Multiple Identity Filter

This is the MIF or Multiple Identity Filter on the ORT. It was the second module that I made for the ORT and it uses a Curtis Electromuse CEM3340 VCF device. The design is by a chap called Craig Anderton who was an electronic music equipment designer who had an article in a magazine called Contemporary Keyboard. This was a big project for the magazine and was spread across 3 editions. You can read the original article at this site (the owner of the site doesn't give his name). I had actually never read the first part until I stumbled upon this pdf on the web! Anyway here is the front panel. It has a very similar layout to the original; which was important for getting the various operating modes right.

The Electronics was again mounted on a piece of veroboard that was attached to the back of the panel. I recently repaired it as you will notice that one of the switches is red. It have been broken for a few years... The module still suffers from a lack of Q or resonance. I suspect that the tantalum capacitor that is part of the AC bypass circuitry has failed but I have yet to actually repair it yet. I have access to a very nice acoustic spectrum anaylser at work so I plan to one day take the filter in and actually measure some of the different modes. It is probably the most complex module in the ORT and probably the most stable, that has probably more to do with the fact that I tinkered less with the design than anything I suspect!!!