Featuring all fifteen of the famed Oberheim Matrix 12 synth filter options, plus an additional All-Pass four-pole phaser mode, totalling a whopping sixteen filters available in one module, AJH Synths raises the bar more than you'd ever think was possible for what constitutes a multi-mode filter with their Matrix VCF. But wait, there's more! Matrix VCF also has a Polyvox-inspired overdrive circuit for each of the chosen filters, effectively offering thirty-two total flavors of filtering under one 14HP roof, all while retaining an all-analog signal path. Craziness.
The filter modes available are Low Pass and High Pass (each offering from one to four poles), Band Pass (two or four poles), Notch, and four combination filter types (Two Pole HP + One Pole LP, Three Pole HP + One Pole LP, Three Pole AP + One Pole LP, and Two Pole Notch + One Pole LP), along with the four pole AP phaser, all neatly displayed along the left side of the module, illuminated with an LED next to each for whichever filter is in operation at the time. There are controls for Frequency (with CV input for modulation, where the control becomes an attenuator) and Resonance (with CV input). There are In and Out controls, with the Output being a VCA that can be modulated with CV, and there's a 1V/Oct input for tracking the filter within a three to five octave range. 1/3 and 2/3 inputs for tracking the cutoff frequency at 3V/Oct and 2V/Oct respectively are also on tap, and of course, saving the most obviously desired feature for what the Matrix VCF offers for last; yes, you can modulate the filter mode, with the Mode control becoming an attenuator when patched.
With so many filter types here and such different behavior for each type, you'll soon grasp how handy the In and Out are for getting a nice level. An LED near the Output will flash red when the signal is too hot, and switching from filter to filter can keep you busy getting levels right so that you don't have any unwanted distortion, especially when you factor in a healthy amount of resonance. Because of this, modulating the Mode can have issues in terms of levels, but we'll get to that.
Matrix VCF operates foremost as an excellent traditional multi-mode filter module. If you've ever had the pleasure of being able to play the Oberheim Matrix 12 in the flesh, as I have—once, about a decade ago; a neighbor of mine had one—it's a synth that leaves an indelible impression. I was pretty green and wasn't able to navigate the synth very well (i.e., at all!), but my neighbor was well versed in it and would punch up settings, then allow me to noodle away. I remember being awestruck by both the possibilities the Matrix 12 offered and the incredible sound coming out of my neighbor’s custom made studio monitors; it was a transformative moment. Until then, I really thought a synthesizer was just an electronic keyboard with weird sounds and didn't fully understand the science or technology behind it all. It set me on the path of synths and electronic music that I've been on ever since.
Even though my monitors are off-the-shelf mid levels, and my studio is nowhere near as acoustically blessed or equipmentally stacked as my old neighbor's, the AJH Matrix VCF sounds every bit as impressive as the Oberheim to my ears. With so many different modes, you can get nearly any filter sound and behavior that you could want, so that creating kicks and snares with every filter type (why not?!), dialing up long mutating drones, and using the Matrix VCF for traditional filter uses only demonstrates how versatile this module is. It might just be the most bang for the buck VCF ever. Really. And while the clean filtering is on point—almost utilitarian at this point—with the P-Vox (Polyvox) mode on, the Matrix VCF really shines, or rather shreds. The interaction in this mode when the resonance is at a certain amount—depending on the filter type—can be truly gnarly. Again, you really have to watch your in and out levels to make sure you're not getting harsh distortion (unless, of course, that's what you want), but the P-Vox setting really pushes this filter over the edge, and a lot of times over the limit.
The 1/3 and 2/3 inputs are really interesting for keyboard tracking, but used as extra modulation inputs (to give a total of four (for the frequency + resonance),) Matrix VCF can do all sorts of things that other filters could only dream of.
Of course, the crème de la crème of Matrix VCF is being able to cycle through the filter modes, going from one to another, though there is one caveat, in that there can be pops—which is totally normal and expected (and explained well in the manual)—that can happen when switching filter types. No matter, if sequenced or modulated at a more rapid pace, it's not so noticeable, and modulating this at audio rate, it becomes more or less part of the sound. Plus, there are workarounds for this by creatively employing various envelopes and techniques and part of the fun of all this modular stuff is problem solving, which is also why modular is so addictive. And also why modular rigs so often start off with nice, modest intentions, only to balloon into gargantuan setups oh so often.
As for modulating the Mode at audio rate, it brought this filter's usage to another level. Patching in a static square wave audio rate signal into the Mode CV input and tweaking the Mode amount and the frequency and res controls, and also the frequency of the VCO to nearly LFO rate and back again, brought me to new sonic territory, in a ring mod realm, but with less metallic over and undertones. Shaping the sound, using Matrix VCF as more of a sound source in this way, provided some stunning moments. Switching between tracking the VCO that was patched into the Mode CV input and tracking with the 1V/Oct input on Matrix VCF to see which I liked better was interesting. I found myself slightly mesmerized watching the range of modes change with the sequenced VCO—how many modes were being cycled through—due to the voltage change of a melodic sequence as opposed to, say, a fully cycling peak-to-peak LFO.
As for that range of modes, using Five 12's QV-L I was able to dial up a triangle LFO with just the right amount of level and offset to pick the location of the filter mode range on Matrix CF and span of modes to where I could cycle through any number of filters, and using a random square wave LFO I could move through the selected range in a non-linear, more organic fashion.
Pursuing further this type of exercise, it's possible to program/sequence filter types by figuring out each filters CV value (5V/16 = 0.3125V from filter to filter), though it's even easier using something like Joranalogue's Step 8 to use the sliders of each stage to select the required voltage for each filter mode on Matrix VCF. Just remember that the Mode control becomes an attenuator when CV is patched, so make sure it's fully CW if you want the full span of all sixteen filters. I decided I wanted to sequence only the four LP filters and figured out the voltage amounts needed to access each; (one pole =+3.75V, two pole =+1.25V, three pole =+4.375V, and four pole =+1.875V). It was a fun math/sequencing exercise and, with some modulation of the frequency and resonance that was synced to the main clock I was using, it created some pretty interesting rhythmic variation to match the pitch changes. Each note was tied to a particular filter type, and therefore had its own specific tone, which could be sculpted further in a myriad of ways. For my LPF only purposes, the differences tended to be somewhat subtle until I added enough resonance to make them more distinct, but it gave me a glimpse into what a more detailed version of this exercise could be. Also, using something like Step 8 for this made selecting the various filter modes a breeze.
Choosing even just a few filter types to sequence made me realize how powerful that could be, and the filtering minutiae available with this methodology is quite vast. Really, outside of just having a ridiculous amount of filter types in one module to audition, this is where the golden sonic explorations lie, that would take many more modules to do in any other instance. This is the most flexible and versatile filter I've ever come across. Bar none.
Filters are not something you have one of and are all set for life in modular, at least not in my case; far from it. There are so many flavors, types, and uses it'd be tempting to build a giant wall of nothing but VCFs. But for those not going that route, the Matrix VCF covers so much ground, and covers it so well it's absurd, and not just in the normal filter use scenarios. It's a great sonic adventure partner. I feel spoiled with it, and I'm not sure I'll ever be satisfied with a normal LP/HP/BP multi-mode VCF ever again.
Price: $469

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