Digital Audio Tape Machine (1)

The Music Telegraph | Text 2019/09/23 [16:38]

Digital Audio Tape Machine (1)

The Music Telegraph| 입력 : 2019/09/23 [16:38]

 

▲ Panasonic SV3700 DAT Recorder



 

Digital Audio Tape Machine (1)

 

 

The DAT (Digital Audio Tape) format permits playing, fast winding and stopping at any point on the tape in a manner similar to any analog tape format. However, the long length of tape (up to 2 hours) and the inability of the DAT machine to mechanically cue accurately to a location, make it more desirable to use an automated function to perform these cue and play operations. 

 

 

Digital Recording and Signal Levels

Digital Recording is very unforgiving when it comes to signal level. Too much signal level and the Analog-to-Digital (A/D) converters become overloaded with more voltage than they can resolve into binary bits. When that happens, the audio may be either highly distorted (the familiar crunchy, "breaking glass" sound) or be muted (depending on the overload circuitry design of your equipment). On the other hand, if your signal is too low, the A/D converters will not have enough voltage to resolve an accurate sample, and noise will result. In order to avoid these problems, DAT recorders are designed to read and display the peak signal being input into their A/D converters because Peak Program Meters (PPMs) are more accurate than averaging VU meters.

 

 

The display panel on the SV3700 (see the above photo) contains peak reading meters. On these meters, 0 dB represents the absolute maximum signal level before distortion occurs (expressed as 'dBfs' pronounced "dee bee full scale"). In theory, this level should never be exceeded. In actual practice however, if very short duration, transient signals exceed the 0 dBfs level, they may not be heard by the engineer as distortion (but will certainly be recorded as such). This "unheard" distortion can later cause inaccurate D/A or D/D conversion when you make copies or clones. For this reason, it is important that you understand the nature of distortion as it relates to the levels on the display panel meters.

 

 

 

 

 

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