About apulSoft

apulSoft is an audio plugin manufacturer based in Z├╝rich, Switzerland and was founded in 2003.

Currently exactly one person fills all roles at apulSoft and that is me, Adrian Pflugshaupt. I did a lot of work as a professional musician (woodwind player) and ended up sharing the stage with some of the all-time greats like Herbie Hancock, Benny Golson, Peter Erskine,..

At the beginning of my career I did sound-engineering and recording work for my own projects. During that time I started creating plugins because I needed a drum trigger plugin. That is how the first apTrigga was born.

For many years I wrote software during train rides and on tour buses travelling to the next concert or rehearsal. I always had a very strong interest in mathematics, signal processing and programming and used the many travel hours to learn everything I could about these topics.

In 2020 I decided to do less live performances in order to focus on apulSoft. New exciting projects are in the pipeline and existing ones will be improved with regular updates.



Adrian performing live for Quincy Jones on his legendary 75th birthday concert at the Montreux Jazz Festival, Switzerland.


signal processing algorithms

Now that an average PC is fast enough to easily handle multi-channel audio processing, dsp algorithms can be pushed much further to provide much improved sound quality. Many of the standard dsp algorithms currently in use come from a time when CPUs were barely able to calculate any audio in real-time. Using more complex mathematics we can now process audio in ways that are no longer musically inferior to analog devices. I am not talking about oversampling here, but mathematically different ways to look at sampled data than what was used before.

For example: In apulSoft products there is an alternative procedure to the bilinear transform which is used to create filters that behave like perfect analog filters. And the plugins use a unique way to apply saturation and distortion that vastly outperforms regular oversampling.

I use math tools like linear algebra, higher-order indefinite integrals and approximation theory to improve the sonic results of audio processing. In the future I plan to share some of these ideas on a dsp blog on this site.



Some math used in apShaper's saturation engine.


user interfaces for audio

An advantage of computers versus analog gear is the existence of a large screen. It can show many types of information at the same time. For my plugins I try to use this to display information with scientific units in real-time and let the user tweak parameters on top of these graphs. So results can be seen in addition to only hearing them. Of course the ears need to be final judge of adjustments, but graphical displays have the advantage of being able to show changes over time and give a larger overview.

I try to keep interfaces as clean as possible. Everything is drawn in code as pure vector graphics. This makes the interface compatible with high resolution displays, allows the user to scale the interface and produces sharp prints of user manuals.



apTrigga3 vector gui with level handles on top of the signal graph.