Linux Audio Development (LAD)
Klangfreund
Linux Audio developer interview with Samuel Gähwiler from Klangfreund
This interview was conducted by Amadeus Paulussen in 2025.
Dear Samuel, I am delighted to be interviewing you! ☺️
I guess most of us know your company, Klangfreund, but could you tell us a little about yourself and how you came to develop plugins for professional audio engineers?
Thank you for having me here, Amadeus!
My interest in music production began around 1992, when I was 12.
After getting a few part-time jobs, I finally had the means to buy a MIDI keyboard and C-LAB Notator for Atari. I spent a lot of time with this basic setup to create music after school.
Later, I studied math and electrical engineering at the university.
During my studies, I created, e.g., a VST plugin that worked like a standalone DJ-player, controllable with a time code signal on a vinyl record (a DVS system inside a DAW).
I also developed the audio engine for an Ambisonics DAW for the Institute for Computer Music and Sound Technology in Zurich (both were Open Source, but are not maintained or available any more).
After completing my studies, I wanted to work as an audio software developer.
At that time, the exchange rate of the Euro and the Swiss Franc was falling rapidly, which meant that most companies in the audio industry in Switzerland were struggling and were unable to offer me a job.
I wanted to stay in the Swiss mountains, where I feel so at home. So I started working four days a week for a company that develops 3D software for the metalworking industry to control machines and industrial robots. This allowed me to improve my C++ skills.
In my spare time, I continued to develop audio software.
In 2011, I met George Massenburg, Bob Katz, Florian Camerer and other interesting engineers at a conference in Rome. The main topic was loudness measurement according to ITU-R BS.1770.
I was eager to use this loudness measurement myself. However, the available loudness meters were very expensive. So I built my own. Others wanted to use it too. That's how my company, Klangfreund, came into being.
Is Klangfreund a full-time job for you?
Yes. Klangfreund also offers additional services that are not mentioned on the website.
I regularly work as an audio engineer at concerts.
I am also a certified tandem paragliding pilot and I fly with passengers in the Swiss mountains where I live.
However, I spend most of my time developing audio software.
I really enjoy this mix of activities.
Would you say that the competition in the "niche" of high-end audio analysis plugins is very different from that of, for example, effect plugins?
I don't know, as I don't have any experience as an effects plugin developer.
One advantage is that most of my customers are professionals, and I really enjoy corresponding with them.
What motivated you to support Linux as a platform in addition to macOS and Windows?
I'm interested in Linux myself. And the JUCE class library that I use makes it relatively easy to compile for Linux.
Only a small fraction of the users of my plugins actually work with Linux.
However, users of other operating systems have the added benefit that, should they ever switch to Linux, they can continue to use their Klangfreund plugins.
Are you thinking about extending the supported platforms of your plugins to iPadOS and/or Android in the future?
I have never received a request to port one of my plugins to iPadOS or Android.
And, even if I did, I would be quite hesitant. This is because every update to one of my plugins requires a lot of manual testing with the most common hosts on each supported platform (Unfortunately, testing a plugin in a host cannot simply be automated). I prefer to spend the time improving the plugins instead.
If you want to use a tablet to display the Multimeter or the LUFS Meter analyzing your main output bus, you can use the tablet as an additional display for your main computer.
Tangentially related to your question:
I once received a request from a blind user who asked me to make the Multimeter more accessible to disabled users. Only then did I realize that it is more difficult than I had expected to use my plugins as a disabled user.
When using the default graphical user interface elements of an operating system, a blind user can navigate them - at least when using Windows or macOS. As far as I know, accessibility is less advanced under Linux.
Anyway, when a framework like JUCE is used, the entire user interface appears as a single canvas for the operating system. That is why it cannot be operated by a blind person. Just think about it. Many audio plugins with their customized user interfaces cannot be used by a blind person at all.
After some consideration I decided to output all the measurement results of the Multimeter as plugin automation parameters. This way, a blind user can easily evaluate them in a DAW. An additional advantage is that these results can now also be used to control something else. For example, you can create a gain rider based on a loudness measurement.
Since then, JUCE has been improved with built in accessibility features.
Yeah, right? It's easy to forget about things like that when you're not personally affected. But I know that, in Wayland in particular, where accessibility hasn't been a big priority until now, greater efforts are being made to improve the situation for Linux accessibility lately. Of course, all of this will only be effective if the relevant frameworks and apps make use of such features. As amazing as computers are already, there is still a lot of room for improvement.
Does one of the platforms you support (or its users) require significantly more effort in development and support, or do they balance each other out?
It is quite balanced.
Some hosts require more work than others because they do not behave in full accordance with the specifications of the plugin interfaces (e.g. VST).
How do you protect your plugins from illegal use and/or distribution?
I use a challenge response copy protection scheme: A plugin calculates a unique computer ID on the system on which it is running. The plugin (or you) sends this computer ID to klangfreund.com. An unlock file is returned if you own a license for the plugin. This unlocks the plugin. Once done, it is not necessary to repeat this process. Most of this is not visible to the user.
I'm aware that this means my server must run reliably. Since my first plugin was released 10 years ago, this has been the case. The server is monitored continuously and automatically. In the worst case scenario, I can set up a new server instance on a different hosting provider.
I would have preferred to omit copy protection altogether. But my company would most likely not have survived without it.
Have you ever thought about releasing your plugins under an open-source license?
In the early days, the LUFS Meter plugin was open source. Almost no one wanted to donate any money for it. Since I wanted to continue working on it as much as possible I switched to a commercial business model.
The main loudness measurement algorithm – the core of my work – is still Open Source, MIT licensed.
Do you maintain an exchange with other Swiss audio software developers, such as TAL Software?
No, sadly, I haven't met Patrick Kunz from TAL Software GmbH yet.
Can you name three plugins by other developers that you use regularly?
- plugdata by Timothy Schoen
- Hollywood Orchestra by East West
- Drambo by Beep Street. Most of the time, I use it on an iPad. It also runs as an AUv3 plugin under macOS.
Do you have any new products in the pipeline, or can you say anything about the future of Klangfreund? Thank you very much for the interview!
I will continue to improve and expand the functionality of the LUFS Meter and the Multimeter.
I also have some ideas and prototypes for unique effect plugins and DJ tools.
A small Open Source utility plugin would also be nice.
Thank you, Amadeus!