The Key To A Great Audio Compressor/Limiter

I've thought this ever since I was young studying electronics and acoustics.  There have been many good compressor and limiter designs over the years.  For me, the key to a great sounding compressor/limiter is it's ability to grab the early peaks and get out, without causing any undesirable distortion.  There are three units that I have used that are capable of grabbing these early peaks VERY quickly.  The Fairchild 670, Spectra Sonics 610, Universal Audio 1176LN and the Aphex 661.

Fairchild 670 attack time: "The attack time is very fast - 50 microseconds (1/5000.of a second) and catches short transients that can, in other limiters, negate the limiting effect."

Spectra Sonics 610 attack time:  100 ns - 2 us.  (100 nanoseconds to 2 microseconds).

Universal Audio 1176LN attack time:  20 - 80 us.  (20 - 80 microseconds).

Aphex 661 attack time:  50 us - 100 milliseconds.  (50 microseconds to 100 milliseconds).