Test: elysia mpressor

by Heiko Wallauer
Apfelwahn Music (Germany) – January 2010

I had my first and very positive encounter with elysia at the Musikmesse in Frankfurt some years ago. The friendly and competent people at the elysia booth explained the design and functions of the alpha compressor and the mpressor in all their details, and the first listening tests already revealed that these are high end products of outstanding quality. Now we have the mpressor as their first plug-in, a compressor for versatile and creative applications.

At first it might seem a little odd that a dedicated hardware specialist adventures into the software realm, but looking at it a little closer makes it become a consequent step. The classic studio with a huge SSL or Neve console and complex patchbays has become a rare thing by now. More and more  (and not only) preproductions and demos are completely produced in the box these days. Of course an 8x8 audio interface and a flexible patchbay is already sufficient to insert hardware into a computer based mix or a DAW mastering. But if one never records complete drumsets and the like, it is not so unlikely that the investment will go into just a few I/O channels of a higher quality.

Quite a lot of living room producers can do with just two channels of I/O, which makes inserting outboard equipment quite impossible, though. Not later than in situations like these, the availability of excellent hardware products in a software format becomes very welcome.

But the range of available dynamic processors is large, no matter if you are looking at hardware or software products. While the great lot of companies rides on vintage or pseudo-vintage vibes when writing code or using the soldering iron with references to Fairchild or Urei, elysia make their own way in terms of design and functionality.

The installation and authorization of the plug-in is very easy, but it needs an iLok. You transfer the license to your dongle, download and install the software and this is it. Easy, fast and efficient. You get the mpressor in the following flavors:
• Audio Unit
• VST
• RTAS and for users of ProTools HD systems a
• TDM version.

The hardware model is a discrete class-A compressor design, and a glance under its hood is nothing  but impressive. Concerning the file size to download, the software is much leaner.

Loading the mpressor into an insert slot of the DAW instantly strikes with a clean and tidy user interface which looks pretty much the same as the hardware and shows a single side of the hardware layout.

A virtual LED chain informs about the amount of gain reduction, which provides more valid information than a fidgeting VU meter recreation. The available controls are typical for a compressor, but there are also some additional features that make the mpressor stand out of the crowd.

The threshold controller sets the working point of the mpressor; it has a range from -18 to 16 dB.

Next to the threshold controller there is a sidechain button which makes it possible to control the mpressor by an additional external signal. A classic scenario for sidechain compression is a bass drum triggering the compression of an electric bass in order to enhance the rhythmic homogeneity. Another example could be a percussive signal triggering a synthesizer pad. As powerful low frequencies can become problematic when using the sidechain, the mpressor has a built-in high pass filter at 80 Hz with a slew rate of -6 dB per octave.

Attack and release don't appear too spectacular at first sight, but both controllers also offer extremely short time parameters. Attack ranges from 0.01 ms to 150 ms and release from 5 ms and 1200 ms. Setting attack and release can generally be a tricky thing, but with the mpressor this works pretty smoothly.

The mpressor has two very nice onboard helpers: The attack controller has a switchable Auto Fast function which automatically reduces the attack time on loud signal parts. With it, a longer attack setting can be chosen without the danger of short peaks breaking through, resulting in audible clicks or distortion. The release controller also provides a special feature: the Anti Log function automatically raises the release time after a strong signal impulse.

The ratio controller on the mpressor is something a bit special, as it also provides negative ratios on top of the standard values. In its positive range the compressor works from 1:1.2 to 1:10, while the negative values go from 1:-0.3 to 1:-4. If we join the dark side, so to say, the negative ratios will have the effect that the compression curve turns back down after crossing the threshold. This effect fits in nicely if making the compressor pump in a groovy way is the goal – or when you are looking for extreme dynamic deformations.

The Niveau Filter of the mpressor is also on the special side and vastly exceeds standard EQ applications. Depending on a variable frequency and the setting of its specific gain controller, the low and the high frequencies can be cut or boosted against each other. In the extreme settings of the gain controller this filter section becomes a low or a high pass respectively.

Let's go on with the gain reduction limiter. The elysia designers have not placed this module after the compressor section as usual, but instead they have integrated it into the compressor itself. This is an effective tool for limiting the amount of gain reduction, and once the value which has been set with the controller has been reached, the full remaining dynamic range stays available.

The gain controller compensates for the loss in level caused by the compression process, but it can also be used to generate additional harmonics and signal saturation.

The mpressor can be used as a mono or stereo compressor. In stereo mode, both channels can be run linked for a true stereo mode or unlinked for dual mono operation. Depending on the signal source, the unlinked mode can result in a fresher sounding mix, but in the worst case this will ruin the stereo image. It's a good idea to listen to this carefully.

The active button switches the plugin into the signal path or out of it respectively.

Sound examples
• Let's start with a bass drum. The first cycle begins with the uncompressed sound, then the mpressor is activated.
• In the next example I added some Led Zep vibes to the drums. Again it starts with the uncompressed signal, then the mpressor is activated on the drum subgroup.
• The same drum part, but this time I made the mpressor work near pumping to achieve an audible FX compression.
• Here I used the features of the mpressor to emphasize the attack phase of the snare.
• Decent compacting of an upright bass is also no problem for the mpressor.
• It also worked well with the percussive character of a rockabilly bass.
• Here the mpressor smoothes out guitar pickings of different intensities.
• A hi hat is used as a trigger signal in the sidechain to breathe live into a static pad sound. Some Niveau Filter action is added on top of it.
• This proves the destruction qualities of the mpressor.
• Negative ratios result in effects that sound more like a reverse gate on the hi hat than actual compression. The snare receives the touch of evil, too.
• Here is another example of how to alienate sounds with the mpressor. Short attack and release times in combination with Anti Log and negative ratios mangle this groove beyond recognition.
• And this is an example of using the mpressor on a sum of a finished mix. It starts in bypass, then the mpressor kicks in. For easy A/B comparison I have switched the compressor in and out from time to time.

Result
I took the mpressor to my heart quickly, because it convinced my ears of its benefits so easily. This plug-in is certainly not a one-trick-pony, but a very flexible one instead. No matter if you want to compress acoustic instruments the decent way, or raise the pressure on drums, or create spectacular effects – the mpressor does it all.

Apart from truly brutal destruction orgies, the mpressor stays transparent and sounds premium. With its many special features like negative ratios, Niveau Filter and the efficient Gain Reduction Limiter the mpressor convinces all along the line. Its handling is coherent.

It have tested the AU version with Logic 9 and Ableton Live 8 running on Mac OSX, and in both hosts everything worked like it should. Finally, does the hardware mpressor sound better? Looking at the quality of the plug-in, this question is not really relevant – if you want to benefit from the excellence of a hardware like this, the complete surrounding has to live up to this standard, too. The plugin is a high quality piece of software which enhances any signal. In summary, it is only consequent to award it with our Editors' Choice commendation.