Surge XT – virtual synthesizer

A software synthesizer, also known as a softsynth, is computer software which creates digital audio. Computer software that generates music is not a recent arrival. However, with processors that offer multiple cores and faster clock speeds, software synthesizers can complete tasks that previously needed dedicated hardware. The advantage, of course, of software synthesizers is that they are less expensive than dedicated hardware, and simpler to integrate with other types of music software.

Surge XT is a hybrid polyphonic synthesizer which supports MIDI Polyphonic Expression (MPE) and runs as an LV2 plugin, or as a VST. The term “hybrid” usually means that the instrument uses a combination of analog and digital components, ideally providing some of the finer aspects of both realms.


The project provides a convenient package for Ubuntu (built for 18.04) as well as binaries for macOS and Windows. The full source code is available. And some Linux distros provide convenient packages too.

On our Ubuntu systems we initially tried to install the software with the command

$ sudo dpkg -i surge-xt-linux-x64-1.0.1.deb

This wasn’t successful as our system was missing a few packages (libxcb-cursor0 and xclip). These packages were installed with the command:

$ sudo apt --fix-broken install

This is cross-platform software. Besides Linux, it runs under macOS and Windows.

In Operation

Surge XT
Click image for full size

The interface is divided into four sections.

Patch / Global – There are two scenes (A & B) and an effect-section. A scene is like a traditional synthesizer patch. With two scenes in each patch you can have layered or split sounds within a patch.

Scene Controls – We have sound generation and sound shaping. Within the sound generation section we find oscillators which generate waveforms according to the notes played. There’s also bend depth, scene pitch and portamento, and a mixer. For sound shaping, there’s routing functionality which are flow charts which show the signal path. There’s also an output section where we can mix effects and left and right panning, as well as a waveshaper, filter envelope generator, and an amplitude envelope generator. Filters can be configured to run in serial or parallel and there’s a huge range available.

Modulation / Routing – This section lets you control the parameters in the other sections from various sources. The routing bar is particularly powerful.

FX – This section controls the 8 effect units of the effect block stored in each patch.  We love the range of effects and the amount of control available.


This synth is quite simply top class and brimming with features. We love the full keyboard microtuning support, the wide selection of filters, and its modulation engine. It’s a very complex piece of software with the ability to change anything. Compose complex patches with this software. Open source software at its finest.

Surge XT was originally sold as a commercial product but nowadays it’s free and open source goodness. The project is under active development.

Unlike many open source software, the project’s manual is beautifully designed with clear and concise information. Wonderful!

Support: GitHub Code Repository
Developer: Vember Audio and contributions by the Surge Synth Team
License: GNU General Public License v3.0

Surge XT is written in C and C++. Learn C with our recommended free books and free tutorials. Learn C++ with our recommended free books and free tutorials.

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