Page 1, 2, 3
The songs transferred into the Fostex D2424 were then exported, eight tracks at a time, to a Soundscape HDR-1 workstation. This required an optical to TDIF interface and a MIDI cable. The D2424 slaved to the workstation better than vice versa. For this application, I was wishing for an all-optical digital patch bay - internal or external - to eliminate repeat visits to the rear panel for each group of eight tracks. Other MIDI and music-related features include Tempo Map, Time Signature and a built-in Metronome. In addition to standard time, the D2424 can also display musical time in Bars and Beats, including Offsets.
OPTIONS: SMPTE and AES
The stock Fostex D2424 ships with RS-422 and Word I/O for. The SMPTE / EBU TimeCode option ($895 list) includes Time Code I/O via XLRs and Video reference I/O while still leaving room for the AES/EBU option ($599 list). I installed the SMPTE board with not much difficulty although it is recommended that this be done by an authorized dealer / service center. Once physically installed, the additional features were enabled.
I took advantage of the SMPTE capabilities of both the Fostex D2424 (via XLR) and the TASCAM DA-78HR (via RCA), requiring only an XLR to RCA adapter. Considering the random access of HD versus linear access of tape, it was more practical to Slave the D2424 to the tape machine. It was here that I encountered what is perhaps the only flaw in the D2424 and that was simply the lack of "feedback" when the sample rates did not agree.
When the HD is formatted at 44.1kHz / 16-bit and the incoming signal is 48kHz / 16-bit, the Fostex D2424 will do everything but record and tell you why. In Stop it will input a digital signal and in Chase it will attempt to sync but not lock. I can't imagine it would be difficult to implement a warning feature for situations such as this. If it is already there, then it was not obvious enough. The solution was simply to mount a new hard drive. Since the review machine did not come with a spare caddy the process took five minutes instead of 2.5 minutes. No big whoop! Say YES to Quick Format and be back in biz.
KITCHEN SYNC
Here are a few of the sync-related options. Press the SETUP button on the front panel to gain access to ALL features and options. The Reference Time code can be either MTC (MIDI Time Code) or LTC (the "virtual" Linear Time Code). Supported Frame Rates are 24, 25, 29.97nd, 29.97df, 30nd and 30df.
In addition to its internal clock, the Fostex D2424 will lock to Word clock as well as a Video reference, provided the 8345 SMPTE card has been installed. There is a Sync Preset option so that the unit always boots in a predictable manner - nothing is more painful than unlocked digital clocks! There is also an RS-422 port that speaks Sony-9-pin protocol.
LOCK AROUND THE CLOCK
When synchronizing, there are two basic options, Vari and Free. In Vari mode, the D2424 will achieve lock with the incoming Time Code by minute variations on clock speed (sample rate) to maintain frame accuracy. In Free mode, the clock reverts to internal (or Word) after Lock is achieved unless the difference between Master and Slave exceeds ten frames. Minute variations in clock speed / sample rate affects the digital outputs, making it hard for the destination device - a digital mixer, for example - to maintain clock lock.
TWICE BAKED
Whenever synchronizing it is always good idea to confirm that a "real lock-up" actually occurred. I did this by transferring the same tracks from the DA-78HR twice - first to tracks 1-8 and then to tracks 9-16 of the Fostex D2424. During the first transfer I did not pay attention to the settings. The next day, while transferring to tracks 9-16, the machines were locked but sounded like they were a sample or two away from each other. The immediately obvious tip off was the comb filter effect when any two "identical" tracks were compared. This may have been the phase difference between the discrete Word Clock versus the "derived" adat lightpipe word clock. I could have lived with and fixed this, but chose to investigate further and try again.
After switching to "Vari" mode, I listened during a transfer and could hear the track pairs "phasing," which was less desirable than being a sample or two delayed. Finally, I re-transferred from scratch, in "Free" mode both times. Now all tracks simply combined as if mult-ed, confirming the SYNC accuracy of both the Tascam DA-78HR and the Fostex D2424. In summary, take nothing for granted when synching any two machines.
__
Reprinted with permission from Eddie Ciletti, Tangible Technology, 2001
© 2001, All Rights Reserved
[an error occurred while processing this directive]
