MIXING & EFFECTS

Fruity Limiter

IL Limiter is a powerful single band compressor/limiter ideal for maximising & compressing final mixes or single tracks. Switching between LIMIT and COMP tabs will change the interface controls to suit the stage. A closely related plugin is Maximus.

Overview

Click on the following links to jump to the section of interest:

• LIMIT (Limiter Controls)
• COMP (Compressor Controls)
• Analysis Display
• Noise Gate
• Comparison Bank

Signal Flow

The signal flow goes from input to Compressor (COMP), Limiter (with integrated Noise Gate), Saturation (SAT) and finally to the plugin output.

Limiter Controls

Limiting is a form of heavy compression (generally used to describe compression ratios greater than 10:1). The purpose is usually to 'limit' the output level to a set maximum level, usually 0 dB, to avoid clipping in a final mix down. The Limiter can be used to maximise the level of a track dramatically without introducing noticeable distortion and so limiting is a favourite effect used in mastering. While louder often sounds better, we draw your attention to the excellent Wikipedia article on loudness wars!

Note: The limiter section can't be bypassed while the compressor section (described below) can.

Loudness

These controls affect the input and limit thresholds for Fruity Limiter.

• GAIN (Purple) - Input gain. Useful for adjusting the signal level relative to the active limiter threshold.
• CEIL (Ceiling) - Limiter ceiling. Sets the level above which the signal will be limited.
• SAT (Saturation) - Controls the threshold level, signals reaching into the red region will be saturated. To lower the threshold, and so increase the saturation turn SAT left. Set by ear.

Note: For the Limiter to work the input signal must exceed the limiter threshold. The options are lowering the CEIL level, increasing the GAIN level or increasing the signal level entering the plugin. Saturation (pleasing to some) is a type of amplitude distortion, usually associated with Valve / Tube Amplifiers, tape or analog circuitry. Generally, as a waveform exceeds the maximum amplitude that an analog system can carry, its shape is rounded or bent. This bending is a mild distortion that progressively increases as the input approaches the maximum (0 dB). Tip: For an alternative saturation sound allow the input to peak over the limit threshold, then blend in some 'Soft-clipping ' from the saturator. Over-limiting adds its own kind of saturation effect that interacts nicely with the saturation process.

Envelope

• ATT (Attack time) - Adjusts how quickly the envelope responds to the start of the signal (in ms). The attack time also sets the 'look-ahead' time for the limiter. Look-ahead adds a delay to the plugin input so that the envelope algorithm can anticipate peaks before they arrive. In summary, the Limiter delay = ATT time.
• CURVE (Attack & Release 2 curves) - Select from curve 1 (steep slope) to 8 (low slope). This control sets both the Attack and Release 2 curves.
• REL - Release time (in ms). There are two release controls, this is the main influence for the compression envelope release time.
• AHEAD - Look ahead sustain window. This is a sustain function to prevent the compression envelope from releasing too early.

Note: In order to trap transient signals before they pass through the Limiter a look-ahead time greater than 0 is needed. If 0 latency is desired then you can set the limiter's attack to zero and then adjust the compressor's attack to achieve the same effect (or as close as possible).

Compressor Controls

Compression is a form of automated gain control that reduces the dynamic range of sounds. When the input signal exceeds a predetermined threshold the gain is reduced. The art of setting a compressor is mainly in fine-tuning the magnitude, speed and timing of the automated gain changes so that the compression process does not introduce artifacts. How can reducing the amplitude peaks make the sound seem louder? To understand we need to consider the way our hearing interprets the start (attack) and body (sustain) portion of sounds. It transpires that the attack is used mainly to form impressions of timbre, clarity, crispness and punch, while the sustain contributes most to the perception of loudness. The sustain is most important because loudness perception comes from an integration (averaging) of the preceding 600-1000 ms to any given moment. Attack transients (of very short duration) simply don’t have as much weight as the body of the sound. Lowering the amplitude of the peak transients, frees up headroom to raise the gain of the sustained portions of the signal (post compression), it is this step that increases loudness. However, as we alluded to earlier, compression represents a trade-off between dynamics and loudness, welcome to the loudness wars!

