Software versus hardware
Software DAW compressors are very capable, but hardware and third-party compressors offer the real deal
The compressors most of us use are software plugins that come with our DAWs, and they do a great job. The flexibility to be able to put as many compressors as we like, anywhere in the audio chain, at any time, is the sort of luxury the engineers who mixed most of our favourite classic tunes could only dream of.
But these simple software compressors bear no relation whatsoever to the hardware compressors that those same engineers still use in their mixing right up to the present day.
These days, it’s pretty easy to mathematically define a compressor in terms of ratio, attack and release times, and so on, and build a plugin that slavishly follows that definition. Back in the golden age of audio, though, that wasn’t the way things were done. Compressors were built with electronic components – transistors, resistors, amplifiers and valves – and these components simply couldn’t offer the infinite control and flexibility that a computer can, so designing compressors was a fine art, a constant process of balancing the technical requirements of the hardware against noise, headroom and cost.
If you listen to a simple digital compressor with a ratio of 1:1, the chances are its output will sound exactly the same as what you put in, even at a high level. A compressor such as the classic Fairchild 670, however, uses no fewer than 20 valves. This means that even when it isn’t compressing things, its output may well cause all kinds of lovely colouration and sonic changes that have nothing to do with compression.
It’s ‘extras’ such as these that explain why bigname engineers love the sound of their expensive racks of analogue hardware.
However, an increasing number of software emulations from the likes of UA, Waves, Softube and many more will offer great emulations of this hardware and are a great route into the world of ‘proper’ compression, without the extortionate price tags of that classic gear.