Additive Synthesis

Physics: Additive synthesis: x(t) = Σ Aₙ·sin(2π·n·f₀·t + φₙ). Hammond organ (1935) uses spinning tonewheels — each drawbar adds a harmonic: 16'=fundamental, 8'=2nd harmonic, 5⅓'=3rd, 4'=4th, etc. Fourier synthesis of a square wave uses only odd harmonics with Aₙ=1/n; sawtooth uses all harmonics Aₙ=1/n. Helmholtz used resonators in the 1860s to build additive synthesizers by controlling which resonators were active.