dreadbox Dreadbox Erebus 3 Erebus_V3_Owners_Manual

Contents

Introduction ..................................................................... 3

The Oscillators ................................................................ 4

The Filter ......................................................................... 5

Envelopes and AMP ....................................................... 6

Low Frequency Oscillators ............................................ 6

Echo ................................................................................. 6

Patch Bay ........................................................................ 7

MIDI Interface and DIP Switch ....................................... 9

Limited Warranty .......................................................... 10

Erebus V3.0 / Release Date: 22.10.2018

Development and Circuit Design

Yiannis Diakoumakos

Firmware

Stratos Bichakis

Following in the tradition of the Erebus V1 and V2, Dreadbox proudly
presents the Erebus V3, a duophonic, analog synth bringing you all the
sonic exquisiteness of the earlier versions, but with even a few more
tricks up its sleeve, including:

• Three voltage controlled oscillators

• A 12db resonating, multimode LP/HP lter

• A unique Triple Ring modulator effect

• Extensive modulation options with 35 patch points

• An analog clock signal generator

• Up to 3 LFOs

• Two ADSR envelopes for shaping both the VCF and VCA

• A white noise generator

• A Patachable Sample and Hold circuit

• A lo- echo/delay effect

• Background automatic tuning

Manual written by Max and Yiannis Diakoumakos

If you have any suggestion or corrections for this manual please send an e-mail to

[e-mail]

3

The Oscillators

The Erebus v3 is equipped with 3 voltage-controlled, analog oscillators (VOCs). Both OSC 1 and OSC 2
offer identical controls and features, except OSC 2 offers a triangle wave instead of a pulse wave.

OSC 3 has a total of 6 wave forms, white noise, and allows a greater range of tuning.

OSC 1 and OSC 2 Controls:

1. TUNE knob - allows for precise tuning of the
VCO approx. ± 11 semi tones.

2. Octave Switch - to transpose the VCO pitch
over 3 octaves.

3. Wave Select Switch - to select either the saw
wave or pulse wave for OSC 1 or the saw wave or
triangle wave for OSC 2. If neither wave is select­ed, the VCO is turned off.

4. GLIDE slider - allows independent control of
the glide amount for each VCO.

5. MIX - controls the mix or comparative loudness
between both OSC 1 and OSC 2. If either VCO1 or VCO2 is switched off, then the MIX control doesn’t
affect the remaining oscillator (it will play at maximum volume).

6. TRIPLE RING - the rst slider (1/2) controls the amount of the modulation from OSC1 on OSC 2
The second slider (1/3) controls the amount of the modulation for OSC 1 to OSC 3. For those who
would like to get more technical information about this:
We use the triangle of OSC 2 and the sine of OSC 3. Then,
there is a switch that shifts between those two, on the rate
of OSC 1 pulse. When the pulse is on a high state, OSC 3 is
on, when it’s on a low state, OSC 2 is on. So keep in mind,
the PW1 patch will drastically affect the sound of the tri­ple ring. Triple ring, is best used individually, without any
other sound sources ON.

1/2

OSC 2 TRIANGLE

OSC 3 SINE

1/3

OSC 1 PULSE

TO FILTER

Some of the deepest bass sounds can be achieved from this part. Here is an example you MUST try.

Make sure that the Oscillators are tuned with precision.

4

OSC 3 Controls:

1. Wave Select knob - sets OSC 3 to one of 6 wave forms including saw­up, saw-down, modulatable pulse wave, triangle, sine, double saw, as
well as a white noise source.

2. TUNE - allows for course tuning of OSC 3 from as low as 0.01 (letting
the VCO also act as an LFO) up to 15kHz

3. FINE - controls ner tuning of OSC 3 ±11 semitones

4. LEVEL - controls the amplitude (loudness) of OSC 3 in the overall mix.

5. FM - controls the amount of frequency modulation from OSC 3.

About OSC 3 PWM and Double saw wave (super saw)

There are 2 waveforms that can be affected by the PW3 patch point. The Square Wave and the Double
Saw (a.k.a. Super Saw).
The Super Saw, sounds like an one octave up Saw (and it actually is), if the PW3 is not used. But when
the PW3 is modulated, interesting things will happen. The Double Saw will start shifting octave up/
down and it will also sound like a PWM , but with a Saw Wave.

OSC 3 Key tracking

OSC 3 will always follow the Pitch of OSC 1. This includes the key track and the octave change. You can
have OSC 3 free of tracking, by inserting a dummy patch cable to the CV3 patch input.

