Doepfer A-106-5 SEM Filter

Doepfer now make a vast range of different filters, each with a different character. Many of them are based on "classic" filters from old analogue synths by such famous manufacturers as Moog and Oberheim, and this module is an example of the Oberheim SEM filter. It provides high and low pass outputs and a band pass too, and by mixing the first two a notch filter effect is available. Doepfer state on their website that the filter does not self-oscillate (in keeping with the original model it is based on) but there is a simple modification that you can do which will provide this facility if you want to. Doepfer are actually very good at publishing suggested modifications to some of their modules, with the the proviso, of course, that you will void the warranty if you do modify the equipment. In my opinion this is one filter that every modular set up should have, not least for it's ability to introduce a pleasant mild distortion to the sound when overdriven.