Surge Synthesizer Surge Save

Synthesizer plug-in (previously released as Vember Audio Surge)

Project README

Surge XT

If you are a musician looking to use Surge XT, please download the appropriate binary from our website. Surge Synth Team makes regular releases for all supported platforms.

CI: CI Build Status Release: Release Build Status Release-XT: Release-XT Build Status

Surge XT is a free and open-source hybrid synthesizer, originally written and sold as a commercial product by @kurasu/Claes Johanson at Vember Audio. In September 2018, Claes decided to release a partially completed version of Surge 1.6 under GPL3, and a group of developers have been improving it since. You can learn more about the team at or connect with us on Discord .

If you would also like to participate in discussions, testing and design of Surge XT, we have details below and also in the contributors section of the Surge XT website.

This readme serves as the root of developer documentation for Surge XT.

Developing Surge XT

We welcome developers! Our workflow revolves around GitHub issues in this repository and conversations at our Discord server. You can read our developer guidelines in our developer guide document. If you want to contribute and are new to Git, we also have a Git How To, tailored at Surge XT development.

The developer guide also contains information about testing and debugging in particular hosts on particular platforms.

Surge XT uses CMake for all of its build-related tasks, and requires a set of free tools to build the synth. If you have a development environment set up, you almost definitely have what you need, but if not, please check out:

Once you have set your environment up, you need to checkout the Surge XT code with Git, grab submodules, run CMake to configure, then run CMake to build. Your IDE may support CMake (more on that below), but a reliable way to build Surge XT on all platforms is:

git clone
cd surge
git submodule update --init --recursive
cmake -Bbuild
cmake --build build --config Release --target surge-staged-assets

This will build all the Surge XT binary assets in the directory build/surge_xt_products and is often enough of a formula to do a build.

Developing from your own fork

Our Git How To explains how we are using Git. If you want to develop from your own fork, please consult there, but the short version is (1) fork this project on GitHub and (2) clone your fork, rather than the main repo as described above. So press the Fork button here and then:

git clone [email protected]:youruserid/surge.git

and the rest of the steps are unchanged.

Building projects for your IDE

When you run the first CMake step, CMake will generate IDE-compatible files for you. On Windows, it will generate Visual Studio files. On Mac it will generate makefiles by default, but if you add the argument -GXcode you can get an XCode project if you want.

Surge XT developers regularly develop with all sorts of tools. CLion, Visual Studio, vim, emacs, VS Code, and many others can work properly with the software.

Building a VST2

Due to licensing restrictions, VST2 builds of Surge XT may not be redistributed. However, it is possible to build a VST2 of Surge XT for your own personal use. First, obtain a local copy of the VST2 SDK, and unzip it to a folder of your choice. Then set VST2SDK_DIR to point to that folder:

export VST2SDK_DIR="/your/path/to/VST2SDK"

or, in the Windows command prompt:

set VST2SDK_DIR=c:\path\to\VST2SDK

Finally, run CMake afresh and build the VST2 targets:

cmake -Bbuild_vst2
cmake --build build_vst2 --config Release --target surge-xt_VST --parallel 4
cmake --build build_vst2 --config Release --target surge-fx_VST --parallel 4

You will then have VST2 plugins in build_vst2/surge-xt_artefacts/Release/VST and build_vst2/surge-fx_artefacts/Release/VST respectively. Adjust the number of cores that will be used for building process by modifying the value of --parallel argument.

Building with support for ASIO

On Windows, building with ASIO is often preferred for Surge XT standalone, since it enables users to use the ASIO low-latency audio driver.

Unfortunately, due to licensing conflicts, binaries of Surge XT that are built with ASIO may not be redistributed. However, you can build Surge XT with ASIO for your own personal use, provided you do not redistribute those builds.

If you already have a copy of the ASIO SDK, simply set the following environment variable and you're good to go!

set ASIOSDK_DIR=c:\path\to\asio

If you DON'T have a copy of the ASIO SDK at hand, CMake can download it for you, and allow you to build with ASIO under your own personal license. To enable this functionality, run your CMake configuration command as follows:


Building an LV2

Surge XT 1.3 family moves to JUCE 7, which includes support for LV2 builds. For a variety of reasons we don't build LV2 either by default or in our CI pipeline. You can activate the LV2 build in your environment by adding -DSURGE_BUILD_LV2=TRUE on your initial CMake build.

Building and Using the Python Bindings

Surge XT uses pybind to expose the innards of the synth to Python code for direct native access to all its features. This is a tool mostly useful for developers, and the surge-python repository shows some uses.

To use Surge XT in this manner, you need to build the Python extension. Here's how (this shows the result on Mac, but Windows and Linux are similar).

First, configure a build with Python bindings activated:


Note the directory ignore/bpy could be anything you want. The ignore directory is handy, since it is ignored via .gitignore.

Then build the Python plugin:

cmake --build ignore/bpy --parallel --target surgepy

which should result in the Python .dll being present:

% ls ignore/bpy/src/surge-python/*so

Now you can finally start Python to load that. Here is an example interactive session, but it will work similarly in the tool of your choosing:

% python3
Python 3.11.4 (main, Jun 20 2023, 17:37:48) [Clang 14.0.0 (clang-1400.0.29.202)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path.append("ignore/bpy/src/surge-python")
>>> import surgepy
>>> surgepy.getVersion()
>>> quit()

Building an Installer

The CMake target surge-xt-distribution builds an install image on your platform at the end of the build process. On Mac and Linux, the installer generator is built into the platform; on Windows, our CMake file uses NuGet to download InnoSetup, so you will need the nuget.exe CLI in your path.

Using CMake on the Command Line for More

We have a variety of other CMake options and targets which can allow you to develop and install Surge XT more easily.

