If you've ever visited a professional recording studio, you may have noticed the large amount of outboard equipment that many studios still employ. Nestling alongside a traditional mixing console, there will probably be an abundance of outboard rack units, offering a host of external processing. It’s likely that many of these will be compressors.
There was a time when compressors were only available in hardware, meaning that you would need a single compressor per track - which could feasibly add up to a large number of units.
