compressor side chain; i don;t quite get it
- Thread starter guhlenn
- Start date
Some compressors implement side-chaining. This feature uses the dynamic level of another input to control the compression level of the signal. This is used by disc jockeys to lower the music volume automatically when speaking, for example (known as ducking). A frequency-specific compressor (often known as a de-esser) may be constructed by feeding a high-pass filtered copy of the original signal into the side-chain input of the compressor so that volume reduction on the original signal only takes place when a specific frequency is present in large amounts (such as sibilant sounds that tend to overdrive preemphasized media such as phonograph records and FM radio). Another use of the side-chain in music production serves to maintain a loud bass track, while still keeping the bass out of the way of the bass drum when the drum hits.
By patching audio processors of different kinds into a compressor's side-chain, all sorts of cool things are possible. One of the most useful is creating a de-esser - a device used to remove sibilance from vocals. Sibilance is a nasty "Shh" sound that occurs when "S" words are spoken or sung, caused by an air blast between the teeth and tongue and burst of white noise. If the speaker or vocalist is close to the microphone, this is picked up as a brief overload and burst of high frequencies. By placing an equalizer set to boost high frequencies in the compressor side-chain the Stereo Compressor will drastically compress the signal when the high frequencies are present, but act normally when they are not. Sibilance can't be eliminated, but it can be minimized with a de-essing.
A similar problem, although at the other end of the audio spectrum, relates to plosive sounds such as "P" and "B" and the "thump" sounds they can produce. These can be minimized by boosting the offending bass frequencies (less than 300 Hz) via the side-chaln.
Another abuse of a compressor is to totally squash an lndividual instrument signal, then restore its level. This is done with vocals, snare drums, kick drums, etc. U2 does this on a lot of their recordings. By squashing instruments that have a percussive quality (such as drums or slap bass) the amount of percussive attacks is increased. This occurs because the circuitry does not respond instantly. The initial attack transient portion of the signal gets through unaffected while the remainder of the signal is compressed normally. The end result is overall increase in the percussive quality of the processed sound.
The Stereo Compressor can also be used as a ducker, a device that reduces one slgnal’s level based on a different signal. This effect gets used a lot on radio commercials. In this case, a different audio signal, such as an announcer’s voice, is fed into the side-chain. When the announcer speaks, the output of the compressor is reduced. This is useful for keeplng background music at maximum volume, but letting the announcer’s voice cut through the background by reducing the music level when the announcer speaks. Listen closely to any radio commercial and you will notice this effect. Duckers are also great for DJs or a presentation with background music.
Ducking is also used in the studio to allow one instrument to cut through on a mix. If you want a particular instrument to be more noticeable, such as a snare drum, send the snare signal into the slde-chain and have the rest of the mix feeding the compressor normally. Whenever the snare drum plays, it will reduce the level of the main mix, increasing the presence of the snare drum without increasing its level. Just by addlng a few jacks, we have increased the power of an already useful tool.
GooGled,
By patching audio processors of different kinds into a compressor's side-chain, all sorts of cool things are possible. One of the most useful is creating a de-esser - a device used to remove sibilance from vocals. Sibilance is a nasty "Shh" sound that occurs when "S" words are spoken or sung, caused by an air blast between the teeth and tongue and burst of white noise. If the speaker or vocalist is close to the microphone, this is picked up as a brief overload and burst of high frequencies. By placing an equalizer set to boost high frequencies in the compressor side-chain the Stereo Compressor will drastically compress the signal when the high frequencies are present, but act normally when they are not. Sibilance can't be eliminated, but it can be minimized with a de-essing.
A similar problem, although at the other end of the audio spectrum, relates to plosive sounds such as "P" and "B" and the "thump" sounds they can produce. These can be minimized by boosting the offending bass frequencies (less than 300 Hz) via the side-chaln.
Another abuse of a compressor is to totally squash an lndividual instrument signal, then restore its level. This is done with vocals, snare drums, kick drums, etc. U2 does this on a lot of their recordings. By squashing instruments that have a percussive quality (such as drums or slap bass) the amount of percussive attacks is increased. This occurs because the circuitry does not respond instantly. The initial attack transient portion of the signal gets through unaffected while the remainder of the signal is compressed normally. The end result is overall increase in the percussive quality of the processed sound.
The Stereo Compressor can also be used as a ducker, a device that reduces one slgnal’s level based on a different signal. This effect gets used a lot on radio commercials. In this case, a different audio signal, such as an announcer’s voice, is fed into the side-chain. When the announcer speaks, the output of the compressor is reduced. This is useful for keeplng background music at maximum volume, but letting the announcer’s voice cut through the background by reducing the music level when the announcer speaks. Listen closely to any radio commercial and you will notice this effect. Duckers are also great for DJs or a presentation with background music.
Ducking is also used in the studio to allow one instrument to cut through on a mix. If you want a particular instrument to be more noticeable, such as a snare drum, send the snare signal into the slde-chain and have the rest of the mix feeding the compressor normally. Whenever the snare drum plays, it will reduce the level of the main mix, increasing the presence of the snare drum without increasing its level. Just by addlng a few jacks, we have increased the power of an already useful tool.
GooGled,
guhlenn
Oh REALLY????
thanks, but i've read this a few times, but still can't quite grasp the concept (mind you, i use very little compression). The side chain signal acts as a controller then and is not affected itself? why would one want to return it then? for live settings?
The "keep the bass out of the kick drum" thing sounds interesting, and i know i just need to try it, but i would imagine it sounds horrible as the bass is compressed to pieces.. (just like background music sounds horrible when the DJ starts talking...) or is it just that I do not own a decent hadware compressor ?
The "keep the bass out of the kick drum" thing sounds interesting, and i know i just need to try it, but i would imagine it sounds horrible as the bass is compressed to pieces.. (just like background music sounds horrible when the DJ starts talking...) or is it just that I do not own a decent hadware compressor ?
Side-chain is input only... and no proccessing is applied to this signal... It's not in the "signal Chain" and is just utilized as a reference for controlling the compression applied to the source signal introduced at the standard input of the compressor.guhlenn said:
Depending on your compression setting (Primarily attack & release)... this can sound very transparent... though it's easy to screw up... and in this particular case you'll want to side-chain compress only the kick drum if at all possible.guhlenn said:The "keep the bass out of the kick drum" thing sounds interesting, and i know i just need to try it, but i would imagine it sounds horrible as the bass is compressed to pieces.. (just like background music sounds horrible when the DJ starts talking...) or is it just that I do not own a decent hadware compressor ?
