Tech Tip:Analog FAQ: Your Questions Answered
How Should I Set Input and Output Controls For the Best Sound?
Ideally the compressor should be set for unity gain - that means what goes in equals what goes out - when it is not doing any gain reduction. Many compressors have switchable meters which enable you to monitor input and output levels. In these cases set the compressor on bypass, and adjust input to read an average of 0 VU. Then switch to monitor the output and set that for 0 VU. Now engage the compressor, set the amount of compression you want and readjust the output control to read 0 VU. If there are no metering options, you'll have to wing it: start with the controls at 12:00 and play around until it sounds right and you have sufficient output to drive your recorder or console.
What is a Good General Compression Ratio to Start With?
For general tracking compression, as one might use when recording raw tracks, I usually start with 2:1 or 3:1 unless I'm working on vocals, bass (or just going for something radical). For vocals I'd start at 6:1, direct bass at 8:1. These are only places to start and will vary according to musical style, players and the effect you're ultimately shooting for.
What Does it Mean When a Compressor is "Pumping"?
Pumping is the sound of a compressor releasing after a transient (like a drum hit) has activated it and the sounds in between transients get "sucked upwards" in the mix. This can be used as a musical effect: if you have a stereo buss compressor (see Compressors, Part 2 - Knob by Knob ) with variable release time, you can make the whole mix pump at the tempo of the song by carefully adjusting the release time to fully release just before each beat.