casio sk, vocoder ??

[SebbeK]

Hi.
This might be quite stupid... but. wouldn't it be possible to somehow bring the mic input sound through to the pitch controll circuit directly instead of saving it first? In other words, build a vocoder into the sk-x ?

/Sebbe K

[Bogus Noise]

You might be thinking more about a pitch shift effect as a vocoder is a bit more complex than that. Paia have an article that explains how vocoders work:

http://www.paia.com/ProdArticles/vocodwrk.htm

I doubt either would be possible directly from the SK though, you'd basically have to build a pitch shifter or vocoder and install it inside, if it'd even fit!

[SebbeK]

Yes sorry, you're right. I didn't mean vocoder really. As a vocoder mixes two signals togeather, or something like it.
What i meant was putting an amplified audiosignal from the mic directly into the pitch circuit instead of saving it in ram first.

The out signal for the first poly signal from the cpu is at pin 89 (i think) The picture is taken from the block diagram in the sk-1 manual. If the signal passing through the red line is pure analog audiosignal, wouldn't it work?

[jamiewoody]

funny, i posted a thread similar to this a week or so ago.

it seems plausable from the right side of the brain, but i am not sure of the logic of it. i mean, if people make body contacts, and there are motion sensitive potentiometers (what are these called anyway???), it seems a voice filtered mic which would pick up the voice AND manipulate the resistence doesn't seem implausible.

[SebbeK]

anyone with a good brain here?
or anyone who dares to try it out?

[jamiewoody]

another option would be to build a voice modulator  as a separate circuit into the same box. velemin has a "robot voice changer", though i have heard there are better quality kits out there.

[SebbeK]

yea but.. then you would need to decode the keyboards signals into something that the voicechanger module could use to change the pitch... would be quite a lot more to do. but if my teory wont work it might still be worth the effort. becouse is would add some more usefullness to the instrument.

[Circuitbenders]

The pitch control will probably work by changing the speed of digital signals and not analogue ones.

Thats not a pitchshifter in the SK. It works by speeding up and slowing down the playback of the digital data, which is why samples play faster and slower to make higher and lower pitches. Its not a realtime thing i.e. the pitch control couldn't play back data at a higher pitch in realtime because it would have to play back the data faster than you were actually supplying it which would prove a bit tricky!

[SebbeK]

oh yea. nice. wouldn't have thought of that myself..
but let's change the topic to solve jamie's idéa. how do you take the keypresses and give them to some kind of realtime pitch circuit (voicechanger) ?

[jamiewoody]

though not a pitch shifter, i actually like the effect of twisting the tuning trimmer on the bottom of these keyboards! it almost has a "computer tape" sound.

[SebbeK]

http://www.maxmidi.com/diy/sk1/article.html
that guy explains how the keyboard signals work... but it requires some i/o ports...