Monitor 03/2010
Gunnar E. Olsson: "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."
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Future Music 02/2010
Stuart Bruce: "From subtle but controlled compression to radical pumping, tonal shaping to complete changes in the feel of a groove, the Mpressor will certainly make a mark on your music. Add to that great sonic quality and this is a very powerful and musical tool that you’ll find yourself reaching for every day."
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Keys 02/2010
Martin Keller: "The mpressor can be used on versatile occasions  […] The sound is excellent, clear and warm with a high resolution. The special features like Anti Log and negative ratios described above allow deep transformations and manipulations which point out the mpressor's qualities as a unique tool."
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Delamar 01/2010
Mario Laemmerhirt: "If you ask me, elysia have kept their promise all along the line. I, for one, could not find a fly in the ointment. The mpressor cuts an extremely fine figure when used as a creative sound shaping tool. I experienced its interesting compression effects to be very convincing. My new reference class."
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Apfelwahn Music 01/2010
Heiko Wallauer: "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. With its many special features it convinces all along the line."
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Audio News Room 01/2010
Fab: "One of the most original compressors of our times, faithfully modeled and ready to be used on multiple tracks on your DAW. The mpressor can be an excellent all-round compressor, but to me it really shines on more experimental tasks, thanks to its unique controls."
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Sonic Scoop 01/2010
Geoff Sanoff: "The mpressor definitely has a color to it, though it’s a color with many gradations of density and tone, far more than most compressors. While it does transparent reasonably well, it does character much better. […] What the Distressor has become to modern recording, the mpressor plug-in may well become to in-the-box mixing."
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96kHz.de 12/2009
Klangfabrique: "The mpressor shines because of its sonic qualities, its accurate and solid dynamics processing, its flexibility and its intuitive operation. Its functionality outranges normal compressors by offering new and and almost playful ways to create unimagined soundscapes. The title 'creative compressor' is justified by all means."
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Recording.de 12/2009
Andreas Ecker: "The mpressor is absolutely convincing: sound and flexibility are top notch. My earlier favorites now have to face a serious rival, as because of its special features it beats them as an allrounder with a good lot of esprit."
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Guitarlounge 12/2009
Ludvig Nylund: "The mpressor is modern and versatile, it’s clean and tight, when you want it to be breathy it breathes, when you tell it to be subtle and transparent it obeys and if you throw it out there to be whacky and angry it does that just as well… all while retaining stellar quality."
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elysia mpressor compressor plugin

by Barry Rudolph
Gear Lust (USA) – May 2010

The mpressor is a virtually modeled version of the company's popular hardware hard-knee compressor unit. The same brain trust that designed the Brainworx plug-ins did all the development and translated the all-discrete circuit design of the mpressor compressor to a software emulation that runs as TDM/RTAS, VST and AU plug-in. Like elysia's niveau filter plug-in, mpressor uses oversampling for higher resolution processing. For sessions running under 50kHz sample rates, it uses 4X oversampling; for sessions between 50kHz and 100kHz rates 2X; and for sessions over 100kHz, there is no oversampling.

I installed the TDM/RTAS version into my PPC Quadcore Mac running OS 10.4.11 and Pro Tools HD Accel ver 7.4cs11. mpressor is iLok authorized and is "good to go" in Windows XP, Vista, and 7 PCs and MAC OS 10.4 or above and on Power PCs or MacTel computers.

Like the hardware unit, the mpressor plug-in has significant features that separate it from other compressors and make it attractive to me for its many processing possibilities and creative uses in music production. It would be against design objectives to include a Soft Knee button on mpressor as its designers are proud to focus and concentrate on its hard knee purpose. I'm glad they did!

GUI and mpressor's functions
A look at the GUI and mpressor's functions reveals the many reasons this is a musically creative processor. Being first of all a compressor, mpressor has all the typical controls any compressor but the additional controls, built-in elysia niveau filter, plus the greatly expanded range of compression parameters and values broaden the sonic creative possibilities.

Threshold and attack controls
mpressor's Threshold control covers a tremendous range: +16 to -18dB or 34dB. Unless you are trying to compress a very low level recording, this range works well to offer good resolution in dialing in the best threshold setting.

Like all the controls on mpressor, Threshold "mouses" smoothly and the plug-in supports mouse wheel use with quick keys for fine mode and standard position noted in the manual for VST, AU, and TDM/RTAS hosts. VST hosts can also toggle its knob action between circular and linear control.

The SC External button switches the control signal from being derived from the input signal over to an external source coming into the sidechain input. (Your DAW host program permitting). The Ext SC input has a built-in 80Hz/6dB per octave high pass filter to reduce unwanted gain reduction swings due to low frequency peaks in the side-chain.

Things get more interesting with the Attack control. Attack ranges from 0.01MS (10 microseconds) to 150MS--fast! I found mpressor to start gain reductions so fast that I could remove all attack of a sound if I wanted. It is useful for adjusting the "length" of the attacks somewhat in the same way as possible with SPL's Transient Designer.

The Auto Fast mode, when switched in, varies the attack time predicated upon the signal's speed and instantaneous level--short and loud moments trigger faster attack times. Otherwise faster attacks are on an "as needed basis" and for all other audio, attack times are as indicated and set.

Release controls
Next is the Release time knob with a setting range of 5MS to 1.2Sec. mpressor scores again with a choice between a linear and logarithmic release time curves switched in using a button called Anti-Log.