How to Tune the oscillators with precision

Let the unit warm up for 5 minutes and have the DIP1 ON (on the back panel, so as the autotune is
active). Usually, OSC 1 Tune should be at 50%. Then turn on OSC 2, and with a starting point of the tune
knob at 50%, try syncing them. OSC 2 will not be exactly at 50%, but it will need to be slightly left or right
(differs from unit to unit) to be in tune. Then close OSC 2 and bring OSC 3 in. Set the FINE knob at 50%,
and then with the TUNE knob try to get the oscillators in sync (this should be at about 11:30 o’clock).
Afterwards, with the FINE tune, you can get them in tune with precision.
If at any point you think that the oscillators have lost their scaling, leave the unit to rest for 5-10 sec
(the autotuning will start only when the amp envelope is fully closed - so it’s a good idea to set a release
time of 0 to the amp) and the autotuning process will be completed in the background.
Also, always remember that the tune knobs are analog, and will not follow the autotuning. You have to
manually set them, so as the unit is in tune.

The Filter

The Erebus V3 has a 2-pole, state variable lter with both 12dB/oct (2-pole) low pass (LP) and high
pass (HP) settings.

Filter Controls:

1. CUTOFF knob - sets the cutoff frequency of the lter

2. RES knob - controls the amount of resonance (sometimes referred to as Q)

to the lter cutoff frequency

3. MODE slider - balances the amount of signal from the high pass and the low

pass lters. With the slider position fully closed, only the signal through the LP
lter will be heard. With the slider position fully open, only the signal through
the HP lter will be heard. The area in between, is a Notch mode.

The lter can self-oscillate, starting when the resonance is above 3 o’ clock. The sound of the self os­cillation will be much different in the 2 lter modes. HP has a more agressive sound. The lter has no

obvious note tracking, but you can easily achieve that via patching.

5

Envelopes and AMP

The Erebus V3 offers two digital (actually this is the only digital part of the synth) linear A-D-S-R

envelopes, dedicated to the lter and amplier respectively. The rst envelope (labeled “ENVELOPE”),
is hard-wired to control the lter cutoff, but it can also be patched so as to modulate a number of other
targets. The second envelope (labeled “AMP”) is hard-wired to control only the voltage-controlled am-
plier (VCA) or the loudness of the patch over time.

The Filter envelope time, varies from 10ms up to 60 sec, for each of the stages.
Note, that if the AMP envelope has a snappy or edgy setting, an audible click will be present, depending

on the source’s settings. This is normal, and expected and it is caused due to the snappiness of the
envelope. To avoid that, you can add a little bit of attack and release to the curve.
Maximum AMP output level, with all sound sources at max, and lter wide open, is 4Vpp.

Envelope Controls:

1. On both envelopes, the ADSR sliders control the
Attack, Decay, Sustain, and the Release stages of the
envelopes.

2. The LEVEL sliders control how strongly the envelope

affects the lter and the amplier.

3. The LOOP switch lets the user set the envelope to
loop from the end of the release stage, behaving like a
LFO that can be shaped with the A ,D ,S controls.
The R will not affect the looping envelope.

Low Frequency Oscillators (LFOs)

The Erebus V3 has up to 4 separate LFO sources:

1. The dedicated LFO (pictured here) - offers a triangle wave that can be patched from
patch point 7, labeled “LFO”. Unless it’s patched, the LFO is hardwired so as to equally mod-
ulate the frequency or pitch of all 3 Oscillators (OSC 1, OSC 2, and OSC 3). The RATE slider
controls the LFO Rate from .0167 to 20 Hz.

2. The Filter envelope - when is set to loop, the envelope can be patched from patch point 3
(labeled “ENV”) so as to modulate other targets, for example an LFO.

3. OSC 3 - can be tuned down to LFO range and variably sweep through saw (up-ramp and
down ramp), pulse/square, triangle, sine, and double-saw waveforms.

4. CLOCK - can be used as a square wave LFO.

Echo

The Erebus V3 inherits the same lo-, classic delay from its earlier versions.
Just like in the original Erebus, the effect can offer reverb, chorus, lo- echo,

tape echo, pitch shifting modulations, or a standard delay.

