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Reel-to-reel |
Reel-to-reel, open reel tape recording is 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 supply reel or 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 tape 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.
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The reel-to-reel format was used in the very earliest tape recorders, including the pioneering German Magnetophons of the 1930s. Originally, this format had no name, since all forms of magnetic tape recorders used it. The name arose only with the need to distinguish it from the several kinds of tape cartridges or cassettes which were introduced in the early 1960s. Thus, the term "reel-to-reel" is an example of a retronym.
Reel-to-reel tape was also used in early tape drives for data storage on mainframe computers, video tape machines, and later for high quality analog and digital audio recorders in the 1980s and 1990s, before hard disk recording effectively eliminated the need for reel-to-reel technology.
Stellavox, Nagra, Denon and Otari are currently making analog reel to reel recorders.
The format was commercially developed in the late 1940s by American audio engineer Jack Mullin with assistance from Bing Crosby. Mullin had been a member of the U.S. Army Signal Corps during World War II. His unit was assigned to investigate German radio and electronics activities and in the course of his duties he acquired two Magnetophon recorders and fifty reels of I.G. Farben recording tape from a German radio station at Bad Nauheim, near Frankfurt. He had these shipped home and over the next two years he worked to develop the machines for commercial use, hoping to interest the Hollywood film studios in using magnetic tape for movie soundtrack recording.
Mullin gave a demonstration of his recorders at MGM Studios in Hollywood in 1947, which led to a meeting with Bing Crosby. Crosby immediately saw the potential of Mullin's recorders to pre-record his radio shows; he invested $50,000 in a local electronics company, Ampex, to enable Mullin to develop a commercial production model of the tape recorder. Using Mullin's tape recorders and with Mullin as his chief engineer, Crosby became the first American performer to master commercial recordings on tape and the first to regularly pre-record his radio programs on tape. Ampex and Mullin subsequently developed commercial stereo and multitrack audio recorders, based on the system invented by musician Les Paul, who had been given one of the first Ampex Model 200 tape decks by Crosby in 1948. Ampex went on to develop the first practical videotape recorders in the early 1950s to pre-record Crosby's TV shows.
Inexpensive reel-to-reel tape recorders were widely used for voice recording in the home and in schools before the Philips "compact cassette", introduced in 1963, took over. Cassettes quickly displaced reel-to-reel recorders for consumer use. However, the narrow tracks and slow recording speeds used in cassettes compromised fidelity.
Following the example set by Bing Crosby, high-speed reel-to-reel tape recorders rapidly became the main recording format used by audiophiles and professional recording studios until the late 1980s when digital audio recording techniques began to allow the use of other types of media (such as DAT cassettes and hard disks).
Even today, many artists of all genres prefer analog tape's "musical", "natural" and especially "warm" sound. Due to harmonic distortion, bass can thicken up, creating the illusion of a fuller-sounding mix. In addition, high end can be slightly compressed, which is more natural to the human ear. It is common for artists to record to digital and re-record the tracks to analog reels for this effect of "natural" sound. In addition to all of these attributes of tape, tape saturation is a unique form of distortion that many rock and blues artists find very pleasing.
Euphonic distortion and noise levels aside, high-quality analog tape currently outstrips the transparency of all but the best digital recording/playback systems: digital systems can suffer from (among other problems) clock jitter, inferior analog circuitry, inferior digital filter design, improper wordlength conversion, and/or lack of correct dithering. Dramatic improvements in the average quality of digital hardware design are narrowing the gap, though, and might soon eliminate the quality distinction altogether.
The earliest reel-to-reel systems used metal wire as a medium (see wire recording), which is robust, but suffers from a number of problems – fidelity is poor, it requires a strong current to imprint the signal onto the wire, it is inconvenient to physically cut and splice to effect an edit, and the wire can kink or even tangle. The invention of cellulose acetate plastic tape coated with iron oxide solved these problems, opening up the use of tape recorders in studios. Wire was also used as a recording medium in black box voice recorders for aviation in the 1950s.
