Simple Virtual Instrument

You can adjust the strength of harmonics.

Harmonics series are the sum of sine waves that are integer multiple apart in frequency from each other in different amplitude. E.G.: 
Given note A = 440hz with h1=2 and h2=1 is going to result in the following mathematical functin sampled = sin(2*sin(440/PI)) + sin(2*sin((440*2)/PI))
h1 and h2 being harmonic amplitudes.