The Alesis NanoCompressor is basically a scaled down version of the same company's Alesis 3630. It is a real-time audio processor that can operate in mono or stereo. The NanoCompressor will work in many different applications, whether you are connecting an instrument directly into it, or connecting it with a mixing console. It can be used for processing either stereo signals or a single mono signal.
In this image the Alesis NanoCompressor is configured to specific settings in use at a campus radio station (LPFM) where it is processing sound from a computer with a high end sound board. It is operating in RMS with hard knee.
Some features of the NanoCompressor include a a side‑chain insert point, a choice of soft or hard knee operation and even a choice of peak or RMS side‑chain sensing. Attack and release times are fully controllable using rotary controls, ratio is variable from 1:1 right up to hard limiting, and threshold is also fully variable. In RMS mode, you get the benefit of program‑dependent attack and release times. You also have gain reduction and output level control.
At any time you can bypass the compressor, thereby allowing the direct signal to pass through the NanoCompressor unchanged, which is useful for comparison. The signal will not pass though the unit if it is powered off.
The connections between the NanoCompressor and your audio source should be low-capacitance shielded cables with a stranded (not solid) internal conductor and a low-resistance shield. Although quality cables cost more, they do make a difference.