Dreadbox Erebus User manual

1. Quick Start
1.1 Box Contents
1.2 Schematic Diagram
1.3 Connections
1.4 Powering up Erebus
2. Operation
2.1 Paraphony
2.2 Midi Interface
2.3 Oscillators
2.4 Filter
2.5 Amplier
2.6 Envelope
2.7 LFO
2.8 Lo-Fi Echo
2.9 Patching
2.10 Eurorack

1. Quick Start
1.1 Box Contents
Erebus Analog Synthesizer, 42HP case, 1x Midi DIN5 to 3.5mm adapter type A, 1x Ribbon cable for
Eurorack Connection.
1.2 Schematic Diagram
HARD
SYNC

MIDI KEYBOARD
MIDI OUT
EXTERNAL
INPUT
DREADBOX
MIDI ADAPTER
USB ADAPTER
1 A or more
USB A Cable
or
1.3 Connections
1.4 Powering up the Erebus
In order to power the Erebus suciently, use a good quality USB power adapter with minimum 1A and
a good quality USB A cable. The USB adapter nor the USB A cable are included in the box.

2. Operation
2.1 Paraphony
We call Paraphonic Synthesis, when the Oscillators can work in polyphony but the signal path is the
same for all voices. In EREBUS we have 2 oscillators sharing the same Filter and VCA. But to be more
specic :
- 1 key pressed : both oscillators will play the pressed note
- 2 keys pressed : Oscillator 1 will play the low note, Oscillator 2 will play the high note
- 3 or more keys pressed: Oscillator 1 will play the low note, Oscillator 2 will play the last played note,
as long as its higher than Oscillator 1.
2.2 MIDI Interface
Erebus Midi interface will allow the following actions:
2.3 Oscillators
The EREBUS oscillators need about 2 to 3 minutes to warm up. You can just turn on the synth and play,
but the tuning will change during that time. They work with the classic 1V/Oct controllers or a Midi
source. By default the tune knobs should point at about 12.00 o’clock for a precise tuning. Always keep
in mind that the Osc2 triangle waveshape will have the feeling of a lower volume in low frequencies.
MIDI Channel Selection
When the switch is set to OMNI, all channels are active. When it is set to CHAN, it will play the last
channel received when the switch was in the OMNI mode.
For example, in order to set Hades to channel 2:
- Set the switch to OMNI mode
- Set your MIDI keyboard to Channel 2
- Play any note
- Then switch to CHAN
- Note(s) on / off. Gate out patch converts Midi ON/OFF note
to analog Gate.
- Pitch tracking up to 7 octaves (C -1 up to C 8). The pitch is
converted to 1V/Oct, which can be accessed via the CV1-CV2
output patches.
- 2 Voice Polyphony or Unison mode.
- Keyboard re-trigger on the ADSR Envelope.
- Pitch wheel for 3 semitones up/down. This is also transmitted
by the CV1-CV2 outputs.
- Modulation wheel (accessible only via patch) 0- 5v

2.4 Filter
The lter of the EREBUS is a 2-pole 12db/octave pre-fed resonating Low Pass
Filter. Pre-fed means that it has a build in pre-resonant accent that it is
always active on the 1/6th of the lter’s total input gain and completely
independent from the normal resonance control, thus making the EREBUS a
much more aggressive and edgy synth. Resonating means that with the
resonance control at 100% you get a self-oscillation.
2.5 Amplier
EREBUS’s amplier has a build-in AR envelope generator. Notice that
when the output Level is at max you get 8V/pp, so be careful not to hurt
your ears or damage your speakers.
When one of the Oscillators is Off (when its dedicated wave switch is in the center position), the MIX
knob will not have any effect and the Oscillator that is ON will always be added to the Filter.
1. Both Oscillators Master Tune.
2. Oscillator 1 Wave selection.
Center position sets the Osc1 OFF
3. Oscillator 2 Detune.
4. Oscillator 2 Wave selection.
Center position sets the Osc2 OFF
5. Oscillator 1 Octave selector.
6. Oscillator 2 Octave selector.
7. Sets the Glide’s Rate for the Osc1 (portamento)
8. Sets the Glide’s Rate for the Osc2 (portamento)
9. Sets the Mix level between Osc1 and Osc2.
10. Hard syncs the Osc2 to Osc1.
1. Sets the Cutoff frequency of the lter.
2. Sets the Post Resonance amount.
Adding Resonance will drastically increase the synth’s output volume, due
to the nature of the Filter.
1. Master volume
2. Attack speed
3. Release speed
1
2
7 8
65
410
9
3
1
2
1
2 3

