One of our readers pointed out this good article on compression and limiting and the different kinds of circuits used to power them.
“VCA Voltage Controlled Amplifier compressors are the most versatile of all and so are the greatest in number. The VCA can quickly change gain in response to many different detectors looking at the same signal. VCA compressors are for the really tough cases where you want strict control over level and dynamics. However, they can be as gentle as any other compressor or anywhere in between. I like a good VCA compressor on vocals, drums, guitars, synths, bass, mix–basically anytime I need a compressor.”
Our Phat Beam Bass Dynamics Processor, is really more than compressor and limiter (product page).
And Cyrus (the author of that review) has his FAQ here