I am working on a project to make a synthesizer for RaspberryPi capable of playing Harmonium/Reed Organ using external MIDI keyboard. I am making it in Python 2.7 using Numpy. Till now I have completed first phase of my project which includes building UI and primary synthesis script, interfacing with keyboard and mapping notes with keys. In my second phase I am planning to move it to RaspberryPi from PC and improving sound quality.
For synthesizing Harmonium sound in first phase, I recorded Harmonium samples and did Fourier transform on it and extracted out dominant frequencies from it and then wrote synthesis function by adding sine waves of those frequencies. However the generated sound is okay for testing, but it is not at par with original Harmonium sound, which is inevitable for final version of the project. Thus I request to suggest me the techniques to generate Harmonium sound. Also is it possible to generate with Oscillators, Filters etc.. which is available in Helm Synthesizer? and if yes, then how to tune them so as to generate perfect Harmonium wave? Please help me as I am beginner in this field.
NB : I have asked this question on music.stackexchange.com, but due to a suggestion from there I have placed the question here, hoping to get some help.