WhySynth Controller
Part 4 - Operation


WhySynth follows the traditional synthesis architecture of oscillators being fed into one or more filters, followed by an amplitude control device. Each of these components are modulated by a combination of envelope generators and low frequency oscillators. In this post I'll explain how to use some of the unique features of these components that you might not find on most synthesizers.

If you're not familiar with the basics of subtractive synthesis, Sound on Sound magazine has an epic series on the matter spanning 5 years of articles. There are also many web sites and books available on the subject. I wont talk in much detail about WhySynth's oscillators or filters in this post as their operation should (hopefully) be straight forward. Instead, I'll jump straight into describing the envelopes and LFOs, as they have a few more options than you might usually find.


Control panel envelope section

A total of five envelopes are available, with 2 accessible at any given time. The controls for envelope 1 are the same you'll find on many synths: attack, decay, sustain and release. The second set of envelope controls address the full capabilities of WhySynth's 5 stage envelopes, with 4 time controls, 3 level controls, sustain stage select and curve editing for each stage.

The time and level controls are much like the controls of a typical ADSR envelope. In fact, you can simplify these controls into an ADSR envelope using the sustain select button. In this mode, only 4 controls are active. These are the ones with small letters to their right. Otherwise, you have complete control over the level and time spent in each stage. Pressing the sustain button moves the sustain stage through 3 separate positions:

  1. Directly after the first stage. Time 1 becomes an attack control, Level 1 sets the sustain level, the others being release levels and times.

  2. After the 2nd stage, resulting in 2 attack stages controlled by the first 2 time controls and the first level control, the sustain level being controlled by level 2, and 2 release stages controlled by time 3, level 3 and release.

  3. Just before the release stage. This makes time 1, 2 and 3 together with level 1 and 2 control the initial attack stages, level 3 controls the sustain level and release controls the last and only release stage.

If that's not enough options for you, there are 3 additional modes also available:

The 4 buttons below the time controls select which stage's shape will be changed when using the shape control. The 7 basic curves are: 3 degrees of lag, linear and 3 degrees of lead. Five additional special shapes are available when the button next to the shape control is pressed:

Envelopes 3 & 4 are accessed using the shift mode. The fifth envelope permanently controls the amplitude, and is accessed using the envelope select button above the second set of envelope controls. Note that this button always toggles between the amplitude envelope and envelope 2/4, regardless of the current shift mode.

* not yet implemented


Control panel LFO section

The main controls for LFO 1 and 2 are straight forward, using just the standard controls found on most LFOs. The 'G' in LFO G stands for global, meaning there is only ever one instance available, regardless of how many voices/notes are currently active. This means that all voices are modulated by the same signal, not per-voice as with LFO 1 and 2.

The controls for LFO G have shifted functions, these actually control two LFO 1 parameters: phase spread and randomize frequency. LFO 1 actually produces four signals. When the phase spread and randomize frequency parameters are zero, all four signals are the same. Changing the phase offset parameter offsets each signal against the previous one. For example, a phase offset of 90° produces signals at 0°, 90°, 180° and 270°. Randomize frequency does what you'd expect, the frequency of each signal is detuned slightly so that they drift in and out of sync over time. This gives you some of the versatility of 4 individual LFOs, with less work required to set them up.

Shift and Alt modes

Control panel shift button

Software synthesizers often have many more controls than their hardware counterparts. WhySynth is no exception, so I've utilized 2 methods to extend the number of controls available.

The first is a shift mode, enabled by pressing the shift button. The LED next to the shift button is illuminated when in shift mode. The 'Shift' label under the button is underlined, this being a visual cue to remind you that any underlined labels refer to the shifted function of a control.

Looking around the panel, you'll see that a second set of oscillators (3 & 4), a second set of envelopes (3 & 4), and a few other less used controls are available in shift mode. Note that all other controls still function normally while in shift mode.

When holding down the shift button, the 'Alternate' mode is temporarily active. This is used in conjunction with the oscillator sync and filter select buttons to copy settings. Pressing a oscillator sync button when holding down shift copies all the settings for that oscillator to the next. This makes it easy to make a patch sound bigger by copying an oscillator's parameters, then tweaking the parameters just sightly to give a doubling effect. Note that oscillator 4 is copied to oscillator 1 when using this feature.

Pressing the filter select button when holding shift copies the filter settings from filter A to filter B. As with the oscillators, this is useful when you want both filters to be similar, tweaked to be different enough to be interesting. Panning the filters left and right gives some nice stereo effects.


Control panel FX section

WhySynth currently has three effects available, with one active at a time. These are a stereo delay, a plate reverb and a regular reverb. The type button cycles between these. The plate reverb is active when both LEDs are illuminated. Since the delay and reverbs have different parameters, some controls have two labels, one for the reverbs and one for the delay. The delay is stereo, with two shifted parameters: the offset between left and right delays and the amount of cross feedback.


Control panel modulation section

WhySynth's modulation is a little bit different to most synthesizers. Rather than a series of virtual patch leads, each modulation destination can have it's own source. This means that there are effectively as many 'patch leads' as there are modulation destinations, of which there are many. So instead of selecting a virtual patch lead to edit, you simply select which modulation destination you want to edit with the right slider. You then use the left slider to select which source will modulate the selected destination. The amount control determines how much modulation takes place and, in most cases, if the modulation is positive or negative.

Note that some of the modulation destinations are hardwired to the keyboard velocity or key value. These have a 'K' or 'V' in front of them to remind you. If you try to change the modulation source, nothing will happen. These sources are hardwired because there's a bit more going on than straight linear modulation.

Building It

Now that I've covered the design, architecture and operation of the controller, the only thing left is construction. So tune in next time when we add the hardware to our software.

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