Compression Basics

Discussion in 'Production' started by freeagent, Feb 18, 2004.

  1. freeagent

    freeagent Almost 30

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    Drum and Bass Compression Basics

    Drum and Bass Compressor Basics

    Compressor settings are always variable. A compressor is a tool that basically turns the volume of a sound down given the variables:

    1 When should the level be turned down? (attack)

    2 When should the level be turned back up? (release)

    3 At what point should the level start being altered? (theshold)

    4 How much should the level be altered per until(e.g 2:1 means for every unit of volume that pases into the compressor, it should be compressed (turned down) 2 units)? (Ratio)

    Since all sounds/songs are different in terms of levels (except for :clown: j/k), compressor settings are always different based on the sound being compressed, the compressor doing the work, and the engineer doing the compression.

    Sub compression:

    What you want to happen is to even out the levels so that the low notes and high notes sound about the same in terms of volume. So let's say your sub is generally peaking at around -10 db, but there are a few notes that are as loud as -8 db. Set the threshold to between -10 and -12 db so that everything over that level will trigger the compressor. Don't mess with the input gain unless the input signal is too hot to set a reasonable threshold for your compressor (which is hardly ever the case), and only adjust the output gain more than 1 or 2 db if you want to crunch up the sound and make it seem louder relative to the threshold. Set the compression level to 3:1 to start, use a larger ratio (4:1 or 5:1) if you want the sub to sound more compressed. Set the attack at 15 ms and release at 150 ms to start so that the beginning punch of the sub gets through before the compressor engages and the compressor stays on for the duration of the sub, then move the attack lower (meaning towards 0) until the sub has just the right punch relative to the kick drum and other sounds. Move the release until you get the whole sub within the compressor. As for auto gain and smooth saturation, I don't use these, but suffice it to say that the auto is probably an algorythm that tries to move the output gain and compressor release based on each individual sound that goes into the compressor so that a more uniform overall level is acheived, and the smooth sat. probably prevents clipping.

    Break/Drum Compression:

    There are a billion and one methods to drum/break compression. Compressing individual hits, compressing entire breaks, compressing snares/hats/kicks/toms, etc. are all different matters. For simplicities' sake, let's focus on compressing a break (such as the Amen or Hot Pants). Let's say the break has a peak level of -1 db on the snare and -6 db on the kick. Set your theshold to -3 db - this should compress the part of the snare that is far louder than the kick, while still making it stand out. Set the attack to about 5 ms (quick) and release to about 50 ms (quick as well) so that overall levels won't be altered too much. Set the ratio to around 3:1 and alter along with attack and release until the break sounds uniform in level and nothing sticks out too much or not enough. Using output gain on a break is a good way to give it some crunch and loudness relative to the threshold you have set. Try 1 or 2 db and see how this effects the break.

    Whole track:

    It's important to use the best quality compressor that you have for this job, as low quality compressors aren't fast enough or add undesired artifacts. As a rule of thumb, you want to err on the side of under compression, as over compressing will really ruin your tune, robbing it of dynamics. Let's say the peak level of your tune is around -1 db, with the average peak around -7 db (If your track is any louder pre-master, use the input gain to take it down a notch to give you some headroom). Most likely, a snare or kick is creating those transient peaks that hit -1 db. Set your threshold at around -3 db, your attack at 20 ms, release at 150 ms, and ratio at 2:1. Adjust the threshold until you are happy with the resultant sound (the highest volume points don't sound muffled) and then adjust the attack and release so that the hard attack sounds like the bass and snare cut through right before or when the compressor turns on and the sustained sounds like bass and pads aren't too compressed. It really is about prudence here, so monitor against the original sound, and if you notice a big difference, back off the compressor settings a bit (especially threshold and attack). You can always compress it more later, or, if it gets put out, it will be compressed and finalized on much better equipment by a full-time engineer.
     
  2. Affliction

    Affliction thought size didnt matter

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    Re: Drum and Bass Compression Basics

    agree with everything apart from this:



    automatic output gain is calculated by the threshold and the ratio.... for example a threshold of -10 and a ratio of 2:1... would result in an automatic output gain of +5 db's.

    i dont know how to write out the equation in a proper mathematical way but it should look something like this:

    OUTPUT GAIN = ABS(Threshold) / RATIO

    Most "Pro" engineers do this calculation in their heads when compressing anyway, so the automatic feature was just a convenience thing....


    good post though :D