How to Program a Synthesizer

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I. Introduction

A synthesizer is a very versatile instrument, capable of a very broad range of sounds – from beautiful pads to aggressive leads. They can, however, be a bit confusing to use, and even the most experienced can have trouble when presented with an exotic interface. This guide will walk you through the components of a synthesizer and provide a basic path to take when programming one.

II. The parts of a Synthesizer

Most synthesizers share the same set of components. These are Oscillators, filters, envelopes, and LFOs.

  • Oscillators: An oscillators produces a sound. Usually there will be at least three waveforms to choose from, being Saw, Sine, and Square/Pulse. You’ll occasionally get triangle and noise. There are many other type of waveforms, too. A waveform defines the timbre, or character, of the synthesizer.
  • Filters: Filters will filter a frequency range from a sound. There are a few basic filter types. Lowpass filters will only allow frequencies under the cutoff point through. A high filter does the opposite, allowing only the frequencies above the cutoff point through. A bandpass allows all of the frequencies in it’s bandwidth, or range of the cutoff point, through.  A band reject does the opposite, again. The cut off point defines at which frequency sound should be cut. A typical filter will have a resonance feature, which amplifies frequencies at about the cut off point.
  • Envelopes: Envelopes are used for modulation and are most often ADSR. Almost every synthesizer will have an envelope for controlling the volume, and many will have an envelope for controlling the filters as well. ADSR stands for Attack, Decay, Sustain, and Release. Think of hitting a note on a piano. It takes a short time for the volume of the piano to reach it’s loudest – or it’s attack. Then it will decrease in volume for another amount of time, or decay. As you hold the key, the note will continue to sound at a level lower than the initial attack, sustain, or until you release the key. When you release the key, there will be another short amount of time for the volume to return to silence, or it’s release.
  • LFOS: LFOs are another source of modulation. They have waveforms too (in fact, LFO actually stands for “Low Frequency Oscillator), and modulate the variable using that waveform. For an example, you can obtain a vibrato effect by having the LFO modulate the pitch of an oscillator with a sine wave. The pitch will rapidly increase and decrease.

III. Shaping the Sound

When creating a sound, I find it best to go from biggest to smallest, or to start out with the biggest things about the sound, and then work on the details.

  1. Choose a waveform. This makes the biggest difference to the timbre of the sound.
  2. Filter it! This will take away much fo the ‘rawness’ of the oscillator and can give it an enjoyable, warm sound.
  3. Define using envelopes. First do the volume, then the pitch or anything else you’d like to control with an envelope. Ask yourself what there is and isn’t: pitch variation? A drum will sharp on the attack, for example.
  4. If you want to do anything with velocity, work on it now (if your synthesizer has the capabilities). A piano doesn’t have the same sound when you hit the keys hard as it does when you hit them softly.
  5. Attack it with the LFO. LFO’s can be very powerful if you use it right. vibrato, tremelo, and wah-wah like sounds.
  6. Define further with effects. Synthesizers will often include built-in effects. They most often aren’t the best, but can be used to do some basic definition to the sound.
  7. Use it!

Some other things should be taken into consideration. Do you want it monophonic or polyphonic? A monophonic patch will only allow one note to be played at a time. Should it have portamento (sliding it’s pitch to the next note), and when should it have portamento?

IV. Conclusion

Perhaps the best way to learn how to use a synthesizer will be to experiment with it. Every synth will behave differently, with varying character and sound. Use this guide for reference, but the best way to learn to use a synthesizer is by experimenting.

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