Man, I am tempted here:

http://www.knifaudi…"]Knif Lumi[/]="http://www.knifaudi…"]Knif Lumi[/]

Lumi utilizes the old age electroluminescence principle. The most famous example of this compressor type is Urei LA-2A . Lumi is a superbly crafted stereo unit with excellent channel balance and tracking. The amplifier section is a single-ended transformer coupled stage capable of huge headroom and nice sonic flavour. An extra load can be switched on to produce about 4% of second harmonic distortion at +22 dBU to give more character to sterile tracks.

A limit/comp switch does exactly what it says. In the limit-position compression ratio turns softly to full limiting. In the compression mode the final ratio is 4:1 after a really wide soft knee area. It is pretty amazing how much can be done with these options only.
There is also a side chain high pass filter. The corner frequency is at about 300 Hz and the slope is first order. The characteristically fast attack time of an EL-compressor makes it sometimes necessary to control the degree to which bass frequencies affect compression.
If you are familiar with LA-2A , you know what I'm trying to tell, if not, just believe it:

This superficially simple compressor does miracles especially to vocals, guitars, bass etc. It is NOT as versatile as Vari-Mu, but the symbiosis of an EL-panel and a light dependent resistor as a gain reduction element "makes music" like no other compressor topology ever.

Technical specs

Maximum compression	26 dB
Channel balance and tracking, 0-10 dB compression
Frequency response 0/-0,5 dB	8Hz - 22kHz
Distortion @ 22dBU 100 Hz -> "clean" and "warm"	0,5% and 4%