Rane Music Pedal G4 User Manual

Manual-5

Figure 2: Look ahead pre- ramping (3 kHz signal)

In the above waveform, the side-chain Gate threshold equals 

the peak sine wave value (first vertical marker). The main input 

signal (yellow trace) is delayed a few microseconds. At 3 kHz, 

the exponential look-ahead ramp guarantees the first cycle is 

fully gated on as it reaches the threshold level (second vertical 

marker). The look ahead and analog converter delays give a total 

propagation delay though the G4 of 1.62 ms, an imperceptible 

amount.

Expand Mode
The basic objective of expansion is the same as gating: expand 

the dynamic range of a signal by reducing the noise floor. 

However, an expander provides a more subtle response than a 

gate in applications requiring smooth, natural decay. It works by 

controlling the ratio of output change to input change, in effect 

dynamically modifying gain below a set threshold. For example, 

if the ratio is set to 4:1 then the output decreases 4 dB for every 

1 dB of decrease in input level (See figure 4).

Compared to gating, expansion typically uses a slower attack 

time and longer release time.

•   Enhance the long, gradual decay of a piano or guitar.

•   Use an expander on a quiet vocalist to reduce stage noise 

between passages.

Figure 3: Look ahead pre-ramping (500 Hz signal)

At 500 Hz the exponential pre-ramp ensures that the first cycle 

is properly gated on. Look ahead pre-ramping produces a more 

natural leading edge to the wave form, tightening up the sound 

without the harsh click that occurs with an instantaneous rise 

time.

Figure 4: Gate vs. Expander

The above graph shows the difference between Gate and 

Expander operation. The solid red trace shows the side-chain 

input.

 The green long-dash trace shows the operation of a 

Gate. The Gate attenuates the signal by a fixed number of dB 

when the signal is below threshold. The response is adjustable 

over a wide range using Attack, Release and Hold controls. It 

is possible to achieve natural decay with string instruments by 

setting the release for slow ramp down. Fast attack, quick release 

and deep depth settings can be used to change the character of 

drums or other percussion instruments.

 The blue short-dash trace shows downward ex-

pansion with a ratio of 2:1. The signal is turned down gradually, 

resulting in lower noise in the absence of signal while allowing 

natural signal decay. Downward expansion generally uses a Re-

lease time of about 500 ms to 1 second and an Attack setting of 

100 ms to 500 ms. The Hold function is not active when using 

the Expander.

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