Alternately, a wavetable synthesizer can use algorithmically-derived waveforms, instead of acoustic musical instrument samples, to generate waveforms that are musically pleasing, but not derived from any actual musical instrument. The concept here is to forget about using a complex algorithm to generate the required waveform, but instead to вЂњrecordвЂќ a conventional musical instrument to obtain the actual waveform of the instrumentвЂ™s sound. This method requires fast microcontrollers (MCUs) and lots of cheap RAM memory-both of which are commonplace today. I wonвЂ™t delve into the various approaches taken in the past, but will concentrate on the modern wavetable synthesis method that is in common use today. To a large extent, the forms of emulation that were commercially developed depended heavily on the available electronic technology of the time.

To emulate conventional musical instruments with an electronic synthesizer, many different approaches have been taken over the last 70 years. I am ignoring the вЂњpercussiveвЂќ voicing on the Hammond organ in this comparison, but it is a limited form of the envelope concept. Conversely, the Hammond organвЂ™s sound goes from complete silence to some fixed amplitude immediately, and stays constant until the key is released, at which time it returns immediately to silence. There are actually more вЂњphasesвЂќ to this amplitude envelope, but you get the idea.

That is, its amplitude rises quickly from silence, stays at some relatively constant value while the note is being held and then decays (usually exponentially) back to silence after the musician stops playing that note. The most notable difference is that when you play a conventional musical instrument, each note has an amplitude envelope. The Hammond organs used mechanical tonewheels to generate 91 sine waves at the required вЂњmusicalвЂќ frequencies, and the organ mixed these to produce a wealth of different вЂњvoices.вЂќ It was based on the mathematical principle that you can generate virtually any desired waveform by combining sine waves consisting of the fundamental tone and various proportions of higher harmonic frequencies.ДЄlthough these organs produced a rich variety of voices, many sonic subtleties are present in conventional musical instruments that were not present in the Hammond organвЂ™s sound-or any electronic organ, for that matter. Back in Circuit CellarВ issue 328 (November 2017), I described a Hammond tonewheel organ emulator using a Teensy 3.6 module.

Synthesia soundfont