hmmm... The D>A mux output is handled using an interrupt and is done in the background to the main program. The VCA is opened and closed using this background timing and the original 3P also does this. The DCO frequencies are updated as notes are pressed in the main program so it is possible that the timing could clash and the VCA level might be coming up during the DCO timer updates. I will have a look to see if this is the problem and if it can be adjusted.

- MH

On 15/02/2012 6:10 a.m., anukirk wrote:

 

I am pretty sure this noise is inherent in most/all DCO architectures. My DSI Evolver exhibits similar behavior.

Basically, the DCO 'remembers' the frequency of the last note played, and starts generating each note at that frequency and slurs up to the new note.

In the case of most note transitions, this is simply not audible. But when you play a LOW note on a particular voice and then play a HIGH note on the same voice, the DCO starts its frequency on the low note, and cuts off abruptly as it transitions to the high note. Not sure if it's a zero-crossing issue or just a side effect of low to suddenly high, but you get the clop/thump/whatever you want to call it.

You will NOT hear this effect when you play the same or near notes repeatedly, and you will not hear it transitioning from high to low, because the waveform completes/changes faster.

You won't hear it with really long attack times because the long attack hides the discontinuity.

You can load up a good DAW and record some low-high transitions and zoom in on the waveform to see for yourself.

So I don't think it is possible to fix - it's a side effect of the circuitry/chips used to create the DCO.

--- In kiwitechnics@yahoogroups.com , "poiskaill" <poiskaill@...> wrote:
>
> Ok, I think you've pointed right: the DCA BAL adjustements make the 'plop' change but, only in it's frequency: when I move a trim, the plop appears more or less often.