// connect all midi devices
(
MIDIClient.init;
MIDIIn.connectAll;

MIDIFunc.trace(true);
)

// on and off notes are tracked using an array
// the synth need to be using a gated envelope.
(
~synths = Array.fill(127, nil);
MIDIdef.noteOn(\on, {
    arg val, num, chan,src;
	// To be absolutely safe
    if(~synths[num] == nil, {
        ~synths[num] = Synth(\pad, [
            \amp, 0.1,
            \freq, num.midicps,
            \harm, exprand(4,20),
			\gate, 1]);
    });
});

MIDIdef.noteOff(\off, {
    arg val, num, chan,src;
	// To be absolutely safe
    if(~synths[num] != nil, {
        ~synths[num].set(\gate, 0);
		// Remove the reference
        ~synths[num] = nil;
    });
});
)

Synth(\pad)