The great advantage of tape for studios was twofold – it allowed a performance to be recorded without the 30 minute time limitation of a phonograph disc, 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, or sometimes glue. This is called a splice. The splicing tape has to be very thin to avoid impeding the tape's motion, and the adhesive is carefully formulated to avoid leaving a sticky residue on the tape or deck. 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. A side effect of cutting the tape at an angle is that on stereo tapes the edit occurs on one channel a split-second before the other.
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 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 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 eight, then sixteen, twenty-four, 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. [The first prerecorded Reel To Reel Tapes were introduced by RCA Victor Record Co. in 1954.] 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. Reel-to-reel tape editing also gained cult-status when many used this technique on hit-singles in the 1980s.
When Ampex broke apart in the 1990s, Quantegy Inc. was formed, later becoming Quantegy Recording Solutions in 2004. Quantegy (and formerly Ampex) led the field in reel-to-reel technology, and Quantegy was the only company left making reel-to-reel tape in the world for a period of two years. In 2006 Recorded Media Group International RMGI in the Netherlands, began manufacturing EMTEC specification tape in Oosterhout and is now the largest open reel tape manufacturer in the world.
ATR Magnetics of York, PA, longtime service and modification shop for multitrack and master recorders, began manufacturing analog multitrack tape, and in November 2006 began beta testing a new formula.
In general, the faster the speed the better the sound quality. In addition to faithfully recording higher frequencies and increasing the magnetic signal strength and therefore the signal to noise ratio, higher tape speeds spread the signal longitudinally over more tape area, reducing the effects of defects in or damage to the medium. Slower speeds conserve tape and are useful in applications where sound quality is not critical.
Speed units of inches per second or in/s are also abbreviated IPS. 3¾ in/s and 7½ in/s are the speeds that were used for (the vast majority of) consumer market releases of commercial recordings on reel-to-reel tape. 3¾ in/s is also the speed used in 8-Track cartridges.)
Tape speeds relate to quality in a way that could be compared to today's MP3, where the sampling rate may be 44.1, but the bit rate is 32, 64, 128, etc. Even though a recording on tape may have been made with studio quality, tape speed was the limiting factor, much like bit rate is today. However, with decreasing MP3 bit rate, an increasing amount of information is selectively thrown away by the MP3 coder, causing more and more audible mechanical-sounding compression artifacts. In contrast, decreasing the speed of analog audio tape causes a uniform decrease in high-frequency presence, increased background noise (hiss), more noticeable dropouts where there are flaws in the magnetic tape, and shifting of the (Gaussian) background noise spectrum toward lower frequencies (where it sounds more "granular",) regardless of the audio content. An MP3 of a noisy rock band at a low bit rate will have many more artifacts than a simple flute solo at the same bitrate, whereas either on low-speed tape will have the same uniform background noise profile and the same limited frequency spectrum (rolled-off high end) but no dynamic distortion patterns.
A recording on magnetic audio tape is linear; unlike today's digital audio, not only was jumping from spot to spot to edit time consuming, editing was destructive -- unless the recording was duplicated before edit, normally taking the same amount of time to copy, in order to preserve 75-90 percentcitation needed of the quality of the original. Editing was done either with a razor blade--by physically cutting and splicing the tape, in a manner similar to motion picture film editing--or electronically by dubbing segments onto an edit tape. The former method preserved the full quality of the recording but not the intact original; the latter incurred the same quality loss involved in dubbing a complete copy of the source tape, but preserved the original.
