The filterdrve is an adaptation of the famous Korg MS-20 analog filter for the api 500 format. I was always looking for an easy way to implement the great sounding MS-20 filter in a recording and mixing setup, and this came out.

The filterdrve has everything you want in a 500 series filter, such as balanced i/o, low noise, great headroom etc. Some features are added like overdrive, audio feedback into the filter and a controllable gain structure.
drive with low noise

Low noise ne5532 opamps are used for great noise performance, while retaining the squelching sounds of the original. Self-oscillation can be attained with the peak control at maximum.

The filter can be switched from low to highpass operation. The bypass switching is done with hardware relays, for full bypass transparency.

The filterdrve runs on a 16v bipolar power supply, which allows for a lot of headroom. The drive control reduces the headroom, for overdriven sounds. Noise is much lower than the original ms-20 filter.

made to be played with

Great care has been taken to make sure the unit has the best sound, with as much control as possible. This unit is meant to be played with and fiddled around, so please do. All the knobs interact with each other due to the circuit design, so it is great fun getting to know every detail of how the unit reacts to different settings.

The filterdrve has alpha metal pots (knobs), an anodized black aluminium faceplate which is laser engraved, and good quality switches.

You can check out the demos below. I will be making and uploading more demos asap.

The filterdrve is available for 275 euros. More information at