Oscillators: Mixing and Blending

Oscillators: Mixing and Blending

31 October, 2007 | 12.52PM

• Written by: francispreve
• Filed under: Music News: guide to synthesis, oscillators, synthesis, synthesizer

Once you understand the harmonic characteristics of the basic oscillator waveforms, the real fun begins. By tuning and mixing various waves, you can create entirely new sounds from scratch.

This week, we’ll cover the essentials of how to tune and mix oscillators.

Note: If you want to follow along at home, fire up your demo version of Reason, create a Subtractor synth and make sure oscillator two is turned on (the orange box next to “Osc 2” should glow).

You can get Reason at www.propellerheads.se.

Detuning

Most oscillators include tuning controls for the octave range, semitone (note) and cents (detuning) of each waveform.

Cents are the smallest musical tuning increment and are used for thickening a sound or making it sound “out of tune”.

While the term “cents” may seem a bit odd, it is used because there are one hundred cents in every semitone (also known as a half-step or note).

One of the most common sounds in epic trance is created by blending two sawtooth oscillators and detuning them by an equal amount in opposite directions.

Herein lies a secret to good sound design: By detuning each oscillator by an equal amount — positive and negative — you retain overall tuning coherence, instead of leaning sharp or flat.

[Trance Lead, above image: This oscillator combination forms the basis for many classic trance leads. Note that in all the examples in this lesson, the filters are wide open, so you can really hear what’s going on.]

Octaves

At the opposite end of the tuning spectrum are octaves.

If you’re not musically inclined yet, here’s an easy way to understand octave tuning.

When two oscillators are tuned to the same octave, playing Middle C generates two tones at the same pitch.

When one octave is lower, it’s like playing Middle C and the C below it simultaneously — and so on.

The track ‘Do It (Original Mix)’ by Cosmic Belt relies on a sample from the Duran Duran classic, ‘Save A Prayer’.

The sound in Duran’s original hit was created by taking two square waves and tuning them apart by an octave, then applying filtering and envelopes.

In this example (see screenshot, above), we create the raw sound of ‘Save A Prayer’ before it is modified by the other modules, like filter and envelope.

By detuning oscillators by even wider amounts, like two octaves or more, we can create still more unique textures.

Nowadays, it would be prohibitively expensive to sample anything by the artist currently known as Prince.

However, we can easily recreate the synthy organ sounds used in many of his early tracks, like ‘Let’s Go Crazy’.

The trick here lies in understanding that the essence of that sound is two sawtooth oscillators tuned two octaves apart (see screenshot, above) with the filters wide open.

For more of that funky Prince goodness, try adding some triangle or sine wave vibrato (via an LFO) to the oscillator pitch.

Intervals

This is where things may get a little confusing.

Some synthesizers integrate interval tuning (AKA tuning by semitones) into the octave control by combining the functions and using a single control called “coarse tuning” or something similar.

Other synths, like Reason’s Subtractor, use discrete controls for octaves and semitones.

The end result is identical; in many cases, interval tuning allows you to create sounds that play two notes with a single key.

In more refined examples, you can use interval tuning to highlight specific harmonics or frequencies.

Here are some examples of each.

Analog B3

By using interval tuning to emphasize certain frequencies, you can create entirely new harmonic textures that are useful for recreating specific instruments or adding shimmery highs to a sound.

For instance, if you want to emulate a jazzy house organ, but don’t have access to a Hammond B3, just take two sine waves and tune them apart by one octave plus seven semitones — or an octave and a fifth, if you’re musically trained.

The settings in the screenshot (above) display the specifics.

This recreates the sound of an organ with the first and third drawbars pulled out.

While this type of sound is ideal for chordal riffs, it also forms the basis for hundreds of classic house bass lines, notably the groove from ‘Show Me Love’ by Robin S, which was recently covered by Mobin Master.

Analog Bells

Another cool interval trick involving two sine waves is the creation of ethereal, mellow chime sounds.

The approach here is to leave one sine wave untouched so it plays the fundamental (AKA the tonic or root).

Next, increase the octave and interval values on the second oscillator by a wide margin, then adjust their relative mix to taste (see screenshot, above).

If you’re familiar with the basics of envelopes, set a long release time on the amplifier envelope so the sound trails off like a real bell.

Experimentation is the key here, so have fun with it.

That Yeah Yeah Sound

Earlier in the series, I mentioned that interval tuning was the secret to creating the lead sound in D. Ramirez’s massive remix of ‘Yeah Yeah’.

Now that you have a better understanding of what’s going on with oscillators, I’ll leave you with a step-by-step tutorial on using these techniques to duplicate that sound using Reason.

Step 1: Fire up Reason and create an instance of Subtractor. Its default initial patch is actually set up nicely in the filters and envelopes, so you won’t have to do much tweaking to get started, other than to make sure oscillator two is turned on (see the intro to this piece for directions).

Step 2: The core of this sound lies in the fact that the oscillators function as both lead and bass because of their extremely wide tunings. Keep the waveforms set to sawtooth, then tune one oscillator down by two octaves, using a value of 2. Next, tune oscillator one up by a major third by raising its semitone value to 4 (see screenshot, right, for exact settings).

Step 3: Play a few notes and you should hear that we’re on the right path.

Step 4: Now, to get that seasick pitch sweep, you’ll need to add some portamento (also known as glide). Portamento causes the oscillators to slide from one note to another like a trombone or slide whistle, rather than jumping in pitch like a piano or organ. To make the effect more consistent, reduce the polyphony amount to 1, so that only one note can be played at a time. Using the screenshot (right) as a reference, set the portamento value to about 60-70% to maximize similarity to the track’s lead.

Step 5: Now, play the following notes: F, F#, G, G#, then C, F#, F and D#. From there, you should be able to figure out the phrasing and rhythm of the lead. The diagram (above) shows exactly which notes are used in the part, for those who are new to keyboards.

Next stop on our journey: Filters!

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