Warm Audio WA-2A Mode D'emploi page 10

THEORY OF OPERATION
The WA-2A, as with any classic optical compressor, appears deceptively simple at first, with so
few controls on the front panel. The attack, release, knee, and ratio controls found on many oth-
er types of 'fully comprehensive' compressors are absent; leaving the user only with a control for compression
threshold (Peak Reduction), makeup gain (Output Gain), and a selection of compress or lim-
it, which changes the ratio from a starting position of about 4:1 to something closer to 100:1. The WA-2A's
attack and release characteristics, as well as its ratio and knee, are determined by a very complex
relationship between the optical attenuator and the audio signal being fed into it. Generally, the WA-2A's attack will be
very fast, with its release character being a rather complex, multi-stage event that, to an extent, is determined by the audio
input and the immediate history of the audio passed through the module (known as its 'memory effect'). Generally, the initial
release will be very fast, with a second, more subtle stage of release taking one or more seconds, and a tiny third stage of
release taking even longer. Due to its extended and smooth time constant, this type of compressor became famous for taming
bass guitar, upright bass, and vocals; however, it has the attack speed and transparency to actually handle many other types
of instruments. As with all things audio, let your ear determine what the music needs and how much compression is enough
to achieve your desired goals. Due to the amount of compression that can achieved; this type of compressor is often a first
choice for instruments that require a fairly strong amount of gain reduction, such as bass; and also often a first choice for more
advanced studio techniques such as series and parallel compression.
Series compression is simply following one compressor/limiter with another one; they do not have
to be the same make or model, but they can be. This is done sometimes when one compressor is
doing much of the heavy lifting of dynamic control, while a second compressor is added be-
cause the engineer favors its particular tonal qualities or 'glue'. In the case of classic optical compres-
sors, some engineers have been known to set one unit to a heavier amount of Peak Reduction in Compress
mode, and follow it by a second unit with a much more modest amount of Peak Reduction, set to Li
it mode. This is done to level off any residual transient peaks not caught by the first unit.
Parallel Compression involves using two compressors side by side working on the same input
signal. They do not have to be the same make or model compressor; but they can be. The
advent of digital audio workstation (DAW) recording actually lends itself quite well to this technique. It
is now very easy to duplicate a track in the DAW and send each copy out to individual hardware channels
simultaneously, with no real signal loss. As with series compression, one unit will generally be set much more
aggressively than the other, and the two compressed tracks can be blended back together in the DAW
to achieve a desired effect. When performed properly, one can give a source both the intensity and
presence of a hyper-compressed track, while still retaining the openness, apparent dynamics, and
detail of an uncompressed track. The WA-2A is an ideal choice for this type of compression, due to
the very high levels of gain reduction it can achieve.
9