Reel-to-reel or open reel tape recording refers to the form of magnetic tape audio recording in which the recording medium is held on a reel, rather than being securely contained within a cassette. In use, the "feed reel" containing the tape is mounted on a spindle; the end of the tape is manually pulled out of the reel, threaded through mechanical guides and a recording head assembly, and attached by friction to the hub of a second, initially empty "takeup reel." The arrangement is similar to that used for motion picture film.
Originally, this format had no name, since all forms of magnetic tape recorder used it. The name arose only with the need to distinguish it from the several kinds of tape cartridge or cassette which were introduced in the early 1960s. Thus, the term "reel-to-reel" is an example of a retronym.
Inexpensive reel-to-reel tape recorders were widely used for voice recording in the home and in schools before the advent of the Philips "compact cassette" in 1963. Cassettes quickly displaced reel-to-reel recorders for consumer use. However, the narrow tracks and slow recording speeds used in cassettes compromised fidelity. Reel-to-reel recorders continued to be used by audiophiles and professionals through the 1980s, when digital audio recording techniques began to allow the use of other types of media (such as DAT cassettes and hard disks).
The earliest reel-to-reel systems used metal wire as a medium, which is robust, but suffers from a number of problems - it takes up a lot of room on the spools, so recording time is limited; it requires a strong current to imprint the signal onto the wire; it is hard to physically cut and splice to effect an edit; the wire was easily kinked, causing dropouts. The invention of a plastic tape coated in a ferromagnetic material (initially iron oxide) solved these problems, opening up the use of tape recorders in studios. Wire is still used as a medium in black box aviation recorders, since the recorded information is more robust, and can even withstand fire to some extent.
The great advantage of tape for studios was twofold - it allowed a performance to be recorded in a more manageable form than cutting a disc directly, and it permitted a recorded performance to be edited. For the first time, audio could be manipulated as a physical entity. Tape editing is performed simply by cutting the tape at the required point, and rejoining it to another section of tape using adhesive tape. This is called a splice. Usually, the cut is made at an angle across the tape so that any 'click" or other noise introduced by the cut is spread across a few milliseconds of the recording. The use of reels to supply and collect the tape also made it very easy for editors to manually move the tape back and forth across the heads to find the exact point they wished to edit. Tape to be spliced was clamped in a special splicing block attached to the deck near the heads to hold the tape accurately while the edit was made. A skilled editor could make these edits very rapidly and accurately.
The performance of tape recording is greatly affected by the width of the tracks used to record a signal, and the speed of the tape. The wider and faster the better, but of course this uses up more tape. These factors lead directly to improved frequency response, signal-to-noise ratio, and high frequency distortion figures. Tape can accommodate multiple parallel tracks, allowing not just stereo recordings, but multi-track recordings too. This gives the producer of the final edit much greater flexibility - allowing a performance to be remixed in any desired fashion long after the performance was originally recorded. This innovation was a great driving force behind the explosion of popular music in the late 1950s and 1960s. The first multi-tracking recorders had four tracks, then 8, then 16, 24 and so on. It was also discovered that new effects were possible using multi-tracking recorders, such as phasing and flanging, delays and echo, so these innovations appeared on pop recordings shortly after multi-tracking recorders were introduced.
For home use, simpler reel-to-reel recorders were available, and a number of track formats and tape speeds were standardised to permit interoperability and prerecorded music. Reel to reel was still popular through to the end of the 1970s, despite the ubiquitous cassette, mostly because of the superior quality of open reel recordings. Audiophiles are willing to accept the relative fiddliness of open reel tape to gain better quality reproduction.