Surge XT

Name: Surge XT
Author: Surge Synth Team

by Surge Synth Team · Synth · Open-source hybrid synth

Not rated yet

Surge XT is a free, open-source hybrid synth with two scenes per patch, three oscillators per scene and 12 oscillator algorithms, from classic and wavetable to FM, string and audio input.

It comes with over 2,800 factory patches, 16 effect slots per patch, MPE, and microtuning through Scala and MTS-ESP.

Best for: Keys & Synths, Bass, Sound Design. Genres: Electronic & EDM, Ambient & Cinematic, Pop.

Keywords: open source, free, hybrid, wavetable, classic, FM, MPE support, preset-driven, sound design, basses, cinematic, leads, pads, polyphonic, sequencer, surgical, vintage.

What it does

Surge XT is the synth that started the Surge Synth Team project, built by volunteers and described as "a sound designer's dream." Each patch holds two complete synth scenes with three oscillators each, which can be split or layered.

Oscillators: 12 algorithms: Classic, Modern, Wavetable, Window, Sine, FM2, FM3, String, Twist, Alias, S&H Noise and Audio Input. Most offer up to 16-voice unison, with oscillator FM in three configurations and ring modulation between oscillators.
Filters: two filter units in 8 configurations, with feedback in 7 of them. Types include 12 and 24 dB lowpass variants, vintage ladder, K35, diode ladder, tri-pole, comb, notch and allpass.
Waveshaper: 43 shapes between the filters.
Modulation: 12 LFOs (6 per voice, 6 global), each with its own DAHDSR envelope. Modes include 7 deformable shapes, a step sequencer, an MSEG with up to 128 nodes and a Lua formula modulator, all assigned by drag and drop.
Effects: 16 effect units (4 inserts per scene, 4 sends, 4 master) drawing on 27 algorithms, including Airwindows (56 effects), Nimbus, Combulator, vocoder, spring reverb and tape. The effects are also offered as a separate plugin.
Tuning and control: Scala and MTS-ESP microtuning, full MPE support and Open Sound Control.
Content: over 2,800 factory patches and over 700 wavetables.

Version 1.3.4 is free and open source.

Source: Surge Synth Team product page

When to use it

Surge XT is the widest free synth on the site, with two scenes per patch, 12 oscillator types, a large filter set and a 16-slot effects rack. Compared with Vital, it has more oscillator and filter types and more effects, but its interface is denser and less visual, and it is less focused on wavetables. It is not as instant as Serum 2 or Pigments 7 and has no sample oscillator or arpeggiator, but it costs nothing. Its Scala and MTS-ESP microtuning make it the stronger pick for microtonal work.

Best for: sound design, basses, leads, pads and microtonal work on any budget.
Genres: electronic, ambient, cinematic and pop production.
Look elsewhere if: you want a simple, guided interface or sample playback; Vital is quicker to learn, and Serum 2 or Pigments 7 add sample engines.
Tip: set up the macro controls in each patch and map them to MIDI CCs, as MusicRadar suggests, so a dense patch is played from a few knobs.

What producers say

Widely treated as one of the best free synths, with the dense interface the main complaint.

KVR users rate it 4.74 out of 5 from 31 reviews, praising the sound, stability and modulation; one wrote "Never have I found a synth so easy to modulate" (2024).
MusicRadar ("OSC" Steve, December 2022) called its feature set "frankly staggering" for a free synth and a strong contender if you could keep only one synth.
Criticisms: a cluttered, dated-looking interface, a learning curve that sends users to the manual, and no arpeggiator or sample oscillator. Views on CPU differ: some KVR users find it lighter than Vital, while MusicRadar called it "fairly CPU-heavy".

Where to buy

Surge Synth Team: Free

Tutorials and reviews

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