PLENI SUNT COELI 2 (2024) for Behringer 2600 synthesizer

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

		Pleni sunt coeli et terra gloria tua.
			Hosanna.

GENERAL

PLENI SUNT COELI 2 is an instrument 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; when the entire control is circled, it indicates that its whole range is in play. (Indeed the control is typically moved from one end to the other.) Unmarked controls are irrelevent.

The instrument requires 8 1/8" mono patchcords plus a 1/8" dummy plug or extra cord. (The Patch Sheet jack marked with an X [KYBD input for VCO 3] takes this plug, or one end of the cord.) 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 CONTROLLERS

PLENI SUNT COELI 2 comprises six sound sources: five pitches, plus brown noise. The lowest pitch issues from the internal clock of the SAMPLE & HOLD module; it is a square wave set to its highest rate. Level is determined by the VCF slider on the MIXER; this slider is its only (and master) control.

In order of ascending frequency, the remaining four pitches are variable-width pulse waves whose levels are set by the first four audio sliders in the VCF. (The first input, Ring Mod, is a product of VCO1 and VCO2, and is pitched below both VCOs.) All pulse widths can be varied in performance.

The brown noise originates from the NOISE GENERATOR at a fairly low Color setting. Its Level control serves as its name suggests, as well as adding a random frequency component to the four upper pitches (the three VCO's). The Noise Gen input to the VCF also controls the source's audio level, but is only operative when the *primary* Level of the NOISE GENERATOR is raised. (This is the only control which is truly dependent on another.)

Finally, the VCA slider on the MIXER is the master control for all sound sources except the lowest pitch.

The AR control input to the VCA (which emanates from the LFO) exercises a unique function: it adds a very slow tremolo to any of the sources, except the lowest pitch, that happens to be sounding at the time.

 OPTIONAL:
An additional element of sonic enrichment is available through use of the VCO2 control input to the VCF. (This control is enclosed by a broken circle in the Patch Chart.) Feel free to add this enhancement to the three or four already-sounding upper frequencies if and when you find it appropriate. (Otherwise the control should remain at zero.)

FREQUENCY SETUP/SELECTION

Complete the Initial Setup, then follow these steps:

1) Verify that the following controls are set:
Initial Oscillator Frequency of VCOs 1, 2, and 3 to max;
Fine Tune of VCO1 to 0 and that of VCO3 to max;
Fine Tune of VCO2 to .5.

2) Check that Rate in the SAMPLE & HOLD module is at max.

3} Raise the two sliders in the MIXER module, as well as the three VCO audio inputs to the VCF.

4) Adjust Fine Tune on the VCO2 module for a rich sonority with minimal beats.

5) Raise the Ring Mod slider in VCF and continue the step 4 adjustment. (This should create an even richer inharmonic sonority, while presenting more beating challenges.)

6) Test the varied combinations of three and four simultaneous upper pitches, both with and without the lowest frequency (VCF slider in MIXER). All should sound sonorous and relatively beat-free. If necessary, make slight adjustments to the fine tuning of VCO1 and/or VCO3 in addition to VCO2. (Note that this action may make it more difficult to recreate this sonority in the future.)

6a) OPTIONAL: If you are considering enhancing the above sonority via the VCO2 control input in VCF, add/mix this control into the various step 6 combinations above. Determine whether the result is compatible, relatively beat-free, and "works for you". When finished, return the control to zero.

7) In preparation for performance, return the first four audio inputs in VCF and both inputs in MIXER to zero.

 OPTIONAL: Performer selection of alternate frequencies.

Performers may wish to more freely select their own frequencies for PLENI SUNT COELI 2. This is a viable option - as long as the lowest pitch (represented by max level of the Rate control in SAMPLE & HOLD) is retained. The only other requirements are: to cover a broad frequency range similar to that specified here (spreading pitches relatively evenly); and to create a rich, inharmonic sonority without significant beating.

Feel free to use any approach you like to identify your alternate sonority. If you anticipate reusing these frequencies, be sure to identify a ready method to recall them. Small variations in frequency can make a significant difference. (Fine-tuning of pitch is probably the most important creative task to be undertaken within this project.)

Frequency settings remain unchanged during a given improvization. Also, no additional modifications should be made to the instrument design.

PERFORMANCE

Performance begins either when the VCF slider on MIXER is raised (sounding the lowest pitch), or when its VCA slider is opened (one or more of the other sound source controls being previously turned up). Performance ends when no source remains sounding. Both opening and closing should be accomplished by a slowish fade.

In general, observe the following guidelines:

1) slider movements should never sound hurried. (Simultaneous movement is always an option, however.)

2) the lowest frequency (VCF slider in MIXER) should be on nearly all the time.

3) at least three of the four higher-pitched sound sources (first four audio inputs to VCF) should always be on, once they are introduced. (The Noise Gen source is in addition to the three minimum.)


Maximum amplitude of this instrument is achieved at the following settings (following general setup):
all *audio* inputs for the VCF and MIXER at maximum;
NOISE GENERATOR Level at maximum;
the AR control input to the VCA tested both at zero and at maximum.

Note that the 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 6 minutes or so. (This is the duration of the demo included on my website. All variable controls, as well as "standard" pitch selection, are utilized in this rendition.)