How Do Synthesizers Work? Video from

I’ve spoken in the past about how synthesizers work, but I just stumbled across this new video which I think you might find helpful:

Here is a summary of the points covered:

  • You start with a basic waveform – usually either sine, triangle, saw, or square.
    • With a square wave, you can vary the width of the pulse. Varying the width at a regular interval is what is known as “Pulse Width Modulation”.
  • Control Voltage is an electronic signal that can be passed to other parts of the synthesizer in order to control its behaviour. This is referred to as “Modulation”.
  • How Do Synthesizers WorkOne way to modulate a sound is by assigning an envelope to it. An envelope has four parts:
    • Attack – how quickly the note reaches its full volume.
    • Decay – how long it takes to go to its sustain level.
    • Sustain – how the note continues while the key remains pressed.
    • Release – how long it takes for the sound to fade after you lift your finger off the key.
  • A filter allows you to remove part of the frequency spectrum of a sound.
    • A low pass filter cuts off everything above a certain frequency.
    • A high pass filter does the opposite.
    • A band pass filter lets a specific band of frequencies through.
    • A notch filter does the opposite.
    • The resonance control boosts the frequencies close to the cutoff point.
  • An envelope can be used to modulate the filter cutoff frequency over the duration of a note.
  • LFO (Low-Frequency Oscillators) can be used to modulate a parameter at a regular cyclical rate.
    • Running a sine wave LFO to control the oscillator’s amplitude can give a vibrato effect.
    • You can change the frequency of the LFO so that it wobbles at different rates.
    • Using a square wave LFO will turn the parameter off and on rather than creating a smooth vibration.

Anyway, I hope you found that interesting. If you have any comments or questions, I would love to read them, so why not post in the comments sections below.

All the best,


  1. JP

    Ah this is way dope. So I’ve always been a little hesitant with synthesizers because they seemed so complicated and I never knew I fi’d be able to figure one out upon buying one. I feel that there is empowerment in understanding something because it makes us more likely to go out and tackle it. Thanks for the post.

    1. Marcus (Post author)

      Yes, that’s the thing, there is a big difference between a keyboard with lots of great presets on it, and an analog synthesizer with lots of different parameters to alter. I think it’s natural for some people to back away from something if they don’t understand it. But there is a whole world of sonic possibilities with synthesizers, so I definitely think they are worth persevering with.

  2. simon

    Interesting post, never really understood the hows of it. The video’s fascinating it amazing just how you can play around with different frequencies to get different sounds. Makes me think back to sci fi movies from the 70’s which used a lot of synthesizer sounds for effects Logan’s Run springs to mind. Good read.

    1. Marcus (Post author)

      Thank you, Simon. I’m glad you liked it.

  3. Henry

    Wow, incredible! As a regular practitioner I’m more of a guitar guy. So, it feels great to find an introduction to the whole another world. Thanks for sharing! I’ve been around different keyboards but not like synthesizers like this.

    Its mimicking ability is quite unbelievable, there are so many different sounds we can generate through combining different frequencies. That’s a sound crafters masterpiece right there. Seriously, & you can give it a vibrato effect too?

    So, a lot of moving parts, which basically means it seems to be extra versatile musical instrument in its own way & the possibilities will go as far as your imagination & creativeness does. The first thing I’d do, I’d like to start playing around with sustain & release, seems like a lot of fun along the way.

    I really enjoyed this introduction to synthesizers. Thanks again for sharing!

    1. Marcus (Post author)

      Yes, it’s amazing once you start delving into how synthesizers work. For example, I usually use Propellerhead Reason for making my music, and that comes with built-in software synthesizers that come with lots of preset sounds. It is so easy just to load up a preset sound, but recently I have started trying to make my own sounds from scratch by just starting with a waveform or two and then filtering it, changing the envelope, and added effects. It can be a really fun thing to get into, actually.


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