Yamaha CBX-D5 7 Recording

20 Chapter 7 : Recording20 Chapter 7 : Recording20 Chapter 7 : Recording

7 Recording

The CBX-D5 can record at any one of four sampling frequencies: 48kHz, 44.1kHz, 32kHz

(as speciﬁed by the AES), or 22.05kHz (analog input only). These sampling frequencies

are commonly used for digital audio, and each has its own speciﬁc applications.

The sampling frequency is set by the controlling software and the CBX-D5’s front panel

REC FREQ indicators show the selected frequency. The selected REC FREQ also

determines the clock rate for all internal processing, i.e., DSP, digital mixer, DEQ, etc.,

except for the output Fs converters, whose clock rate is determined by the PB FREQ.

At 48kHz an audio bandwidth of about 22kHz is possible. Consumer DAT and DCC

recorders can record at 48kHz only. Professional equipment also supports this frequency.

With this sampling frequency an audio bandwidth of about 20kHz is possible. This

frequency is used for all prerecorded CDs, DATs (if there are any), and DCC cassettes.

Although a higher audio bandwidth is possible using 48kHz, 44.1kHz is considered to be

good enough for most applications, and most professional digital audio engineers use this

sampling frequency.

At this sampling frequency an audio bandwidth of about 15kHz is possible. This frequency

is widely used for broadcast applications where a 15kHz audio bandwidth, roughly that of

FM radio, is acceptable. Many DSB (Direct Satellite Broadcasting) transmissions use this

frequency, although, some may also use 48kHz.

At this frequency an audio bandwidth of about 10kHz is available. This frequency is

widely used in multimedia applications. It might not seem very useful for your audio

applications, but if you are limited by hard disk space or the audio material you are

recording already has a limited bandwidth it may be useful.

Since the CBX-D5 contains a sampling frequency converter, digital audio can be output at

a different sampling frequency to that which was used during recording. However, playing

back a sound ﬁle at a higher sampling frequency will not improve the audio quality, as the

audio frequency bandwidth of a sound ﬁle is determined by the record sampling frequency,

not the playback frequency.

This leaves you with two deciding factors for choosing a sampling frequency. Firstly, what

audio bandwidth (audio quality) do you want to use, and secondly, how much free disk

space is available? See “Hard disk size” on page13 for a listing of recording times that are

available at each sampling frequency for a given size of hard disk (free disk space).

With some tape based digital recorders it is possible to vary the speed of playback and

recording. When varispeed is used the sampling frequency of the digital audio is changed.

Since the CBX-D5 can playback digital audio at a sampling frequency different to that

used for recording, varispeed digital audio can be recorded.

NOTE: When using the digital inputs, you should set the CBX-D5’s REC FREQ to

match the digital input signal’s sampling frequency. It is not essential, but we

recommend it.