An audio mixer is comprised of several parts, the input channel routing buses, output controls, groups and monitored and gauges. Often also incorporate other signal processing systems such as compressors or limiters noise gates.
Although they had manufactured several models of Radio Broadcasting Equipment directed only to the field of official radio support, it was only in 1947 that they launched the first special audio mixers electrical recording disc that became known as 90A models and 90B.
Each input signal enters a channel input. This usually supports generally two different entries, one for microphone and one for line level. The selection is performed by a switching system which is gain adjustment. Then usually applied one high pass filter with a cutoff frequency of 60Hz, to eliminate any noise from the mains voltage. Then usually comes equalization stage, usually structured in three frequency ranges although very variable.
At some point the channel is usually placed an insertion point, so that you can extract the signal of the same, try and reinsert. It is indistinguishable from the analog signal, which is the typical vinyl record reference.
The digital file recorded can be subjected to a subsequent compression treatment in order to reduce its size. This step, depending on the compression system used, may lead to an irreversible loss of data.
In any case, the efficiency of the algorithms implemented for the purpose is based on the psychoacoustics of the human ear to produce a minimum degradation, despite a considerable elimination of data.
The main advantage of digital music is that you can copy easily an indefinite number of times, without ever altering the starting signal. The ability to create an unlimited number of copies of a piece of music, has created obvious problems of copyright.
To avoid the creation of unauthorized copies the record producers introduced digital formats, which, using a particular encryption algorithm, automatically prevent unauthorized copying of files.
For many years, digital music, however, remained limited because of the high cost of the live radio broadcasting equipment. By the eighties, the electronics revolution allowed the birth of economic systems that can manage and process digital music.
The spread of the Compact discs (CDs) in the mid-nineties began to supplant analog recordings. At the end of the second millennium, with the advent of peer-to- peer networks, the music industry started facing a crisis that has lasted to the present day, due to the dramatic decline in sales of CDs caused by the success of these types of programs, which encouraged piracy and the illegal exchange of music through the Internet.
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