DARK ENERGY
Vorankündigung / preliminary

Dark Energy is a monophonic stand-alone synthesizer with USB and Midi interface. The sound generation and all modulation sources are 100% analog, only the USB/Midi interface contains digital components. Dark Energy is built into a rugged black metal case with wooden side plates. High quality potentiometers with metal shafts are used and each potentiometer is fixed to the case (no wobbly shafts and knobs). The distance between the controls is a bit wider compared to A-100 modules and knobs with vintage look are used.

VCO

• Triangle based VCO core
• manual tune control (with an internal jumper the range can be set to ~ +/-1 half an octave or ~ +/-2.5 octaves)
• range switch -1 / 0 / +1 octave
• frequency range about 10Hz ... 12kHz
• FM (frequency modulation) control with modulation source switch (LFO1 / off / ADSR)
• manual pulsewidth control for rectangle waveform
• PWM control with modulation source switch (LFO2 / off / ADSR)
• waveform switch (sawtooth / off / triangle) 
• the sum of the waveform chosen by this switch and the rectangle is fed into the VCF (to turn the rectangle off the PW control has to be set fully CCW)
• external CV input for VCO frequency (1V/octave)
• external CV input for external PWM of the rectangle
• internal CV input for frequency (1V/octave) connected to the CV1 output of the built-in USB/Midi interface

VCF

• 24 dB low pass
• ~ 12 octaves frequency range
• manual frequency control
• tracking switch half - off - full (internally connected to the external frequency CV input of the VCO, i.e. the VCF tracks to the VCO if the switch is set to "half" or "full" position)
• XM: exponential FM (frequency modulation) control with modulation source switch (LFO2 / off / ADSR)
• LM: linear FM (frequency modulation) control to modulate the VCF by the triangle of the VCO in a linear (!) manner
• both FM types are available at the same time !
• manual resonance control (up to self oscillation for usage of the VCF as a sine VCO)
• external audio input (this signal is added to the VCO signal)
• external CV input for filter frequency (1V/oct)
• 1V/octave tracking for usage of the VCF as a sine wave oscillator (not as precise as the VCO but much better than most of the other filters)

VCA

• manual amplitude control
• AM (amplitude modulation) control with modulation source switch (LFO1 / off / ADSR)
• external CV input for VCA amplitude
• special control scale: exponential scale in the range from about -20dB to -80/90dB, linear scale from about -20dB to 0dB
  Remark: this special control scale results in a loudness behaviour that is a bit different from pure linear or exponential VCAs

LFO1 and LFO2

• manual frequency control
• waveform switch (triangle / off / rectangle)
• range switch (low, audio, medium)
• LED display (dual green/red color for positive/negative share of the signal)
• the LFO1 signal is available as an additional socket (to use the LFO1 signal for external modules)
• an internal jumper can be used to select between the LFO1 signal or the inverted LFO1 signal

ADSR

• manual controls for Attack, Decay, Sustain, Release
• range switch (long, short, medium)
• blue LED display
• ADSR signal is available as an additional socket (to use the ADSR signal for external modules)
• External Gate input (normalled via switching contact of the socket to the Gate output of the built-in USB/Midi interface)

USB/Midi-Interface

• Midi channel and reference note are adjusted by means of a learn button and LED at the rear panel
• The interface generates the gate signal that controls the envelope generator and three analog control voltages: CV1 is used to control the pitch of the VCO, CV2 the VCF frequency (free assignable Midi controller) and CV3 is available as an additional socket at the rear panel (controlled by volume/velocity). It can be patched e.g. to the VCA control input.
• The three CVs and the gate signal are also available at the rear panel as jack sockets
• cascading of several units via internal Midi Out/Midi In connection, because of shortage of space the unit has no Midi Out socket available this connection has to be established internally, for this the metal case has a hole on both sides so that the Midi Out/In connection can be made via this hole provided that both units are mounted to one another, the Midi Out has Midi Thru function with one exception: the signal does not include the Midi note messages that have been processed already, consequently polyphonic cascading (all daisy-chained Dark Energies on the same Midi channel) or monophonic cascading (different Midi channels) is possible, it's possible to connect only the first unit to USB and pass on the Midi data via the internal Midi link to other devices)

