Compressor

Overview

Simply put, a compressor adjusts dynamic range. Most commonly, it reduces it using downward compression, but as you’ll discover, Neutron is capable of both upwards and downwards compression.

compressor

Global Controls

Vintage mode

compressor

Neutron’s Compressor is capable of two very different styles of compression, Digital and Vintage mode. Where Digital is a more transparent, surgical compressor, Vintage is more colorful, emulating a number of sonic behaviors from a variety of beloved older analog compressors. In Vintage mode, the Attack reacts much more quickly (indeed, an 1176 is capable of very low Attack times) but then begins to ease in, which sounds punchier, but less transparent than the Digital mode. Knee is inaccessible in Vintage mode, as it scales with Threshold. The Release is also gentler, which is why some might describe this algorithm as sounding more pumpy, when such an adjective is desirable for your mix. Analog isn’t better than digital isn’t better than analog. It’s all about options, folks!

Output Gain

If you’re using the Compressor in a downward direction, to reduce dynamic range, there are two ways you may wish to add a transparent Gain boost to the overall output of the module to compensate. The opposite is true of using it in upwards mode, where you may subsequently need output gain attenuation. This slider allows you to dial in a manual amount of Gain adjustment to the output of the Compressor module, to ensure optimum gain staging as it passes into the next module. This is especially useful if you have Compressor 1 and Compressor 2 in series. The other method is to use the Auto Gain control, which is described just below.

LFE Bypass (surround only)

This button only appears when Neutron is loaded in either a 5.1 or 7.1 surround-sound configuration. When in surround-sound configurations, Neutron processes all channels equally. When enabled, the LFE Bypass will ensure that any audio information in the LFE channel is passed through unprocessed, but with the correct latency compensation.

Level Detection mode

These three buttons, RMS, Peak, and True, allow you to adjust which level detection mode the Compressor uses, as follows:

  1. Peak enables Neutron’s detection circuit to look at peak levels of the incoming signal. In general, this setting is useful when you are trying to even out sudden transients in your music.
  2. RMS enables Neutron to look at the average level of the incoming signal. RMS detection is useful when you are trying to increase the overall volume level without changing the character of the sound.
  3. True mode behaves much like RMS mode, but with some key advantages. Unlike RMS, True mode produces even levels across all frequencies. Additionally, True mode will not produce the aliasing or artifacts that RMS detection can cause (a signal-dependent behavior that is true of any RMS-based compressor, not just Neutron). At times these may sound good to your ears, but at other times they may sound like a word we’re not allowed to print.

Learn

In multiband mode, this searches for natural crossover cutoff points using a few criteria, including minima in the spectrum. Once Neutron has found a stable and transparent place for the cutoffs, the Learn function will disable automatically.

###Reset

This will reset the entire Compressor to default values if you wish to start over. If you click this button and experience instant remorse, never fear…you can open the Undo History and revert the change to go back to the settings you had prior to reset. De-compression, if you will.

Gain Reduction Trace

This view offers a scrolling meter that displays the incoming signal’s waveform with a superimposed curve that illustrates the amount of gain reduction taking place in real time. It uses a rectified waveform to better illustrate the compression behavior.

When using multiband processing, the current selected band’s gain reduction and waveform are drawn in this meter. The Gain Reduction Trace can help you to set attack and release controls appropriately and monitor the envelope of gain reduction.

When seeking to achieve maximum transparency, it’s important to pay close attention to the trace juxtaposed over the waveform, and how it illustrates the effect a changing Release time can have on allowing audio to return to 0 dB of gain reduction before the next transient. Note: the scale can be adjusted on the left-hand side.

VU meters

In Vintage mode, the gain reduction meters use a VU meter, one per band. There is something magical about the audio/visual connection between the gain reduction that’s occurring and the way the ballistics of the VU meter give you a sense of what’s going on.

Detection filter

This filter, enabled via the Detection filter button on the bottom-left of the multiband spectrum view, allows you to specify the frequency response of the detection circuit used by the Compressor, so that it is more or less sensitive to certain frequencies. It includes low- and high-resonant pass filters.

This is particularly useful when using the Compressor in single-band mode, as you could roll off all of the lows, but at a mid-range or a high resonance, to have the Compressor respond much more to sibilance or harshness, or a snare drum’s crack rather than thwack (technical term).

When enabled, you’ll see an node for each low and high filter overlaid on the multiband spectrum. Click to grab and drag an node horizontally to adjust frequency, and vertically to adjust resonance.

Detection filter solo

This allows you to audition the filtered sidechain signal only, so that you may hear the same audio input that’s triggering the compressor. Click the button to the right of Detection filter (just below the multiband spectrum view) to engage it. It definitely helps dial in the sidechain filter EQ described above.

Auto Gain

When selected, Auto Gain compensation calculates levels of both the input and output signals of the compressor for each crossover band and applies the appropriate gain to the output signal to compensate for the difference. This automatically brings audio volume to a level comparable to the unprocessed audio, and acts as a smart “make-up gain” control that adapts to the mix over time.

This is a useful way of helping to ensure that your audio isn’t better because it’s louder.

Auto Release

This automatically adjusts the Release time of the Compressor based on analysis of the input signal. If a transient signal is detected, the Release time is scaled to be shorter for less pumping. If a sustained note is detected, the Release time is scaled to be longer for lower distortion.

