Korg Forums

[Liviou2004]

Hello,

Appart from turning a front panel knob, is there a means to modulate the Ratio parameter of an operator in MOD-7 engine. (I dont' see any AMS parameter attributed to this parameter).

[Mike Conway]

Definitely. Press the EXi 1 tab. Select any VPM (1 - 6). In the OSCILLATOR pane, touch RATIO or FINE.

If you touch something and it can be modulated, a set of modulation parameters will appear in the PARAMETER DETAILS pane (upper right). Touch the AMS tab and select a mod source from the list.

Note: Korg modulators are often "mulitpliers," meaning that you need to have a value higher than "0." The smallest value you can select is OSCILLATOR RATIO 0.000 and FINE 0.001.

You can select an AMS Mixer as a mod source. OFFSET works really well, as it can go far beyond the set values. If you want to use Knob 6 to control the FINE ratio, set AMS 1 to AMS Mixer 1. Set the Intensity up to maximum value (+48 semi-tones).

Go to the SEQ, LFO & AMS MIXER tab. Select AMS 1/2. Under AMS 1, go to MIXER TYPE and Select OFFSET. Set AMS A to Knob 6 and Set OFFSET to maximum (+199) and you can sweep the whole pitch range from too low to hear to too high to hear. (For knob 6 to work, you need to be in RT KNOBS/KARMA mode.)

[CharlesFerraro]

Excellent observation Liviou. The AMS controls that pop up when selecting Ratio actually control pitch in a smooth, continuous fashion as opposed to jumping between whole number harmonic ratios. To get around the problem I decided to assign the Step SEQ with modulation intensity at the full +48 semitones. That way I could set the value of an individual step to the harmonic of my choosing, all the way up to the 16th harmonic overtone. However, it's only possible to get so close without the equally tempered semitones being offset from pure whole number ratios. Note that changing Temperament in the Common tab does nothing to remedy this as the different temperaments are a kind of MIDI detuning (or retuning) as opposed to the set programmed values of pitch modulation. Anyway the values for specific harmonics are as follows...

Ratio value > Step SEQ value
1 > 0
2 > 25
3 > 40*
4 > 50
5 > 58*
6 > 65*
7 > 70*
8 > 75
9 > 79*
10 > 83*
11 > 86*
12 > 90*
13 > 93*
14 > 95*
15 > 98*
16 > 100

*denotes a pitch offset

Naturally it is possible to get closer to specific harmonic values if you lower the modulation intensity; thereby also sacrificing the ability to reach higher harmonics. You might also try using a multiplicative AMS mixer to retune individual step values with the Common Step Sequencer... but the Common Step Sequencer is monophonic I believe... The engine's Step Sequencer is polyphonic. So you could run into issues there.
This kind of "harmonic jump" modulation can be applied to basically any facet of the Kronos from oscillators in other engines to filters or whatever you want! But now I'm getting off topic and into other advanced sound design territory.
_________________
paypal.me/CharlesFerraro

[Liviou2004]

Thank you very much Mike and Charles. I will experiment what you said.
Thanks