Done with digital compression? Bring back analog.

Sunday 12 July 2020

We have just released a new DSP development kit: the Koala Analog Compressor SDK. It features four analog compression algorithms:


The attack and release settings of a FET style compressor are fast and don’t have a lot of range. Despite the lack of range these compressors are a favorite in many studio’s around the world. Their transient shaping possibilities make them very well suited for drums, but they work on just about anything. An example of a FET compressor is the well known Urei 1176.


Opto compressors are not that sensitive to transients and peaks, but are smooth and slow. They’re great for preserving the impression of performance dynamics despite quite extreme level management. These compressors usually don’t offer controls for the attack and release settings. The attack time is frequency dependent which is the main reason these units have such character. An example of an opto compressor is the Teletronix LA-2A.


VCA compressors use RMS and are known for their fully controllable circuits, allowing you to really fine tune each setting. They can be very transparent while still being able to add the glue a mix or a bus needs. Drums sound great through these compressors because they are very good at transparently taming sharp peaks. An example of a VCA compressor is the SSL G bus compressor.


The first types of compressors were Vari-Mu compressors that were designed for use in broadcasts.  They have a fast, sub millisecond, attack and use fixed time constant settings. The ratio of the gain reduction is increased as you hit these units harder; this is musically pleasing when you lay into it more aggressively. These compressors have an extremely soft-knee compression curve so the ratio just continues increasing as the input signal level gets higher. Vari-MU compressors are also great for saturation. The most famous example of a Vari-Mu compressor is the Fairchild 660.

The SDK has a very user friendly API and supports mono and stereo processing, as well as single and double floating point precision. Please get in touch with us if you want to know how to obtain a license to use the Koala Analog Compressor SDK in your application.