The Release time is not arbitrarily made up. It’s scaled in relation to the Release value set by the user. For example, if you are using the Compressor with the Release time set to 100 ms, the Release time will be automatically adjusted to a value within a range of 20 ms to 200 ms, depending on the type of signal that is being processed.

Auto Release is one of those secret weapons allowing producers good, transparent, and responsive compression. You may well find that once you’re comfortable with the result, it stays on the majority of the time. Indeed, in Vintage mode, Auto Release is always on, as it helps support the vintage-modeled release behaviors.

Mix

The Mix slider in the module chain is a highly useful feature, allowing you to do parallel compression. At 100%, you’re hearing only the audio processed by Compressor, whereas at 50% you’re hearing an even blend between unprocessed and processed audio. Often times, blending in more extreme compression settings (as in…majorly crushed) with completely unprocessed signal (typically around 50 - 80% dry, 50 - 30% wet) gives you a much smoother, more polished sound without eliminating the musicality that peaks and dynamic range have to offer. Note that this a global setting, where unprocessed means audio input to the Compressor, and processed means audio output from the Compressor. Audio output from the Compressor may contain some dry audio, due to the per-band Mix control.

Per-band Controls

Threshold

Threshold sets the point at which the dynamics processing begins to take place. With positive ratios, this means signals overshooting the threshold, and with negative ratios, this means signals falling below the threshold.

Ratio

Ratio allows you to adjust the amount of level adjustment the compressor will apply from any given input signal. A ratio of 3:1 means the for every 3 dB a signal overshoots the Threshold, only 1 dB of gain increase will occur.

Neutron’s Compressor is capable of both upwards compression (with a negative ratio) and downwards compression (with a positive ratio). Additionally, the Compressor supports positive ratios high enough to be considered a Limiter, which when combined with the multiband-capable processing, is particularly useful for processing electronic sounds, or working in genres typified by high RMS values. For acoustic material, we recommend lower ratios and more gentle compression. Only you can prevent over-compression.

Knee

This variable knee allows you to adjust this control to set the desired character of the compression. Since “character” is arguably one of audio’s most overused words, here’s what we mean here: Higher settings result in a “soft knee” setting with a subtler, natural-sounding compression, whereas lower settings result in a “hard knee” setting with a more aggressive-sounding compression, often used as an intended effect on individual tracks such as kick and snare drum(s).

Attack / Release

Adjust the attack and release controls to set how quickly the Compressor module reacts to audio that crosses the threshold.

  • Attack determines how quickly the dynamic processor reacts when the threshold is reached.
  • Release determines the amount of time before the dynamics processor returns the level to normal once the signal is no longer above the threshold.

Mix

Adjust this slider to control the dry/wet mix of the direct, unprocessed signal to the processed signal for the module.

Gain

This behavior is identical to the Output Gain parameter described above, but is specific to whichever band you have selected.

Sidechain

Neutron’s Compressor has powerful and detailed sidechain support, meaning you can have a band’s dynamic behavior dictated by a wide variety of other input signals.

By default, a band is triggered by its own audio input but you can use the Internal function to choose any other band of the Compressor. You might like the warm midrange of a guitar (say, band 2) to actually trigger the boomy, muddy low end (say, band 1) dynamically up or down. It’s a phenomenally powerful way to balance a signal within itself. You can also select Internal Full, which will take the full bandwidth of the audio signal, and not anything node specific.

If you’re using the DAW’s external bus routing functionality, you can take audio from another track or bus, and use that as the sidechain/key input into Neutron. Not only can you take the External Full bandwidth audio signal, but you could also choose any External Bands, which passes the External audio through the same internal bands to allow you to choose only certain areas of your External signal as sidechain/key inputs.

Bypass

Bypass the processing for the associated band by clicking the ‘B’ button

Solo

Solo the associated band by clicking the ’S’ button

Add/remove

Add/remove the associated band by clicking on the power button (next to S and B buttons)

More information

Limiters/Compressors were originally invented to prevent overmodulation in a radio broadcast signal. As decades past, and engineers realized more of the practical and aesthetic use cases, compressors have become one of the most used audio processing techniques in modern recording, mixing, and mastering. They can help improve intelligibility in vocals, tame an overly aggressive snare drum, and restrict dynamic range across a mix so that the listener does not have to keep adjusting the volume on their playback system.

Compression is one of the effects we hear most but, if done correctly, the listener will not even be aware that it’s there. While many mix engineers favor compressors that color their audio, when it comes to mixing, transparency is key. One of the challenges mixing engineers face is that different parts of the frequency spectrum will require different compression settings to effectively reduce dynamic range. Individually tuning the attack time, or the length of time before the compressor begins reducing gain, is key.

If a recording of a bright guitar and a bass drum is sent through a compressor with a short attack time, the transients of the guitar will be tamed, but the bass drum will lose its punch and feel choked. With the short attack time, the low frequency transient information in the bass drum does not have enough time to make it through before the compressor kicks in. If the attack time is set longer, the bass drum may have the desired punch before the compressor kicks in but the guitar will sound harsh. Its high frequency transients take a far shorter time to get through—and as a result, the compressor will not compress the guitar much at all.