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Digital Audio

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By 1937, British scientist Alec Reeves invented and patented the Pulse Code Modulation (PCM). The digital revolution has also been pushed forward by the advent of cheap and powerful computational devices. We must also keep in mind the immense contribution of the military in any great leap in technology. The First World War brought in electricity and vacuum tubes. By the Second World War, solid state electronics were invented and this is the first impetus in bringing in the era of miniaturization and power. By 1950s and 1960s, computers were developed and used by the military to build the World Wide Web, which later on in the 1990s were made available to the average consumer. In 1957, Max Matthews of The Bell Laboratory demonstrated how to record sound digitally using computer. The digital recording process consists essentially of an Analogue to Digital conversion. This is achieved by chopping up the signal into small intervals at a rate at least twice the highest perceivable frequency. Each part of the sample is then coded using binary numbering system and recorded as pulses. The earlier experiments were done using tape as a storage medium but later discs replaced them. They had a higher density. In chopping up the signal at the rate of 44.1 KHz (in case of ACDs), the amplitude of each part of the waveform sampled is expressed as a binary number containing the equivalent of a combination of 16- zeroes and ones (if 16 Bit quantization is used as in ACDs) or any lower number depending upon the system. This means that the amplitude of this small part of the signal sampled can be expressed in as many as 16 to the power 16 or 65,536 increments. Such a high number of increments to describe a small part of the signal required fast recording density and speed. Therefore video tape recorders were used to record digitally converted audio signal. Discs carrying video frequencies were made to rotate up to 1800 rpm and between 150 and 400 rpm for audio programs. To record a full album digitally, we had to wait until 1976. The first ever 16 bit digital recording was made by Dr. Stockham of Soundstream using a Soundstream Recorder in the U.S. Santa Fe Opera. Sony introduced its flagship D/A converter the PCM 1 in the same year. Now digital recording was in the hands of anyone who can afford the machine and hook it up with an existing VHS VCR to convert it into a digital recorder. In 1979, the first fully digital album was released by Ry Cooder: Bop till you Drop. It was recorded using a 32 track digital multi-track recorder built by 3M. In 1980, Sony and Philips announced the arrival of Audio Compact Disc. The possibility of easy and lossless distribution of high quality digital audio content finally brought in the first waves of the digital boom. In the sphere of studio systems, during 1985, there were only three models of Digital Audio Workstations (DAW) available and only two of them were disk based systems. Audio File from AMS and Direct to Disc by NED, were the only two options the third by Denon was the DN 052 ED. But in the years immediately after this, the Digital Audio Workstations were the order of the day for any studios. 3M, Sony, Mitsubishi and Studer introduced their own versions of the DAW. By 1986, the digital consoles started coming in and RDAT was introduced in Japan, making it possible to make digital replicas of recordings easily. If CD was to replace the LP, RDAT was supposed to replace