The Compression control affects the gain to the side-chain of the compressor. Use it along with Slope to adjust the amount of compression.
Slope is similar to the compression ratio controls found on other compressors. However, on the JOEMEEK, the actual ratio varies based on program material so the term Slope is used instead. In practice, 1 is very gentle compression and 2 or 3 are typically right for voice and submixes. The higher numbers are better for instruments and extreme sounds. (At the suggestion of the original designers, the 5 setting found on the later-model JOEMEEK SC2.2 were added. Use 5 to create severe pumping effects.)
Attack sets the time that the compressor takes to act. Slower attacks are typically used when the sound of the compression needs to be less obvious.
Release sets the time during which signal returns to normal after compression. With longer release times, the compression is less noticeable.