OTA Voltage Controls in the Polymoog - Pictures

Front panel

This is an inside view showing the front panel on top and the right control board on the bottom.

This is an up close look at the right hand control board. The 4007 chips are all socketed. Behind them are the preset resistors, also in sockets. In the center you see the resistors for the mod amt control (57k and 33k from left to right). Only two of the presets have LFO filter modulation. That's a pretty old school way to handle presets.

Back view of the sliders. All are hand wired. The green wire is ground and the red wire is V₊, which are daisy chained across several controls.

This is the top right board, which handles the VCF, keyboard CV, and other functions. The three 3080s in a row are from left to right mod amt, S+H, and contour. The coresponding transistors Q6, Q5, and Q10 are below each 3080.