What are VCA compressors?


VCA (stands for voltage controlled amplifier) compressors are perhaps compressors with the fastest response of the attack and release parameters. They are usually cheaper than tube or optical compressors. VCA’s also tend to have less “coloration” compared to optical or tube compressors somewhat similar to the digital vs. analog tape comparison in recording. Besides that, they are known to offer the highest possible amounts of gain reduction often followed by the best transparency. This makes their use widely applicable to general duties where transparency is the main goal.

On other hand, they exhibit distortion if pushed hard. Also, the less qualified version of the VCA compressors often remove high frequencies of the processed audio signal. One of the most popular VCA compressors, that became commercially available in early 1970`s, was now famous Dbx 160. Due to the characteristics of the sound that produces, it still has a prominent place in many professional music studios.


VCA application


VCA compressor utilize a voltage controlled amplifier in their compressor circuit. This allows for full control of attack and release parameters and smooth response to the compression itself. This makes it applicable to almost anything, from mastering tasks to taming down exaggerated transients. One of the great features of VCA chip-style designs is that it is possible to obtain a very effective compressor unit in a relatively small box. While many compressors could effectively be described as a voltage controlled amplifier circuit,

VCAs traditionally utilize IC chip-based transistors to determine the input voltage. This will control the resulting gain reduction, giving you the clean and controllable compression characteristic that VCA compressors users often look for. VCA designs also have a ‘colorful’ sound quality, but the color they produce is quite unlike that obtained from tube designs. A voltage–controlled amplifier, we might say, applies more or less gain depending on the level of a control voltage; when that control voltage is derived from the audio input signal itself, it can be used as a compressor.


SSL series


The above mentioned design was at the heart of some of the most famous solid-state mix buss compressors like SSL G series compressor. Since its first appearance as the part of 4000 series of the SSL consoles, this piece of gear became one of the most important tools that were responsible for shaping of modern recorded music. Besides its straightforward attack, release, threshold and makeup gain settings it featured auto release setting that is program independent. It was praised among mix engineers for its transparency and ability to “ glue “ the mix together. Judging by the words of many famous recording, mix and mastering engineers you almost never can go wrong by placing this unit on the any mix in order to bring things to life.


From mixing to mastering


In specific applications, you can find VCA compressors in almost all aspects of audio, from tracking to mixing to mastering. To sum everything up it would be safe to say that, of all of their analogue equivalents, solid-state voltage controlled amplifiers are providing the most precise and controllable gain manipulation. Their native accuracy broadened the possibilities compressor designers had and made VCA`s the favorite in modern designs.


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