Convert Stereo Signal to mono


Is there a simple way to convert a stereo signal to mono? Basically a reverse of Pan2.

I have this synth def, which is outputting in stereo.

SynthDef(\droneFM, {
	arg f1Freq=0.1, f2Freq=1.1, f3Freq=2.2, m1Ratio=1, m2Ratio=2, m3Ratio=3,
	amp=0.1, dur=55, ampM=0.84;
	var sig, car1, mod1, car2, mod2, car3, mod3, env, index, nFreq, out;
	index =, 12);
		env =
		Env.adsr(\, \, \, \,
		doneAction: 2
	mod1 =[\ * m1Ratio, \ * m1Ratio], mul:\ * m1Ratio * index) * ampM;
	car1 = + mod1);
	mod2 =[\ * m2Ratio, \ * m2Ratio], mul:\ * m2Ratio * index) * ampM;
	car2 = + mod2);
	mod3 =[\ * m3Ratio, \ * m3Ratio], mul:\ * m3Ratio * index) * ampM;
	car3 = + mod3) * 0.4;
	sig = car1 + car2 + car3 * env * amp;
	//sig =, pan);\, sig);

But I want to convert the signal to mono. I’m not sure why it’s outputting in stereo, I haven’t specified it to be stereo.

Here is the copy of the Pbind I’m using with it

~dronesBucket = Pbind(
	\instrument, \droneFM,
	\nFreq, 242.5,//485,
	\dur, 30,
	\ampM, 0.4,
	\out, 8,

You are specifying the frequency of your first SinOsc as

[\ * m3Ratio, \ * m3Ratio]

This is an Array of 2 elements - SC will multichannel expand this into an array of 2 signals.

If you want to mix them to mono use arrayOfSignals )

Could I arrayOfSignals ) on the output,

For example\, sig));

To sum the output channel down to mono?


your array of signals is sig.

\ is a control called out that is used to select the output bus

like so: \,

To break this one down a bit:

The first argument to Out is a bus number. It normally doesn’t make sense to sum bus numbers.

The second argument is the signal (or array of signals) to output – this would be appropriate to mix down.

\ produces a control input named “out.” By convention, “out” is generally the leftmost bus number for the output. Usually we define the default bus number as 0, so that the output will begin on the lowest numbered hardware channel. The (1) after kr sets the default to 1, so that your single-channel output would come out the right-hand speaker in a stereo setup. This may or may not be what you want – just to be clear what it’s doing.

If you wanted to mix down to mono and then play on both left and right channels, it would be Mix(sig).dup or even sig.sum.dup (onto bus 0).

(Aside: There’s no significant difference between Mix(sig) and sig.sum – Mix might be a holdover from SC2 and might disappear in SC4.)


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