How tape decks work
In general, the faster the speed the better the sound quality, with the proviso that faster tapes also have slightly more tape hiss. Slower speeds conserve tape and are useful in applications where sound quality is not critical.
- 15/16 inch per second (ips) - used for very long-duration recordings (e.g. recording a radio station's entire output in case of complaints)
- 1 7/8 ips - usually the slowest domestic speed, best for long duration speech recordings
- 3 3/4 ips - common domestic speed, used on most single-speed domestic machines, reasonable quality for speech and off-air radio recordings
- 7 1/2 ips - highest domestic speed, also slowest professional; used by some radio stations for speech programs
- 15 ips - professional music recording and radio programming
- 30 ips - used where the best possible treble response is demanded, e.g., many classical music recording
A capstan is a rotating machine used to control or apply force to another element, usually linear. The term was first used for the capstan on a ship, which is used to control ropes that are wound around it. The rope is wound around one or more times, but is not stored on a capstan - that arrangement is usually called a winch. Ships' capstans were traditionally manually operated - consisting of a shaped wooden drum with handles inserted into the rim, at which men could push or pull. Modern capstans are powered electrically.
Capstans are also found in the mechanisms of tape recorders, where they have a similar function - they apply force to the tape causing it to be drawn off the spool, past the heads, and onto the take-up spool. Such capstans are precision-machined spindles, with a very accurate surface profile - any out-of-roundness or imperfections cause an audible effect called "flutter". The tape is held against the capstan by a rubber wheel called the pinch wheel or pinch roller.
In French the word "cassette" is abbreviated as "K7" (ka-sept); the "K7" shorthand also works in Portuguese: ca-sete. In Spanish it is known by the letters KCT (pronounced "ka-ce-te").