The Bus Compressor provided with Duende is based on the classic SSL Bus Comp found in many of our analogue and digital consoles.
The design is such that when the ratio is set to 2:1 the compressor has an extremely soft knee response. This means that gain reduction is present even with a peak signal of -20db going in.
For experienced SSL users this is considered normal, and contributes to the magical quality afforded by the bus comp. To those new to SSL this may seem slightly odd!
To put the compressor in a more 'normal' behaviour where if the threshold is +20db there is no gain reduction, use the 4:1 or 20:1 ratio setting.
If you feel the need to compress your mix with the 2:1 ratio but find there is too much gain reduction happening, simply place a gain plugin before the bus comp and then gain back up afterwards.
Why does the Bus Compressor reduce gain when the threshold is fully up?
Why does the Bus Compressor reduce gain when the threshold is fully up?