Plugin Development

JUCE supports a mode where a plugin (AU, VST3, etc...) is copied to a local install area after a build. This is off by default with CMake, but you can turn it on with -DSURGE_COPY_AFTER_BUILD=True at cmake time. If you do this on Unixes, building the VST3 or AU targets will copy them to the appropriate local area (~/.vst3 on Linux, ~/Library/Audio/Plugins on Mac). On Windows it will attempt to install the VST3, so setting this option may require administrator privileges in your build environment.

CMake Install Targets (Linux and other non-Apple Unixes only)

On systems which are UNIX AND NOT APPLE, the CMake file provides an install target which will install all needed assets to the CMAKE_INSTALL_PREFIX. This means a complete install can be accomplished by:

cmake -Bignore/sxt -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
cmake --build ignore/sxt --config Release --parallel 8
sudo cmake --install ignore/sxt

and you should get a working install in /usr/bin, /usr/share and /usr/lib.

Platform Specific Choices

Building 32- vs 64-bit on Windows

If you are building with Visual Studio 2019, use the -A flag in your CMake command to specify 32/64-bit:

# 64-bit
cmake -Bbuild -G"Visual Studio 16 2019" -A x64

# 32-bit
cmake -Bbuild32 -G"Visual Studio 16 2019" -A Win32

If you are using an older version of Visual Studio, you must specify your preference with your choice of CMake generator:

# 64-bit
cmake -Bbuild -G"Visual Studio 15 2017 Win64"

# 32-bit
cmake -Bbuild32 -G"Visual Studio 15 2017"

Building a Mac Fat Binary (ARM/Intel)

To build a fat binary on a Mac, simply add the following CMake argument to your initial CMake run:


Building for Raspberry Pi

Surge XT builds natively on 64-bit Raspberry Pi operating systems. Install your compiler toolchain and run the standard CMake commands. Surge XT will not build on 32-bit Raspberry Pi systems, giving an error in Spring Reverb and elsewhere in DSP code. If you would like to work on fixing this, see the comment in CMakeLists.txt or drop us a line on our Discord or GitHub.

As of June 2023, though, gcc in some distributions has an apparent bug which generates a specious warning which we promote to an error. We found Surge XT compiles cleanly with gcc (Debian 10.2.1-6) 10.2.1 20210110, but not with others. Surge XT also compiles with Clang 11. The error in question takes the form:

/home/pi/Documents/github/surge/libs/sst/sst-filters/include/sst/filters/QuadFilterUnit_Impl.h:539:26: error: requested alignment 16 is larger than 8 [-Werror=attributes]
     int DTi alignas(16)[4], SEi alignas(16)[4];

If you get that error and are working on RPi, your options are:

  1. Change to a gcc version which doesn't mis-tag that as an error
  2. Use Clang instead of gcc, as detailed below
  3. Figure out how to suppress that error in CMake just for gcc on Raspberry Pi and send us a pull request

To build with Clang:

sudo apt install clang
cmake -Bignore/s13clang -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
cmake --build ignore/s13clang --target surge-xt_Standalone --parallel 3

Cross-compiling for aarch64

To cross-compile for aarch64, use the CMake Linux toolchain for aarch64, as shown in the Azure pipeline here:

cmake -Bignore/xc64 -DCMAKE_TOOLCHAIN_FILE=cmake/linux-aarch64-ubuntu-crosscompile-toolchain.cmake -DCMAKE_BUILD_TYPE=DEBUG -GNinja
cmake --build ignore/xc64 --config Debug --target surge-testrunner

Of course, that toolchain makes specific choices. You can make other choices as long as (1) you set the CMake variable LINUX_ON_ARM and (2) you make sure your host and your target compiler are both 64-bit.

Cross-compiling for macOS

Surge XT cross-compiles to macOS Intel from Linux and BSD.

  1. Install osxcross. Make sure to also install the libclang_rt library built by their script.
  2. Configure and build Surge XT:
cmake -DCMAKE_TOOLCHAIN_FILE=cmake/x86_64-apple-darwin20.4-clang.cmake -DCMAKE_FIND_ROOT_PATH=<path_to_osxcross_sdk> -Bbuild
cmake --build build

Building older versions

Each version of Surge from 1.6 beta 6 or so has a branch in this repository. Just check it out and read the associated README.

Setting up for Your OS


You need to install the following:


To build on macOS, you need Xcode, Xcode Command Line Utilities, and CMake. Once you have installed Xcode from the App Store, the command line to install the Xcode Command Line Utilities is:

xcode-select --install

There are a variety of ways to install CMake. If you use homebrew, you can:

brew install cmake


Most Linux systems have CMake, Git and a modern C++ compiler installed. Make sure yours does. We test with most gccs older than 7 or so and clangs after 9 or 10. You will also need to install a set of dependencies. If you use apt, do:

sudo apt install build-essential libcairo-dev libxkbcommon-x11-dev libxkbcommon-dev libxcb-cursor-dev libxcb-keysyms1-dev libxcb-util-dev libxrandr-dev libxinerama-dev libxcursor-dev libasound2-dev libjack-jackd2-dev

You can find more info about Surge XT on Linux and other Unix-like distros in this document.

Continuous Integration

In addition to the build commands above, we use Azure pipelines for continuous integration. This means that each and every pull request will be automatically built across all our environment,and a clean build on all platforms is an obvious pre-requisite. If you have questions about our CI tools, don't hesitate to ask on our Discord server. We are grateful to Microsoft for providing Azure pipelines for free to the open-source community!


  • Most Surge XT-related conversation happens on the Surge Synthesizer Discord server. You can join via this link.
  • Discussion at KvR forum here.
Open Source Agenda is not affiliated with "Surge Synthesizer Surge" Project. README Source: surge-synthesizer/surge
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