Journey into modular with Elevator Sound: Oscillators (part two)

A picture of the inside of Elevator Sound.

A new series of articles for those looking to patch into the world of modular synthesis from Elevator Sound

One of the leading independent music hardware stores who specialise in Eurorack modular, synthesisers & drum machines in the UK, Elevator Sound is a highly respected team of friendly, like-minded machine music enthusiasts based in Bristol.

To help those of you thinking about taking the plunge and patching yourself into the world of modular sound, they’ve kindly agreed to present a series of exclusive articles for Innate – to help set you on your way and get a better idea of what you need to know.

If you’ve yet to visit their store on Stokes Croft in Bristol or perused their website, you’ll be pleased to know their highly knowledgeable and friendly staff have been around the block a few times over the years – so are more than happy to field any questions. Where they really win out is they’re more interested in showcasing exciting, unique and high-quality affordable products, rather than what’s cool or popular.

Having dedicated their time to making, listening and playing music for decades, they’re more than happy to help you find that dream machine to create that perfect noise you really want… which is exactly why we couldn’t think of anyone better to ask how all those wires and pieces of equipment fit together!

For their next instalment, Head of sales, web and customer support Ben Chilton focuses on the subject of ‘Oscillators’:


At the heart of every modular synthesizer is a little creature, tucked away in the rack – constantly humming, gurgling and growling away. These are the oscillators and they form a vital part of the traditional modular setup – Sound Generators!

By definition, ‘oscillation’ means constant movement between two points, when we translate this into sound it shows up as ‘waves’. To sum up the basic function of the oscillator, it outputs these electronic waves, which can be shaped and modulated to create synthesized sound.

When a wave oscillates between its highest and lowest point and this electronic movement is routed through to the speakers, it causes the speaker cone to move inwards and outwards, following the curve of the wave. This in turn pushes the air, those waves in the air hit our ears and we hear it as sound.

The shape of the wave determines how it sounds to us, sine waves sound smooth and pure due to their flowing movement, whereas waves with a sharp drop (such as: saw/squares) have a ‘buzzing’ sound to them due to the sudden speaker movement.

An image of the different kind of waves

In a Eurorack system, oscillators behave a little differently from their desktop counterparts, as long as they’re turned on the oscillator, or ‘VCO’ will continually drone – putting out its steady waves at whatever you’ve set the frequency to. But how do we make this into a usable musical tool beyond a drone?

The first step is getting some rhythm and space in your drone, and for this we use a VCA (voltage controlled attenuator). Some oscillators have their own built in ‘VCA’ section, but for those that don’t we have to patch through one. The VCA can be seen as a voltage controlled volume knob, it creates silence between the notes by turning the oscillator signal down to 0 when no CV input (for example: an ADSR Envelope) is present.

Now we’ve got a rhythm, it’s time to add some notes

Eurorack uses a standard called 1 Volt per Octave for pitch input. This allows us to control the pitch in the same way we would on a keyboard or piano, 12 notes (or 1 Volt) = 1 octave. This is typically labeled as 1v/o, 1v/oct or any variation of this. This is where you’d route the ‘Pitch CV’ out from your keyboard or sequencer, or get creative and patch an LFO or some Sample & Hold in there!

Diagram for a basic synth voice patch.
Block diagram for a basic synth voice patch

Tuning, the big question!

Getting your oscillators in tune in a modular system is a unique approach, as you can change the frequency regardless of any input. In order to tune, you match the input ‘pitch’ (or 1v/octave) signal to the output pitch. You can even use a simple phone app tuner for this, connect your controller or sequencer and patch into the Pitch input of your oscillator. Send in a C3 note and simply tune your oscillator until the output pitch is matching at C3. Simple as that!

It’s worth bearing in mind that simpler waveforms are easier to tune, so a sine or triangle output are best for this.

Oscillators come in MANY different shapes, sizes and sonics. From expansive Complex Oscillators, to digital multifunction modules and classic analog clones, the possibilities are endless!

Now you understand how they work, where do you start?

Oscillators are the core of any systems’ sound and each one has slightly different features which helps set them apart. Considering what features (as well as what sound) you want can easily narrow things down. Would you prefer something with polyphonic capability? Maybe stereo output, or a VCO which responds well to FM? Something with a wide range, or a perfect Moog clone?

There are tonnes of super flexible and creative oscillators out there so have a sniff around!

Image with different types of oscillators.

Find out more about Elevator Sound

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