Sculpt Your Sound with Advanced Controls

Aside from being a generally great-sounding plugin, Open Compressor’s ethos is rooted in two main areas. The first is providing lots of visual feedback about your sound, so you can make objective decisions while producing, mixing and mastering music. The second is controllability; giving you all the control you need to perform literally any dynamics-processing task. 

We cover the main plugin features elsewhere on the blog, but today we’re talking about the advanced controls that let you dig more deeply into your sound. From Open Compressor’s front panel, all these controls are accessible and clearly labelled. We don’t obscure features behind knobs with mysterious names, or hide features behind menus or dropdowns (though you can simplify the UI layout to conserve screen space). 

Open Compressor’s advanced features are found on the left-hand panel. Here’s a run-down, top-to-bottom:

Sidechain/detector Filtering

The sidechain/detector circuit on any compressor is the signal that tells the compressor how and when to act. Open Compressor features high-pass and low-pass filters (HPF and LPF) on its sidechain/detector circuit, allowing you to filter out certain frequencies from the input signal, without affecting the tone of the output. Say you want to prevent the kick drum from triggering the compressor, you can increase the high-pass filter frequency to exclude any frequencies below the cutoff. 

Lookahead Control

Applying lookahead to your signal allows the compressor to more accurately anticipate peaks, so it can apply faster and more transparent gain reduction. It does this by first copying the input signal and delaying the output signal, so it can ‘look ahead’ and prepare itself to react to transients in advance. You can choose 2ms, 5ms or 10ms — but it’s important to understand that this will introduce that latency on your DAW session, so you should turn Lookahead to 0ms (off) while recording. 

Peak vs RMS 

This switch controls how Open Compressor monitors the input signal. In Peak mode, the compressor responds immediately to the transients of your audio. This is great for controlling drums and providing fast, aggressive control over fast transients. In RMS mode, Open Compressor responds to an average signal, which is determined by the RMS Window, selectable between 5ms, 10ms, 25ms, 50ms and 100ms. RMS mode provides a much smoother response and is great for a less aggressive compression style, on orchestral sounds or acoustic instruments, for example.

Regular vs Optical Ballistics

This control changes the attack/release characteristics of Open Compressor. Regular mode provides linear attack and release curves for predictable, accurate control. Optical mode mimics the behaviour of classic opto-compressors with program-dependent timing characteristics:

Heat Simulation Longer periods of compression result in slower recovery times, simulating the thermal behaviour of photocells in classic hardware units.

Variable Attack Time Attack response depends on recent activity. If there has been recent activity the attack time is faster (around 15ms) and if there has been no recent activity the attack time is slower (around 70ms).

Multi-Stage Release Initial fast release stage (70ms) followed by roughly 50% recovery in approximately 1 second, then a slower tail for the remaining 50% recovery (as long as 12 seconds). Release time is also affected by how much activity there is, with slower release times kicking in if there is a lot of activity.

Program Dependency The timing characteristics change based on the duration and intensity of gain reduction, creating the musical "breathing" effect characteristic of vintage optical compressors.

Feedback vs Feedforward Architecture

This switch determines the architecture of the compressor, and transforms its behaviour. 

Feedforward mode (F-FWD) Here, the detector circuit occurs before gain reduction, a common configuration for digital compressors. The outcome is a clean, modern, precise and clinical sound, which provides predictable results. 

Feedback mode (F-BACK) The detector element is fed by the signal after gain reduction has been applied. This creates a gooey, analogue, musical vibe similar to an analogue compressor. Important note: it’s not possible to use Lookahead or External Sidechain in Feedback mode. (If you have either Lookahead or External Sidechain enabled while the compressor is in Feedback mode, it will operate in Feedforward mode regardless of the setting on the Feedforward/Feedback toggle.)

Hopefully this article gives you a full picture of the options available when using Open Compressor. For a more detailed guide, check out the user manual, and watch the official walkthrough video.

Open Compressor is an AU, VST and AAX plugin, making it compatible with every DAW. You can try it free for 7 days.