|
Since the widespread adoption of reel-to-reel audio tape recording in the 1950s, audio tapes and tape cassettes have been available in many formats. This article describes the length, tape thickness and playing times of some of the most common ones. All tape thicknesses here refer to the total tape thickness unless otherwise specified, including the base, the oxide coating and any back coating. In the USA, tape thickness is often expressed as the thickness of the base alone. However, this varies from manufacturer to manufacturer and also between tape formulations from the same manufacturer. Outside of the USA, the overall thickness is more often quoted, and is the more relevant measurement when relating the thickness to the length that can be fit onto a reel or into a cassette. ==Reel-to-reel ¼"== The tape decks of the 1950s were mainly designed to use tape ¼" wide and to accept one of two reel formats: * Ten-and-a-half-inch reels, almost always with metal flanges, which fit over a hub three inches in diameter. These reels and hubs were similar to those used for wider tape formats such as ½", 1" and 2" tape widths, and were principally used for studio- and other professional applications. The reels were known as NAB reels and the hubs on which they were mounted as NAB hubs. * Reels of up to seven inches in diameter, most commonly with plastic flanges but metal was also used, which fit over a splined ¼" shaft known as a cine spindle. These reels dominated domestic applications. The most common sizes were seven, five and three inches in diameter. In each case the shaft or hub had three splines. In machines designed to allow for vertical mounting, the upper part of the shaft or hub could commonly be rotated by 60° so the upper splines locked the reel in place. Some tape decks could accommodate either format by using removable hubs for the larger reel size. When in use these hubs were locked onto the cine spindles by the same mechanism used to secure the smaller reels. Reel capacity is affected by both the reel diameter and the reel hub diameter. The standard ten and a half inch reel has approximately twice the capacity of the seven inch reel, which in turn has twice the capacity of the five inch. Some (not all) reels described as three inches are in fact three and a quarter inches in diameter, in order to have half the capacity of a five-inch reel. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Audio tape specifications」の詳細全文を読む スポンサード リンク
|