How To

What is a Synthesizer – The Beginners Guide: Together in Electric Dreams

Photograph of the blog post author, Pete briley

Pete briley

4.12.2019

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The Synth. 

Moog Side Angle

Without it, Modern Music as we know it just wouldn’t exist, and half of the greatest songs of the 1980s wouldn’t have happened (I mean, what would Europe’s ‘The Final Countdown’ even be like without that Synth hook?!?!). 

There are very early examples of music synthesisers dating all the way back to the 1920s but they really started to play a part in music after Synth godfather Robert Moog (pronounced so that it rhymes with Vogue)

He started selling his Prototype Synths in the mid 1960s, with rapid expansion in the 1970s and 1980s. 

For many artists, a synth is an incredible tool – from atmospheric pads to face-melting lead lines, fat basslines to weird noises – you can literally make any sound come to life with a synth. 

But for many (myself included) – that’s the rub.

Knowing how to operate a synth properly is like learning a whole new language – in fact, it would appear that to really get the most out of a synthesiser you might need a degree in physics, electrical engineering and music so there is often a huge learning curve involved in getting the sounds you are looking for. 

My Dad is a seasoned keys session musician player, so growing up, there was no shortage of pianos, electronic keyboards and various synths lying around the house. 

I didn’t know it at the time but mucking around with his Roland SH-101 was something I should have perhaps treasured more as they are now pretty highly regarded by people who know anything about synths. 

I could never really wrap my head around this electronic musical instruments world with words like Oscillator, LFO, and Envelope – preferring instead to stick to a guitar.

But the lure of the synth is strong and I couldn’t help but delve into this world and try to make sense of it!

As a note, there are tons of different kinds of modular synthesizers in the market. Although I have covered general elements of a Synth that appear on pretty much all models.

I have chosen to base this blog on the Moog Sub Phatty which is a good beginner’s synth but the principles I talk about apply to all synths.

Moog Front Panel

Types of Music Synthesizer

The first thing I learned when I started looking at into this was that there are tons of different types – Analog, Digital, Mono, Poly and of course Virtual.

The classic synths are all analogue – the sound is made by old-fashioned sound-generating circuitry which creates a sound wave that you then manipulate through the use of filters and envelopes (Stay with me!!! We’ll come back to waves and manipulation shortly!). 

Digital synths use digital processers – they are in essence a computer with a piano keyboard and typically some kind of LCD as an interface. Since the birth of Modern DAWs (Digital Audio Workstations – recording software like Logic Pro X or Pro Tools) – VST Plugins that allow producers to access a world of different synth sounds. Try out Xfer Serum VST for example!

VST Synths are very similar to Digital Synths in how they work but of course with the added bonus of using MIDI so you can change the sound later and experiment with all sorts of different sounds. 

As with all things analogue vs digital – there is a general perception that analogue sound is best and for me, the analogue instruments in my studio are my favourites. 

However, I am yet to produce anything that has used exclusively analogue – the VST and Digital synths will always have a space in the recording studio and give any producer/recording artist multiple options.

Digital and VST synths are generally much cheaper than their analogue counterparts (and in truth, these days the sound is pretty close to the originals – but don’t argue with any purists out there).

Beyond that, you have Mono and Poly Synths. The old Synths were generally all Mono (short for monophonic) – i.e. they played one sound at a time – and required quite a chunk of complex circuitry to achieve that one sound. 

Whereas the digital synths are often simpler (because they have a number of digital processors) so in any case they can support multiple notes at the same time, making them Polyphonic. 

How to Use a Synth

“I Can Feel What’s Going On Inside a Piece of Electronic Equipment. It’s Something Between Discovering and Witnessing” – Robert Moog

The key to understanding how to use a synth is underpinned by understanding how a synth works. 

Acoustic instruments produce sound through vibration – a guitar string is plucked and that vibrating string moves the air molecules around it to create the sound – creating a simple wave that looked at individually is called a Sine wave (think back to your high school physics days). 

But, there’s more to the picture – the reason a C on the flute instrumental sounds different to a C on the violin is that they have different timbres. Timbre is how different resonant frequencies are sounded at different levels when a note is played and if you view those frequencies all as one wave you get different, more complex waves with audible characteristics.

