Virtual Analog (VA)
The VA button on each Source’s Additive element sub-page gives you access to Alchemy’s ‘Virtual Analog’ mode. In this mode, you can use the additive engine as a bank of raw oscillators such as you might find in a classic analog synthesizer.
The controls in VA mode are the same as in ADD mode. The Additive page gives you detailed descriptions of each control. The discussion below focuses on using these controls to perform various analog-synthesis tasks.
When you initialize Alchemy, using the ‘Clear’ command in the Title bar’s FILE menu, the Source A Additive element is turned on and switched into VA mode. By default, a single oscillator is active and the Saw wave is selected.
VA techniques in Alchemy
To select the oscillator waveform, use the Wave pop-up menu. The ‘Basic’ category offers Saw, Sine, Square, and Triangle waves. A large variety of more specialized waves is also provided. You can browse through the available waveforms using the forward and back buttons, or make a direct selection from the pop-up menu.
To adjust the pulsewidth, use the Symmetry control. A setting of 50% preserves the original waveform, while higher or lower settings stretch one half of the wave and compress the other half. Starting with a Square wave gives you a classic variable-width pulse wave, but you can adjust the symmetry of every waveform in Alchemy. Symmetry values as low as 5% and as high as 95% are typically useful; at the most extreme settings, the sound may become very thin or unstable.
For pulsewidth modulation (PWM), modulate the Symmetry parameter with an LFO, AHDSR, or other modulator.
To control oscillator phase, use the PVar knob. Values from 0% to 99.9% set a consistent starting position for the oscillator. When PVar = 100%, the starting phase of the waveform varies randomly per note.
Note that the PVar knob has a different meaning in ADD versus VA mode. In VA mode, it provides control over phase. In ADD mode, it controls the depth of response to partial pitch variations in the additive data.
Set the number of oscillators using the NOsc knob. (The Pitch knob, described below, provides unison with variable detuning.) Alchemy lets you stack up to 600 oscillators per source (!) — but the high end of this range is really intended to provide sufficient sinewave partials for detailed additive resynthesis. In VA mode, typical settings of NOsc range from 1 for single-oscillator sounds, up to 20 or so for ‘supersaw’ and related effects. Higher settings of NOsc consume more CPU.
To control the amount of detuning (with NOsc = 2 or more), choose ‘Unison’ in the Pitch pop-up menu and adjust the Pitch knob. A value of 0% tunes the oscillators to a perfect unison, while 100% provides the maximum amount of detuning.
To spread unison oscillators across the stereo field, choose ‘Unison’ in the Pan pop-up menu and adjust the Pan knob. A value of 50% keeps all the oscillators centered, while higher or lower values distribute the oscillators from left to right.
Note that you won’t hear the effect of Pan unless the Source’s Stereo button is engaged.
For white and filtered noise, use the Spectral element in WHITENOISE mode. (See the Spectral page for details.)
Example: Creating a ‘supersaw’ effect
- Initialize Alchemy by choosing the ‘Clear’ command in the Title bar’s FILE menu. This puts Source A into VA mode.
- If the Source A Additive sub-page is not already in view, click the A button and then click the Source A ADDITIVE button.
- The Saw wave should already be selected in the Wave pop-up menu.
- Increase NOsc to about 10. You may also wish to increase the value of Pitch above 50% for more extreme detuning.
- Finally, try a couple of refinements:
- For modwheel control of the filter cutoff, go to the Perform sub-page and choose ‘Auto Assign All’ from the FILE menu at the far right. Filter cutoff is now mapped to Perform Control 3, so choose ‘Control3’ in the ModWheel pop-up menu.
- Experiment with various effects modules in the Effects rack. (Compressor and Camel Reverb are good ones to try.)