There are at least 3 different versions of this circuit. The first DM-2 version was using the MN3005 BBD and the MN3101 Clock Driver IC (PCB marking: ET5214-510). Later they changed the clock driver to MN3102 and the BBD to the low current version of the same circuit, the MN3205 (PCB markings: ET5214-510A an
d ET5214-510B). The MN3205 is a little noisier, but it generates less distortion (only 0. 8% compared to 1% for the MN3005).