Common compression parameters

The following definitions apply to most of BFD3's dynamics processors. However, please note that the DCAM EnvShaper device has a very different approach to its time-related parameters (Attack and Sustain).

Attack

The Attack control on a compressor represents the speed at which the gain is reduced when transients pass through it.

This control is often misunderstood - the Attack time does NOT indicate the amount of time taken before the compressor starts to compress.

Release

The Release control on a compressor sets the speed at which the gain level returns to normal after a transient has passed.

Ratio

The Ratio specifies the gain reduction applied by the compressor. The numbers in the ratio represent the change in gain before and after compression.

For example, assuming that the threshold level has been breached, then a ratio of 2:1 would mean that for every 2 dB of increased signal level coming into the compressor, the output level rises by 1dB.

Advanced features in BFD3's dynamics processors

SideChain button

The BFD3 Comp Bus, NoiseGate and DCAM EnvShaper feature the ability to process a signal using the transient characteristics of another. By enabling the SideChain button, the device's peak detection circuit reacts to the channel's SideChain input rather than the main input but still applies the processing to the main input signal. This allows you to control the dynamics of the main input signal with another signal entirely.

The Filter Mod device also features a SideChain button for driving its envelope follower and FM functions while the EQ and EQ8 devices also have a SideChain button for EQ-ing the channel's SideChain signal.

Parallel compression and the Mix control

Parallel compression involves mixing a compressed signal (usually fairly heavily compressed) with the original dry signal, in order to achieve the 'huge' sound of a compressed drum mix while keeping the transients of the original drums intact.

While it is uncommon to see a wet/dry mix control on a compressor, the Mix control on BFD3's compressors is very useful for applying parallel compression to a single mono or stereo channel without needing to create additional Aux channels. If you need to apply parallel compression to more than one channel at once, you must first create a sub-mix on an Aux channel.

 

Comp Chan

dfx_compchan

Comp Chan (channel compressor) is derived from a classic 'feedback-based FET limiting amplifier' design.

It features a 'fixed-threshold' design – the threshold at which compression starts is not adjustable. In practice, this means you may need to adjust the Input and Output levels when changing ratios.

Input & Output

This control adjusts the level of the signal entering the compressor. Once the input level has reached the internal threshold, compression begins. When this happens, use the Output control to turn down the increased input. The Input control ranges from -20 tp +40 dB, while the Output control ranges from -40 dB to +20 dB.

Attack

The Attack control has a range between 0.02 ms and 0.8 ms.

Release

The Release control has a range between 50ms and 1.1 seconds.

Ratio

This control sets the compression Ratio to 4:1 , 8:1 , 12:1, 20:1 or 'Nuke', which is an emulation of the 'all buttons' mode on a classic limiting amplifier design. It results in a particularly brutal type of compression with accompanying distortion artifacts.
 

Comp Bus

dfx_compbus

This device is based on a classic bus compressor design from the centre section of a well-known British large-format mixing console.

It is most commonly used to add 'glue' and power to a drum bus. However, it also works very well as a channel compressor in its own right, offering a different flavour of compression compared to the Comp Chan.

Key HP (Key signal High-pass)

The Key HP control adjusts a variable high pass filter on the key signal that is used for the compressor's amplitude detection. It is applied whether the main input or the SideChain input is being used to drive the compressor. No filtering is applied to the audible signal - only to that being used to drive the peak detection circuit.

This control is useful when there is too much low-end in the sidechain signal, resulting in the compressor reacting more heavily than desired.

Attack

Six Attack times are available: 0.1 ms, 0.3 ms, 1 ms, 3 ms, 10 ms, 30 ms.

Release

Five Release settings are available: 0.1 ms, 0.3 ms, 0.6 ms, 1.2 ms and Auto.

Ratio

Three Ratio settings are available: 2:1, 4:1 and 10:1.

Threshold

Unlike the Comp Chan, the Comp Bus device allows you to adjust the Threshold, which represents the signal level at which the compressor begins to react.

Output

The Output control allows you to increase the overall output level after the compressor circuit has applied gain reduction to the input signal.

Limit

The Limit button applies analog non-linearities to the input to the compressor's amplitude detection circuit (while not affecting the input signal itself). This results in a more transparent character to the compression effect, especially on attack phases of transients.

 

Comp VCA

4 pg 68 comp VCA

The Comp VCA device is a modelled emulation of a VCA-based compressor   circuit with a fast and clean compression characteristic.

Input

The Input control adjusts the signal level entering the compressor circuit. Higher levels result in the compressor circuit reacting more heavily.

Attack

The Attack time can be set between 100μs (microseconds) and 100ms (milliseconds).

Release

The Release time can be set between 10ms and 2s.

Ratio

The Ratio can be set between 1:1 and 50:1.

Threshold

The Threshold represents the signal level at which the compressor begins to react.

Output

The Output control allows you to increase the overall output level after the compressor circuit has applied gain reduction to the input signal.

 

 


 

DCAM EnvShaper

dfx_dcamenvshaper

DCAM EnvShaper offers an alternative approach to dynamics processing by allowing you to adjust the intensity of the attack and sustain portions of transients.

Attack

The Attack control adjusts the intensity of the attack phase of detected peaks in the audio signal. Increase the control to intensify attack transients, and decrease it to soften transients.

Sustain

The Sustain control adjusts the intensity of release portions of detected peaks in the audio signal, which increases or decreases the apparent sustain of sounds in the signal.