Echo Controls:

1. The MIX slider controls the amount of dry and wet signal of the effect.

2. The FEED slider controls the amount of feedback to the signal.

3. The TIME knob lets you set delay times from 50ms up to about 400ms.

6

Patch Bay

The Erebus V3 has 35 patch points, offering endless routing and modulation possibilities.
The Patch Bay is consisted of 7 major parts:

GENERAL INPUTS

21. CV1 : CV for OSC 1

22. CV2 : CV for OSC 2

23. CV3 : CV for OSC 3 - When this is patched, the keyboard track­ing is disabled

24. CV : CV for all Oscillators

26. PW1 : Pulse width for OSC 1 - This must never be plugged in
and not be connected to another patch, otherwise the PW will
produce unwanted noise

27. ECHO :CV for the echo time

28. PW3 : Pulse width for OSC 3 - This must never be plugged in
and not be connected to another patch, otherwise the PW will
produce noise

29. GATE input : expects a 0-5V pulse. Do not use more than 5.5V
gate signals

31. CUT : Filter cutoff CV- it is not a precise 1V/ocv tracking input

32. RES : Filter resonance CV. Expects a 0-5V CV. If a bi-polar CV
is sent, it won’t cancel it, but it will not be modulated properly

33. IN/FILTER : Filter’s external audio signal input

34. IN/AMP : Amp’s external signal input

GENERAL OUTPUTS

1. GATE output : sends 6,4V gate

2. MOD: Modulation wheel output, 0-5V Level

3. ENV : Filter’s envelope output, 0-4V level

4. NOISE: White noise output

6. CV : 1V/ocv out (tracking from OSC 1 is sent - including octave change)

7. LFO output : when patched, the hardwired modulation to the oscillators will be eliminated

8. OSC3 out put : when patched, the LEVEL knob in the OSC 3 section is the amount sent to the patch

and the hardwired connection to the lter input is disabled.

VC ANALOG WIDE RANGE CLOCK

5. CLOCK Rate CV input

20. CLOCK output

The RATE knob controls the clock frequency, from about 50 sec up to almost 2700HZ. As the clock is
analog, this might vary from unit to unit. At 11:30 o’clock , you are entering the audio range (20hz)
The DUTY will control the % of time the clock is high. Be careful, as when DUTY is at the extremes, the
clock will freeze.

A great way to use the VC clock is as an extra oscillator. There is not a 1V/ocv precision tracking, but it
is nice to use it as a drone source.

VC AMPLIFIER / ATTENUATOR / INVERTER

9. OUT+ : VCA non inverting output

10. IN :VCA input

11. CV : VCA CV input

12. OUT- : VCA inverting output

This is a simple but effective free VCA. As there is both an inverting and a none inverting input, this is
even more handy to reverse voltages, like an envelope or a modulation wheel.

7

The VCA itself is logarithmic, and near the end of the Level range, you should get a +18db gain, or x10
gain on voltage. Unity gain is at about 3 o’clock. Maximum voltage is +/-10V output.

SAMPLE AND HOLD

13. IN : S+H in - white noise is hardwired unless patched

14. CLOCK : S+H clock input - clock out is hardwired unless patched

15. OUT : S+H output

This is a classic S+H circuit. Again, this is fully analog, with all the cons are pros that comes with. For
example, the clock input it can accept, can be up to 9kHZ (!), but with very slow clocks some drifting
must be expected.
By default, the input has the white noise hardwired, so you will get a random modulation at the output.
Here is a nice tip. You can also use this as a digital kind of noise source. Try patching its output to the
in/lter input or to the in/amp, set the CLOCK rate at max (DUTY not to extremes), and listen as you get
a digital noise, where the clock rate changes the pitch.

ANALOG SWITCHER

16. X : Switch in or out

17. Y : Switch in or out

18. CLOCK : Switch clock - hardwired to clock out unless it is patched

19. Z : Switch in or out

This is an analog switch, where the clock determines whether the X is connected to the Z (clock low),
or the Y is connected to the Z (clock high).
The DUTY of the clock will determine how long each side is connected.
You can either use Z as an input, and X, Y as an output, or the reverse.

Here is an example you MUST try:
Patch NOISE -> X , OSC3 -> Y , Z -> IN/AMP

Set a relative low clock rate (1 sec or something similar) , and DUTY at 50%. Close all other sound
sources, but keep OSC 3 LEVEL knob at max. Also, do not set the noise wave for OSC 3. Then trigger
the synth, and listen while OSC 3 and NOISE are shifting the sound. Afterwards, change the DUTY and
the relative time, each of this is on, will alter.
Finally, remove OSC3 ->Y patch, close the OSC 3 LEVEL knob, and set the DUTY so as the noise can
only sound for a very small amount of time, like almost a click. Congrats, you just made a hi-hat!
You can now open some sound sources, and play along with it!

