M-AUDIO Dman 2044 - Manual (Page 27)

problems since they cause the disk drive heads to seek often, and fre-
quent seeking is detrimental to hard disk performance. On the other
hand, unfragmented audio files are easily accessed and performance is
therefore greater. Oh yeah, and don’t forget to back up your files before
optimizing or defragmenting your hard disk!
Choosing an Audio Format
The DMAN 2044 supports recording and playback in several audio for-
mats. When selecting an audio format, you are usually trading off sound
quality versus the amount of storage space the recorded audio will con-
sume. In general, sound quality increases as the sample rate increases, as
the number of bits used increases, and as stereo is used instead of mono.
Sample Rate is the parameter most directly related to frequency response
and should be chosen carefully (unless you have unlimited disk space
available!). Choose a sample rate that is at least twice the frequency (this
is called the Nyquist value) of the highest audio frequencies you want to
record. For example, if your source material has a frequency range of 30
Hz to 23 kHz, you should usually record at a sample rate of 48 kHz.
However, decreasing to 44.1 kHz is unlikely to degrade the audio quality
in this case, and will take less disk space to store the file. Keep in mind
also that if you are working on a project that is destined to be burnt to an
audio CD-ROM, you should choose 44.1 kHz because that is the native
sampling rate of current CD-ROM technology. Otherwise you may have
to subject your audio data to sample rate conversion, which can deterio-
rate the sound somewhat. 16-bit data takes up twice as much storage
space as 8-bit data, but gives much better results. Stereo data also takes
up twice as much storage space as monophonic data, but is usually the
choice for recorded audio, with the exception of spoken words.
Troubleshooting Resource Conflicts
This section addresses the most common hardware problems within the
PC-compatible environment, resource conflicts. Within the PC environ-
ment there are a limited number of hardware resources (addresses,
IRQ’s, and DMA channels) available for use by all installed devices.
Since most audio cards require many resources, most audio card installa-
tion problems arise from improperly set IRQ and DMA values.
Fortunately, the DMAN 2044 does not require any DMA channels, and
requires only one IRQ. The table below lists the IRQ assignments nor-
mally used in the PC environment. When you experience problems that
indicate a resource conflict, you can compare the conflicting IRQ with
those shown in the table below.
27