the final playing time was 70:57), I wished for a gigabyte of hard disk capacity. Consequently, I had to assemble the master in two sections, transferring the first edited half to DAT to make room on the hard disk for the second half.

Because it took longer than I anticipated to assemble all the pieces of the project (musical selections as well as the editing hardware), I found myself up all night editing just before my plane left Albuquerque for California and the disc-cutting session. I was transferring one large section from the hard disk to the DAT master tape when I heard a series of glitches lasting about two seconds. I started the transfer again and heard the glitches at the same spot. After listening to that section directly from the hard disk (not through the playlist), I became perplexed: there were no glitches when just that section was played back. My plane was scheduled to leave in just a few hours. After some experimentation, I discovered that the glitches occurred exactly when the screen dimmed. The video display monitor has a feature that automatically turns down the brightness after five minutes of no keyboard strokes or mouse movements. This function was interrupting the flow of digital audio data from the computer to the DAT master tape. Because of this and a few other technical problems, I ended up flying to California without a completely edited, ready-to-master tape.

When I got to LAX, I called my old friends, Ben and Bryan Shaw, also known as The Digital Brothers. They have a Sonic Solutions "Sonic System," the crème de la crème of hard-disk editing and CD master-tape preparation systems. Would they help me finish the master before the CD mastering session that day? Fortunately, they made time available for me on short notice. We loaded the two sections of the DAT master I had assembled on Sound Tools onto their 1.5-gigabyte hard disks and did some touch-up editing as well as putting the two sections together. In addition, the Sonic System located the PQ points (track begin, end, and index points) and output the final program to ¾" U-Matic tape for CD mastering. Off to Disctronics for actual PQ encoding and disc cutting.

At Disctronics, the PQ points were manually entered into a Sony DAQ subcode editor. The DAQ-1000 has a feature called "Cue/Review" that plays back the master tape just before and after track changes and index points, beeping when the exact point occurs. This allows verification of index and track point location before cutting a disc. During this check, I noticed that Peter Mitchell's organ recording seemed bright. Could the CD from which I took the audio data have been preemphasized in the recording? If the signal had been preemphasized, we would have to set the flag in the CD subcode that identified this track as having emphasis. This flag engages the deemphasis circuitry in the CD player, restoring flat response. I could not be sure because I was listening to playback on JBL 4311s, a speaker not noted for its accuracy. Not wanting to take a chance on being wrong, I postponed the laser mastering until I could verify that the CD was emphasized. (Checking the CD back in New Mexico confirmed that it was.) Since I knew the master tape was good, with correct PQ codes, I left the master tape in the capable hands of Disctronics and anticipated the arrival of the finished discs.

It was a rewarding experience to be so intimately involved in the technical aspects of creating the Stereophile Test CD.—Robert Harley