PLENI SUNT COELI 3 (2024) for Behringer 2600 synthesizer

Arthur B. Hunkins
abhunkin@uncg.edu
www.arthunkins.com

		Pleni sunt coeli et terra gloria tua. . . .
	              Benedictus qui venit in nomine Domini.

GENERAL

PLENI SUNT COELI 3 is a sequel to its predecessor, PLENI SUNT COELI 2. It is an instrument similarly designed for the Behringer 2600 synthesizer, and intended for solo improvisation. Virtually no instructions are given for performance; realization is totally left to the performer's creativity.

Instrument setup is specifed on a Patch Sheet, which is included here. This sheet contains both patching and the initial (or preset) settings for various controllers. Sliders to be varied in performance are circled. (Many are typically moved from one extreme to the other.) Sliders marked "adjust" are to be freely set/preset by the performer. Several "intermediate" presets are accompanied by a specification ranging between 0 and 1 (max). Unmarked controls are irrelevent.

The instrument requires 10 1/8" mono patchcords. (Two additional cords are optional - for adding an auxiliary output as detailed below.) Routing to a stereo amplifier (or headphones) is from a minijack at the 2600's bottom right. Note that the output is actually two-channel mono.

THE TWO SUB-INSTRUMENTS

PLENI SUNT COELI 3 comprises two sub-instruments: a Ring Modulation (RM) sub-instrument and an Amplitude Modulation (AM) sub-instrument. RM consists of the following modules: VCO1, LFO, RING MOD, and VCF. AM includes: VCO2, VCO3, SAMPLE & HOLD, and VCF. The sliders within each set of modules is unique to each sub-instrument, i.e., each sub-instrument is independent of the other.

Be aware of one particular feature of the AM sub-instrument: VCO3 will have no effect unless the AR slider in the VCA module is raised. With the AR fader at zero, the sound will consist of a simple triangle wave; you will want to raise this control at least part way most of the time. Doing so will enable AM to better approach the richness of the RM sonority.

The master output of each sub-instrument is located in MIXER: for RM it is the VCF control; for AM, the VCA control.

PERFORMANCE

Performance begins when one of the MIXER sliders is raised above its initial zero. It ends when neither sub-instrument remains sounding. Both opening and closing should be accomplished by a slow fade.

In general, observe the following guidelines:

1) Vary any and all circled controls starting from their preset positions - but see #2 below. Slider movements should always be slow and even, frequently consisting of the entire range (exceptions to the "range norm" are the VCO Fine Tune and Pulse Width controls). Simultaneous movement is always an option.

2) The following sliders, which govern basic oscillator frequency, should only be adjusted when its sub-instrument is OFF: VCO 1, 2, and 3 Fine Tune. (Note that VCO3 Fine Tune can also be moved whenever the AR control in the VCA module is at zero.)

3) These frequency settings should be chosen so as to avoid harsh sonority and aggressive beating. (See Auxiliary Audio Setup below, to deal with possible issues.)

4) A sub-instrument is faded out primarily to change frequency. It should  not remain silent any longer than necessary to revise its settings.

5) One of the sub-instruments must always be on. (As soon as both are silent, the performance is over!)


Maximum amplitude of this instrument is achieved (following general setup) with both audio inputs to MIXER at maximum;

Note that *overall* output level can be adjusted at the Phones knob (bottom right).

Needless to say, a performance has no specific or anticipated duration. A typical improvisation might last 5 minutes or more. (This is the duration of the demo included on my website. The demo uses all of the variable controllers and was made without the use of the auxiliary audio setup.)

AUXILIARY AUDIO SETUP (Optional)

The base audio frequencies of the three VCO's are crucial to the design of this instrument. It is important that the overall sonority is not raucous, grating, or involve harsh beating. Your choice of initial Fine Tune settings should reflect this requirement. (When testing, be sure raise the AR input in VCA to include all the latter's frequency components).

Whenever these base frequencies are sounding, they remain unchanged. However, Fine Tune controls (with their resultant pitches) *may be reset while the relevant sub-instrument is silent*. The problem arises that, without actual audio feedback, it is dificult to anticipate the precise result of any changes made.

For such troublesome situations, an auxiliary audio setup is available. It involves the two additional patchcords indicated (in gray on the Patch Chart) and either headphone or earbud. (The auxiliary output is mono, and is thus routed to a single ear.)

This output bypasses the MIXER and its level controls, making both sub-instruments audible (to the performer alone) at all times, and permitting precise adjustment of frequencies before they are heard by an audience. Such an arrangement may well help avoid the undesirable results mentioned above.