DIY Stompboxes => Digital & DSP => Topic started by: Processaurus on May 18, 2007, 02:39:11 AM

Title: Trainable digital LFOs
Post by: Processaurus on May 18, 2007, 02:39:11 AM
I just saw this ( commercial tremolo and thought it had a really interesting feature, a thing where it apparently records 6 seconds of twisting a knob and then loops it and saves it as a custom LFO.  Too cool!  Automation for pedals.   Wonder how it works/how advanced of a program they had to write to do something like this, it looks like a tiny company...
Title: Re: Trainable digital LFOs
Post by: rockgardenlove on May 18, 2007, 03:25:30 AM
Genius idea.
Title: Re: Trainable digital LFOs
Post by: widdly on May 18, 2007, 05:55:02 AM
Neat Idea.

I'm guessing they have a microcontroller with a A/D attached to the depth/wave knob and a D/A generating a control signal to the VCA.  Then you could take periodic samples from an A/D and store them in a lookup table.  Then step through the lookup table during playback and write the value to the D/A.  My guess is the samplerate they use is pretty low and they uses some interpolation to get a smooth output.  During playback the A/D would be sampling a value for tremolo depth that would be used as a mulitplier for the output value of the interpolater.

You could probably implement the whole thing on a PIC and use a resistor ladder for the D/A. 

It would be nice if they added midi sync too.