State variable filters continue to be one of my favorite creative tools in synthesis, and recently I’ve been keeping a few modules in a small desktop skiff for processing any given audio source that needs additional shaping and character. During a recent trip to California, I tucked Animal Factory's Bonesaw into my backpack for some much needed creative time while traveling. Stepping away from normal life left some free headspace to dive deep into the module and learn a bit about the company's amazing work. Based in Mumbai, India, founder Aditya Nandwana leads a small team specializing in both Eurorack and pedal designs that “sing, shriek, and wail.” I don’t usually lean towards this aesthetic in my music, but the more I use Bonesaw, the more I realize what I’ve been missing. I’m truly impressed with Bonesaw’s musicality, build quality, and its ability to express some very serious sonic bliss.
What’s so special about Bonesaw? The first thing you notice is the panel design; it's quite striking—really visually interesting—and almost gives the impression of being etched by hand. Behind that faceplate, Bonesaw is a great sounding 6dB state variable filter, with a pre-filter drive control and an interesting FM implementation, which is fairly complex. The layout includes individual outputs for the lowpass, bandpass and highpass filters (yes!), and modulation inputs are plentiful, allowing for flexible CV control over Filter cutoff, FM amount, and Resonance, with translucent shafted attenuators for each feature for dialing in the perfect amount. The attenuators illuminate white with positive voltages and blue with negative and this is immensely helpful in keeping track of input activity, especially in a live setting.
As mentioned, the FM implementation is unique and one of my favorite features on Bonesaw. With nothing connected to the FM modulation input, the bandpass signal output is normalled to the FM input, creating a brilliant feedback loop. This does need a decent amount of resonance to activate, but once dialed in, raising the FM amount will start to produce a magical, woozy sawtooth that can be tracked with the filter CV input and treated like an oscillator, albeit one with a welcomed instability. The bipolar FM phase attenuator will impact the sound by shifting the phase positive or negative while FM amount is engaged, and the resulting sound…well, it depends! As each filter type has a specific reaction, it's different for each setting, which is where the complexity of this module really starts to register. Listening to the lowpass output while shifting the phase slightly in either direction starts to increase the gain and become slightly more jagged and by two o’clock the glistening metallic onslaught of frequency modulation pierces and flaps
Along with FM, the drive stage helps define the character of Bonesaw. Coupled with resonance and drive, the filter really sings in so many ways, and I was surprised how quickly I landed on an aggressive sounding 303 acid line without even trying, not to mention the thick, menacing bass tones that bloom and contort. I love how it pushes other parameters around in ways that are unpredictable and creative; everything is sympathetic and highly influenced by the drive, there's so much discovery to be had.
Animal Factory's Vivisect, their four-channel CV processor/offset and noise source, connects to Bonesaw via a six-wire cable on the back of the module, expanding the capabilities and value of this filter. I didn’t have Vivisect for this review, but in reading the documentation I can see how the pairing would be great for managing gain stages and summing different filter combinations, helpful for producing a shelving EQ, comb filter and even individually tapping the drive output for straight up distortion. I really appreciate when manufacturers offer stand-alone modules that also pair with others in their line-up as it offers options to either grow or pare down. In this case, I would easily grow my system to fit both.
Bonesaw is another great addition from Animal Factory, who continue to make unique sounding instruments that have immediacy, musicality, and an impressive realm of sonics. Even if distortion is not your thing, the textures it can make are truly vast and inspiring. By the time I was finishing up the review, I had connected multiple gate signals pinging the input, which in turn, produced the coolest murmurs, glitches and fuzz I'd yet to experience with my modular. Moments like that make Bonesaw feel endlessly inspiring, and it's a unique opportunity to place a state variable filter front and center, leading the way. 

Price: $209

animalfactoryamps.com