Xfer Serum synthesizer review

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Xfer Serum is a capable, powerful synthesiser with an extensive feature set and a killer sound.

Serum's main window looks packed with information but still quite easily legible. Let's dive right in and look through the different sections.

The sound engine is based on two independent wavetable oscillators, and they're very well featured. Xfer's implementation of wavetable synthesis is among the best ever in my opinion, there are multiple ways to warp the waves, very easy controls for voice stacking and detuning and all the parameters and the wavescanning itself can be easily modulated via the envelopes and the lfos.
What's more important though is that it all sounds stunning. Some wavetable synths have an inherently digital, gritty, lo-fi kind of sound that can't be escaped, but Serum can produce very pure waveforms as well, just try one of the many included analog sampled wavesets and you'll be able to easily get classic subtractive sounds out of the engine to rival any virtual analog.

It's also remarkably easy to make your own wavetables, the oscillator window supports audio samples drag and drop, and the editor window is just a click away and features extensive controls for shaping the sounds and smoothing the transitions. Even without digging in the manual I was able to get excellent results in minutes and turn some old samples into perfectly rendered and organic sounding oscillators.
The sound engine is also complemented by a Sub Oscillator section with basic waveforms and a very cool Noise Oscillator which can load samples and can be creatively abused to add almost any kind of texture or pitched sample content to the sound.

All the oscillators can then be routed through the filter, which has a ton of different modes and models to choose from. There's many different styles on offer (clean, moogish, german style) of classic lowpass / bandpass / highpass circuit designs all provided with pole variations (6-12-24), some weird combination algos that come with a morph control that can modulate between LP and HP responses and some even more experimental types such as formant, allpass, phaser and comb.
This will all be quite familiar for people who have tried the filter section in Xfer's Lfotool , but for other people the sheer amount of options can feel a little bit overwhelming at first, it really pays off to sit down and demo the different filter types to find out what are the ones you like best and how they respond to different types of input and modulation.

Speaking of modulation, this is another of the strong suits of Serum and it's clear that a lot of care has been put into the design of this section. There's three ADSR envelopes and up to 8 lfos on offer, and assigning modulation can be done easily via a drag and drop on the main interface panel or with more fine-grained control via the modulation matrix window.
The matrix offers some destinations that aren't available  on the main page (such as overall Amp and Tune, lfo rate, length of single envelope stages), the ability to switch modulation from bipolar to unipolar and an auxiliary section for modulating the modulator (helpful to assign variable modulation from the mod wheel for example)
All in all the modulation system works in a similar way to massive, and fans of NI's synth will feel right at home. Lfos use an interface with nodes and segments, again similar to Xfer's LfoTool, which makes it easy to create advanced shapes, synced to a grid or free running, and besides curves you can also as easily create stepped sequences, for arpeggiator style modulation. There's of course already a healthy dose of LFO shapes on deck, from the classic sine and ramp waves to crazier more complex waves, and the lfos can also be set to single cycle for when you feel like 3 envelopes is not enough.
All in all the modulation system is comprehensive and allows you to create very organic / evolving patches with the wavetables, but it's not a completely modular system and there's some routings that aren't available (at least for the moment) in the matrix.

The effects section is also very good and while personally i'm not a huge fan of on board fx they can still be useful. It's worth noting that the effects can be stacked in different order via a very simple drag and drop interface, and all the parameters can be controlled via the modulation matrix, making some creative opportunities available that would be impossible to achieve by just adding effects on an insert track in your daw.
The fx section also comes as a separate plugin as a bonus, it's a good sounding multi-fx plugin, with a lot of cool modulation capabilities that can be tempo-synced to your host in a way that many 'vintage style' effects often can't.

All in all Serum is an extremely flexible and powerful synthesizer, and while the combination of wavetable, comb filters, multiple tempo synced lfos would immediately suggest dubstep wobble / growlers and all the kinds of 'edgy' edm sounds, it's just as easy to create organic tones, evolving cinematic beds and straight up analog subtractive patches.
I've tried to showcase some more experimental and strange sounds in the demos on this page, which are made with just serum.
Creating a new synth in today's competitive market is not an easy feat, and balancing an extensive feature set with good UI and UX is even harder, but I think Serum manages that perfectly with some very well thought out design and an open, classy sound.

As a final note, I am ashamed to admit that I ran into some trouble while installing Serum on my mac, a baffling bug kept popping up and I have to say that XFER went above and beyond to solve the issue, Steve himself was very gracious in sorting out the issue.