DMG Audio Compassion review

It's been a while since we've seen a dynamics plug-in that fully embraces the power of digital, but Compassion is here to rectify the situation with its incredible array of features.

It's the most configurable dynamics plug-in we've encountered, offering compression, expansion/gating, transient shaping, and limiting/clipping. It's got over 80 parameters that can be used to approximate the sound of any compressor, reckon DMG. It's in VST, AU and RTAS formats.

Thankfully, you can treat it as a normal compressor to begin with, with the advanced controls hidden. In this mode, you'll see familiar knobs for Threshold, Ratio, Attack, Release, Dry/Wet mix and Makeup gain. There are automatic options for release time and makeup gain, and you can enable an external sidechain.

There are several visual feedback aids: a knee/transfer graph; a rolling display showing how the waveform is compressed in real time; level meters with gain reduction; and, most unusually, a graph showing the response of the attack and release curves.

Flick through the presets and you'll see the graphs change, indicating the flexibility of the advanced mode. There are only 15 presets, but Compassion also offers over 30 Mods, which are partial presets that alter only certain parameters, ie, the ones responsible for the compressor's character (you can save your own, too).

So, you can dial in the threshold, attack time, etc, then try out Mods with names like Classic FET, Classic Opto and British Type 1. They absolutely sound the part.

At the top of the interface is a toolbar with eight slots for preset comparison, which is handy, although we'd prefer eight buttons to the less immediate dropdown menu. The toolbar is also where you'll find the button for revealing the advanced parameters. Let's give it a click…

Manual intervention

In the advanced view, the lower half of the GUI shows small panels for paging through and tweaking parameters related to attack, ratio, etc. Each can be 'maximised' to show all related parameters at once.

It's all a bit overwhelming at first - we strongly recommend reading the manual, downloadable from DMG Audio's site, as it gives a clear explanation of each parameter.

The shape of attack and release curves can be modified extensively, with the results shown on the Response Graph. For instance, increasing Attack or Release Type can give a more squashy, delayed reaction to the input.

Likewise, the Knee Graph can be radically reshaped. The knee can be softened, a ceiling set so that compression is relaxed above a certain level (great for explosive drum sounds, allowing the transient to 'poke through'), and hysteresis dialled in, which you'd use to prevent 'chatter' in gating/expansion.

Over-easy compression can be dialled in using negative ratios and/or the Bleed control, which causes the compression amount to gradually increase above the threshold.

The attack and release times go right down to 0ms. With ultra-fast times, the sound can get rather gritty, as expected, but there are smoothing controls in the Global Parameters to effectively reduce any undesired distortion.

Go global

Other highlights of the Global Parameters are an RMS control for adjusting between peak and RMS tracking, Lookahead up to 180ms and mid/side operation. There's also an oversampling option; however, we found that it subtly dulled the treble of any signal passing through the plug-in.

If you use Compassion on, say, drum overheads, drum buss and master buss, the net effect of this is a little too noticeable. DMG Audio is aware of the issue and says they'll look into it.

One aspect that shouldn't be overlooked is the optional transient shaper/clipper/limiter section. The transient shaper sounds superb, and is ideal for restoring snap or suppressing sustain of over-compressed sounds. In some mixing situations, we discovered that transient shaping was in fact what we needed, so we ended up using this instead of compression.

The Clip Limiter offers clipping, limiting, or a 'blend' between the two, with a Softness control.

Putting Compassion to work in real-world mixing situations, we were surprised at how quick it was to get the desired results. We could use the presets/Mods to get going, and the advanced controls to tune the response to fit the sound in our head. You're essentially building the right compressor for the job.

The GUI is well designed given the underlying complexity, and you don't need to learn all of the advanced controls to create effective custom setups.

Feel the pump

The range of compression styles you can dial in is vast, ranging from super-precise, clean digital on through to outrageous, pumping analogue tones.

Impressively, we were able to create compression effects that we couldn't recreate with any of our other dynamics plug-ins; for example, we hit upon a drum buss setting that somehow thickened and enhanced the low end in a most pleasing and appropriate manner.

And the over-easy style of compression is great for bigging-up complex signals so that they sound massive and in-your-face yet still coherent.

Breaking the chains

Compassion's sidechaining goes beyond that of most dynamics plug-ins. First, there's an EQ section consisting of high- and low-pass filters with adjustable slope - they can be switched for shelving types too. You also get a bell peak.

Here, you've already got a highly flexible system for fine-tuning which frequencies Compassion responds to. You can also mix noise into the sidechain signal, for a looser, more analogue response. External sidechaining is possible, too, of course.

There's a Main EQ section too, which affects the audible signal (and, optionally, the sidechain signal), and it has the same EQ options, and again, the option to inject noise, which can enhance pumping compression effects. You can even apply a low-pass filter to the dry signal, so that you can mix in the uncompressed bottom end to restore low-end thump.

Perhaps most advanced is the Split EQ feature, which uses a linear-phase filter to split the dry and wet signals according to your main EQ settings. As the manual explains, this facilitates using Compassion as a dynamic EQ, or even using multiple instances to build a multiband processor.

However, for multiband work, we found this approach unwieldy and would rather use a dedicated processor.

Compassion's extreme flexibility and superb sound make it suitable for all occasions, from individual instruments and voices on through to busses and mastering. We particularly enjoyed using it on drums, since this instrument offers so much scope for dynamic reshaping.

So can you ditch your other compressors? While Compassion is a splendid go-to plug-in, we don't think it negates the value of owning others, especially ones with a specific sound that you know you can reach for. Still, it'll be interesting if more Mods become available that mimic certain compressors.

Experienced engineers should definitely check Compassion out. It's also great for anyone seeking a deeper understanding of dynamics processing on a fundamental level, as you can learn a lot by tweaking the under-the-hood parameters.

Beginners could, in theory, stick to the simple mode, but we think they'd be best off learning a less complex plug-in inside out.

Compassion could've turned out to be a baffling boffins' curiosity, but DMG Audio has done a superb job of making a complex concept accessible, and with a stellar sound to boot.

Now listen to our audio demos to hear Compassion in action:

Drumkit - dry

Drumkit - Drum Punch preset

Drumkit - Smooth preset cranked

Drumkit - Main Buss preset

Acoustic guitar - dry

Acoustic guitar - Smooth preset cranked

Acoustic guitar - Smooth preset gentle