As discussed in the PATCH PARAMETERS / CONTROL chapter, the PATCH CONFIGURATION button selects the basic synthesis setup of Chroma's A and B voice paths (or C and D for the Expander). There are a total of 16 possible configurations, divided across five categories.
So we don't go nuts typing (and driving you mad with parentheticals like this one), all examples in this section will refer to voice paths A and B, and it will be understood that these are identical to the C and D voice paths in the Expander.
Remember that Patch Configuration can be set not only by clicking its button in the CONTROL section, but also by clicking directly on the Patch Configuration block diagram.
Single Layer- The most basic of the patch configurations, this consists of a single oscillator>filter>amp voice path. The B voice path is disabled, as are all associated controls in the MASTER and EDIT MODE sections. It should go without saying that Single Layer mode should be used for simple sounds.
Dual Layers- The same as Single Layer, but with two independent oscillator>filter>amp voice paths. Dual Layer is useful for standard two-oscillator polysynth patches, such as detuned pads. Because it has independent filters, interesting timbres are possible using individual filter cutoff frequency settings, or setting one filter to lowpass mode and the other to highpass mode.
Dual Layers + Osc Sync- This is the same as Dual Layers, but adds the ability to hard sync the frequency of Oscillator B to Oscillator A. To get familiar "tearing" sync sounds, alter or modulate Oscillator B's frequency controls in the PITCH B section. Reduce the VOICE VOLUME A slider for a more emphasized sync tone.
Dual Layers + Ring Modulation- This is like the Dual Layers voice configuration, but with a ring modulator in place of oscillator A. For those not familiar with ring mod, following is a brief recap that I lazily copied from some other Cherry Audio manual:
When two audio sources are inputted, the output contains only the sum and difference frequencies of the two signals, while removing common frequencies. The audio result is useful for creating sounds with inharmonic frequency content, which is useful for synthesizing bell and metallic sounds.
Ring mod is heard through the A channel; we recommend manipulating (and modulating) PITCH A and B controls. Also be aware that ring mod makes use of oscillator pulse waves only regardless of the current WAVE SHAPEsetting, so make sure WAVE SHAPE WIDTH is at a setting other than minimum or maximum.
Filter Modulation- The standard Dual Layers voice path, but instead of being used for audio, the B path is used to modulate the A path's cutoff frequency for dramatic audio-rate modulation.
Parallel Filters- This routes both oscillators to both filters in parallel, with oscillator B volume controlled by Amp B, and Amp acting as a master volume for the entire patch. A notch filter can be created by setting of the filters to highpass mode. Phasey effects can be created by manipulating cutoff - this works especially well when EDIT MODE EDIT A+B is chosen, effectively moving both cutoff sliders at once.
Parallel Filters + Osc Sync- Like the preceding Parallel Filters voice path, but adds sync between the OSC A and B.
Parallel Filters + Ring Mod- Like the Parallel Filters voice path, but replaces Osc A with a ring modulator. This can be used for ring mod effects with notch filtering as described in the Parallel Filters section.
Parallel Filters + Filter FM- Same as the Filter FM voice path, but AMP B's output modulates the cutoff frequency of Filter A.
Series Filters- This routes both oscillators to both filters in series with Osc B volume controlled by Amp B, and Amp A acting as a master volume for the entire patch. Because Chroma's filters are 12dB/oct, this "stacking" creates a steeper 24 dB/oct response.
Series Filters + Osc Sync- Like the preceding Series Filters voice path, but adds sync between the Osc A and B. To mute Osc A (i.e. to better isolate the synced Osc B), set WAVE SHAPE A WAVE SHAPE to Pulse and WIDTH to 0. Use this voice configuration for oscillator sync sounds with a 24 db/oct filter response.
Series Filters + Ring Mod- Like the Series Filters voice path, but replaces Osc A with a ring modulator. To mute Osc B (i.e. to better isolate the ring-modded OscA), set WAVE SHAPE A WAVE SHAPE to Pulse and WIDTH to 0. Use this voice configuration for ring mod sounds with a 24 db/oct filter response.
Series Filters + Filter FM- Like the Series Filters voice path, but the output of Amp B modulates Filter A cutoff frequency.
Variable Filters- Osc A and B outputs are mixed, then fed into both filters. Each amp controls levels from each filter, allowing the creation of asymmetrical notches. (Incidentally, I saw Asymmetrical Notches open for The Modern Lovers at The Rat in Boston in '79). This Patch Configuration is useful for creating phase-y/flange-y timbres when one of the filters is set to highpass mode and cutoff is modulated.
Variable Filters + Osc Sync- Same as Variable Filters but Osc B is synced to Osc A. This is useful for notch-filtered sync sounds, and "duo timbre" filter effects with sync.
Variable Filters + Ring Mod- Same as Variable Filters but Osc A is replaced with a ring modulator. Useful for atonal/bell tones with notch filtering.
