3.5 Studio tape recorders
The importance of tape recording to record production cannot be overemphasised. From its development until the coming of digital tape recorders in the late 1970s, the analogue tape recorder was at the heart of the professional music recording studio. Initially, the full width of the standard quarter-inch tape was used for making monophonic recordings. Stereo needed two tracks – one for each channel. Rather than doubling the tape width, a decision was made to halve the track width by incorporating two discrete heads one above the other in a single head assembly. This reduced the signal-to-noise ratio by 3 dB because of the reduced output signal from the replay head. As technology advanced, more tracks were able to be added whilst keeping the noise to an acceptable level. By also widening the tape, even more tracks could be incorporated so allowing individual instruments to be recorded on separate tracks for down-mixing at a later date. Figure 25 shows a professional 24-track analogue tape recorder using special 5-cm (2-inch) wide tape.
These complex machines are capable of reproducing high-quality sound for each track with a bandwidth equalling the average human ear and they represent the pinnacle of analogue multitrack tape recorders.
Why is it important that the plastic backing material of magnetic tape be as resistant as possible to stretching?
The effect of stretching the tape is to make it longer. This means that it takes more time for the original length of tape to pass the head, effectively slowing the tape speed. The pitch of the signal in the original recording will consequently be lowered.