Eight Voice Architecture
The Eight Voice can be thought of as eight independent dual-oscillator monophonic synthesizer voice modules. In actuality, this is how one could think of most polyphonic analog synthesizers, but unlike other poly synths, the Eight Voice contains separate controls for all parameters for each voice. Looking at the panel, it's easy to see the eight identical voice modules, with Voice 1-4 in the top row, and Voice 5-8 in in the row beneath. For example, Eight Voice has a filter cutoff knob for the filter of each voice module. Conversely, a typical classic poly synth (think Sequential Prophet-5 or a Roland Juno-series) would have a single filter cutoff control. In reality, this control is multiplexed to control the filter cutoff of multiple filters simultaneously (five filters in the case of the Prophet, or six of them in the Juno). The original Oberheim Two, Four, and Eight Voice instruments predated microprocessor that allowed this control multiplexing.
Lucky for you, it isn't 1978, and the Cherry Audio Eight Voice features intelligent Link Groups that allow highly flexible linking of controls. This makes programming homogenous polyphonic patches a breeze (by "homogenous," we mean all notes sound the same). What's even niftier is that voice linking can be easily disabled, allowing individual editing of each voice - this works particularly well for minute tuning, panning, or filter changes that breathe life into poly patches in a way "normal" synths can't.
The voice modules themselves bear a great resemblance to the original Oberheim SEM modules of the 70s. Each of these features two oscillators, a state-variable filter with continuously variable lowpass-to-highpass response or bandpass mode, two ADS envelope generators, and a low-frequency oscillator.
At the bottom of each module are its voice assign controls; these allow each modules to react differently (or similarly) to notes played on the keyboard or via the eight-step Mini Sequencer. These are where the Eight Voice's true power lies - it can behave as monophonic synth with up to 16 oscillators, an eight-voice polyphonic synth or anything combination thereof. Any number of the voices can be played by the Mini Sequencer, and notes played on the keyboard may optionally transpose sequencer CV playback. Additionally, each voice module can play within a user-defined key range. This makes splitting and layering very easy. (Right around now perhaps you're thinking, "this thing rules!," and you would be correct.)
We'll explain the synthesis and module voice assign specifics of the eight modules in later sections.
Each voice module has a master volume and pan control (excellent for super-wide detuned patches). These get routed to Eight Voice's syncable mod delay and reverb sections, and then onto the master volume control. We've also included a transparent limiter, because sometimes Eight Voice's huge sounds can get a little out of hand, level-wise.
The bottom strip also contains master controls that affect all voices, including tuning, transpose, and pitch bender depth, a master filter offset control (more on this in the VCF section), poly and unison mode and portamento (glide) controls, a "bonus" global, syncable LFO, and the aforementioned Mini Sequencer.