TX16Wx: The Mechanics of Controlled Modulation

[DarkStar]

I hope that this is of interest.

Here's are some examples of the control of Modulation from a host VSTi parameter. In all cases I have a 2Hz square wave LFO modulating the pitch

(a) "Positive" control
Set the LFO1 Amp base value to 0 (no depth)
Map Param 00 to LFO1 Amp with an amount of +1.00 (so the range is 0 to (0+1) =1)
Map LFO1 to Pitch with a value of 400 Ct (4 semitones)

Now vary the Param 00 value in your host, press a key and listen to the two-tone results
Param 00 value: 0.00 .. 0.25 ..... 0.50 .... 0.75 .... 1.00
Note range: ...... G ..... F#/G# ... F/A ..... E/A# ... D#/B
The higher the parameter the more the tone range

(b) "Negative" control
Set the LFO1 Amp base value to 1 (maximum depth)
Map Param 00 to LFO1 Amp with an amount of -1.00 (so the range is 1 to (1+-1) = 0))
Map LFO1 to Pitch with a value of 400 Ct (4 semitones)

Now vary the Param 00 value in your host, press a key and listen to the two-tone results
Param 00 value: 0.00 ..... 0.25 ..... 0.50 ... 0.75 ...... 1.00
Note range: ...... D#/B ... E/A# ..... F/A .... F#/G# ... G
This is the same effect as in (A) but reversed
The higher the parameter the less the tone range

(c) "Combined" control
There is no need to use two Modulation slots.

Set the LFO1 Amp base value to 1 (maximum depth)
Map LFO1 to Pitch with a value of 0 Ct (no change)
Select "Param 00" as the "via" modulator with an amount of 400 Ct (4 semitones)

Now vary the Param 00 value in your host, press a key and listen to the two-tone results
Param 00 value: 0.00 .. 0.25 ..... 0.50 .... 0.75 .... 1.00
Note range: ...... G ..... F#/G# ... F/A ..... E/A# ... D#/B
The higher the parameter the more the tone range

Here are screenshots showing the settings for all 3 cases:
>>> http://i.imgur.com/C7d7qvt.png

[DarkStar]

And here is an example of 2 MIDI CC messages mapped to control the AEG Amplitude and the Filter Cutoff Frequency (for a Low Pass Filter).

>>> http://i.imgur.com/Jpulzc5.png

(a) The initial (fixed) AEG amplitude value is 1, and the modulation amount is set to -1. Maximum modulation will change the AEG amplitude to the initial value plus the amount, 1 + -1, that is 0. The higher the MIDI CC message data value the lower the amplitude.

(b) The initial Cutoff Frequency is 200 Hz (set, as can be seen, in the Filter panel) and the Modulation amount is set to +1,800Hz. Maximum modulation will change the Cutoff Frequency to the initial value plus the amount, 200 Hz + +1,800Hz, that is 2,000 Hz. The higher the MIDI CC data value the higher the Cutoff Frequency.