1594 Chapter 45
Figure 45-1. 70 mm six-track magnetic was regarded by the film industry as the supreme audio format until the advent of
multichannel digital in the early 1990s. Shown is the format as it evolved in the late 1970s, with tracks 2 and 4 carrying
supplemental bass information.
Figure 45-2. Four-channel surround sound from optical soundtracks, first introduced in 1975, remains the standard analog
format today, although much improved by the SR process.
1 2 3 4 56B. Loudspeaker layout for 70 mm magnetic film.A. 70 mm prints provided six channels recorded on four magnetic stripes.1,2 3 4 5,6Magnetic SoundtracksSurroundScreen
Left Center RightOptional
subwooferPower
amplifiersSound
processor
Projector