Loudness

These controls affect the input and compression thresholds for Fruity Limiter.

• GAIN (Purple) - Input gain. Useful for adjusting the signal level relative to the active limiter threshold.
• THRESH (Blue) - Compressor threshold. Sets the level above which the signal will be compressed.
• RATIO (Blue) - Compression ratio. Sets the amount of compression to be applied once the threshold is exceeded.
• KNEE (Blue) - Compression rate. Sets the transition between no and full compression. The compression ratio can be set to increase gradually (soft knee) or rapidly (hard knee). The compression envelope will display while the knob is held.
• SAT (Saturation) - Controls the level over which saturation will be applied. The Lower the threshold (turn left) the more saturation will be applied to the signal. Set by ear.

Envelope

• ATT (Attack time) - Adjusts how quickly the envelope responds to the start of the signal (in ms). The attack time also sets the 'look-ahead' time for the limiter. Look-ahead adds a delay to the plugin input so that the envelope algorithm can anticipate peaks before they arrive, and so the attack time therefore adds a delay to the plugin output equal to the ATT time.
• CURVE (Attack & Release curve) - Select from curve 1 (steep slope) to 8 (low slope). This control sets both the Attack and Release curves.
• REL - Release time (in ms). There are two release controls, this is the main influence for the compression envelope release time.
• AHEAD - Look ahead sustain window. This is an envelope sustain time to prevent the compression envelope from releasing too early. Note that this has no effect on the signal throughput delay.

Note: You don't need to be overly concerned about compressor transients peaking over 0 dB since the limiter section can catch these.

Analysis Display

The analysis display is a valuable analysis tool to observe how the various plugin settings interact with the input / output sounds. Click on the display to Pause the display.

Display Controls & Options

Options - Displays plugin information.

Show input peaks - Display the input level graph.

Show output peaks - Display the output level graph.

Show analysis & gain envelopes - Displays the analysis and gain envelopes. applied to the selected band (compression envelope).

Show level markers - Displays the GAIN (purple), CEIL (green) & THRESH (blue) level settings. In the default position the lines overlap at 0 dB and show as a single white line.

Speed - Scroll speed slider (up is faster, down is slower).

To PAUSE the display, click on the display area. Once paused, you can continue to change display modes to examine data of interest.

Note: The limiter works on peak levels and the compressor on RMS (average) levels. The blue signal trace is the RMS signal with the compressor envelope applied.

Noise Gate

These controls affect the gating function in IL Limiter.

• GAIN (Noise gain) - Adjusts the signal level passing through the gate in the closed condition (the default 100%, i.e. no gating). Turn to the left for more gating effect.
• THRESH (Noise threshold) - Gate threshold. When the input level passes the Noise threshold the gate opens (immediately). The gate release is triggered when the signal falls below this same threshold to stop the signal.
• REL - (Noise release time). Longer release times cause the gate to close slowly, short release times cause abrupt closures. This acts in the same way as the release in an ADSR envelope.

Note: The Gate is useful to supress the noise that sometimes becomes audible on the tail-end of heavily compressed sounds using high levels of make-up (POST) gain. The gate can restore silence between the desired parts of signals.

Comparison Bank

In the bottom right corner of the plugin you will find:

• Store in spare state (Down arrow symbol) - Saves the current state to the comparison bank. Lock spare state, under the General options, allows this state to be protected from overwriting.
• Flip with spare state (A/B compare) - Selecting this control will allow you to make A/B comparisons between the stored and current settings. Useful for hearing the effect of a tweak more clearly.

Plugin Credits

Didier Dambrin: Plugin & Interface.

Frederic Vanmol: VST Port.

Laurent de Soras: Saturation algorithm.

Robert Bristow-Johnson: Filter algorithm.

Thanks to: The music-dsp mailing list.