I found a new (to me, anyway) type of distortion on the NM--feeding the output of the ring modulator back to the modulation input. (For some reason I couldn't get this to work with the gain control module.) I quite like the sound of this technique, and this is my favorite patch so far using it. It's a bouncy sequence on one pitch (controlled by the keyboard). Knob 1 controls the input to the ring modulator, which effectively controls the distortion and makes the overall effect more staccato or legato. Knobs 2 and 3 make it wackier. Knob 4 turns it off.

I never saw it done with the Ring modulator module but there are some related types of distortion.

Have a look at the accompanying patch with four worked out examples of similar types.

1) The basic idea is to simply feedback the output of a mixer module to one of its inputs. If the feedback signal would be more than 'unity gain' (mixer knob fully open) a potential oscillation situation might occur. But up to and including 'unity gain' an interesting situation occurs, the signal is boosted outside the digital headroom space and the output is simply clipped. The clippoint in the NM is at 256 or -256 units (4x64 units). To reduce the clipped signal back to a normal level the amplifier module set to x0.25 is used.

A peculiarity of this feedback is that there is a one sample delay in the feedback, its always the outputvalue of the last sample that is fed back to the current sample. This creates a so called 'integrator', the main ingredient of a filter where each pole is actually made with an 'integrator'. The fact that it is actually the previous sample that is fed back creates a sort of microscopic reverb effect causing the signal not only to clip but to phaseshift parts of the signal as well. This causes a 'saturated' effect, reducing the very high spectral components.

This type of feedback distortion does work on the NM due to the one sample delay of the output and the perfect control on the gain. In fact the unity gain of the knob and the one sample delay combined will result in a feedback 'approaching' unity gain, preventing the mixer from starting to oscillate.

There are two basic parameters to control the distortion: input level and feedback. But a third parameter can be added: symmetry. By adding a constant 'voltage' to the input the mixer is pushed into an assymmetric behaviour introducing even harmonics and changing the dynamic behaviour. Using a LFO instead of a constant value creates a PWM-like effect in the sound.

2) Adding a 6 dB HP filter in the feedback line introduces some more timbre control with a strong resonant character at very high feedback levels.

3) Using a clipper to control the outputlevel instead of reducing the level back to x0.25 makes the clipping sound more sharp as well. (my favourite)

4) And a HP filter together with the clipper. In most cases input signal levels should be pretty high and the LFO level about half the level of the input signal.