A module reads any voltage above about +3V as a high gate and below 1V as low

In the A-100 (and most Eurorack), gate, trigger, and clock inputs sense a voltage threshold rather than a specific level: any voltage beyond roughly +3 V is treated as ‘high’ (so +5 V, +8 V, +10 V, +12 V all fire an ADSR, sequencer, clock divider, etc.), and any voltage below 1 V is treated as ‘low’. This is why a nominal 0/+5 V gate spec is only typical, not required — a wide range of signals will trigger. It also explains why an audio-rate or LFO signal that swings well above +3 V can be (mis)used to clock or gate a module, and why triggering wants a fast rising edge that crosses the threshold cleanly. Module-specific exceptions are noted per module.

Examples

Patching a +10 V square LFO into an ADSR gate input fires the envelope on every cycle. A signal that only peaks at +2 V never crosses the ~+3 V threshold, so the envelope never triggers.

Assessment

What voltage range does a Eurorack gate input read as ‘high’, and what as ‘low’? Why can a +8 V square wave trigger an envelope even though the gate spec says 0/+5 V?