There are 2 categories that signal processors come under.
They are as follows;
1) Complimentary Effects
These are effects such as reverb, pitch-shift, phase, delay, modulation etc.
Which complements the signal and you can actually hear it working.
2) Non-Complimentary Effects (Dynamic Signal Processor's)
These are effects such as compressor's, noise gates, filtering, expanding & ducking etc.
You cannot hear these effects working,
Though if you can hear these effects working then there is something wrong and you should sort it out immediately,
Unless you are using it as an experimental effect.
Compressor's are used to control the dynamic range (Quietest & Loudest Points) of a signal or volume.
It reduce's gain once a signal has exceeded the threshold level.
Anything with a ratio of up to 10:1 is compression.
Anything with a ratio of up to 20:1 is limiting.
Anything with a ratio of up to 50:1 is peak limiting.
Threshold is the start of when the compressor starts to work, It basically is the level at which the compressor comes in at.
Ratio Is the amount of compression that you want to apply to the signal.
Attack is how quick you want the compressor to respond to the signal after its past the threshold level that you selected.
Release is how quick you want the compressor to return back to its normal state after its fallen below the threshold level that has been selected.
Gain is the output control of the signal leaving the compressor,
To basically make up for any of the volume that may of been lost through compression.
Peak Limit control deals with very high transients which are fast and sharp, This is often used on drums etc.
LED Meters tell you how much compression is taking place,
When in VU Mode at the output it tells you how much level you are losing through compression.
Link allows you have a stereo image on the compression,
You need to have 2 compressors it will then basically allow the one compressor to control the other one.
Bypass button allows you to listen to the signal without compression.
Listen button allows you to listen to the signal with compression otherwise known as Normal Mode.
S/C (Side Chain) is an extra input which allows you to connect a secondary device such as a graphic equaliser.
This basically allows you to compress certain frequencies which evade the compressor.
Compressing 4K and above will reduce sibilance.
By using the side-chain and an equaliser it turns the compressor into a De-esser (Frequency Conscious Compressor).
A De-esser is a frequency conscious compressor,
It reduces sibilants which are caused by S words and similar words to S which has tails like SHHHH etc.
De-essing is achieved by inserting a graphic equalizer into the sidechain, Which is a secondary input on the compressor.
This allows you to boost the frequencies that are causing you the problem by being under the threshold.
These are the ones that the compressor cannot deal with.
By boosting the frequencies this allows the compressor to compress the awkward frequencies.
This technique of de-essing is used on vocals but it can be used on any other sound source's that are causing frequency problems.
A noise-gate is a device that allows a signal to pass through after a signal has exceeded the threshold.
It can be used as a complementary effect but mostly used for reducing spill and reducing noise.
Some noise-gates have a variety of different functions.
Not only is it a noise gate but it can also be an expander and ducker.
When expanding it has variable attenuation when the gate is closed
(You can choose the level you can hear coming through when the gate is closed).
This can be used as an effect to emphasize a sound, It is similar to gating but it has variable attenuation.
When ducking it is basically the reverse of a noise-gate but it lets all the signal through and when the signal drops below the threshold it starts to attenuate (Lets all the signal pass through unaffected after it falls below the threshold).
Ducking is used on the radio e.g.. DJ talks the music drops to the background and when he stops the music rises back up again.
This Does Not Work Like A Compressor.
The threshold is the level at which the gate opens.
The attack is how quickly the gate opens after the signal has exceeded the threshold.(0.5ms-2.5sec).
The hold controls how long the gate stays open before shutting.
The decay/release is how quickly the gate closes after it has fallen below the threshold.
The attenuation/range lets you set the amount of signal that passes through the gate when it is closed.
Norm lets you listen to the affected signal.
Filter knobs let you filter away problem frequencies (LF = HPF, HF = LPF).
Red = Gate closed attenuation taking place.
Green = How long the gate is staying open.
Yellow = How quickly the gate is opening and closing.
The Key input (External/Internal) lets you trigger the gate with an external sound source.
(Otherwise known as Keying).
Key Listen lets you listen to the key filters.
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