Surge XT provides digital ring modulation between oscillator pairs in the mixer and as a filter configuration

Surge XT offers two forms of ring modulation. In the mixer, channels Ring Mod 1×2 and Ring Mod 2×3 multiply the raw outputs of two oscillator pairs. Multiple ring modulation modes are available: Ring Modulation, Continuous XOR, and nine Scale-Invariant Linear Modulation variants, selectable per channel via right-click. Additionally, the Ring filter configuration multiplies the two filter outputs (rather than summing them), creating frequency-shifting/sideband effects. For the filter Ring config, audio must be routed to both Filter 1 and Filter 2 separately or no output results. Ring modulation creates sum and difference frequencies between the two source timbres, producing inharmonic metallic sounds.

Examples

Route Oscillator 1 (a pad tone) to Filter 1 and Oscillator 2 (a sine) to Filter 2, set configuration to Ring — the ring modulation produces beating inharmonic tones.

Assessment

Why does Surge XT require audio in both Filter 1 and Filter 2 for the Ring filter configuration to produce sound? What frequencies does ring modulation create from two input tones at 200 Hz and 300 Hz?