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Doepfer Dark Energy 2 LFO breakout

First modification (mod) of the Doepfer Dark Energy II / Dark Energy 2.



DIY Eurorack Wall Cabinet

A temporary solution for the spare A-100 modules. A DIY eurorack Wall Cabinet based on three Doepfer A100-LC9 low cost case. Cheap and fast to build Housing for modular eurorack synthesizer.


Wooden wall cabinet for modular synthesizer. The three painted Doepfer A100-LC9 wooden cases are not fixed in the frame. You can put them in the cabinet through the backside of the frame.

But if you skip the masking frame at the front (for hiding the RGB led strips) it is much easier to slide-in the cases at the front of the cabinet.

With the shown solution you have to put the three modular cases in the frame first before hanging the total frame at the wall.. (quite heavy, but it is possible :-) )

Modular Synthesizer on the wall.



Wall Cabinet Synthesizer with RGB led strips. A color for every mood.

Temporary DIY Wall Cabinet for eurorack A-100 modules together with the Dark Quaternity. (blue leds)

RGB led strip green.

RGB led strip red and white..

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Doepfer Dark Energy II (2)

Doepfer Dark Energy II (2)

Underneath some pictures of the Doepfer Dark Energy II inside.

Specs at:

Soon more explanation and comments.


Dark Energy 2 LFO breakout strip


Doepfer Dark Energy 1 vs 2 (comparison)




As the Dark Energy (I) had to be discontinued because an important electronic part (CEM3394) is no longer available we decided to do a redesign of the Dark Energy. The new Dark Energy II looks like the Dark Energy I at first sight. But the basic sound of Dark Energy II is clearly different from version I because of the new circuits for VCO, VCF and VCA. In the following description of the Dark Energy II the differences to Dark Energy I are marked blue:

Dark Energy II 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 - except the filter mode control - 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.


Sawtooth 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
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 / clipped/inverted sawtooth)
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
because of the pure analog circuit and the temperature control it may take up to 30 minutes until the VCO is in tune.


12dB multimode filter with lowpass, notch, highpass and bandpass
mode control for continuous transition from lowpass via notch to highpass and along to bandpass
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)
exponential frequency modulation control (XFM) with modulation source switch (LFO2 / off / ADSR), the XFM control has polarizer function, i.e. the modulation source (LFO2 or ADSR) selected by the Source switch may affect the filter frequency in a positive (right half of the control range) or negative way (left half of the control range)
manual resonance control (up to self oscillation)
external audio input (this signal is added to the VCO signal)
external CV input for filter frequency
1V/octave tracking for usage of the VCF as a sine wave oscillator over a few octaves  (not as precise as the VCO and not temperature compensated, but much better than most of the other filters)


manual amplitude control (initial gain)
AM (amplitude modulation) control with modulation source switch (LFO1 / off / ADSR)
external CV input for VCA amplitude
exponential scale.

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


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)


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 threes 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 (all monophonic 3.5 mm jack sockets, except USB, Midi and power supply)

