| Ever wanted to get a more even tone when playing | | | | hence the ratio 3:1. If you have a setting of infinity:1, this |
| finger-style acoustic guitar? How about enhancing your | | | | is more accurately described as a 'Limiter'. This is |
| percussive rhythm strumming when playing styles such | | | | because the output level is never permitted to rise |
| as funk, reggae or ska? Compression for Guitars | | | | beyond the pre-set threshold. |
| might be the answer. In simple terms, this effect | | | | Attack |
| produces a smoother, more evenly consistent sound | | | | Usually measured between 1 and 20 milliseconds, the |
| by elevating the level of soft notes, whilst the louder | | | | attack determines how long it takes for the |
| signals are reduced. This has the effect of averaging | | | | compressor to kick in. How you use the attack |
| out the overall audio signal. Think of it as an automatic | | | | parameter is dependent on the nature of the signal |
| control for adjusting the volume that is far more | | | | being effected. For example, a slow attack allows the |
| effective than what a human could do manually by | | | | percussive qualities of instruments to come through at |
| manipulating a knob or fader. | | | | the very start. The remainder of the signal is then |
| When using compression for guitars, it is normal to | | | | gradually evened out. This is very handy for drums |
| place it first in an effects chain, as it gives any effects | | | | and rhythm guitars. A fast attack on the other hand will |
| following it a smoother signal. Compression is very | | | | result in a consistently smooth sound and as a result, is |
| useful for lead guitar playing as it enhances sustain by | | | | ideally suited to vocals. |
| boosting the signal when it would normally fade. There | | | | Release |
| are many options for the guitarist, ranging from foot | | | | The release determines how long it takes for the |
| pedals through to digital rack-mounted units and in-built | | | | compressors gain to come back up to normal once |
| compression in some mixing desks. Depending on | | | | the input signal has dropped back below the level of |
| what unit you have access to, there are different | | | | the threshold. You need to be careful with this setting |
| levels of control available, but the basic settings are as | | | | as if it is set too fast, the result can be a pumping |
| follows. | | | | effect to the signal. |
| Threshold | | | | Hard Knee and Soft Knee |
| The threshold is basically the benchmark level above | | | | This setting will determine how aggressive the |
| which the signal is not allowed to exceed - until it hits a | | | | compression will be. A Soft Knee compressor allows |
| pre-determined amount beyond. When the | | | | the gain reduction to be brought in progressively, |
| pre-determined level is reached, the compressor kicks | | | | usually when the audio signal comes within 10 dB of |
| in and reduces the signal by a second pre-determined | | | | the Threshold. This produces in a gentler, more natural |
| amount. This is explained more in the paragraph about | | | | sounding effect.With a hard Knee compressor, the full |
| ratio. The Threshold is commonly calibrated in dBs. | | | | gain reduction will kick in when the signal hits the |
| Ratio | | | | Threshold. So it's a more abrupt compression. |
| The Ratio determines the amount of gain reduction | | | | Useful Compression Settings: |
| that will be applied to the signal and is the crux of the | | | | Electric Guitar |
| whole idea behind compression. It's usually expressed | | | | Attack: 2 -5 ms |
| as: | | | | Release: 0.5seconds/Auto |
| 6:1 | | | | Ratio: 8:1 |
| 4:1, | | | | Knee: Hard |
| 3:1,infinity:1 and similar. | | | | Acoustic Guitar |
| If you have a compression ratio of 3:1, this will mean | | | | Attack: 5 -10 ms |
| that a signal must exceed the pre-set Threshold by | | | | Release: 0.5seconds/Auto |
| 3dB to allow for a level 1dB above the Threshold. So, it | | | | Ratio: 5 - 10:1 |
| is reduced by 2 dB from 3dB above, to 1dB above, | | | | Knee: Soft. |