# Sine-on-sine linear FM A cycling GTS supplies audio-rate modulation to the NTO linear FM input. ## Start here Lower the monitoring level before patching. These are documented patch designs, not claims of hardware audition. Unless this recipe uses the right Mix Pro for control voltage: center its DC offset, zero unused channels, and bring up only the cabled audio inputs. Connect Audio Interface MIX OUT to your normal monitoring chain. 1. Tune NTO to a mid-register note. Set GTS lower to symmetric audio-rate cycling, near the same pitch. 2. Start NTO LIN FM depth at zero; increase gradually. ## Cables 1. GTS XL lower END OUT → GTS XL lower TRIG IN. 2. GTS XL lower SINE (AC) → NTO LIN FM. 3. NTO SINE → Edelweiss right Mix Pro IN 1. 4. Edelweiss right Mix Pro OUT → Audio Interface AUX IN. ## Listen for The sine acquires sidebands. Simple frequency ratios sound more harmonic; detuning introduces moving roughness. ## Play it Move the GTS pitch through unison, octave and in-between positions at moderate FM depth. ## If it misbehaves If the carrier slides far in pitch, reduce modulation depth; use the black AC SINE jack beside lower END OUT, not the white SINE below it. ## Module references - https://serge-modular.com/docs/GTS%20XL%20manual.pdf