Here are a couple samples I've made of the passive ring mod. Nothing special. These are in mp3 format, 160kbit. Levels were not quite right so I adjusted them in Audacity. The MP3s sounded close enough to the original WAVs to be usable.

RingModDemo-1.mp3 - Simple two oscillator demo. First tone is the modulator which is a Ray Wilson VCO since wave being modulated by an EFM LFO. Second constant tone is the carrier which is a Blacet Darkstar. Third is the result bumped up in level a little with the preamp onboard the EFM LFO. Passive ringmods, being passive, do attenuate the single a bit so a simple preamp is a requirement.

RingModulator-2-drums.mp3 - This is a $5 thrift-store found drum machine as carrier again with the Ray Wilson VCO as modulator. 4 sets using Sine, Triangle, Ramp, and Pulse waves. I'm sweeping them by hand with a joystick, pardon me if its 5am as I'm doing this and I'm jittery from all the caffiene.