SUMU Review
Madrona Labs Sumu has been anticipated for some time now, I’ve had the honor to be able to beta test this one, and you can read my beta preview here. An addition to their lineup of semi-modular experimental plugins, Sumu focusses on FM and additive resynthesis this time. Sumu’s UI is nice and simple, I love the soft grey with colorful patch cables running down the middle. A well, seeing the partials texture, scope pattern, pulses, and 3D envelope and space gives it a very fun and quirky design, lots of visual elements to play with.
The main oscillator in Sumu is a 64 partial additive resynthesis engine. This engine loads partial files which you can crate in the free open source program Vutu. This resynthesis method is quite novel, rather than detecting amplitude across an array of bands, Vutu looks for constant and drifting frequencies. This means all partials are utilized to their fullest potential, and any partial motion is contiguous rather than hopping from partial to partial. The analysis also includes a noise metric, so while 64 partials is quite low in other methods, it’s fairly adequate for most audio sources.
The resynthesized partials can then be played back as an oscillator, you can assign the time modulator to scan through them, or use other modulation sources to move around the partial array as you wish. It’s quite a nice alternative to granular scanning or wavetables, as you don’t have the same artifacts from stretching (though you do get some new ones). This additive engine then feeds into an FM/AM process, where you can modulate the partials individually to create new lively sounds and textures. The pitch and amplitude information of each partial can be applied as a modulation source for the various parameters as well. It’s fun smearing around the partial time position with different modulation elements, you can really destroy audio in some clever ways. I imagine there’s room to discover new transformative secrets in sound design here.
This sound engine then feeds into an advanced spacial positioning system, where each partial gets its own particle in 3D space. You can move around the partials in many different patterns and directions, or even apply noise to their position, which causes an incredibly pleasant dispersion effect. I really enjoy the Nebula pattern, however, I wish the particles had a different randomized location with each instance. After this everything is fed into an analog modeled filter, almost an odd choice with how digital the rest of this plugin is, but it adds some nice texture and contrast.
There are two modulation sources in Sumu, a per partial envelope, and a partial pulsing system. The envelope can be skewed, giving higher or lower partials faster motion. This is very useful for physical modeling or skewing the timing position on the resynthesized playback. The pulses section is very interesting, it outputs random envelopes or gates per partial, but you can select which partials are targeted via a definable curve. These envelopes can be a variety of shapes with a few different patterns as well. It’s like a strange rain drop modulation system, it’s definitely worth plugging into the scope to get visuals to help understand what it’s doing. One of my favorite tricks with the pulses envelope is to turn noise all the way off and use hi-scale to get these lovely sweeping patterns that rotate through various phases, great for all really bizarre “polyrhythmic” style sound design.
All this combined with the ability to patch the different sections around like a modular synthesizer makes for one of the most unique and unusual sound design tools out there. I’d love to see another synth play with the Vutu resynthesis system, I’d love to play around with the partials in some more ways than is available here. I also think Sumu benefits greatly from a reverb, some form of additive reverb, like what you can find in Razor, would really push Sumu into new grounds. The “decay” control on the gates is close, but not quite it. I think you need to abandon expectations for traditional sounds with this one, some physically modeled plucks are very approachable, but the majority of experimentation leads to rather abstract results. While Sumu is great for plucks, pads and ambiences, I think it could be a secret weapon for risers and glitchy sound design, especially for swarming spatial micro textures.
You can pick up SUMU from Madrona Labs website here: https://madronalabs.com/products/sumu?locale=us