Introduction

When I first started making electronic music I was overwhelmed with all the possibilities of sound generation and it took me a long time to figure out which instruments can be made which way. Even after I knew what all the knobs in synthesizers do, I was still unable to apply that knowledge to, e.g., make a drum sound.

So, I thought I could write the manual which I hope I could have had at the time. If you know nothing about sound synthesis this may be a hard read. However, if you know what a filter and modulation is, this may hopefully help you.

Recipes

Bassline Wobbles

This effect can be heard often in dubstep or neurofunk. Essentially it is a pulse wave which is lowpass filtered with resonance. The cutoff frequency of the lowpass filter is modulated with something slow. Sometimes there is also modulation of the pulse width to make the sound more lively. Even if the cutoff frequency is modulated with a sine wave it can sound cool if parts of the sound are muted and the brain cannot hear the sine. Normally the modulation is irregular and done by some hand drawn automation. Often the input is not a pulse wave but may be more processed, e.g, some frequency modulated stuff or a distorted pulse. The only rule is that it should have a large spectrum to be interesting.

Neurofunk Bass

This is basically a very gritty bass. Take some saw waves and detune them a little bit. Then put a second saw wave one octave below. And then put a sine two octaves below. This sine is the secret ingredient which makes it sound very deep and dark. Finally, put an LFO on the lowpass cutoff as above and add some phasers.

Trance Leads

Have you ever listened to trance music and noted the typical leads which are the same in nearly every trance song? This is called a supersaw and is done with a lot of saw waves. Take some saw saves and detune them very little. Then copy this to the octave above. And to the octave above that. Put some chorus and reverb over it. Done.

Kick Drum

Put the sustain off. A kick drum is very dry and does not have any sustain. If you think about it, when a drum is hit, its skin stretches. Stretched stuff produces higher notes (think of guitar strings). If the drum head relaxes, its frequency is lower. And that is how you synthesize drums. Take a sine wave which starts high and then decreases quickly in frequency. This can be automated by a frequency envelope, even on most hardware, since the envelope is not needed for the volume. Depending on taste, put some distortion on it.

Snare Drum

Snare drums can be made like a kick drum, but with a higher starting and ending frequency and some highpass filtered noise. Try to make the noise and the frequency enveloped sine sound as belonging to the same instrument.

Bonus Snare Drum

What also works is filtering white noise with a bandpass envelope with quickly decaying cutoff frequency. This makes it sound more dirty. Then more unfiltered noise can be added.

Hi Hat

There are many ways to create a hi hat sound by putting together wave forms. The easiest way is to make a very high pitched snare. Another way is to play around with subtractive synthesis. Take some noise and filter it with a high pass or band pass. If you want an open hi hat, simply change the envelope by adding some sustain.

Clap

A Clap is a snare with more noise. This sounds somehow wrong, but in the world of sound synthesis it is true. The noise can be either louder or the cutoff frequency of the high pass can be lower.

Bonus: Chiptunes

Recently, I played around with some chiptune music. This is music from old hardware chips like the SID, built into the Commodore 64 or the old NES sounds. These two examples are the ones I have looked into. Old platforms have very hard restrictions which makes it challenging to create anything that sounds good.

The SID for example has three oscillators, which have four waveforms each: triangle, pulse, noise, and saw. From each of those four wave forms each of the three oscillators can play one or multiple at each time. So there are basically three channels. There are no fancy effects like chorus or echo.

The NES is even more shitty, since it has only four oscillators each of whom can only do one waveform. The first two can do pulses, the second is for triangles and the third for noise. There is an additional fifth channel which can play lo-fi samples, but I never managed to work with that successfully. Yeah, there is no saw.

Drums

On NES, there are two styles of drums. One is made by taking the noise and filtering it with a band pass. The mid frequency of the bandpass then decreases. If this is done at the “correct” frequencies it sounds like a snare or a kick drum or a hi hat. This can be heard in a lot of asian games.

The western way works the same, but with a triangle which quickly decreases in frequency, instead of the noise. Sometimes the noise is added, if you can afford to block two channels. This gives the drums a clearer defined pitch.

For the SID, I did not understand how to make drums, since there are no fast frequency envelopes. So I will reference other people who were able to make drums. I give you the hex values for the registers in brackets, so you can play along in your tracker software.

The snare drum from the goattracker manual works as follows: The first frame is square and triangle and gate (in hex 40+10+01=51) at the fixed pitch 90. The second frame is just saw and gate (20+1=21) at the fixed pitch A0. Then it ends in noise without gate (80) at the pitch DF. Yeah, noise in SID can have a pitch. Do not forget to stop the execution of the wave table by the FF command. The ADSR is set to 32F9.

The e-book Creating Chip Tunes with Sid Wizard) also contains a nice snare:

  • noise + gate (81), fixed pitch CE
  • pulse (41), pitch AD
  • pulse (41), pitch AC
  • noise + no gate (80), pitch C4
  • noise + no gate (80), pitch C5
  • in pulse table 88
  • in ADSR: 0DE9

Bass

For the SID Bass, let me again reference “Creating Chip Tunes with Sid Wizard”:

  • pulse + gate (41)
  • in pulse table 82 (+ octave transpose -3)
  • in pulse table 40 20 (increase pulse width by 20, 40 times)
  • ADSR: 089A
  • add some vibrato
  • low-pass in filter table 9B 45 (9 selects the low pass, 4 is the resonance, 45 is the cutoff frequency.
  • in the nect row of the filter table: 40 05 (add 05 to the cutoff frequency 40 times)

Actually SID basses are easy. Simply play around with one of the basic waveforms. Do not touch noise.

For the NES Bass take the square. Or take two squares and detune them a little bit, if you can afford to occupy two channels. You can also take the triangle. Since the NES does not have a saw, I think those are all the options.

Flute

I have reverse engineered this one from SID sounds and then recreated on NES. A flute is a high pitched triangle wave with vibrato.

Conclusion

I hope this helped someone out there. For recreating sounds on SID or NES it is possible to look at the wave forms, e.g., in audacity, and then use educated guessing to get something similar. In the commodore stuff I heard that it is also possible to run an emulator and then prick the values of the sound chip from the register, but I have never done this.

For recreating more complex sounds it sometimes helps to start with a waveform which seems appropriate and then modify the sound until you are happy with it. This is harder than in the chiptune world and when it comes to frequency modulated sound I am still completely lost.



Published

27 June 2018

Category

lesson

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