There are several issues to be considered here. First, the firmware present in most CD300 drives has difficulty correctly transferring digital audio. The problem has been corrected in the newer CD300 Plus drives.
Second, there is a basic throughput issue. In order to correctly read digital audio data, you need to read a chunk of audio, byte swap it, write it to disk, and issue another read command to the CD ROM drive before the drive overruns its read buffer. If you try this on a Macintosh with synchronous read and write calls, it is impossible to do.
There are a few things which the user can do to get the best performance from the Macintosh AV machines:
* Disable File Sharing. File sharing slows down overall system performance.
For best results, disable file sharing before using digital audio
software. Use the "Sharing Setup" control panel to disable file sharing.
* Unmount File Servers. For the reason mentioned above, unmount any network
file servers before using digital audio software.
* Turn off Virtual Memory. Virtual Memory (VM) allows you to use part of
your hard disk as if is was RAM. In general, sound editing applications
do not work well with VM enabled. Use the Memory control panel to turn
off VM and reboot your Macintosh.
* Turn off Speech Recognition. Apple's Speech Recognition software on the
660 and 840AV uses the DSP (Digital Signal Processor) to do its
processing. Digital audio software requires nearly 100% of the DSP to
perform its operations. Use the Speech setup control panel to disable
Speech Recognition.
* Turn off the Express Modem. Apple's Express Modem software also makes
heavy use of the DSP. Use the Express Modem control panel to turn off the
Express Modem before using digital audio software.
* "Run Lean". Disable any unnecessary Extensions and Control Panels in the
System Folder. Many Extensions and Control Panels use up some of the
processing power of your Macintosh. To get the best performance from
digital audio software, disable any unnecessary Extensions and Control
Panels.
* Use╩High Speed Hard Disks. High Speed internal or external hard disks
with SCSI-2 interfaces will work best for recording digital audio. You
should also look for disks that don't use thermal recalibration or do it
in the background when you are not recording audio.
* Optimize Your Hard Disk. Recording digital audio places a large burden on
your hard disk. For best results use a hard disk optimizing program such
as Speed Disk which is included in the Norton Utilities or the FWB
Toolkit from FWB Software.
Article Change History:
23 March 1994 - Added specific tips on getting the most from the AV.
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