Not the little brother!

by Franck Ernould
Réalisason (France) – April 2008

Unlike its price suggests, the mpressor, released a year later for the 2007 Musikmesse, is not the alpha compressor’s little brother. In spite of a couple similar novel features (the Auto Fast mode and the tilt EQ in the signal path) and the same build quality (e.g. the oversized power supply, discrete class-A technology, the (only;-) 8 mm front panel made of a strange “granited” material) it is designed to be a sound machine: The Anti Log function, for instance, provides an unusual release curve. We also get some negative ratios. The electronic design of the mpressor was tailored to generate some harmonic distortion with loud input levels.

What also differentiates the mpressor from the alpha is its ability to limit the amount of gain reduction to a definite value (via the GR Limit controller), between 0 to 21 dB. However, the novel and interesting M/S mode has disappeared. This is normal because of its price and positioning (towards recording studios more than mastering). The front panel features less controllers than the alpha compressor (2x4 pots + 2x3 switches per side, plus 3 switches in the middle back-lighted in red, which is maybe not as fancy as the noble white of the alpha), the double half-circle of red LEDs (only 13 per side) has changed into some lightly curved lines.

The back-lighted white circle with the logo of the company is still there. As on the alpha, the implementation of the controllers follows a consequent logic: The compression parameters with the Auto Fast (only for attack), and Anti Log mode switches on the upper level, and the EQ and gain controllers on the lower level.

Sound Design
The impressions we got in Tom Van Den Heuvel’s studio and later tests confirmed the “strong character” of the unit… mild settings make the mpressor be a well-behaved, efficient and transparent compressor, able to control the most tormented signals without being noticed. Tickle it a bit too much with some high input levels, the Anti Log release curve and negative ratios, and reveal the beast within, turning an acoustic snare drum into an 8-bit-drum-machine-snare, a GarageBand loop into a heavy-weight-beat, with its own type of saturation, not reminiscent of its “tube” counterparts. Unlike the alpha compressor, the mpressor works in hard-knee mode.

The attack time goes down to 10 micro-seconds if desired, and the Auto Fast mode avoids unwanted artifacts on bassy signals. The Auto Fast mode on the release on the alpha has been replaced here by a switchable Anti Log function. The release then follows an anti-logarithmic curve with the effect of a more intense pumping effect impossible to achieve with a more traditional compressor. The same effect could be done on Olivier Bolling’s Dynax, aka Mr. al.so…

The negative ratios are another unusual feature: Once you get to 1:10, you continue to -1:0.3… down to 1:-4. Not quite the same as an expander though, as the compressor will continue to work over the threshold… if this is giving you a headache, just one piece of advice: try it for real. By setting the right amount of negative ratio and GR Limit you will literally be able to shape your loops… And if the sound needs some extra bite, increase the input level and lower the gain knob accordingly. Wicked sound guaranteed!

Final Word
A different unit than the alpha, but just as captivating, even if it is aimed more for production than mastering. To some extent, the two units make a great combination! The price is pretty hefty, but so are the build quality and the sound.