Channel Compressor/Limiter Section

The Channel Compressor is used to artistically manipulate the dynamic content of a signal. Some of the effects possible with a compressor are: make a sung or spoken voice sound more consistent; increase the ‘room’ sound in a drum mix; or accentuate the attack of a percussive sound like a drum or picked guitar

Controls:

• Mode Selector: the mode selector provides 3 options: Leveler, Compressor and Limiter
• Threshold Slider: drag the threshold slider down to meet the average signal level
• Input Meter: this meter indicates the level (post-emphasis-filter) that is being fed to the compressor’s detector
• Gain Reduction meter: this meter indicates the amount of gain-reduction being applied. The first 4 LEDs each indicate 2dB of gain reduction.
• Ratio Knob: increase this knob to increase the effect of the Compressor processing. The range of this control can vary depending on the Mode selection.
• Attack: this knob adjusts the speed at which the compressor will engage, when the input signal exceeds the threshold slider. The range of this control can vary depending on the Mode selection.
• Release: this knob adjusts the speed at which the compressor will return to unity gain, if compression was occurring and now the input signal sinks below the threshold slider. The range of this control can vary depending on the Mode selection.
• Emph: increase the Emphasis knob to increases the sensitivity of the compressor to high frequencies. This causes the compressor to act more quickly on transients but slower on lower frequencies, resulting in a more vintage character that is associated with tube and opto-coupled compression devices.
• Gain: this knob increases the output level, post-compressor. Since a compressor normally reduces the volume of a signal, it is desirable to raise the overall level, post-compression. This extra gain is disabled when you disable the compressor, which allows you to compare the compressed and uncompressed (dry) signal at a comparable volume.

Compressor Modes:

1. Leveling: The “leveler” mode has a very low ratio with a small adjustment range, a very fast release with a small adjustment range, and a widely adjustable attack. Due to mic technique or other elements out of our control, sometimes a signal has a very wide dynamic range. The “leveler” with a fast attack can be used to transparently reduce the level of the loudest parts, so that the track has a more consistent level. Reducing the dynamic range of our tracks can make them easier to mix, although it might rob some of the performance’s natural dynamics. The leveler with a slow attack allows the initial sound (the first syllable of a word or phrase, for example), to be passed through at full volume, while reducing the “body” of the sound slightly. This retains and enhances the character of the recording, and it can help improve intelligibility of words and instruments in a busy mix.
2. Compression: The “compressor” mode is the most adjustable of the 3 modes, with full control over ratio, attack, and release. Compression is a natural effect of amps driven to their limits, or vocal shouting. Therefore our brains perceive compressed signals as “louder”, regardless of their actual volume. Because the loud signals are brought much lower, it makes the quiet signals sound as loud as the loud parts. This means that mouth noises, valve noises, and other ancillary sounds will sound more pronounced. This can impart a “nearby, in-your-face” effect. The compressor has a multi-stage envelope follower which allows it to respond to changes in overall level, while still applying the ‘compressed’ effect.
3. Limiting: The “limiter” mode has a nearly-instant attack with little adjustment, a high ratio, and a widely variable release time. A limiter is a very fast-acting compressor, and these were initially designed to capture signal peaks before they were passed on to sensitive broadcast transmitters, disc-cutting lathes, or speaker systems. By taming the transients of a very dynamic instrument (like drums), the limiter has the effect of extending the instrument’s decay, and an inherent increase in room-sound (reverb), sometimes called ‘bloom’ or ambience. A common use of the Limiter is to increase the room&ambience of a drum mix.

*Mixbus32C’s channelstrip limiter mode is an ‘effect’ intended to sound like desirable analog devices. It is not a brickwall digital peak limiter. For those purposes, you can use Mixbus’s built-in limiter on the master-bus, or the bundled x42 Lookahead Limiter, or a third-party plugin.

!Lookahead Latency : the Limiter effect requires a ‘lookahead’ time so it can accurately open before a drum transient. When any channel’s Limiter mode is enabled, Mixbus must delay all the other channels to accommodate this latency. This is called ‘latency compensation’ and is inherent to Mixbus’s operation. However, there are a few cases where the additional latency is objectionable (for example: if you want to play a midi keyboard, and hear a virtual instrument played from a track in Mixbus). In this case you can disable PDC (plugin delay compensation) via the Latency Toolbar.

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