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Favorite Free Virtual Instrument - Best Audio and MIDI Software - KVR Audio Readers' Choice Awards 2022Favorite Free Virtual Instrument - Best Audio and MIDI Software - KVR Audio Readers' Choice Awards 2020
Surge XT by Surge Synth Team is a Virtual Instrument Audio Plugin for macOS, Windows and Linux. It functions as an Audio Units Plugin, a VST 3 Plugin, a LV2 Plugin and a CLAP Plugin.
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Open Source
My KVR - Groups, Versions, & More
1073 KVR members have added Surge XT to 465 My KVR groups 1363 times.
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+465 in private groups

KVR Rank

Overall: 24   18   24   5

30-Day: 27; 7-Day: 34; Yesterday: 41


  • Synthesis method: Subtractive hybrid.
  • Each patch contain two scenes which are separate instances of the entire synthesis engine (except effects) that can be used for layered or split patches.
  • Category-based patch browser.
  • MPE support.


  • 3 oscillators per scene.
  • 12 versatile oscillator algorithms: Classic, Modern, Wavetable, Window, Sine, FM2, FM3, String, Twist, Alias, S&H Noise, and audio input.
  • Classic oscillator is a morphable pulse/saw/dual saw oscillator with a sub-oscillator and hard sync.
  • Modern oscillator is a mixable saw/pulse/triangle oscillator with an optional sub-oscillator mode for triangle (and it can also change to sine or square) and hard sync.
  • FM2 and FM3 oscillators consist of a carrier and 2 or 3 modulators and various options.
  • String oscillator uses two filtered waveguides to emulate plucked or bowed string sounds.
  • Twist oscillator is based on a very famous Eurorack macro oscillator, and it offers a myriad of synthesis options in a very easy to use way.
  • Most algorithms (except FM2, FM3, Twist and Audio Input) offer up to 16-voice unison at the oscillator level.
  • Oscillator FM in 3 different configurations and ring modulation between oscillators 1-3 and 2-3.
  • Most oscillator algorithms (except FM2, FM3, Sine and Alias) are strictly band-limited, yet still cover the entire audible spectrum, delivering a clear punchy yet clean sound.
  • Noise generator with variable spectrum (available directly in the oscillator mixer).

Filter Block:

  • Two filter units in 8 different configurations.
  • Feedback loop available in 7 of those configurations.
  • Available filter algorithms: Lowpass (12 and 24 dB/oct, each with 3 variations), Legacy Ladder Lowpass (6-24 dB/oct), Vintage Ladder Lowpass (2 variations, each with and without gain compensation), Highpass (12 and 24 dB/oct, each with 3 variations), Bandpass (12 and 24 dB/oct, each with 3 variations), Notch (12 and 24 dB/oct, each with 2 variations), Allpass (3 variations), Comb (positive and negative), S&H.
  • Open-source additions to our filter bank contain: K35 and Diode Ladder filter types from Odin 2 synthesizer, 12 and 24 dB/oct multimode filters from OB-Xd, and weird but fascinating Cutoff Warp, Resonance Warp and Tri-Pole filters by Jatin Chowdhury.
  • Filters can self-oscillate (with excitation) and respond amazingly fast to cutoff frequency changes.
  • Waveshaper (43 shapes).


  • 12 LFO units available, 6 are per voice and 6 are global for the whole scene.
  • DAHDSR envelope generators on every LFO.
  • LFO shapes consist of 7 deformable LFO waveforms, step sequencer, a fully-fledged multi-segment envelope generator (MSEG) with various curves and up to 128 nodes, and last but not the least - a formula modulator which utilizes Lua scripting language to provide completely custom modulator output.
  • Voice LFOs allow envelope retriggering in step sequencer mode.
  • Extremely fast and flexible modulation routing. Almost every continuous parameter can be modulated.


  • 16 effect units arranged as 4 inserts per scene, 4 sends and 4 master effects.
  • 27 effect algorithms:
      • 3-band fully parametric EQ.
      • 11-band graphic EQ.
      • Exciter (based on a famous "type B" studio rack unit).
      • Resonator (inspired by a resonator from a vintage polysynth that rhymes with "vogue").
      • CHOW (maximally truculent distortion with compressor-like controls).
      • Distortion.
      • Neuron (distortion based on Gated Recurrent Unit).
      • Tape (based on the awesome ChowDSP ChowTapeModel!).
      • Waveshaper (the same one as in the filter block).
      • Combulator (like resonator, but using comb filters instead).
      • Frequency Shifter.
      • Nimbus (a famous Eurorack live input granularizer).
      • Ring Modulator.
      • Treemonster (pitch-tracked ring modulator from Shortcircuit 2!).
      • Vocoder.
      • Chorus.
      • Ensemble (BBD-based or clean!).
      • Flanger.
      • Phaser.
      • Rotary Speaker.
    • TIME & SPACE:
      • Delay.
      • Reverb 1.
      • Reverb 2.
      • Spring Reverb.
    • Airwindows (itself containing 56 wonderful effects of various kinds!).
    • Conditioner (low/high EQ, stereo image and limiter).
    • Mid-Side Tool.

