[sdiy] Speaking of dsPIC microcontrollers...

[Tom Wiltshire]

On 22 Dec 2010, at 18:08, Speth, John wrote:

>>>> Using a dsPIC and SSM2044 and MF10 filters:
>>>> http://www.youtube.com/watch?v=TJenM5xrqr4
>>>> http://www.youtube.com/watch?v=3PV4Us6Uc0M
>>>> http://www.youtube.com/watch?v=kErBx2ZNiwE
>>>> Is that any of y'all? I'd love to read up more on those
>> projects.
>> 
>> It's really nice, but on the video's I can hear some kind of
>> harmonic
>> distortion on all the sounds. Was the audio distorted by the
>> recording
>> of the videos?
> 
> I wondered that too.  He's using the MF10 switched cap filter which he characterizes as "gritty".  Maybe we're hearing that grit which doesn't sound that bad if that's what one likes.
> 
> JJS

Judging by the output on the scope in the second of those links, they're all naive waveforms (no bandlimiting) so a good amount of aliasing would be expected. That'd generate distortion, although I wouldn't describe it as "harmonic". Especially with those crazy mix modes making dozens of abrupt transitions in the waveform.

There's no sweep of the oscillators from low to high (or I didn't find it - didn't listen to everything). If there were, I'd expect to hear the give away tweeties coming down from on high.

T.