<snip> The TAP dynamics plugin has an expander setting. There is also the SWH SE4. Expanders are not quite the same as gates, as they boost signals above the threshold by the ratio, rather than attenuating signals below it. They tend to be a little finicky for full noise reduction on mixes in my experience, as it's quite hard to get the settings bang on so the pumpy artifacts of the expansion are less annoying than the noise. Then you want to compress the result to get rid of the pumping and you are back where you started. :) Can work great on single instruments though, or as an effect to give things a little more punch. It's all curves anyway. You can make your own ones with the TAP dynamics somehow to get odd combinations like expander/compressor/gate. I've never actually tried doing multiband expansion for noise reduction on a mix to be honest, but if the noise is pretty steady, and limited to a certain range of frequencies then it should work.