MULTIPLIER

25. Multiplier point

30. Multiplier point

35. Multiplier point
A simple multiplier, to double CV outputs. DO NOT try to patch 2 outputs here!

8

The MIDI Interface and DIP Switch

The Erebus V3 has a relatively simple MIDI interface, as it is an improvisation synthesizer, where the
extensive patch bay use, is needed so as to get the most out of it.
Both MIDI IN and MIDI THRU jacks can translate MIDI input as described in the table below. Please
note that MIDI THRU will not transfer the MIDI ground. This is needed for some gear in order to work
properly. If that is the case, avoid using the MIDI THRU.
Also, the MIDI THRU can be used to send a second MIDI device to control the Erebus at the same time.
Here is the complete list that the MIDI interface will handle:

- Note tracking

- Gate on/off

- Pitch wheel

- Mod wheel

- Channels from OMNI up to 7.

MIDI CHANNELS

In order to change the MIDI channel, just use the DIP switch located on the back panel of the Erebus V3.
For the MIDI selection, we use DIP 3,4, and 5.

OMNI 3,4,5 off
CH1 5 on
CH2 4 on
CH3 4,5 on
CH4 3 on
CH5 3,5 on
CH6 3,4 on
CH7 3,4,5 on

UNISON / DUOPHONIC MODE

Erebus V3 is a Duophonic synthesizer, but it can also be used in standard Unison (mono) mode. In or­der to change between the 2 modes, use the DIP switch 2 on the back panel. By default when 2 is off,
Paraphonic mode is enabled.

When in paraphonic mode, by hitting a single key all VCOs will follow this note, but by hitting a second
at the same, it will have OSC 1 and OSC 3 playing the low note, and OSC 2 playing the higher note. This
is always a low note priority. In duophonic mode, envelopes are always on a retrigger mode. Normally,
when releasing 2 pressed notes, all sources will follow the note last pressed. You can avoid this, by
releasing the note at the exact same time (there is a 5ms delay for that). Some practice is needed in
order to fully master this.

In Unison or mono mode, only one note will follow, and when hitting a second note at the same time
will not have any effect, unless it is higher than the one already pressed (high note priority). Envelopes
on this mode are always without retrigger.

AUTOTUNING

When DIP 1 is On, the background autotuning is active. This means that whenever the AMP envelope
is at a rest, (the release stage must have ended!) the autotuning will kick in, after 1 second. This will
calibrate the scaling of the oscillators, so as they are constantly in tune. Each calibration takes about
2-3 seconds and it will run in an endless loop. After just 1 calibration, the unit is ready to play, but it is
strongly suggested that you allow the synth to warm up for at least 5 minutes before playing.

You can deactivate this by setting DIP 1 to off position. This will force the unit to make a single auto­tune - regardless the AMP state. For example, have OSC 1 on, set the lter to a wide open state and the
sustain and release of the AMP at max. Press a key and immediately turn the DIP 1 off. This will do a
single audible autotuning process.

9

The only reason to set the DIP 1 to the off position, is the need to use the OSC 3 output for modular pur-
poses with other gear, as when the AMP is low, the OSCs will be calibrated and they will shift in octaves.
Thia might be a rare occassion and most of the times you will want the DIP 1 set to on. Nontheless, if
you have to do it, let the unit warm up for 20 minutes, and then you can turn the DIP 1 off, with con-
dence that the Oscillators are in tune.

SYSEX UPDATE
DIP 6 is used to update the rmware of the unit. When a new rmware update is announced, along with

the rmware le, there will be instruction on how to install it.

For now, all you need to know, is to never set DIP 6 on, and if you do so, turn it off and reset the unit (turn
the power supply on/off). You cannot damage the unit, it will not respond properly when DIP 6 is ON.

Limited Warranty

Dreadbox warrants this product to be free of defects in materials or construction for one year from
the date of purchase. Proof of purchase is necessary when the warranty claim is made. Malfunctions
resulting from improper power supply voltages, backward or faulty cable connection, abuse of the
product or any other causes determined by Dreadbox to be the fault of the user, are not covered by its
warranty (normal service rates will be applied). All defective products will be replaced or repaired at
the discretion of Dreadbox. Products must be returned directly to Dreadbox with the customer paying
the shipping costs. Dreadbox implies and accepts no responsibility for harm to a person or apparatus
through the operation of this product.
Please contact [e-mail] for the return to manufacturer authorization, or for any oth­er technical questions or concerns.

Kindly note that the wooden sides and the screen printing are done by hand, which means that natural
differences or imperfections are normal and expected.

WARNING!

Do not open the unit
Use a Dust cover
Turn off the synthesizer when you are not using it
Keep the original packaging

10

PRESET : ...........................................................

Notes :