[sdiy] Re: SYN8535 (AVR synth)

[Jaroslaw Ziembicki]

> 1.) Is the output waveform a real saw or rather a staircase?

For low frequencies (below 122Hz), it's an 8-bit staircase (256 stairs).
As the frequency rises, the number of the stairs decreases.


> 2.) Your DCF - formula is y[i] = y[i-1] + m*( x[i] - y[i-1] )
> - Is i your sampling index moving through a wave cycle and y the amplitude
of the position?
> If I am right, what do you mean with x[i]?

i is the number of the sample (represents time in time-discrete systems).
Explanations of the symbols used:
x[i]     = input sample (current)
y[i]     = output sample (current)
y[i-1] = output sample (previous)
"Input" means the input of the filter = the output of the "oscillator bank".
"Output" means the output of the filter = the input of the DCAmp.

> - do you get a kind of resonance if m becomes greater 1?

Definitely not. This is a 1st order filter, thus not able to resonate. If
you
set m equal or above 1, the filter will become unstable. I'm sure it
wouldn't be an useful effect (but maybe I'm wrong).


> 3.) Any other experiences or tips?

There were some on the forum in the last 2-3 months.
See also the homepages:
http://www.jarek.synth.net
http://www.elby-designs.com

Best regards,
Jarek