Born Free – As Free as This Free Softsynth Goes

Almost all the best synths in life aren’t free. But SURGE is, as Jim Aikin reports (in this article and in the “don’t miss” video and audio that goes with it).

Looking back a few years, my impression of freeware synthesizers was that they were unstable, glitch-prone, limited in their features, and also ugly. But as Bob Dylan once said, “The times, they are a-changin’.”

The Surge VST synth would be a good value at $129 – and it’s free! Okay, the default skin is ugly, but what you’re seeing here is the Royal Surge skin, which is quite handsome:

Looks aren’t everything. How does it sound? Wonderful. Stellar. And how about the feature set? Deep, deep, deep. There’s too much going on here to cover it all in one review, so I’ll hit the high spots. There’s a lot of good basic information on the Surge web page itself, but I’ll mention a few things that aren’t covered there. This review is of version 1.9.

Surge is being maintained and developed by an active online community of developers, whom you can find and chat with on Discord. It’s open-source, so if you’re a clever DSP programmer, you could contribute. It was first created by Claes Johanson, who is now at Bitwig.

Overview. A Surge preset has two independent Scenes, which can operate in dual (layered) mode, as a keyboard split, or on separate MIDI channels. Each Scene has three oscillators, a waveshaper, two filters with several routing options, 15 modulation sources not including the external MIDI modulation inputs, and two insert effects. In addition, there are two send effects and two master effects, which are shared by the Scenes.

There are too many presets to count, as they’re lodged in dozens of categories and sub-categories. A couple of thousand, according to the web page – and even the few that I didn’t care for were easy to tweak in order to produce something useful. Rumor has it that in a future release it will be possible to tag your favorites in the preset browser; that would be a welcome addition. The online manual is surprisingly good. Surge is MPE-ready, and will even load Scala tuning files.

I spotted only one factor that may concern a few musicians: the Surge plug-in is VST3 and AU only. If you’re using Reason or some other DAW that doesn’t yet support VST3 (most of them do), you’ll need to find a different host program in order to use Surge. Also, when you first approach the synth, you may not see how to do certain things. A few important parameters are hidden within right-click menus, and the method of applying modulation won’t be apparent at all until you read the manual. There’s no visible sync-to-transport switch for the LFOs, sequencers, or delays, for instance, but tempo sync is in the right-click menus. Overall, though, the user interface is extremely easy to navigate.

Oxcillators. Each oscillator gives you a choice of several hundred different wave sources. The available parameters will vary depending on what type you’ve chosen, but you may find sliders for things like Morph and Formant. And that’s just the analog-style waveforms. There are also what sound like physical modeling oscillator modes (with controls for Material, Brightness, and Exciter Mix), a granular oscillator with controls for grain density and pitch randomness, and a two-dimensional wavetable setup with X and Y morphing controls and a built-in lowpass gate.

A single oscillator can do three-operator FM – but above and beyond that, the three oscillators in a single Scene can also be set in an FM configuration, so really you can do 18-operator FM synthesis, if you dare. The oscillator mixer section includes the output routing of each oscillator to either filter or both, plus a couple of ring modulator signals and the obligatory noise source. An analog drift slider will let you dial in the amount of pitch variability you want, for that vintage vibe. Each oscillator also has a slider for the number of unisons it will produce, with a detune amount for the unisons. Multi-voice unisons are always spread across the stereo field.

The only thing that concerns me at all about the oscillators is that sync is always self-sync, and is available only with the standard analog-type waveforms. That is, you can’t sync osc 2 or 3 to osc 1 directly, though you can easily modulate the pitch of the invisible master oscillator to which the real oscillator is synced. It’s a viable design choice, just unexpected.

Filters. Are your eyes crossing from reading about all the voicing options? We haven’t even gotten started yet. The two filters and waveshaper can be patched in eight different configurations, which are conveniently illustrated on the panel. Each of the filters has 32 different modes, and there are five different waveshaper modes, plus a shaping amount slider. There’s also a feedback loop within the filter section. In one topology, for instance, filter 2 is in the feedback loop. In another, the two filters are in parallel, and the waveshaper operates only on the output of filter 1.

