Mpressive Software Emulation

by Gunnar E. Olsson
Monitor (Sweden) – March 2010

In June 2007, Monitor Magazine tested a piece of gear that truly belongs to the most modern and high end compressors in the market ever: the elysia alpha. A little bit later, the competent Germans introduced an equally inspiring follower: the mpressor. The price tags for these hardware monsters prevented many smaller studios from using their advantages, though. Now this problem is solved by introducing a software version of the mpressor.

The price of an alpha is around 8,000 Euro excl. VAT and the mpressor is not that far away with its 3,500 Euro. The software version addresses smaller studios and musicians, however. Our editor Jörgen Cremonese is still of the opinion that the alpha which he titled 'Miracle Machine' is worth every Cent of its price, but a price tag of around 290 Euro for the software version of the mpressor pleases the eye much better. This price seems to be much less daunting.

The cooperation with another German company (which is Brainworx who have also programmed the software versions of the SPL hardware – Monitor 07/09) made it possible to emulate the very sophisticated mpressor hardware, which is a fully discrete design running in class-A mode. And without exaggeration one can say that the mpressor (just like the alpha) is truly impressive, and it also sounds this way.

Features
The mpressor is a stereo compressor with the possibility to run its two channels linked or separate from each other. The compressor can be triggered from external source signals (side-chain) and it can be used as a universal and flexible tool for many tasks, even for mastering. In order to be able to use the sidechain functionality, your host software must support this feature, but most of the actual versions do this anyway.

But the mpressor also offers some special functions which have partly been borrowed from its big brother. 'Auto Fast' means that the attack time is automatically adapted to the source material, becoming very short on fast transients. elysia aimed at keeping this functions free from artifacts, and they obviously succeeded in doing so.

The 'Anti Log' for the release curve results in a different sound character than we are used to, and it can be used to create some very interesting sound effects. In this mode, the beginning of a signal is processed with a longer release time which is shortened while the signal sustains. If you want to get those drums pumpin', just activate the Anti Log function.

The 'Gain Reduction Limiter' is not the standard limiter you might have in mind. Instead of limiting the audio output level, the Gain Reduktion Limiter controls the maximum allowed amount of gain reduction instead. For this reason, the limiter is not placed in the audio path, but in a place where it can have its influence on the virtual control voltage. This means: not matter how high the input level is, the compressor will never process a signal any stronger than you have allowed with the GRL controller. This way, the weaker signal parts can be compressed while the dynamics of the stronger signal parts remain intact – opening the floodgates to creative musical ideas.

The 'Niveau Filter' is another great function which can be used in very creative ways. It is similar to the tilt filter type that can be found on some HiFi products. It influences both sides around a selectable center frequency differently and can shape the tonal balance radically with just two controllers. The first pot sets the center frequency, and the second one sets the intensity of the filter's effect. The basis for this EQ Gain controller is the middle 0-position. When it is turned clockwise, the bass is boosted and the treble is cut at the same time. When turned into the other direction, the effect works the other way round. Finally, there is an additional button which multiplies the chosen frequency times ten. Very effective! In the outer regions of the EQ Frequency controller range the character of the filter changes, becoming a low pass filter or a high pass filter respectively in the extreme positions of the controller.

The function 'Negative Ratios' should not be mistaken for expansion. With the usual ratio settings used, the mpressor behaves like a typical hard knee compressor, and the ratio curve changes in the typical way once the threshold has been passed. When negative ratios are set, though, the curve goes back down again. This means: The stronger the input signal is, the further it is bent down. In combination with the other specials of the mpressor this gives you the possibility to create fascinating sound collages. Echo and reverb effects can be given a life of their own. However, the M/S matrix of the alpha compressor has not been included. If you are looking for something like this, Brainworx offers some very interesting products here (www.brainworx.de).

Handling
If you need some help, you can download a manual in PDF format. This manual has a good structure, is well written and really does what it's supposed to. It provides lots of demo settings which can be used as a basis for your own work. A difference to the hardware is that the software does not have an individual set of controls for its left and right channel. When two single mono channels are to be compressed, two channels of mpressor have to be opened. But this does not require too much CPU power, therefore quite a lot of mpressor instances can be opened at the same time without the processor getting into trouble.

The mpressor has all the controllers you would expect to see on a compressor: Threshold, attack, release, ratio, make-up gain and an LED meter that shows the amount of gain reduction and eventual activity of the Gain Reduction Limiter. On top of this there are some controllers and buttons for the additional special features of the mpressor.

But even with all these fantastic advantages, the software has a little problem. The construction of the hardware is incredibly solid, with metal knobs that ooze quality in all their aspects. But the attempt to emulate this in all its aspects in software can cause some problems concerning the interface design. While the three-dimensionality and the illumination of the hardware are a good help, the values on the software front panel can be hard to read. Especially the numbers around the pots could benefit from a larger size. Of course this is a matter of taste, and a monitor with a different resolution could improve the situation. However, I had some difficulties in reading my settings from time to time...

Sound
The mpressor has all the possibilities you would expect from a top class compressor. It works exceptionally well with all conventional settings – and the same is true of its sound. Experimenting with the Auto Fast, Gain Reduction Limiter and Niveau Filter features results in sounds that only very few other units can generate. 'Transparency' is not really the first impression which comes to mind then, but it's also not ment to be. To sum it up, the mpressor easily covers the complete range of possible sounds – from discreet and transparent processing to very punchy sound effects. It's getting full marks for its sound!

Summary
I was not able to provide a direct A/B test between the hardware and the software, but I can't get rid of the impression that the transfer of the hardware mpressor's motto – sound quality without compromise – went really well. The software works as fine as a mixing and mastering compressor as it does as a creative sound tool. Working with the mpressor is extremely easy, but it is full of great surprises at the same time. And should you still be in doubt after reading this: there is a trial version that can be downloaded from the manufacturer's website. All you need is an iLok. My opinion: very mpressive!