My build progress

Not yet!

The filter core is similar to this one that you posted:

I looked at the matched pair transistors they use on the x0x box and am using some of them for the exp conv for the cutoff and the current sink - might see if I can use them for the diodes in the filter stages too. That way it may be possible to have a diode ladder and a transistor ladder on the same PCB?

http://timstinchcombe.co.uk/synth/Moog_ladder_tf.pdf is a good resource too.

Once I manage to get a voltage controlled resonance circuit going I’ve got some ideas to try out - feedback some of the original input to counter any bass loss, and see if I can do some analog maths and derive a HP from it.

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