In/Outputs

• front panel:
  • CV In VCO frequency (1V/oct)
  • CV In VCO pulsewidth
  • CV In VCF frequency (1V/oct)
  • CV In VCA amplitude
  • Gate In
  • External Audio In
  • LFO1 Out
  • Envelope Out
  • Audio Out
• rear panel:
  • USB
  • Midi In
  • Learn button
  • Gate Out (with LED for Gate display and learn function)
  • CV1 (controlled by Midi note messages, internally connected to VCO CV input)
  • CV2 (controlled by Midi control change messages, free assignale controller, internally connected to VCF CV socket)
  • CV3 (controlled by Midi velocity/volume, no internal connection, can be patched e.g. to VCA CV input)
  • Audio Out or additional control voltage (CV4, controlled probably by After Touch), function can be selected by an internal jumper, factory setting audio output
  • power supply (15V AC, 400mA)

Remarks:

• As the LFO frequencies can go up to moderate audio range (~ 5kHz) even audio FM effects of VCO (pitch and pulsewidth), VCF and ADSR are possible !
• If the VCO is turned off (waveform switch = center position, pulsewidth control = fully CCW) and the VCF resonance is set to maximum the module can be used as a sine oscillator. The sine can be modulated in a linear manner from the triangle wave of the VCO and by LFO2 in an exponential manner at the same time !
• from the factory the socket labelled "LFO1" outputs the inverted LFO1 signal. But as the module has several internal pin headers available even another signal may appear at this socket by changing the internal module patch. These six pin headers are available: LFO1 output, LFO2 output, ADSR output, inverter input, inverter output, output socket. The internal default patch is LFO1 ->  inverter input, inverter output -> output socket (i.e. socket = inverted LFO1). But even another signal can be patched to this socket (e.g. inverted ADSR, non-inverted LFO1, inverted or non-inverted LFO2). It is also possible to add a blind panel next to the A-111-5 with a couple of sockets that are connected to the corresponding pins of the A-111-5 pc board. The in- and outputs of the VCO, VCF and VCA are not available as pin headers because the VCO, VCF and VCA are internally connected in the circuit which is used in this module.
• The attenuators for VCO FM and VCF FM are exponential types to enable a better resolution of the modulation depth in the lower range
• Dark Energy is the stand-alone version of the module A-111-5 

Dimensions: overall about 185 x 145 x 65 mm, about 145 x 135 x 55 without wooden site plates
Weight: about 1.2 kg

The wooden side plates can be removed if desired. They are mounted by means of two screws to the metal box. The holes in the metal box can be used also to mount several devices together, e.g. with only one wooden side plate on each end or with a wooden side plate on each end and between each device (for this application an additional hole has to be drilled into the middle plate(s) if the internal Midi link is wanted).

This is a preliminary information about the planned device. The features are still subject to change and all specifications are still preliminary without any obligation !

In the samples only an A-155 with LFO clock source and the A-111-5 are used (A-155 CV Out 1 -> CV In A-155-1, A-155 Trig out 1 -> A-111-5 Gate In)!

A1115_Synth_01.mp3

This is nothing exceptional. Just the standard VCO/VCF/VCA synthesizer patch. These operations carried out during the example: 

• default setting: VCO waveform = sawtooth + rectangle, VCF frequency = maximum, VCF resonance = minimum, VCF modulation = minimum, ADSR times at medium settings
• VCO tuned manually from maximum to about position 2
• filter frequency lowered
• ADSR times manually reduced
• VCF frequency, VCF modulation depth and VCF resonance altered manually (modulation source = ADSR)
• PWM added (about at the center of the example, leads to a richer sound), modulation source = triangle LFO 1
• VCO octave switch operated (center/up/center/down/center)
• VCO tune changed

A1115_FM_01.mp3

This example shows some FM sounds that can be generated by the A-111-5. Only the self-oscillation VCF is used as sound source. The VCO is not heard but only used for linear FM (LM). 

• default setting: VCO = off, VCF resonance = maximum, no VCF FM or LM, ADSR times at medium settings
• ADSR times manually reduced
• Linear FM (LM) control from zero to about middle position and back to zero
• Exponential FM (XM) control from zero to about middle position and back to zero, modulation source = LFO2 triangle in audio range
• Linear and exponential FM (LM and XM) controls both from zero to about middle position
• small VCO modulation added, modulations source = ADSR
• Linear and exponential FM (LM and XM) controls both back to zero