Two of the eight filter topologies are stereo. This allows one oscillator to be panned left and the other right within a single Scene. The Scene as a whole can be panned, but individual oscillators can’t be, other than via the filter routing.

At first glance, it will appear that the two filters share a single ADSR envelope, but this low-rent setup is deceptive. There are actually lots of envelope generators. And that brings us to one of the more powerful aspects of the Surge….

Modulation. In place of dedicated LFOs, Surge sports half a dozen general-purpose modulation generators at the level of the individual voice and another six at the level of the Scene. That is, the Scene modulations will be applied to all of the voices currently playing in that Scene, while the voice modulations may be different from one voice to another within a single chord.

In addition, there are eight MIDI controller inputs that serve as macros. The nice thing about the MIDI inputs is that modulation from them applies to both Scenes, not just to one Scene, so in dual voice mode you can change the whole sound with a single gesture on a MIDI hardware controller.

Each mod generator can be an LFO, an envelope, or a 16-step sequencer. The envelopes can be either DAHDSR or multi-segment. I don’t know how many segments are the max, but I was able to add more than 16 breakpoints without hitting the ceiling. Each segment in the multi-segment envelope has an adjustable curvature, as you’ll see in the video. The multi-segs can loop, and the loop start and end breakpoints can be whatever you like. (Sorry I didn’t demonstrate changing the loop points in the video. I was sitting too far from the screen, so I didn’t see the tiny little widget the mouse has to grab.)

With several step sequencers available per voice (and more per Scene), each of which can be synced to its own rhythm value, creating complex note patterns is not difficult. Also, the voice sequencers can trigger the main filter envelope, the main amp envelope, or both together, which can lead to some elaborate rhythm patterns. There appears to be no way to get the sequencers to trigger anything other than the two main envelopes, however.

Some synthesizers limit each modulation source to one destination. Not a problem here: each source can control as many destinations as you like, each with its own amplitude and polarity, and each destination parameter can be modulated by several sources at once. There’s no dedicated mod matrix, and none is needed.

Effects. Reverb, chorus, phaser, delay, limiter, EQ, compressor, no need to talk about those things. Surge has a few extra tricks up its sleeve, including resonators, a tape emulator, a granulizer, rotary speaker (no acceleration or braking – sorry), and a pitch shifter. The effects section seems to be a work in progress: at present there’s an option called CHOW that doesn’t seem to do anything.

The topology here is fixed: the inserts for the two Scenes are in series, the sends are parallel, and the master effects are in series. Each Scene has send level controls for the two sends, and the effects section includes return level controls for the two send effects.

About the audio tracks

The music clip (“Surge in General”) uses eight Surge instances – kick, snare, a sort of hand percussion groove, bass, electric piano, and lead, plus a pad and a plucked sound that are heard only in the intro. All of these are factory patches, or at least they ship with Surge; some of them are in the folders of patches contributed by various people. I may have tweaked the filter cutoff on one or two of them.

With the files that showcase the basses, pads, and sequences, I may have synced something to the DAW transport so that its tempo would match, but other than that these are all stock sounds that ship with Surge. In the last part of the sequences demo, I did play three notes, not just one, but the drum groove in that same demo is all one MIDI note, not a pattern I programmed using multiple tracks.

The recordings were done in FL Studio. No processing was done in FL, other than the fade-in of the percussion at the start of the music track.

Summing up. If you’re into sound design, you’ll love making your own presets in Surge. And if you just want to play other people’s presets, you’ll have a massive library to choose from. Thanks to the variety of oscillator models and the versatile filter section, Surge is a do-everything synth. I’ve had so much fun using it I’ll probably be switching my creative music-making from Reason (which doesn’t yet support VST 3 plugins) to FL Studio in order to have Surge available at all times.

Click here for the Surge website