Advanced Modular Research #3 ~ Moog-flavored analog FM

Here's another way to get nice FM sounds. For high quality sine waves and decent tracking, why not use the A-108 Moog filter? Add an A-133 Polarizer for ring modulation and you're almost there.

Here's the patch. The yellow signals are control voltages, the green signals are audio. For musical inspiration, check out this mp3 featuring this Moog-style FM-patch and some drums.

For DX7-style FM you need good tracking and thru-zero modulation. The A-108 Moog-based filter doesn't have perfect tracking but it's close enough. The two self-oscillating A-108's act.. as oscillators. The right filter has an A-133 polarizer in it's feedback loop for ring modulation (faking thru-zero). The 6dB output modulates the frequency of the left filter. The A-143-9 Quadrature LFO can actually do thru-zero but here it's used mainly because it's sine wave is pure.

You could use other filters, like the A-105, which also has good tracking and self-oscillation. The A-133 can be substituted by a ring modulator (but the A-114 gives less control and it sounds harsh).

The BP output of the modulating filter is connected to the CV input of the Quadrature LFO, but this is optional. The A-118 adds extra variation to the quantized random voltages of the A-149-1. Flip the switches of the Precision Adder, and try different settings of the VCADSR and the VCLFO-speed for virtually unlimited variations.