Reply To: Feedforward Optical Compressor

[Ted Fletcher]

Hmmm, this is an interesting question……

I have an intellectual problem with feedforward dynamic control; to me it is unnatural…. which may sound odd, I will explain: We all have a very effective inbuilt compressor in our heads. It reacts in numerous ways, simply, in conversation our ears are very sensitive and we can discern low sound levels. At the other end of the scale, when music gets too loud our ears almost ‘shut down’. Between those extremes there are infinite variations of sensitivity, some physical in the way the cilia react in the inner ear, and many more psychoacoustic, alterations in perception in the brain. Compressors and limiters in the studio are used to alter perception of volumes changing with time and as our ‘inbuilt compressor’ is most certainly a feedback type; the perception is altering as a result of stimulus, then the ‘natural’ way is to mimic that in electronics.

Of course, technically, there would seem to be enormous advantages with feedforward, but does it sound right? My own experiments some years ago told me that feedforward was fine for protecting the hardware when disk cutting, but is a technique that should stay in the cutting room (or transmitter room!)

This argument is quite similar to my argument for optical compression where the shape of the variation of gain during both attack and release should mimic what happens in our own brains…. but that’s an even more complicated story.