Tape speed is not the only factor affecting the quality of the recording. Other factors affecting quality include track width, tape formulation, and backing material and thickness. The design and quality of the recorder are also important factors, in many ways that are not applicable to digital recording systems (of any kind.) The machine's speed stability (wow and flutter), head gap size, head quality, and general head design and technology, and the machine's alignment (mostly a maintenance issue, but also a matter of design--how well and precisely it can be aligned) electro-mechanically affect the quality of the recording. The regulation of tape tension affects contact between the tape and the heads and has a very significant impact on the recording and reproduction of high frequencies. The track width of the machine, which is a question of format rather than individual machine design, is one of two major machine factors controlling signal to noise (S/N) ratio (assuming the electronics have high enough S/N not to be a factor), the other being tape speed. S/N ratio varies directly with track width, due to the Gaussian nature of tape noise; doubling the track width doubles the S/N ratio (hence, with good electronics and comparable heads, 8-Track cartridges should have half the signal-to-noise of quarter-track 1/4" tape at the same speed, 3-3/4 IPS.) Tape formulation affects the retention of the magnetic signal, especially high frequencies, the frequency linearity of the tape, the S/N ratio, print-through, optimum AC bias level (which must be set by a technician aligning the machine to match the tape type used, or more crudely set with a switch to approximate the optimum setting.) Tape formulation varies between different tape types (Ferric Oxide [FeO], Chromium Dioxide [CrO2], etc.) and also in the precise composition of a specific brand and batch of tape. (Studios theerfore generally align their machines for one brand and model number of tape and use only that brand and model.) Backing material type and thickness affect the tensile strength and elasticity of the tape, which affect wow and flutter and tape stretch; stretched tape will have a pitch error, possibly fluctuating. Backing thickness also effects print-through, the phenomenon of adjacent layers of tape wound on a reel picking up weak copies of the magnetic signal from each other. Print-through causes unintended pre- and post-echoes on playback, and is generally not fully reversible once it has occurred. The print through effect is another, not well-known limitation of analog tape recording, whether in open-reel or cassette/cartridge formats.
As studio audio production progressed and became more and more advanced, it became desirable to record the separate instruments and human voices separately and mix them down to one, two, or more speaker channels later, rather than in real time in the studio before recording. Thus multi-track recording was born. In addition to allowing recording engineers and producers to experiment with different mixing arrangements, effects, etc. on the same performance and to produce multiple versions of a recording (without having multiple duplicates of all the studio control room equipment used for mixing), multi-tracking enables the use of non-real-time effects or effects that cannot be produced in the same studio where the musicians perform. Reel-to-reel recorders with eight, sixteen, twenty four, and even thirty two tracks were eventually built, with as many heads recording synchronized parallel linear tracks. Some of these machines were larger than a laundry washing machine and used tape as wide as 2 inches. A single new reel of 1" or wider tape, blank, could easily cost over $100, even $200 or more. Still, in professional studios, most tapes were recorded only once, and all recording was on new tape, to ensure the maximum quality, as studio time and the time of skilled musicians was much higher than the cost of tape, making it not worth the risk of a recording being lost or degraded due to using media that had been previously recorded.
As professional audio evolved from analog magnetic tape to digital media, engineers adapted magnetic tape technology to digital recording, producing digital reel-to-reel magnetic tape machines. Before large hard disks became economical enough to make hard disk recorders viable, and before recordable CD technology was introduced, studio digital recording meant recording on digital tape. One extremely elite brand in this field was the Nagra brand, whose digital reel-to-reel tape recorders are to more mainstream professional tape recorders as Ferrari sports cars are to major market automobiles (e.g. Toyota, Ford, Cadillac) --with similarly analogous prices. Nagra built analog reel-to-reel audio tape equipment before becoming a pioneer in digital reel-to-reel tape recording. Digital reel-to-reel tape eliminated all the traditional quality limitations of analog tape, including background noise (hiss), high frequency roll-off, wow and flutter, pitch error, nonlinearity, print-through, and degeneration with copying, but the tape media was even more expensive than professional analog open reel tape, and the linear nature of tape still placed restrictions on access, and winding time to find a particular spot was still a significant drawback. Also, while the quality of digital tape did not progressively degrade with use of the tape, the physical sliding of the tape over the heads and guides meant that the tape still did wear, and eventually that wear would lead to digital errors and permanent loss of quality if the tape was not copied before reaching that point. Still, digital reel-to-reel tape was a giant leap in audio recording technology, and most who could afford to record using digital tape generally did.
Early reel-to-reel users realized that segments of tape could be spliced together and otherwise manipulated by adjusting playback speed or direction of a given recording. In the same way as modern keyboards allow sampling and playback at different speeds, a reel-to-reel could accomplish similar feats in the hands of a talented user. Consider:
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