Low Frequency Side-Chain Compression

Discussion in 'Tracking / Mixing / Editing' started by ThirdBird, Oct 4, 2009.

  1. ThirdBird

    ThirdBird Active Member

    As a newbie, I would like to start a discussion on side-chaining low frequency instrument tracks, specifically the kick drum and bass guitar (or synth).

    Can the pros comment on the

    1 - Application of

    2 - Theory behind

    .... having them be connected through some form of compression?

  2. dvdhawk

    dvdhawk Well-Known Member

    Side-chaining an EQ into your compressor is really handy with bass guitar and synth.

    1 - Application: The room I run sound in every Sunday has a wicked bad room mode in the 40Hz & 80Hz bands (an octave apart). So if my bass guitar player hits a low E (41Hz) the room starts reflecting and boosting the note like crazy. As the band moves to other notes in the chord progression the room deals with the other bass notes normally. The result is the bass sounds uneven in the scale, with a surge in volume everytime the song rolls through the key of E.

    2 - Application & Theory: By picking the 40Hz & 80Hz frequency of an EQ plugged into the side-chain or "key" jack on one of my compressors I can even out the volume of all the notes in the scale. It makes the compressor more sensitive to certain frequencies. The compressor keys in on the selected frequency(ies) and automatically reduces the volume when it senses that frequency coming in (in my case 40Hz & 80Hz). I adjust the threshold and ratio on the compressor until the E sounds comparable in volume to the other notes.

    The compressor steps on the signal, before it gets unleashed into the room.

    I hope that makes sense.
  3. ThirdBird

    ThirdBird Active Member

    Would you boost or lower the eq?

    Is there a way and reason to side-chain the bass and kick together?
  4. moonbaby

    moonbaby Mmmmmm Well-Known Member

    You BOOST the band that you want the compressor to be more sensitive to spank. Yes, if the kick and bass are locked together and the sum of their levels is too much, you can 'chain 'em. However, in recording, it is probably more common to use the key/sidechain input on a gate wth a bass, running the kick into that to open/close the bass to "synch" it with the kick...
  5. dvdhawk

    dvdhawk Well-Known Member

    In live PA use, I would EQ the kick so it wasn't dominant at the problem frequency of the room.

    For recording, I'd use EQ to notch a little dip in the bass guitar where I wanted the meat of the kick drum so the kick and bass weren't stepping on each other. Give them each their own place in the audio spectrum - if you know what I mean.

    I find side-chain much more useful in live applications to battle room anomalies.

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