Latest User Reviews

Average user rating of 4.75 from 28 reviews
Surge XT

Reviewed By digitalboytn [all]
December 9th, 2023
Version reviewed: 1.3 on Windows

Surge XT is a really versatile synth that covers a lot of sonic territory....

It's a solid workhorse and it's getting better with every revision....

A great deal of gratitude and appreciation is owed to the team behind this synth....

Thanks guys....

This one's a 5 Star winner.

Read Review
Surge XT

Reviewed By phil299 [all]
January 26th, 2023
Version reviewed: 3.7.2 on Windows

Clearly one of the best free VST synths along with "Vital", loads of usable presets both installed and from the community.

Personally I think sound is up there with top level paid vsts.

I think the GUI could be better and it is possible to crash it in sound design but do not let that put you off this is a must have vst.

Read Review
Surge XT

Reviewed By huggorm [all]
September 7th, 2022
Version reviewed: 1.9 on Windows

For those of us not skilled in synthesizing, Surge has a lot of presets both installed by the installer and downloadable from communities. From there you can modify and customize sounds, even make your own with some practise. You'll have a hard time to find any better free synthesizer.

Read Review
Surge XT

Reviewed By loungedumore [all]
July 11th, 2022
Version reviewed: 1.01 on Mac

VA, Wavetables, FM based synth with multiple options of each type.

Massive amount of easy to use modulation .

Mutable Instruments Plaits & Clouds, OB-Xd filters, Oden II filters, Air Windows fx all built in.

It's one of the best, most flexible synths period ...that also happens to be free and open source.

Just surface scratches really stop reading this review and go Download it.

Read Review
Surge XT

Reviewed By kgarboski [all]
April 29th, 2022
Version reviewed: 1.0.1 on Mac

Amazing synth that is absolutely jam packed with features, including lots of stuff that is "under the hood". Many oscillator options and many great sounding filters with various sub-modes, tons of modulation options, wave-shaping, tons of FX; just had everything you really need.

It'll do EDM supersaws, vintage, dubstep growl, wavetable, fm, string, ambient/textural stuff, experimental and complex stuff. Really versatile and functional, well thought-out, and complex.

A huge thing is that is sounds excellent and has many features to affect the tone like oscillator pitch/drift variation, wave-shaping, oscillator brightness, random modulation (which can affect pitches, envelopes, etc), and insert/send FX to really give it a rich character and allowing to you make it sound "warmer" and more vintage, based on how far you want to go and the limits of your own abilities.

Comes with a lot of good presets, but this thing truly shines when you dig deep and learn it inside and out. It's easy to write off because of it's non-flashy but practical interface, by it's native presets, or by the fact that it's free; but it is really really amazing. The user manual is a must read to really get into the deeper aspects as there are features that aren't quite obvious right out of the gate.

I have personally narrowed down my digital synth library down to Surge XT and logic pro native plugins, to fit my personal goal of minimalism and creative limitation; focusing on full mastery of what is available rather than grasping for new plugins all the time. I could tell you that I really don't miss or care about using the other synth plugins anymore and have gotten rid of that "Gear Acquisition Syndrome" mindset, and that this synth serves as both my standard bread-and-butter synth and in situations where more complex modulation is required.

A+++++++ would buy if it costed anything

Read Review

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Comments & Discussion for Surge Synth Team Surge XT

Discussion: Active
27 January 2012 at 9:23am

Had this one for a while now and it definitely fills the part of being the "odd VST amongst your normal ones".

What I like about it the most is the attack and the digital kind of grittiness.

And as said before the GUi is actually very user friendly. For example, the way you drag and drop assign things in the modulation matrix by "drag and drop" is something I really miss on more expensive plugins. Vember has really ignored fancy looks (yeah it's ugly ) and instead focused on making a practical tool.

7 April 2012 at 7:56pm

It just seat in every mix. It's truly a powerhouse and a learning tool for modulation and the effects routing is genius.

2 July 2012 at 9:16pm

I would like to say that Surge is the only synth I've used that I've been able to make crazy-scary renditions of acoustic sounds from woodwind to brass to dog vocal tracts. Surge is definitely one of the only synths on the market that allows you to explore these things because of its combination of featureset and tweakability. To tap into this, just enable the feedback routing, add feedback, add resonance in the filters, enable keytracking of filter, etc.

I will, however, agree that it does not sound sweet like modern synths. But what modern synths lacks, Surge definitely has. Its tweakability invites insanity.

3 August 2012 at 9:36pm

Hello everyone, just wanted to say I purchased Surge in Feb 2012 and haven't looked back yet.

Though it may not be the most technically advanced soft-synth out there it definitely has a certain something about it. I keep finding myself creating really exciting and attention-grabbing sounds whenever I just sit down and start experimenting with it. This is something I have not really found with the two other synths I have taken the time to learn in depth - Albino and Zebra.

