Moog's Evolution? - Rossum (E-mu) Evolution Filter

Hey folks,

following my slightly provocative headline, I couldn’t find much info or user experiences on Dave Rossum’s Evolution Filter, neither here nor on muffwiggler. Before E-mu got into Samplers in the 80’s, E-mu was actually producing some amazing and super rare modular synths. Amongst others, E-mu’s Dave Rossum took Bob Moog’s ladder filter patent and allegedly even improved it here and there. Now 40 years later Dave Rossum released a eurorack filter.

From the few demos that are out there, I’m really intrigued. Also I can get it for just 200€.

Check out these videos

Rossum Evolution Filter vs Moog Sub Phatty
Rossum Evolution 1/4: Overview

Since I’m thinking of getting another filter module, what do you think of it (compared to the AJH, Intellijel Polaris… etc)? Thanks for your experiences / opinions

I have one, I’ve not done a huge amount with my modular. But it sounds good.

Dave’s stuff is purely a labour of love these days, I’m sure he could easily afford to retire.

As his website mentions, this is a classic “mod” he did to the Moog filter years ago. If you like the sound of the ladder filter then this is even better.

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So I used the Emu modular in college (UCSC) and can confirm the low pass filter is amazing. I recall it as being really rich and resonant with plenty of bass passing though even as the resonance is turned up, it made a big impression on me as a youth when compared with the digital filter in my Roland keyboard. Encountering the Evolution in my friend’s eurorack was a trip down memory lane! The sound I remembered is intact, and the added parameters do enhance the versatility as advertised. My only complaint is the placement of the cutoff knob. All my other filters have a cutoff knob that is somewhat larger than the others and offset from the rest with the understanding that it is a performance parameter and you will want to use it more than the rest. The Evolution places cutoff pretty close to the edge of the module as well as the other knobs, which are the same size. So, if you end up getting one, place it next to modules that allow you to access the top and side.

I happen to have the Polaris filter and have nothing but good things to say about it. The LP, BP, and HP outputs all have clean defined sounds with beautifully balanced resonance that work in patches where the filter isn’t the star of the show. The multi output, however allows you to switch between different configurations with inverted stages and unusual filter types such as notch and allpass that cover a LOT of ground, especially when internally driven with multi-distort. The dual CV inputs, one attenuverter and the other scaling up to VPO make Polaris my patching work horse. I will never sell Polaris.

I also have a AJH Sonic XV Diode Wave filter, which I acquired because of the design similarities to the VCS3 and the unusual addition of a diode waveshaper. The front panel definitely receives a top score for build quality, clarity, and ergonomics. The sound however is very specific. While the Polaris is adept at sounding like many filters, the Sonic XV imprints itself on any signal that runs through it, subtly distorting sounds even when the filter is “open.” Sometimes I will struggle to get a sound out of it that isn’t muffled or super crunchy, and then I will find a sweet spot that makes all the travail worth while. In other words, I got more than I bargained for. The fickleness of old designs turn out to be part and parcel of their authenticity.

Etc. filters in my rack are a pair if Pittsburgh filters. The LPG II is a really nice-sounding RESONANT (because it is loud when it self-oscillates) low pass reminiscent of an MS-20 but with a lagging vactrol response. I tend to use LPG II when I am looking to filter a feedback loop or in a simple subtractive voice. My second Pittsburgh filter is a Binary Filter. In contrast to the LPG II, the Binary has a BP and HP outputs in addition to low pass and has a limiting circuit for resonance allowing for gummy fat sound that is a joy to sweep across a lead synth sound. Alternatively, you can turn off the resonance limiting and it will be just as ill-mannered as the LPG II. Neither filter has VPO inputs so making keyboard tracking patches with them requires a little CV mixing. This bothered me at first, but being forced to patch around this limitation lead to many pleasing sonic accidents so I can’t really say it’s a weakness. Overall I would say the Pittsburgh filters are enjoyable, compact but with a big honking cutoff knob, and inexpensive.

And that, is my life story.