Tag Archives: acoustics

Mar
22
2011

Masters Thesis: Modelling Non-linear Behaviour in Valve Amplifiers

I have finally completed my masters thesis on modelling valve distortion in guitar amplifiers. It’s been a fascinating project that has introduced me to many interesting modelling techniques. A large portion of the project has been looking at Volterra series representations, and although these have revealed some intruiging behaviour, I have not yet managed to use them to produce acceptable audio output. I had a bit more success using neural networks, particularly using the nnsysid toolbox. You can download the main report below along with the preparation report (supplement with some more of the theory). 

Download: Main Project Report [pdf]
Download: Project Prepartion Report [pdf]

exponential sine sweeps

Spectrogram showing the response of a valve amplifier to exponentially swept sine signals.

Mar
19
2010

Towards a realistic, non-realtime reverberation model

Today marks the end of a 2 month investigation into various techniques of simulating reverberant sound. Using MATLAB, I developed two contrasting models:

  • Image Source method
  • Monte Carlo Ray Tracing method

The report in full is available to read here, though for a lighter overview, this poster is recommended. All sample output, including the odd phasing behaviour described in Section 4.1.2 can be downloaded here. Any feedback is greatly appreciated!