Sine Wave Graph

The Oscillator

Instead of creating sound acoustically using vibration, synths generate electrical signals that are amplified and converted to sound. This electrical signal is generated by the Synth’s Oscillator

The Oscillator’s waveform can be a simple Sine wave, or you can also choose Triangle, Sawtooth, Square and Pulse waves. 

Oscillators

Triangle waves consist of odd-numbered harmonics only so it’s quite a simple sound with a strong overriding note.

A Sawtooth wave is much brighter because you also get all the harmonics and as they grow weaker in amplitude (how strong the wave is) they can be good for making fat bass sounds and brassy tones.

Pulse waves are kind of similar to Triangle waves because they only have odd-numbered harmonics but you can change the balance of the odd-numbered harmonics so it offers loads of flexibility in terms of making sounds. 

And a square wave is the same as a pulse wave but the pulse width is 50% less so each pulse in the wave has a unique sound – these waves have a kind of natural single-note arpeggiator sound but each note has a slightly different sound.

A lot of synths also have a 2nd Oscillator which you can either run in parallel with your 1st Oscillator or you can assign a different waveform to it or even de-tune the second note the thicken up the sound.

The Filter 

Pitch Filter

Your Oscillator’s signal then flows through a Filter. The Filter removes certain frequencies from audio and alters the waveform to further affect the sound. The Filter is a low pass (allowing low frequencies to be heard) made up of a Cutoff dial which allows you to set where the Low-Pass filter kicks in. 

There is also a Resonance setting which controls how much signal is routed form the filter’s output back to its input – generally, once you get to the higher levels of this setting you can also get your synth to start to self-oscillate which is pretty cool for making soundscapes and atmospheric pads, etc.

The Envelope

Envelope

From the Filter, the Oscillator’s wave then flows through the Envelope. The envelope is where you really get into the nuts and bolts of sound design. 

Synths have 4 main controls in the envelope 

Attack (how quickly a sound reaches its full strength and brightness)

Decay (how quickly the sound declines after the initial attack)

Sustain (how long the note lasts)

Release (how long the note takes to return to silence once the key is lifted), often abbreviated to ADSR.

Some synths have only one set of envelope controls whilst others have 2 – one for the Filter and then a 2nd envelope for the Amplifier. 

The Filter Envelope will control the timbre of a sound whilst the Amplifier envelope controls the amplitude (or strength) of the sound. 

Modulation

Modulation

Controlling Modulation (often abbreviated to Mod) is an important aspect of how the sound is shaped. 

When you modulate a control signal, you effectively change something about the effect your control signal has on the wave from the Oscillator. 

You can modulate things like Pitch, filter cutoff and even the waveform to shape the sound. You can often control the Modulation signal’s depth using a wheel or slider next to the keyboard called a Modwheel. 

The Modulation panel often includes an LFO (Low-Frequency Oscillator) which mirror the waveform in the sub-audio range and give some additional beef to your signal or you can increase the LFO range to the audible range to add some harmonic depth to what you’re doing. 

The LFO Rate dial controls the rate of modulation on the LFO which adds some really interesting effects.

If you’re working with Analogue synths especially, the Modulation Panel is a good place to look if your notes sound out of tune. 

Analog synthesizers all have their own little quirks and especially some of the older synths have pitch adjustments as they warm up so you often have a pitch adjustment knob to help make sure you’re notes are in tune (or properly out of tune if that’s what you’re going for!)

Mixer

The Mixer looks different from Synth to Synth but generally, you have your Oscillator and Sub-Oscillator balance and if you have a 2nd Oscillator a control for that is also there. You also have a noise generator.

As you would expect, this is essentially just a level of white noise that is overlaid on your sound. It’s particularly useful if you’re looking to mimic percussive drum sounds, spacey wind effects or just a noisy bass line. 

Hopefully, this will give some insight into how a synth works and how to use it. That said, my Dad’s advice is probably the best approach – just play with the thing until you know how it works.  Enjoy!

Pete with SH-101


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