front panel:
CV In VCO frequency (1V/oct)
CV In VCO pulsewidth (about 5V range for full scale)
CV In VCF frequency (~ 1V/oct)
CV In VCA amplitude (0...+5V)
Gate In (0/+5...12V)
External Audio In (typ. 1Vss without distortion)
inverted LFO1 Out (~ -2.5 ... +2.5V)
Envelope Out (~ 0 ... +6V)
Audio Out (line output, typ. 1Vss, monophonic)
rear panel:
Midi In
Learn button
Gate Out (with LED for Gate display and learn function), 0/+5V
CV1: controlled by Midi note messages, 1V/Oct, 0...+5V, internally connected to VCO CV input
CV2: controlled by Midi pitch bend, ~ -2.5...+2.5V or ~ 0...+5V (can be selected by an internal jumper), no internal connection, the socket can be patched e.g. to the VCO or VCF CV input at the front panel
CV3: controlled by Midi velocity, 0...+5V,  no internal connection, the socket can be patched e.g. to the VCF or VCA CV input at the front panel
CV4: controlled by Midi control change messages, free assignale controller in learn mode, no internal connection, the socket can be patched e.g. to the VCF or VCO pulsewidht input at the front panel
the CV4 socket can be used also as audio output, the function of the socket can be selected by an internal jumper, factory setting is CV4, when changed to audio output no cable at the front panel is required (unless one wants to patch something), in this case CV4 is not available
power supply (12...15V AC, min. 400mA)
internal connections
Midi out (pin header with 2 pins for internal routing of the Midi signal to another Dark Energy)
Midi in (pin header with 2 pins for internal routing of the Midi signal from another Dark Energy)
By means of this internal connections several Dark Energy devices can be daisy-chained. Only the first device has to be connected to the Midi or USB transmitter. For this purpose the side plates of the metal case are equipped with holes that allow the internal connection of 2 or more Dark Energy devices. For this the metal cases have to be mounted directly to each other without wooden sideplate between the units. If a wooden side plate is desired between the devices one has to drill a hole to enable the internal connection.
Several devices can be daisy-chained multiple monophonic (i.e. each Dark Energy received at a different Midi channel) or polyphonic (i.e. all devices are adjusted to the same Midi channel). For polyphonic applications a special stack mode is available. In this mode the device in question does not transmit note messages at the Midi output that are used to generate the tone in the device. Only "unused" note messages are transmitted.

Additional remarks and specs:

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 inputs 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
Weight: about 1.2 kg (without power supply)
Distance between the knobs (center - center): ~ 25 mm, diameter of the knobs: ~ 16 mm
The metal case is made of 1 mm steel, black coated with white printing
Overall dimensions: about 185 x 145 x 75 mm
Dimension of the metal case only (without side plates and knobs): about 145 x 135 x 55
Side plates dimensions: about 145 x 65 x 12.5 mm
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 common wooden side plates on both ends).
The device can be positioned horizontal (desk top) or vertical
These parts are included: power supply (12 AC/min. 800mA) for 230V mains voltage with European mains plug, one adapter cable 3.5 mm - 6.3 mm /1/4" jack plug (1.5 m length), one USB cable (type A-B, 2 m length) and two A-100 patch cables (50 cm length)
Powering the device via USB is not possible, because the analog circuits require a dual voltage (+/-12V).
A lot of additional functions are available as internal pin headers (e.g. VCO outputs, linear FM input for VCO, hard SYNC input for VCO, VCF outputs, LFO outputs, LFO connections for optional reset/direction features, ADSR outout, inverter input and output). Important note: warranty is void if a defect caused by wrong wiring of these additional pin headers is discovered !

For detailed information the user's manual (Dark_Energy_II_Manual.pdf) and a document with additional technical information (e.g. for modifications, adjustment) is available (Dark_Energy_II_technical_information.pdf). The glide option contains a pre-wired glide potentiometer with two nuts and a Dark Energy style rotary knob.

In addition there are some answers on our FAQ pages: Dark Energy FAQ

Remark: The supply connector at the rear panel of the first series of Dark Energy II is labelled "15V AC/400mA". That's wrong ! The correct power supply is 12V AC / min. 800 mA (i.a. 800 mA or more). The power supplies delivered with the Dark Energy II are the right ones !

Once again the differences between Dark Energy I and II as summary:

12dB multimode filter with lowpass, notch, highpass and bandpass (instead of 24dB lowpass of Dark Energy I)

the previous LM control of the filter becomes the filter type control Mode (continuous crossfade lowpass - notch - highpass - bandpass)

the modulation level control of the filter "XFM" has so-called "polarizer" function. The modulation source (LFO2 or ADSR) selected by the Source switch may affect the filter frequency in a positive (right half of the control range) or negative way (left half of the control range)

the waveform switch is used to select between saw and clipped, inverted saw (in the center position the saw is off)

the basic waveform of the VCO is saw (not triangle like the Dark Energy I).

the VCA has a exponential scale (not the combined linear/exponential scale of Dark Energy I)

because of the pure analog circuit and the temperature control it may take up to 20-30 minutes until the VCO is in tune.

The sound of the Dark Energy II differs clearly from the Dark Energy I (mainly because of the completely different filter type). If you already own a Dark Energy I the Dark Energy II can be used as an expansion. But you will not be able to copy sounds of the Dark Energy I with the Dark Energy II (and vice versa) !

