MELT routes FM1 through an inverter and a voltage-controlled depth stage before the signal reaches its analog cutoff circuit. FM2 provides a conventional attenuated cutoff input, while FM1 lets another control voltage change how strongly its source moves the filter. That difference turns a fixed sweep into a performance variable.
The useful distinction is between modulation and modulation amount. An envelope or LFO connected to FM1 supplies the movement, while a signal at AMT1 changes its depth. You can alter the strength of the original pattern without replacing its timing or shape.
Now patch a second control signal into AMT1. This input does not become another direct cutoff source. It changes the amount assigned to FM1, allowing the envelope sweep to grow or recede while the envelope itself remains unchanged.
That architecture makes cutoff movement with changing depth possible inside one filter module. A sequencer lane, stepped random source, velocity-derived voltage, or slow envelope can control AMT1. Each can reshape the prominence of the FM1 gesture without needing an external VCA for the modulation source.
The FM1 knob still matters after AMT1 is patched. It establishes an offset from which AMT1 works, rather than acting as a simple ceiling. This behavior is central to MELT’s voltage-controlled filter architecture and explains why the result can initially seem stronger than expected.
For a predictable first patch, leave AMT1 disconnected and adjust FM1 until the envelope produces a modest sweep. Connect a slowly changing positive voltage to AMT1, then listen as the same contour expands. Reduce the FM1 knob if the combined amount pushes the cutoff against the end of its useful range.
That last detail supports a clean reveal effect. Set FM1 to zero, send an LFO or envelope into FM1, and use a positive envelope at AMT1 to bring the motion forward only during selected notes. When the AMT1 envelope falls, the cutoff movement retreats without changing the FM1 source.
Negative voltage serves a different purpose. Start with an audible amount on the FM1 knob, then apply negative CV at AMT1 to reduce that movement for particular steps or phrases. This creates controlled restraint without changing the cutoff knob or editing the source envelope.
Do not confuse negative AMT1 voltage with the FM1 polarity switch. The switch reverses the direction of the FM1 signal, whereas negative AMT1 voltage reduces its assigned depth. If a patch moves the wrong way, change polarity; if it moves too far, adjust the amount or AMT1 voltage.
Bipolar modulation at AMT1 can make the depth rise and fall around the amount established by the FM1 knob. Keep the starting amount moderate so the negative half has room to reduce it and the positive half can expand it. Large offsets can make part of the cycle appear pinned near the cutoff’s practical limit.
A slower envelope creates broader phrasing. Send a short envelope to FM1 for the note-level sweep and a longer envelope to AMT1 for movement across several beats. The fast contour remains recognizable as the longer voltage gradually increases or reduces its reach.
FM2 can operate beside this patch without competing for the same task. Use FM2 for a steady background motion, such as a restrained slow LFO, while FM1 and AMT1 handle changing articulation. Adjust FM2 first so its movement does not hide the depth changes you are trying to hear.
Troubleshooting starts by removing AMT1. Confirm that FM1 moves the cutoff, verify the polarity switch, and set a conservative amount. Reconnect AMT1 with a simple positive envelope before trying bipolar or stepped sources, since this exposes offset behavior without several changing variables.
When modulation seems absent, turn FM1 up briefly and hold AMT1 at zero to confirm the source reaches the jack. When it seems excessive, lower both the FM1 amount and the AMT1 signal rather than closing the main cutoff. That preserves room for the filter to respond across the phrase instead of forcing every sweep against one boundary.
The useful distinction is between modulation and modulation amount. An envelope or LFO connected to FM1 supplies the movement, while a signal at AMT1 changes its depth. You can alter the strength of the original pattern without replacing its timing or shape.
FM1 and AMT1 perform different jobs
Begin with an oscillator feeding MELT and an envelope connected to FM1. The FM1 knob establishes the starting amount of cutoff movement, and the polarity switch determines whether the envelope drives the cutoff in its normal or inverted direction. Set the manual cutoff low enough to hear the full contour clearly.Now patch a second control signal into AMT1. This input does not become another direct cutoff source. It changes the amount assigned to FM1, allowing the envelope sweep to grow or recede while the envelope itself remains unchanged.
That architecture makes cutoff movement with changing depth possible inside one filter module. A sequencer lane, stepped random source, velocity-derived voltage, or slow envelope can control AMT1. Each can reshape the prominence of the FM1 gesture without needing an external VCA for the modulation source.
The FM1 knob still matters after AMT1 is patched. It establishes an offset from which AMT1 works, rather than acting as a simple ceiling. This behavior is central to MELT’s voltage-controlled filter architecture and explains why the result can initially seem stronger than expected.
For a predictable first patch, leave AMT1 disconnected and adjust FM1 until the envelope produces a modest sweep. Connect a slowly changing positive voltage to AMT1, then listen as the same contour expands. Reduce the FM1 knob if the combined amount pushes the cutoff against the end of its useful range.
Positive and negative CV reshape each sweep
AMT1 adds an offset to the FM1 setting. Positive CV increases modulation depth, while negative CV reduces it. A positive voltage can introduce FM1 movement even when the FM1 knob is turned fully down.That last detail supports a clean reveal effect. Set FM1 to zero, send an LFO or envelope into FM1, and use a positive envelope at AMT1 to bring the motion forward only during selected notes. When the AMT1 envelope falls, the cutoff movement retreats without changing the FM1 source.
Negative voltage serves a different purpose. Start with an audible amount on the FM1 knob, then apply negative CV at AMT1 to reduce that movement for particular steps or phrases. This creates controlled restraint without changing the cutoff knob or editing the source envelope.
Do not confuse negative AMT1 voltage with the FM1 polarity switch. The switch reverses the direction of the FM1 signal, whereas negative AMT1 voltage reduces its assigned depth. If a patch moves the wrong way, change polarity; if it moves too far, adjust the amount or AMT1 voltage.
Bipolar modulation at AMT1 can make the depth rise and fall around the amount established by the FM1 knob. Keep the starting amount moderate so the negative half has room to reduce it and the positive half can expand it. Large offsets can make part of the cycle appear pinned near the cutoff’s practical limit.
Two modulators turn repetition into phrasing
A stepped random source at AMT1 is useful when repeated notes need unequal filter emphasis. Patch a consistent envelope into FM1, then let each random step alter its depth. The attack timing remains stable, but some notes open brightly while others stay contained.A slower envelope creates broader phrasing. Send a short envelope to FM1 for the note-level sweep and a longer envelope to AMT1 for movement across several beats. The fast contour remains recognizable as the longer voltage gradually increases or reduces its reach.
FM2 can operate beside this patch without competing for the same task. Use FM2 for a steady background motion, such as a restrained slow LFO, while FM1 and AMT1 handle changing articulation. Adjust FM2 first so its movement does not hide the depth changes you are trying to hear.
Troubleshooting starts by removing AMT1. Confirm that FM1 moves the cutoff, verify the polarity switch, and set a conservative amount. Reconnect AMT1 with a simple positive envelope before trying bipolar or stepped sources, since this exposes offset behavior without several changing variables.
When modulation seems absent, turn FM1 up briefly and hold AMT1 at zero to confirm the source reaches the jack. When it seems excessive, lower both the FM1 amount and the AMT1 signal rather than closing the main cutoff. That preserves room for the filter to respond across the phrase instead of forcing every sweep against one boundary.