Those 'in the know' say it is best to just pick one machine and learn to program it really well, as opposed to purchasing all the vsti's out there. So, following on from that I have made Surge my number one sound-software, along with Reaper and Halion 3. Surge seems to do a really good job of most of the basic sounds like bass, drums, keys and fx.

I think what makes it for me is it's fundamentally rock 'n' roll sound quality, everything sounds so fat and juicy with a great attitude - it seems incapable of making bland sounds. Claes, the developer, really has done a great job on this synth - it looks like he really knows about programming nice sounding oscillator and filter algorithms.

That's all for now, I've just got to go and program a totally overdriven, pulse-width-modulated, digitally aliased, resonant-comb-filtered, waveshaped, step-sequenced and delay-drenched monstrosity! Dave.

13 May 2013 at 12:36pm

This Synth is an absolute BEAST!!!!! How this doesn't get more attention or credit is beyond me. I cant wait to see what Vember puts out next cause I'm a huge fan of theirs. Anybody who hasnt tried this synth out needs to ASAP!!! Amazing work to those involved in the development of this great machine. Please tell me you guys are working on VST's to release soon or in the near future.

30 November 2014 at 12:13am

+10 from me. probably used this longer than most other synth plugs but i still find things it can do. once you know your way around it can pretty much fill any sound needs. a brilliant bit of kit :)

30 November 2014 at 10:11am


I agree, for me too, this is the synth that i have been using for the longest time. It has a unique sound and a great user interface, and even if it can't really compete with modern synths like Spire and SynthMaster, when it comes to modern edm sounds, it still has "it" and is great fun to play around with. To bad Claes/Vember Audio doesn't develop it anymore. I guess that Bitwig took all of his time.

18 August 2016 at 4:17pm


An evergreen in Software Synthesis with his a own digital character. Intresting how many still using these synth.

Good work.

28 September 2018 at 12:33am

Surge is now free and open source, the price and links should be updated.

Purple Six Recordz
Purple Six Recordz
22 October 2018 at 12:46pm

This VST is a keeper. So many sound presets and options for free VST is amazing. Love that there are a lot of sounds with dark, creepy vibe to them. :).

I also made a demo video for the VST for people to check out before downloading.


16 May 2019 at 6:14am

Thank you for synth and for opensource.

How about a portable version of one?

It'd be really great.

Big up.

18 June 2019 at 7:04am

Just wanted to say I've created a FB group:

A few people from the project have already joined -- hopefully the group will help the synth grow. I'm a big fan of the synth myself, I think the modulation system is absolutely brilliant, combining LFO and envelopes that way. I'll be spending a lot of time with this synth :).

22 September 2019 at 12:19pm

I am impressed with this synthesizer. Its wide possibilities impress me. This is one of the best synthesizers to date. Although free.

24 September 2019 at 7:57am

Oh wow, have just discovered Surge - as others have noted, it's a bit odd, but once you start playing around with it, the capability really shines. Early days for me yet, but just mucking about with the A/B dual and split scenes takes me back to the good old days of hard synths where it was a norm (at least on all the machines I've used). Add to that the arsenal of patches already available, quality of sound and and parameter controls it's awesome - and goddam it, this baby is free!!!! Despite only a couple of hours in, the control layout, which initially threw me off, is actually very intelligently designed - the patch management is very clear and functional (love being able to add a comment and add my own category), the FX management looks very comprehensive, love the routing / filter configuration approach) and the wavetable capability looks very comprehensive, very quick to create an interesting sound.


3 November 2021 at 2:44am

I've had Surge for some time and I started wondering if you could combine presets, say a sequence with a pad and its doable. Bring up a sequence preset, right click on A and copy it, then open up a pad preset and right click on B and paste. Click Dual for both A and B then presto you have two presets in one without reinventing the wheel. You can save it to your User folder with a new name and for added fun turn on more oscillators.


13 December 2021 at 7:08pm

Hello all.

I am using Surge via Blue Cat Audios Patchwork and for whatever reason, Surge now refuses to load presets. I am providing a link to the error message below:


The weird thing is, it was loading presets fine earlier, now it won't. I don't recall changing anything that would cause Surge to stop loading presets. Any advice?

2 February 2022 at 4:49am

Surge XT has a different VST id, host can't do it...

14 January 2022 at 9:29pm

Wants only to be installed on the C-drive. Like it's 1981. So, no install, no points.

2 February 2022 at 4:47am

You can set the path. Check it.

John CK
John CK
7 August 2022 at 12:43am

Incredible synth, just incredible.

Vampire TNA
Vampire TNA
8 March 2024 at 8:54pm

A collection of FREE organic/analog sounding presets, including a new skin for Surge XT + new SKIN: https://coroniumrecords.blogspot.com/2024/02/30-free-presets-for-surge-xt-synth.html

8 May 2024 at 9:16pm

Does anyone know of an iOS build of Surge XT being possible? I've dabbled in compiling it from source myself for iOS but my skills (esp. with iOS) are limited.
It seems the UI might be the biggest hurdle.

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