For users with electronic knowledge the Dark Energy II offers much more internal expansion features than the Dark Energy I. For example terminals (pin headers) for these features are available: VCO Hard Sync, linear VCO FM, rectangle and sawtoooth output of the VCO, lowpass/bandpass/highpass output of the VC, Reset/Sync/Direction for each LFO, rectangle and triangle output for each LFO. In addition an improved version of the glide option is is the planning stage that allows to turn on/off the glide function via Midi control change messages.

During the Musikmesse 2012 the first prototype of Dark Energy II has been presented. A few videos and sound examples are available:

Sonicstate: (English)
Musikmachen / Keyboards: (German)
Debug: (German)


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The Dark Trilogy 2, darker than before (blue edition)

The second edition of the Dark Trilogy is black and the internal Dark Time has blue leds now, like the three Dark Energy's. Technical the black version is almost the same as the former one. The final version, with a complete new design, will see the light this coming Autumn. For now you can read some more technical information on the page below illustrated with some pictures of the internal electronics.  Custom Synth

"01 May 2012: This page is still under construction!"

Doepfer Dark Trilogy II

This version is not for sale yet. It is a new prototype which has more functionality than the former one, but the next couple of months additions will be done in a dockable upper case. After evaluation and testing these additions they will not be mounted in a dockable case, but next to the sequencer on the left, so it will be more useful for live performances. This black one has probably the last three available Dark Energy I on board. The final version can be BTO and probably will be based on the Dark Energy II. Which will be available this Autumn. If you like to keep updated please fill in the gitwform

Sidepanels removed by opening the case, remove the interface board, and screw the units together.

Stripping the multicable for the three glide controls (for instance a Dsub9 rs232 cable)

Measuring the pots: which cable is which glide pot..

Twisting the right color pairs, remember them and cut off the rest..

Leading the multicable through the glide option hole in the middle, second Dark Energy.

MIDI - Stacking the units, JP6 of the interface board is MIDI out...(Dark Energy 1)

MIDI - Stacking the units, JP5 of the interface board is MIDI in...(Dark Energy 2)and JP6 is out...

MIDI - Stacking the units, JP5 of the interface board is MIDI in...(Dark Energy 3)...

Use CV4 as an audio output by changing the jumper JP10 to the lower position... (original state)

Use CV4 as an audio output by chaning the jumper JP10 to the lower position... (lower state)


Finished basic changes...

For easy acces to the Dark Energy outputs and the in-output of the Dark Time 27 cables are needed...

Soldering the patchcables to the patchpanel which will be placed in the temporay upper docking cabinet....


Adding a VCA- and Audiomixer to the patchpanel...... (Doepfer A-138a and A-138b) with black knobs...

Current stage of the patchpanel...

Labeling the patchcables....

The temporary black dockable cabninet for extra CV-control and patching. For now two A-100mnt power supplies are added to the top cabinet....

In the top cabinet als a blue led light is mounted.... (on the left: Her Majesty: The Dark Quaternity, on the right: the little black performer: The Dark Trilogy II)

For now this is the Testcase for the Dark Trilogy II. In this dockable case extra patchpanels, controllers and extra modules will be tested for the final design of the Dark Trilogy II (which will be finished this summer..)

Doepfer Dark Trilogy and A-103 / A-108 (controlled by pitchwheel)

Doepfer Dark Trilogy and A-156 (controlled by Dark Energy LFO1)


Here you will find the progression of the development of the new Dark Trilogy Design.

Soon more info.

This project is on hold for now.

A possible new concept for the DTxl


The wrong designed filterboard in the Testcase for the DTII for test purposes..

It's current state...

Detail of the concept of the Doepfer Dark Trilogy XL

September 1: The Story goes on...

All new functions of the to be built new Doepfer Dark Trilogy XL will be designed and tested in the upper testcase of the Dark Trilogy.

underneath a possible control/filter- and patchboard:

August 30: New control/filterboard for the DT-xl:

From left to right:: 4 big CV-controls (rough and fine control), CV outputs and extra cv control, Moog filter (108), 303 filter (103) patchfield DT and DE's, Audiomixer (138b)



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go to the original Dark Trilogy page

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