Leveller

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The leveller will attempt to keep the nominal level of the signal close to the desired target level set by the user, by gently changing the gain. An intelligent detection algorithm makes this processing object very free of side effects and easy to set up.

Inputs and Outputs

One audio input and one audio output.

Properties

Voice band Filter: Optionally included so that the levelling action favours frequencies in the human vocal range, helping to discriminate from noise signals.

Control Panel

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Target Output control
Adjusts the level which the leveller tries to maintain. The more positive the value, the higher the output level will be.

Ratio control
Adjusts the aggressiveness of levelling. Lower values allow more tolerance; allowing the output level to differ more from the target level, which preserves more of the original dynamics of the signal at the expense of firm control over the level. Higher ratio values cause the output level to be more tightly 'driven' towards the target level.

Maximum Gain control
Determines how much gain the object is allowed to apply to bring a low level signal up to the target level. Higher gain values allow the leveller to add more gain when the signal level is low, but will also bring up the noise floor more.

Speed control
Adjusts the time it takes for the leveller to recover from high levels when low levels are encountered. Higher values make the recovery slower, so there are no sudden jumps in gain. Lower (faster) values allow the leveller to track and counteract rapidly decreasing levels.

Bypass button
Removes the leveller from the signal path.
!
WARNING - significant changes in signal level can be caused by this control.

Threshold control
Determines the lowest input level that the Leveller will attempt to correct. Correct setting of this control is critical to the leveller's ability to discriminate unwanted noise from the wanted signal. Lower values will allow the leveller to 'pull-up' lower level signals, but will also make it more prone to activate on noise signals. Note that the intelligent detection algorithm helps to prevent noise signals from triggering levelling action even when they are above the threshold level, (if the leveller does not recognise them as vocal signals).

Active LED
Shows when the intelligent detector is allowing levelling action to take place. This is used along with the Threshold control to confirm that noise signals do not activate the detector, but wanted signals do.

Gain meter
Displays how much adjustment the leveller is applying to the signal.

Notes

! It should be noted that this object is capable of raising signal levels beyond the clipping point, so care should be exercised when using large Maximum Gain values.

! It is recommended that a Limiter be used on the output of the Leveller so that short-term high-level signals (which may not be attenuated by the Leveller), are not allowed to pass through to the output.

An expander connected on the input side of the leveller may be useful in aiding the leveller to discriminate noise signals from wanted signals