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CompressorBank Applications

The McDSP CompressorBank v6 plug-in is a truly flexible dynamic range compression device. The plug-in comes with 3 configurations covering the basic compressor (CB101) to the ultra tweaky (CB303).

But the curse of too many options is, well, too many options. How should the unique Knee and BITE controls be used? What exactly is the pre-filter section capable of? Can you explain the difference between the Static and Dynamic EQ modes? If any of these questions seem familiar, then read on! In this issue we’ll look at various applications of CompressorBank.

The Thwack Effect – BITE vs. Attack

In addition to offering the standard attack control – the rate at which the compressor starts to reduce output level (i.e. compress it!), CompressorBank comes with a unique control called BITE, and is included on CompressorBank configurations CB101, CB202, and CB303. BITE stands for Bi-directional Intelligent Transient Enhancement. When the BITE control is set to its minimum value, it has no effect on the compressor output. As the BITE control is increased, signal transients (the initial hit from a snare or crash cymbal for example) pass through the compressor unaffected, while the rest of the signal is processed as per the Attack control. What does it sound like? Well, like more ‘bite’ is being added to the sound!

A great way to audition the BITE control is using a heavy compressed setting (for example: a low threshold of –40 dB, a high compression ratio of 8:1, and a modest release of 100 msec) processing a drum kit. Set the BITE and attack controls to their minimum settings. Now slowly increase the attack time. Return the attack to its minimum setting, and now slowly increase the BITE. The overall sound of the kit – the snare and kick hits, etc. become less compressed as the attack time is increased. But when the BITE control is increased instead, only the initial hit of the percussion comes out, the rest remains somewhat compressed.

I’ll be the first the admit the range of the BITE control is too large – I have always found values from about 2.0 to 10.0 work for most applications. BITE values nearly 20.0 and greater put the whole compressor into a ‘near failure’ state, but many customers like the sound, and so the range remains.

There are some presets included in the CompressorBank installed called ‘Drum Thwack’ that illustrate the effect of the BITE control very well. Other presets are included at the end of this article.

PreFiltering – Why, How, What

Using a pre-filter really opens up the application possibilities for a compressor. The pre-filter section in CompressorBank configurations CB202 and CB303 offer high pass, band pass, low pass, and parametric EQ options. Below are a few good uses of this filter/EQ types as a pre-filter for dynamic range compression.

Mid-Range Boost/Cut

Human hearing is more sensitive to mid range frequencies (let’s say between 600 and 3 kHz). So why not setup the compressor to do the same? Choose the parametric mode in the pre-filter section, a Q value of 0.7, a boost of between 4 and 6 dB, and a frequency between 600 and 3 kHz. Some program material or another drum kit, audition the effect of first changing only the amount of gain (vary it between 0 and 6 dB). Then try out different frequencies (use a gain of 6 dB for maximum effect). The compressor can get a little pump in it, which may (or may not) be desirable. But note how much of the character of the compressor has changed just from adjusting the freq or gain control of the parametric EQ in the pre-filter section. You can try tighter Q values (2.0 or greater), but that can make the compressor too frequency selective. Wide Q settings (less than 0.7) reduce the frequency selectivity.

De-esser

CompressorBank can be made into a decent de-esser by choosing a high pass filter as the pre-filter type. Select a vocal or dialog track with some ‘ssss’ in it (the sibilant kind, hopefully not the background noise kind!). Put the pre-filter in high pass filter mode, keep the Q at the nominal 0.7, and choose a frequency around 1 to 3 kHz. Start playback, and put the filter mode INLINE – this will allow you to hear the effect of the pre filter, and observe how the compressor is responding. For de-essing, try at attack around 0.1 to 1 msec, a release of 40 to 60 msec, the max compression ratio (10:1), and vary the threshold to suit the input. The idea is to get the ‘sss’ events to trigger the compression action, while normal dialog or singing) triggers it very little. Once the pre-filter appears to be about right, disable the INLINE mode. Now you have a de-esser! Vary the threshold level as needed.

Another approach is the same as the above, but use a band pass filter at the same frequency (keep the Q at 0.7 as well). Still another variation is to go back to the high pass filter and increase the Q for a resonant peak that will further emphasis the ‘sss’ events you are trying to get rid off.

Smooth Comp / Bass Comp

Sometimes the luxury of digital gets us into trouble. Have you ever noticed your digital compressor puts some buzzing artifacts into your tracks? Well, back off the fast attack and release times dang it! But even when modest attack and release times are selected (attack greater than 5 msec, release greater than 250 msec), the buzzing can persist in bass heavy tracks like bass guitar.

Enter the pre-filter section again. Choose the low pass filter mode, a default Q of 0.7, and a frequency between 200 and 800 Hz. Now listen to that playback again. By filtering out the high frequencies from the key signal, the compressor is no longer tracking those signals, and hence no longer produces buzzing at the output.

Broaden this approach to program material. On a two track mix, try the same low pass filter prefilter setup, but choose a frequency between 2 and 8 kHz. Note the compressor response becomes smoother (even with the same attack and release times). A nice way to round out your mix.

Static/Dynamic EQ

CompressorBank CB303 included a parametric EQ after the compressor stage that can operate as a fixed EQ, or actively track the dynamic range compression. The Static, or fixed mode, is a normal parametric EQ. EQ after compression is a good way to re-introduce parts of the audio that was ‘compressed out’. The Dynamic, or active mode, varies its gain between 0 dB and the selected gain value, at a rate equal to the attack and release of the compressor, and only when the compressor is actually compressing.

So did that make sense? Yeah, it is a mouthful. Let’s break it down this way. Put CB3 on a two track drum sub mix. Compress the heck out of it (threshold = -40 dB, comp ratio = 10.0, attack = 1 msec, release = 80 msec). Choose the Static EQ setting, a gain of +12 dB, and a frequency of somewhere between 800 and 2kHz – right around the snare hit. You’ll note the track is much brighter and harsher. Now set the comp ratio to 1:1 so the compressor is not doing anything to the signal, and choose the Dynamic EQ mode. Note how the harsh mid range is only EQ’d in as the snare hit occurs. To further increase this effect, go to the pre-filter section, choose a Q of 0.7, band pass filter mode, and the same frequency as selected in the Static/Dynamic EQ section. Now the compressor is only listening to frequencies near the selected frequency, and then only triggering the active EQ for those events (snare hits) with even greater selectivity.

The Static/Dynamic EQ section in CB303 really opens up some possibilities. You could add some subtle mid range cut as the compressor does its thing, for a smoother ‘warm’ sound. You could use the Dynamic EQ as a de-esser by using frequencies listed in the de-esser section above, and a cut gain of –24 dB. Or you could give tracks some top end lift with a high frequency (20 kHz), wide Q (0.2), and a gain of +3 dB.

Well, the possibilities are there. Tweak away. Be sure to bill your client for all those hours!

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