Time controls, style and knee
The section at the right of the interface contains the controls that affect the speed and feel
of the current chosen gate/expander style.
With the Style selection button, you can choose between various gate/expander styles, all
tailored and fine-tuned carefully to meet specific needs or offer a certain character:
This style brings you the flavor of gating and expansion as often found in vintage, high end
mixer channel strips. It can be quite aggressive, but also subtle when needed. It's a great
all-round style for mixing purposes and works especially well on drums.
Designed to be as clean as possible and minimize flutter and distortion, the Clean style is
great for transparent gating and expanding.
Since a gate/expander is very often used on vocals, we have developed a special vocal gating
algorithm. It retains the natural feel of the vocal, opening the gate gently when the singer
breathes in, and releasing gently, yet fast enough to reduce unwanted noise or bleed.
Another common application of a gate/expander is on electric guitar before distortion, to
reduce or miminize rumble. With this style, expecially when used in the lower ratio range (2:1
to 5:1), Pro-G gently follows the natural decay of the guitar sound, ensuring that even after
distortion, the result still sounds very natural and lively.
As a special treat, an upward expansion algorithm is also included. When you choose this style,
separate Threshold and Ratio parameters are used with custom, smaller ranges. In Upward mode,
the expander will amplify signals above the threshold instead of reducing them below threshold.
When used moderately and with care, you can achieve very natural and transparent sounding
Finally, Pro-G also features a dedicated ducking mode, as found in many classic gates. A
typical application of ducking is to automatically lower the level of a musical background
track when a voice-over starts, and to automatically bring the level up again when the
voice-over stops (in movies and on radio broadcasts). It is similar to compression with a
side-chain, but it can sound quite different, because it's processed as 'inverted' gating
instead of compression. Ducking can also be used to achieve the well-known and very popular
'pumping' effect, much used in modern dance music.
All styles have built-in, carefully tuned hysteresis where needed. This will cause the
gate to close at a slightly lower threshold level than the threshold at which it will open (as
set by the Threshold knob), avoiding flutter when the incoming audio signal hovers around the
The Attack knob sets the speed with which the expander/gate will open when the signal level
exceeds the threshold. For transient-rich program material like drums, fast attack times are
needed to preserve punch. FabFilter Pro-G is capable of very fast attack times and they are
The Release knob sets the time that the expander/gate takes to close and reach maximum gain
reduction. Just like the attack, the behavior is very program dependent, depending heavily on the
audio you're processing.
The Hold knob sets the minimum time that the gate/expander will remain fully opened after the
sound level has exceeded the threshold.
By choosing a custom soft knee setting, the gate/expander will react more gradually when sound
drops below the threshold. You can of course clearly see the effect of the Knee in the transfer
curve shown within the level display.
With the Lookahead knob (often also called pre-open), the gate/expander can be set to
open up to 10 ms before the audio level actually exceeds the threshold. This is an excellent way
to preserve transients, while still avoiding ultra-fast attack times that might cause distortion
You can enable or disable look-ahead with the Lookahead Enabled button, just at the right-top
of the Lookahead knob. When look-ahead is disabled and oversampling is off, Pro-G works without
any latency. When enabled, the latency will be 10 ms, plus a small additional latency if
oversampling is enabled.
- When using Upward expansion, it's best to avoid using high ratios in combination with a low
threshold, because this can lead to quite extreme amplification.