So Many Tape Speeds
Sound is reproduced as a tape runs across a playback head. The magnetic signals imprinted on the tape create a flow of electricity in the head. That tiny signal is amplified and turned into sound. In general, the faster the speed, the better the reproduction quality. Slower tape speeds conserve tape and are useful in applications where sound quality is not critical.
These are the standard tape speeds and their common uses:
15/16ths of an inch per second – Half-speed for an audio cassette, and has been used for dictation. Radio stations have used this speed in reel-to-reel machines to make back-up logs of the day’s programming.
1⅞ in/s – Standard speed of an audio cassette. It also has been used for long-duration reel-to-reel speech recordings.
3¾ in/s – Common speed for home-use reel-to-reels, reasonable quality for speech and off-air radio recordings.
7½ in/s – The highest home-use reel-to-reel speed, and the slowest professional speed, often used by radio stations for copies of commercial announcements and for “air checks” to document and demonstrate the work of air staff.
15 in/s – For professional music recording and radio programming.
30 in/s – Used only when the best possible treble response and lowest noise-floor are demanded.