
13 2
Analog Electronics
frequencies rises, since the 'pantograph' draws a
larger and larger version of F{s).
The all-pass filter is useful as a phase equalizer to
correct phase distortion. For example, the high-
frequency attenuation associated with tape record-
ing is not a minimum phase shift process, whereas
the compensation applied in record and playback
amplifiers is. The resultant phase distortion in the
reproduced signal is of no consequence for audio
signals but can cause errors when playing back
computer programs. Figure 6.4 shows a tape
conditioner unit for correcting the playback of
programs recorded on an ordinary domestic tape
recorder. ...