Most compressors, in an attempt to be "unheard" or appear to do little to the sound employ variations of linear and logarithmic release times--a smooth and natural curve or ramp of the change in gain when a compressor returns from gain reduction back to unity.

After a deep gain reduction from a loud peak such as a snare drum hit, a logarithmic release curve raises the gain back up faster than when using a release time with a straight-line, linear release shape. This action works well for drum compression when using fast release time settings.

Flipping the log curve upside down, this inverse release time curve or anti-logarithmic releases initially slower after a deep gain reduction. This is wacky and invites all sorts of goofy "characteristics" to the sonic party! (More later on using this feature!)

Ratio and negative ratio
Ratios are continuously variable from 1:1 to 10:1 to -4.0:1. That's right a negative 4:1 ratio. Setting ratio is like any other compressor except you can go negative--below 1:1. A negative ratio causes the output level to go lower with increased input signal level. This produces a pronounced pumping and dynamic expansion during the release time period. (I'll explain this more during my In The Studio testing)

Niveau filter
Post compressor is elysia's niveau filter for tonal shaping the compressed sound. This is a sliding high and low shelving filter with just two controls: EQ Gain and EQ Frequency.

After you set a center frequency position, boosting the gain control raises the level of all frequencies above and reduces all frequencies below this center frequency. Conversely, moving the gain control CCW reduces all frequencies above and boosts all frequencies below. This filter has 6dB/octave slope, In/Out button and a X10 switch to jump the frequency range from 26Hz to 2.2kHz up to 260Hz to 22kHz. I found this filter to "carve" or limit the bandwidth of any sound in a musical way so that it fits better into a dense mix.

GR limit
Also with an In/Out button, the Gain Reduction Limiter applies a second control signal to the gain controlling engine within mpressor. The GR Limiter section does not pass audio itself but rather offers up to 21dB of protection. Working like a dynamic "lid", GR Limit will not allow level above its setting.

Gain
Output make up gain is controlled by the Gain control. Like the hardware unit it is modeled after, mpresssor imparts more harmonic content as this control is cranked. At first use, I thought the output level of mpressor was low since winding up this control produced little increase. It does go up in level but adds more of a broadening effect on the overall sound due to the addition of 2nd and 3rd harmonic distortion.

The mpressor hardware unit (which the plug-in closely follows) is specified at producing a THD+N @ 0dBu at 0.04% and at +10dBu, 0.33%. Very cool but if you need more clean level, make it up with the track fader or by adding another plug-in afterwards.

In the studio
Here at my Tones 4 $ Studios first up were typical compressor jobs mixers run into everyday: electric guitar and electric bass guitar.

The guitar track sample (all samples are 192kBps .mp3 files) is a well-recorded rhythm guitar part I needed to have stand taller in the track. In this example, results are not dramatically different except for the way the guitar now sits in the mix. It is now a more constant element--a almost droning part without much dynamical sparkle to draw a lot of attention to it. I also liked its new intensity caused by mpressor.

For this song my bass guitar track got a similar treatment like the guitar but with a lower ratio and higher threshold settings. I also used a slower attack and especially a longer release time setting. Listening to the sound samples indicates a smoother bass track--mpressor is working in a very 'pro', old-school mixing manner here. I'm going for a cleaner and deeper (Check the niveau setting), fatter bass sound so I did not crank the output extremely high--just enough to give the bass a little "hair."

My snare drum track sample example shows how to mangle a perfectly nice-sounding snare drum recording! Notice the fairly high threshold and equally fast attack and release time settings. I've also set a negative ratio and have the Anti-Log button in. All these settings achieved an extremely clean pumping sound free of nasty compressor artifacts most compressors emit when pushed this far. It has the effect of nearly dynamically reversing the snare drum envelope.

For this song, I actually back it all down--you can go much more extreme than this and elysia's Web site has some more radical examples! This kind of processing works great on a lot of different sound sources. You can carefully set the release time so that the effect is in sync with the session tempo. Locking release time to tempo might make a nice update for this plug. The only plug-in I can think of that has release time lockable to session tempo is called H-Comp--it's part of the WAVES Hybrid Bundle.

Above are two mpressors I used on a mono drum loop. I duplicated the original loop and panned each track left and right. The differences in the settings on each instance of mpressor are very different. I'm using GR Limit on the right but not the left. I'm also using vastly different niveau filter settings too. Since each side is pumping differently, the next result is a kind of "animation" to the loop without any phase trickery or delay use.

Big thumbs up!
I found many uses for the mpressor all around my mixes. It is extremely versatile and not just a special effects plug-in. I did get into the Auto Fast feature and found it to work well when first setting up any compression when you are not sure of the "ebb and flow" of a particular vocal or instrumental track.

The negative ratio and Anti Log release mode are strictly fun! I can do crazy effects like I used to do with the old Eventide Omnipressor unit and now with their plug-in but in a lot more direct, faster and less tweaky way.

The Gain Reduction Limiter is an important tool to control the plug-in's output no matter how extreme you get because it is completely independent from the threshold and ratio settings. My next experiments will be to control the mpressor using the external sidechain input for syncing compression with session tempos.

I'm highly recommending the mpressor for its versatility and unique abilities not obtainable with any other processor. It excels especially in the creative side by radically altering the dynamic envelope of sounds yet it can also behave very civilized when you require.