04
Jan
10

The second oscillator

There are many sounds that can be generated with just one oscillator. But when the second oscillator is used as well, there are plenty of creative possibilities. You can use the second oscillator to add a new waveform or a new pitch to the sound, and this drastically changes the sound, as we’ll see.

Notice the octave knob next to Osc 1. This allows you to generate sounds at an octave different from what you are playing. Play around with the knob, and you’ll see how it works.

Osc 2, however, has additional knobs, tune and fine. They allow you to control the pitch of Osc 2 in a much finer detail. Tune allows you to change the pitch by semitones, and fine allows pitch adjustments over one semitone. Turn the Osc mix knob all the way towards Osc 2, so that you hear only the second oscillator, and move these knobs and see how it affects the sound.

Set these two knobs back to the default for now. Play the Osc 1 saw wave alone, with the filter turned off and the Osc Mix knob turned fully to the left. Select the same saw wave for Osc 2 as well, and while playing, turn the mix knob gradually to the middle. You can hear the sound of the second saw wave getting into the mix. Leave the mix knob at the middle so that both the oscillators sound at equal volume.

Think about this. Why is the sound different from the individual saw waves? When two sounds that are exactly same come together, the resultant sound should sound like the volume has been doubled. However, there should be no change in the characteristic of the sound, isn’t it? For example, two pairs of hands clapping exactly at the same time sound like a single hand clap at double the volume.

Yes, that’s true when the sounds are exactly the same. But here they are not. Even though they are two saw waves at the same Octave and pitch.

What’s the difference between these two waveforms below?

Both are saw waveforms that have the same frequency and amplitude. The difference is in the timing. Waveform 2 seems to “start” a bit early. Without getting into too much physics, when such two waveforms with different timing, but otherwise identical, mix together, they add up to form a completely different wave form. This difference is called “phase difference”. In most synths, the oscillators are programmed to have a phase difference, so that this new sound is possible.

Of course, there are times when you’d want the match the phase of both oscillators. That’s when you’ll use the sync button in the mix panel. Don’t worry about this for now. We’ll use this later when we start making sounds.

Okay… let’s start using the two oscillators now. Set the Osc Mix to 50-50. As you’ve seen before, the fun in using two oscillators is if they are “different” somehow. We’ve seen the effect of phase difference. Now let’s see how a pitch difference sounds.

Increase the semitone value (the tune knob) of Osc 2 by one value. (Push it up just a little bit while a note is playing so that you can hear the change). The sound is wobbly now. But if you increase the tone value further, you’ll gradually hear the sound smoothens over, and there’s more depth.

Set the tune knob back to zero and try the fine knob this time. You’ll hear a “zeeeeooooww” sound. This is actually the wobble you heard last time, in slow motion! As you increase the value of the fine knob, the wobble increases in speed. As you can see, the more the difference in pitch, the more the “wobbling”. So much that, after a point, the wobbling becomes so fast that it is heard as one sound.

Now, try this setting for a classic synth sound. Set Osc 1 to default. For Osc 2, set the semitone to 7. Since the knob in Clearsynth is not numbered, the best way to do this is to set the knob to the middle (the knob range is 0 – 12, so middle is 6), and then slightly increase till you hear a change in the sound.

Notice the depth in the sound that’s caused by the two oscillators bouncing off each other. If you like the sound, save it away for use in your productions!

Exercise: Try using the high-pass or low-pass filter to shape the sound. As discussed before, you can use them to remove some of the low frequencies to “brighten” the sound further, or remove the high frequencies to “dampen” the sound further. This is useful if you decide to use this sound in any of your productions, and you want to “place” the sound in a mix without messing up the other frequencies.

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2 Responses to “The second oscillator”


  1. 1 Eric Layne
    January 14, 2010 at 2:19 am

    Classic synth sound = C64/Amiga? 😉


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