The encyclopedia · Software & IT · Product decision · 1978–1982
The CD standardised at 74 minutes to fit Beethoven's Ninth - a Sony demand that won.
Sony's Norio Ohga insisted the disc hold 74 minutes so the whole Ninth Symphony fit; Philips agreed, fixing the 120mm size and the format everyone adopted.
Philips · Sony
the move
In the late 1970s Philips and Sony were separately developing optical audio discs and agreed to co-operate on one spec rather than fight a format war. Every physical dimension - diameter, playing time, data rate - had to be settled.
Sony wanted a larger disc and a longer playing time for both technical and commercial reasons; its deputy president Norio Ohga, a trained opera singer, pressed for enough capacity to hold the whole of Beethoven's Ninth Symphony. That pushed the diameter to 120mm and the playing time to roughly 74 minutes.
A single open specification meant all consumer electronics firms could build compatible CD players and discs, and the format could reach the enormous classical and popular catalogue without forcing a compromise a listener would notice.
why it works
- Both companies wanted one standard, so a design choice - the 74-minute capacity - became a joint and instantly global spec.
- Capacitance sized to the Ninth meant the flagship classical recording fit without cutting, which made the format credible to serious listeners.
- The larger disc gave Sony a 120mm claim and a playing-time edge over Philips' earlier 11.5cm, 60-minute proposal.
- Once the size was fixed, every hardware maker and record label aligned on the same media, so adoption needed no winner-take-all fight.
what transfers
When you set a standard, the specification everyone accepts can be chosen to fit the one must-have use case your market already loves - so the standard sells itself.
what came after
The CD was launched in 1982 and became the dominant music format of the 1980s and 1990s, eventually displacing vinyl and cassette. The 74-minute capacity and 120mm size remain the physical basis of the compact disc, and the 'fits Beethoven's Ninth' story is the standard account of how the number was chosen.
references
spotted an error? The archive wants to know.