2.6 Envelope
EREBUS’s ADSR is dedicated to the Filter at all times. It may deliver up to 5V of envelope (also
accessible on a patch).
2.7 LFO
The LFO can be accessed only via its patch. It has a wide range of frequencies, from 10 minutes up to
3kHz (3000Hz).
2.8 Lo-Fi Echo
EREBUS is equipped with an all analog signal path CV controlled echo module. The mix knob allows
you to go from a dry to a completely wet mode of sound. Setting the feed pot at max, it will start the
self oscillation process. Note that the time knob allows you to get long echo times with a very Lo-Fi
sound. This module serves also as a chorus (modulation with the LFO on very low time settings), Lo-Fi
machine, tape sounds , pitch shifting modulations or a standard delay.
Please note that when setting the Mix knob at 50%, a slight volume drop is expected.
1. Attack speed
2. Decay speed
3. Sustain point
4. Release speed
5. Envelope’s amount to Filter
1. Sets the initial Rate of the LFO
2. Sets the initial Depth of the LFO
3. Selects the output waveform
1. Sets the time of the Echo
2. Sets the depth of the Feedback
3. Sets the Mix between Dry and Wet signal
1 2 3 4 5
1 2
3
1 2 3

2.9 Patching
EREBUS’s right side is dedicated to patching. Learning to patch needs lots of experimentation. We
strongly suggest spending lots of time and trying as much connections as possible. You will nd out
that half the possibilities of the synth comes from it. Patching is divided in 3 areas:
OUTPUTS - those patches only send voltage. You can send their CV to other devices, but rst be sure
that the receiver can accept such a voltage.
INPUTS - those patches can only receive voltage. It’s safe to send much more voltage than indicated
(see specs or chap. 9B) but it won’t always have results.
MIDI INTERFACE - those patches are for MIDI and Audio handling.
MOD: Modulation Wheel. Sends 0-5V and it can be controlled by the
Midi Keyboard’s modulation wheel. The small depth knob above,
acts as an attenuator, it limits the maximum voltage to be delivered.
GATE: Sends note on/off from the midi keyboard in the analog form
of 0V(off) 5V(on).
ENV: Sends 0-5V from the ADSR envelope generator. Again the
small knob above acts as an attenuator.
CV1: Sends the 1V/Oct that Oscillator 1 is currently using.
CV2: Sends the 1V/oct that Oscillator 2 is currently using. When in
Unison mode, this is exactly the same amount of voltage as CV1.
LFO: Sends the LFO output to a +/-5V form. This is the only way to
use the LFO, as it is not hard-wired.
NEVER CONNECT AN OUTPUT WITH ANOTHER OUTPUT
This might cause serious damage to the unit and Dreadbox will not take any responsibility.
TIP:
CV1, CV2 and gate are great to use with other cv/gate controlled devices to achieve paraphony. You
may also multiply the gate to control two different devices at a time. Sending CV1 at one and CV2 to
the other will make them work in a paraphonic way between them.
A. OUTPUTS

OSC1: Controls Oscillator 1. Best operated at 1V/Oct. Max +/-12V
OSC2: Controls Oscillator 2. Best operated at 1V/Oct. Max +/-12V
VCF: Controls the lter’s Cutoff. Best operated at +/-5V. Max +/-12V
CV: Controls both oscillators at the same time.
Best operated at 1V/Oct. Max +/-12V
ECHO: Controls the echo’s time. Best operated at 0-2,5V. Max +/-5V
GATE: Controls the envelope’s on-off. The EREBUS gate is different
from common gate controls because the ADSR envelope works in
an on/off function but the amp’s envelope has a logarithmic
opening function.
LFO/R: Controls the rate of the LFO.
Works best at +/-5V and accepts +/-10V
PW: Controls the pulse width of the Osc1 square wave.
Works best at +/-5V and accepts +/-10V
VCA: Controls the amplitude modulation of the Amp.
Works best at +/-5V and accepts max +/-10V
OUT: Master Output of the synthesizer.
It can also be connected with headphones.
IN: Mono input to the Filter. If the synth is not triggered, the sound
will not pass through.
MIDI: Midi input. Use only the type-A dedicated adapter included in the box
B. INPUTS
B. MIDI INTERFACE
2.10 Eurorack
In order to use the Hades Reissue in a eurorack case, do the following:
A. Unscrew the 4 corner bolts, which keep the module attached to the case
B. Remove the module from the case. Afterwards, unscrew the 2 bolts that connect the small PCB to
the USB adapter and detach them.
C. Plug the provided ribbon cable and connect it to the power bus board of a eurorack case.