On Sat, 26 May 2007 11:09:49 -0700 Ken Restivo <ken@xxxxxxxxxxx> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Sat, May 26, 2007 at 04:38:46PM +0200, Georg Holzmann wrote: > > Hallo! > > > > >http://www.geocities.com/CollegePark/Library/1355/tonemachine.gif > > >http://www.geofex.com/FX_images/foxxfuzz.gif > > > > Okay, I did not mean the circuit, but a schema of the mathematic behind > > it ... ;) > > Then it should be easy to build in software ... > > > > Maybe model the circuit in something like SPICE, and have a look at what the modelled circuit does to a sine-wave input, or, and impulse? > > http://www.linuxjournal.com/article/2169 > > Hmm. An interesting project might be hacking SPICE into being a kind of a deconvolution engine, to build a WAV impulse response file of a circuit. Then you could use that IR to "play" through the circuit using JACE or similar. > > The maths involved in such a thing would be way beyond my meager skills, however. > > - -ken The preamp stage gives some filtering that seems to lift at around 3kHz (fairly typical 'brightness'). The funny bit is a variation on a full-wave rectifier which has the effect of crude frequency doubling. Instead of a switch it is better to make the 'bottom' half variable so you can control the amplitude of the doubled effect. Don't know quite how you'd do this is software, you need to sort of 'fold' the signal so the negative bits go positive instead. That is followed by a single amplifier giving the drive to an ordinary 2 diode limiter (fuzz). This kind of limiter doesn't give a hard cutoff, but a slightly rounded waveform - sounds smoother. The 'sustain' control is simply drive level. More drive = more distortion and longer before it comes out of limiting. Followed by a slightly unusual tone control - quite interesting - and a final buffer amp. -- Will J G _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo.cgi/linux-audio-user
