Why Sonic 2 instead of Sonic 1? Because Sonic 2 has a sound test! Hurray for sound tests!
To ease into Genesis sound design, I’m starting with a couple sounds that forego the YM2612’s FM synthesis. Sonic’s jump and his skid when he changes directions both use a simple square wave from the Genesis’s PSG.
The pickup note functions much like the pulse width modulation in Mario’s jump, giving a little extra punch to the start. However, Sonic’s pitch bend covers a wider, higher range, and it’s sustained instead of percussive, which all contribute to Sonic’s image as a more energetic alternative to Mario.
Although the interval covered in the pitch bend would sound dissonant in a melodic line, it sounds just fine in a slide. In general, slides tend to obscure tonal centers, so when making your own bending sounds, don’t rule out an interval because it doesn’t make musical sense.
The rapidly alternating notes nicely imitate a car tire’s dissonant squeal, and the stutter is an effect that’s used all the time in film sound design (seriously, ring modulators are EVERYWHERE in vehicle sounds).
In my favorite square-wave-producing synth, I get closer to the original sound by setting polyphony to 2 voices. Your mileage may vary, though.
A simple C Major arpeggio for a simple reward sound.
The patch is a little more interesting, though, as it introduces the concept of ratio families in FM synthesis. There are two carrier-modulator pairs for this sound, one with a ratio of 2:7, the other with a ratio of 9:7. These two ratios are in the same family, meaning they produce different balances of the same frequency content. They have the same fundamental frequency, and they’re both essentially bell-like, but their timbres are slightly different. (You can read more about ratio families here.)
These slightly different timbres wouldn’t actually sound interesting together without an additional trick – by detuning the carriers you can bring out the individual timbres to create a rich, complex sound. At lower pitches, this patch makes a great church bell!
As a unique touch, the ring pickup alternates between hard left and hard right panning. It makes picking up groups of rings sound nice and wide, but it’s a bit odd when you pick up one at a time. It’s not really a technique that survived to the modern day.
Appropriately, this sound uses the same patch as the ring pickup.
The rhythm is fittingly chaotic, and the notes being a whole step apart creates plenty of dissonance.
I love this sound so much. The gentle attacks, decaying modulation, and rising pitch all work together to imitate vocal sounds.
A single modulator acts on 3 carriers; two of the carriers are in the same ratio family (7:5 and 8:5) while the third (9:5) produces a fundamental an octave lower, lending some body to the sound.
The notation may look like an E Minor arpeggio, but the slides eliminate any melancholy. The benign octave is really the dominant musical feature here.
Fifths and octaves keep this neutral, but the wide range keeps it interesting.
The sound gets its wonderful punch from two separate FM techniques.
First, one of the FM pairs is in a 1:3 ratio, and the modulator’s dynamic envelope is short and percussive, adding a mid-range smack to the start of the carrier and then disappearing. The carrier is also percussive, but it lasts longer, continuing on as a sine wave after the modulator finishes.
And second, the other pair abuses extreme frequency modulation to produce what is essentially white noise. It’s also very short and percussive, providing a hi-hat-like burst.
Note: There’s some more added noise from the PSG that isn’t represented in the patch or the notation!
The spin also uses the noise trick, although the 8:1 ratio here has a more clearly defined pitch than the 1:15 ratio above.
The non-noise pair uses a simple bit of 1:1 brightening.
The grace note is very subtle – almost inaudible. It provides a tiny push before the fade out begins. The tritone builds some nice tension that’s released when the player lets go of the button and blasts off.