I've always assumed that Elysia is a made up name but when I finally got round to checking, it turns out that Elysia is a genus of sea slug! Maybe its because slugs are squishy as are some compressors? Never mind. On to talking about the Mpressor.
The Alpha Compressor was Elysia's first product, it is a high-end mastering compressor and as such is designed to be clean and transparent, generally benign in the way we're all supposed to want our compressors to be - An ultimate compressor. The problem is that when I use these "grown up" compressors, I usually find myself hankering after something a little more assertive, something which wants to shout about itself a little more. That's pretty much what the Mpressor is about.
The Mpressor offers very flexible compression and besides the usual suspects of threshold, attack, release, ratio and make-up gain, there are a few extras which extend the capabilities of this design beyond traditional designs. These include:
Auto fast - This feature allows the compressor to react differently to loud, fast attack transients, significantly shortening the attack time in response to these transients but responding with the attack time as indicated on the front panel the rest of the time. Allowing your attack time to not be dictated by the drums or other sharp transients in your material.
Anti Log - We all know that fast release times give the audible, pumpy compression artefacts which characterise so many obvious compression effects. Logarithmic release times are common on compressors because they offer a progressive speeding up of the release time meaning that the deeper the compression, the faster the release - a bit like a spring - the further you go the faster the release. Elysia offer an anti log behaviour where the release time gets longer the further into gain reduction you go. Odd, counter-intuitive and therefore interesting.
Gain Reduction Limiting - I first came across this in the excellent Pro Compressor from Avid. It's very easy to understand and so useful, I wonder how I got by without it. You can set a limit on the maximum amount of gain reduction applied by the limiter. To my ears this is a much more acceptable way to use heavy-handed compression and back off its excesses than using paralell compression. You can compress the middle of the dynamic range of a signal while controlling the effect this compression will have on the peaks.
Niveau filter - Available as a free plug in on its own from Plug In Alliance, this filter is designed to shape the whole spectrum using only two controls and its combination of a dual shelf/tilt EQ which becomes a high or low pass filter combined with a centre frequency control offers every combination of brighter through to darker I can ever imagine needing.
Negative Compression Ratios - I was first aware ot these on the early Waves compressors. Contronting the fundamentals of dynamics, namely that as sounds get louder into a compressor, they still get louder on the way out, or in the case of limiting, stay the same level. In the case of negative compression ratios once the threshold is exceeded the output actually falls. This opens up a whole new world of level-based effects, from wild pumping effects through to pseudo backwards sounds. If you want to make your compression noticeable, people will notice this!