Computer Recording
Contents |
Introduction
Computer recording is a standard today among both studios and home users, even though there is some state-of-the-art studios that still uses analog tapes. The evolution has been developing very fast since it first was introduced round the 70/80's. In this article I will cover some of the history and the basic concepts and terms of digital recording.
History
The art of digital recording was pioneered by Tom Stockham at MIT as early as 1961, when he was making the first digital tape recordings with the assistance of a large TX-0 computer and a A/D-D/A converter from Bernie Gordon at EPSCO. He later founded the company Soundstream that recorded the first 16-bit digital recording in 1976 at the Santa Fe Opera. However, digital technology was present even before in instruments like the Hammond organ and the Mellotron and in some effect-processors.
In 1975 Sydney Alonso/Jon Appleton/Cameron Jones developed the Synclavier digital synthesizer at Dartmouth College. They formed the New England Digital Corporation the next year (later became Demas) and sold their product mostly to the recording industry. In 1979 was the Fairlight synthesizer introduced, which actually was a workstation capable of making full recordings stored on floppy-disks.
The beginning of the digital era came when Philips/Sony made a collaboration about the standards of the compact disc in 1980-81, even though there was some attempts to make a standard before. (Betamax,Pioneer Laserdisc,PCM) The specifications were 16-bit encoding and a sampling frequency of 44,100 per second, which still is the specification of a compact disc. (CD) The first truly digital recordings were made in 1982 by Tom Jung at the jazz-label DMP, who recorded directly down to to disc.
In 1981 was the first "white papers" of the MIDI-specification released by Dave Smith and Chet Wood from Sequential Circuits (Prophet-5) at the AES fair. This was truly revolutionary and two years later, in 1983, the first synthesizers from Roland, Yamaha (DX7) and Sequential Circuits implementing the MIDI protocol. (see terminology)
The use of MIDI in home/smaller studios wasn't established until 1986 when Steinberg made their first release of Cubase for the ATARI-platform, even though there was some programs even earlier at the AMIGA-platform. LOGIC was released about the same time, and for years a battle raged between the two opponents. However, large studios was using Macintosh computers and Pro Tools already back then.
The DAT-format (Digital Audio Tape) introduced in 1986, was setting a new standard in digital mastering, but it took several years until the prices of consumer machines dropped to reasonable levels.
The next landmark came in 1991 when ALESIS released their first multitrack for digital recording based on Video tapes. 3M has made multitracks for digital recording since the beginning of the 80's, but due to it's price, there was only studios like Abbey Road, Polar Studios and others that really could afford the digital technique. The 8-channel A-DAT was a technical revolution and allowed up to 16 machines to be used in conjunction. Originally priced at 4000$, it made it possible for smaller studios to adopt the digital technique.
In 1998 there was an agreement upon the DVD-Audio Format 1.0 specifications. The capacity would be the same 4.7/8.5/9.4/17 GB as DVD-Video, but the sampling rate of 88.2 kHz and 176.4 kHz will be higher for a frequency response of 0-96 kHz rather than 0-48 kHz for DVD-Video at 44.1 kHz and 5-20 kHz for the audio CD. The Maximum Transfer Rate for Audio will be 9.6 Mbps rather than 6.1 Mbps for DVD-Video or 1.4 Mbps for audio CD.
Hard disk recording system were introduced in the beginning of the 90's when Fairlight ESP Pty Ltd developed the MFX2, the first 24 track disk recorder. It was followed in 1993 by the RADAR system which was a replacement for OTARI's analog 24-track systems. The prizes on hard-disks as well as the storage volume has continued to drop since then, and is by the time this is written not really an issue anymore.
Digital Technique
AD/DA Converters
In order to make a digital recording, the first point to mention is the converters for converting an analog sound to a digital. These are called AD/DA converters. (see terminology) In the recording process, the DA-converters are used most for actually getting the sound out to the monitors. The AD-converters is more critical since the more precise a converter is, the more will it cost. AD/DA-converts exists in all soundcards to computers, and is one of the most important issues when doing a good digital recording.
About sampling of the analog signal
In order for an AD-converter to sample an analog signal, some basic theory applies. Due to the Nyquist–Shannon sampling theorem, a perfect reconstruction of a signal is possible when the sampling frequency is greater than twice the maximum frequency of the signal being sampled. Eg. if a tone of 440 Hz is going to be sampled, the frequency of the sampler must be at least 880 Hz. Hz stand for Hertz, and is the frequency of samples taken/second or the movement of air of a note/second. Based on these theories its pretty simple to understand that the greater sampling frequency - the greater will the reproduction of the analog signal be.
Smaller title
Terminology
AD/DA -converters
AD stands for Analog-Digital and DA stands for Digital-Analog.
DAT
MIDI
MIDI stands for Musical Instrument Digital Interface, which is a technology that describes a user's interaction with a (digital) instrument, rather than performs any actual computer processing.
PCM
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See also
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