Increase this control for more sustain, and decrease it for less sustain. This control is useful for adjusting the perceived level of ambience in a channel. Negative settings can produce damping effects for drum sounds.

Signal Bias

The Signal Bias control adjusts the sensitivity and release characteristics of DCAM EnvShaper. At low settings it is more sensitive to short transients while at higher settings it is more sensitive to longer transients.

 

NoiseGate

dfx_noisegate

A noise gate is a type of dynamics processor that attenuates the input signal until its amplitude exceeds an adjustable threshold level, at which time the gate 'opens' to allow audio through at its actual level.

They are often used during drum mixing in order to isolate drums within signals containing bleed or spill from other drums. Another common use is to reduce the decay of toms and kicks. Noise gates are often referred to simply as 'gates'.

While BFD3 contains bleed channels, these can be turned down or off completely rather than having to use gates to minimize bleed. Likewise, the decay of kit-pieces can be adjusted using the Damping controls in the Drum Editor. However, using gates can be good for creative effects, or simply for recreating the types of techniques used in real drum mixing sessions.

BFD3's NoiseGate has a SideChain function which allows you to create triggered 'chopping' effects very easily. For example, route any channel such as a hihat or a user sample direct channel to the master channel's sidechain input and insert a noise gate in one of the master channel's effect slots. Enable the sidechain button for the gate and adjust the threshold until the sidechain input triggers the audio on the channel.

When setting very fast Attack and Release times, it is common to hear 'clicks' in the audio when the gate opens and closes, especially with sounds predominantly comprised of low frequencies such as kicks and toms. This behaviour is completely normal - these times simply need to be increased slightly to overcome the problem.

Attack

The Attack control adjusts the speed at which the gate opens once the Threshold has been exceeded by the input signal's amplitude.

Hold

The Hold parameter controls the amount of time the gate remains open after the input signal has dropped below the Threshold level.

Release

The Release control adjusts the speed at which the gate closes at the end of the hold time.

Threshold

The Threshold control allows you to set the level at which the gate starts to open. When the input signal amplitude exceeds the level specified by the Threshold control, the gate starts to open to allow audio through.

Input Filter

This control provides high-pass and low-pass filters to process the input signal used to trigger the gate (whether it is the main input signal or the SideChain input signal) while leaving the actual processed signal unfiltered. This allows you to isolate certain frequencies in the input to improve the gating response – for example, excessive low frequencies in the input can make the gate react more sensitively than required.

To adjust this control, click and drag the light blue arrows at the left and right of the blue active frequency band the light-blue arrows represent the cutoff frequencies of the high-pass and low-pass filters.

Key Listen

Enabling the Key Listen button lets you hear the key input being used to trigger the NoiseGate's amplitude detection circuit instead of the processed input signal. The key signal can be either the main input or the sidechain input.

It is very useful when using the Input Filter and/or the SideChain input.

Hysteresis

Noise gates have a tendency to open and close very quickly when the input signal's amplitude remains close to the threshold level for longer periods, something that can result in 'gate chatter'.

Increasing the Hysteresis control smooths out the gate response to reduce this problem, although the gate becomes less sensitive to small changes around the threshold level.

Mix

With the Mix control at 100%, the NoiseGate mutes the signal completely when closed. If you want to let the signal through at a low level, decrease the Mix control to allow more of the dry signal through.

 

Distortion

dfx_distortion-dcam

The Distortion device is an updated version of BFD2's Drive processor which is now available within the Legacy sub-menu.

Mode

The Mode drop-down menu selects between a wide variety of distortion types.

Drive

The Drive control sets the amount of distortion that takes place.

Input Filter

This control provides high-pass and low-pass filters before the distortion stage to enable you to shape the tonal characteristics of the signal going into the drive circuit.

For example, you may want to distort the high end of a kick drum while leaving the deep low end unchanged.

To adjust this control, click and drag the light blue arrows at the left and right of the blue active frequency band the light-blue arrows represent the cutoff frequencies of the high-pass and low-pass filters.

These filters are crossover filters – the active frequency band is processed by the distortion circuit with its level adjustable via the Dirty control. The frequencies that are filtered out before the distortion stage are accessible via the Clean control.

Dirty & Clean

The Dirty control sets the amount of post-distortion signal that is heard at the output.

The Clean control sets the amount of the clean signal, which is comprised of the signals filtered out by Input Filter control.

Please note that these are not 'wet' and 'dry' controls – use the standard Mix control at the top of the effect interface in order to mix between the pre- and post-effect signals.

Tone

The Tone control provides a simple -6 dB/oct low-pass filter for the processed signal after the distortion stage. It allows you to roll off unwanted high frequencies that may have been generated in the signal as part of the distortion effect.

 

Limiter

dfx_limiter

A limiter is effectively a compressor with a very fast attack time and a high ratio for signals that exceed the maximum level.

Input

The Input control adjusts the level of the signal going into the Limiter algorithm. Higher input levels lead to more pronounced and 'brutal' limiting.

Hardness

The Hardness control adjusts the strength of the Limiter's 'knee'. At high settings, peaks are clipped with a 'brick-wall' limiting effect. At lower settings, gain reduction occurs more slowly (with slower attack and release settings), leading to a more natural effect with less 'pumping'.

Output

The Output control allows you to attenuate the processed output signal from the Limiter.

 

Gain

dfx_gain

The Gain effect is a simple tool for increasing or decreasing a channel's level.

Gain

The Gain control lets you increase the channel's gain up to 18 dB, or decrease it up to -inf dB.