Sound of 2 played notes becomes 1 in between

[Pholand]

In general when you play 2 notes like C and C# it will sound very unpleasant and unuseful to me.
When I used the Ableton pack 'retro synths'and use the 'Mallethead' preset, playing C and C# gives me a nice techno sound, which sounds like it is playing somewhere between C and C#.
Could anyone explain me how this is happening, why this is happening in the 'Mallethead'preset and can I create this effect with any sound ?

Thanks in advance for responding

[yur2die4]

This is know. As 'beating'. Let's say you walk past two fences. One has pickets every step. The other has pickets just slightly lower than every step. There will be a perceived average rate at which the pickets come. Kind of an average. It'll be a rate slightly between both. That is the frequency between the two. And since it is the combination of both, it is the 'loudest' since they're doubled up.

At some points you'll walk past two exactly next to each other. Other times they'll be exact opposite. In sound that results in cancelling out so that they are Zero, or No sound during those moments.

So the beating part is where it gradually goes between No sound and doubled sound nonstop. Basically like an LFO. If the frequency of pickets (or notes) are very very similar to each other it'll take much longer to go in and out. Making long drawn out loud and quiet parts. But if they're further apart in frequency. Like a minor third interval, it happens so fast and at such a weird pattern that you are more likely to perceive the individual notes. But you still get a grindy noice which is kind of harmonic.

This is why an Octave sounds clean and a Fifth sounds crisp and sharp. The intervals are 2 pickets per step VS 1 picket per step. Very exact. Or a fifth is 3:2. They match so cleanly you don't get that strong sense of phasing out.

Wrote this in a hurry so it's not 100% exact. To do similar effects try those notes at really high and really low positive on the keyboard. You'll get different results.