Chameleon Labs 7720: VCA stereo compressor

Chameleon Labs 7720 is a VCA (Voltage Controlled Amplifier) compressor, designed to be used on the mixbuss or in the audio mastering stage.

This compressor is inspired by the famous SSL G Series compressor, with some extra useful features, like an additional ratio setting (1,5:1) and an internal HPF filter for the sidechain. This is a "true stereo" compressor, so it compress both channels with a unique set of controls, a very useful feature to work on stereo material.
From left to right, we have:

• The power and bypass switches
• The VU meter with the relative switch to chose what to check (input level, output level, gain reduction). When is set to "Comp", in the mastering stage, the meter will just barely move, because even small movements will represent relevant gain reductions
• The switch to activate the external side-chain (it is possible to connect, on the rear panel, an equalizer, to equalize the signal in the side-chain circuitry)
• The rotary switch to set the HPF for the internal side-chain (OFF, 60, 90, 130, 200, 440 Hz). Using an HPF filter in the side-chain helps to reduce the "pumping" effect caused by the low frequencies transients
• The continuous pot to set the threshold
• The rotary switch to set the attack time (0,1 ms; 0,3 ms; 1 ms; 3 ms; 10 ms; 30 ms)
• The rotary switch to set the release time (100 ms; 300 ms; 600 ms; 1200 ms; Auto)
• The rotary switch to set the compression ratio (1:5, 2:0, 4:0, 10:0)
• The continuous pot to increase the output level and compensate the level reduction caused by the compression (when set completely on the left, there is no gain boost)

As usual with VCA compressors, the Chameleon Labs 7720 is characterized by quite fast attack and release times. However, the "Auto" release feature is very interesting because it allows to use a fast release time when the gain reduction is high (during transients), and a slow release time when the gain reduction is low (during "flat" sounds). This setting is very useful  for obtaining a natural and transparent compression.
Another interesting feature is the HPF filter of the side-chain, which makes this compressor really versatile. In fact, it is possible to disable the filter, for obtaining a certain pumping effect, or to set it to 200 or 440 Hz, to minimize the same effect (along with a a slow attack time, like 30 ms).
The positive technical aspects of this compressor are clear,  while on the dark side I have to mention the noise level which is a little high (-80 dBu), but acceptable.
When used in the mastering stage, this compressor is very useful because of its versatility and easy-to-use. Just to make some examples, it is possible to use the following settings:

• For a dense sound with a slight pumping effect, useful in EDM or techno genres, it is possible to set the attack to 30 ms, release to 100 ms, ratio to 2:1 or 4:1, HPF off
• For a natural compression of the macro dynamics, while maintaining the transients impact, it is possible to set the attack to 30 ms, release to "Auto", ratio to 2:1 and HPF to 130 Hz
• To compress the transients on mid and high frequencies, without reducing the impact of the low frequencies, it is possible to set the attack to 1 ms, release to 100 ms, ratio to 2:1 and HPF to 200 or 440 Hz

These are only some examples: the versatility of this processor makes it useful for multiple purposes.
This compressor is very transparent too, because there is no significant difference between the non-compressed, non-bypassed sound and the bypassed sound. The compressed sound is characterized by a certain "punch" (a common characteristic among VCA compressors), which becomes more accentuated with long attack times and short release times.
In summary, this is a great compressor, easy to use and very versatile. I suggest it for the mastering studio that wants to achieve multiple solutions for analog compression, without evident sound coloration.