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The most famous compressor in the industry


Throughout the history of audio, as electronic technology has progressed, various audio compressors have been developed by electronic engineers. Initially, in radio stations, they were used to give consistency to the signal emitted by the antennas and thus reach the listeners' receivers more efficiently, since a good signal increased the audience. Later, the engineers in charge of the process of printing audio on vinyl records began to use them to give dynamic consistency to the songs, which contributed to their productions having a "radio-ready" sound and being preferred by programmers. content of the stations.


With the rise of rock and roll, compressors also began to be used during the recording process for both artistic and technical purposes. One of the most popular compressors due to its "musicality" is the optical compressor, which converts dynamic variations into light impulses captured by a photocell, on which the signal compression process depends, hence its name "optical". As a result of this design, the audio that passes through the compressor is leveled smoothly, without affecting the transients or more abrupt sections of the signal, operating more on the general dynamics to give consistency and body to the audio.


The most famous of the optical compressors is the Teletronix LA2A, which for decades has been a standard in thousands of recording studios around the world due to its pleasant sound and generous with the audio signal, especially with certain types of vocals, basses, strings and winds, although not so much with percussions. These days, almost every digital audio plugin brand has a version of the LA2A, all of which are pretty good and behave like an optical compressor should. It is important to add that, being a compressor based on vacuum tubes, the signal that passes through it suffers from the addition of harmonic distortion, generated mainly by one of the 12AX7 tubes inside. This distortion adds richness to the audio, which is highly appreciated by recording and mixing engineers.


In my opinion, not all signals benefit from using the LA2A, or at least not as the first compressor in the chain. In some cases where the audio signal is more fluctuating in its dynamics, either due to characteristics of the instrument or voice, or due to the musician's lack of experience who is unable to deliver a dynamically consistent performance, it is necessary to use a more "aggressive" compressor. " and fast that "evens out" the signal dynamics more drastically, affecting fast transients. An LA2A can then be added once the signal is controlled by the first compressor, to give you more consistent and richer audio.

The LA2A uses only two controls: gain reduction level and output level, plus a switch to adjust the compression ratio between the input signal level and the output signal level. These are 3:1 in "compression" mode and 10:1 in "limiting" mode.

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