ADDAC107 Acid Source Instruments Sonic Expression

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ADDAC107 ACID SOURCE

Specifications

• Width: 9HP
• Depth: 4cm
• Power Consumption: 80mA +12V, 80mA -12V

Description

The ADDAC107 Acid Source module is a versatile synth voice
featuring a Voltage Controlled Oscillator (VCO) and a Filter with
multiple options for sound shaping. It offers various controls and
inputs for creating unique sonic expressions.

Features

• VCO with Frequency and Fine Tune knobs
• Waveform selection between Triangle and Saw waves
• Filter with Cutoff and Resonance controls
• Highpass, Bandpass, and Lowpass filter types
• CV inputs for Frequency and Cutoff adjustments
• Accent input for external sound sources
• LED monitor and CV output

Usage Instructions

VCO Controls

• Adjust the VCO Frequency using the Frequency knob.
• Fine-tune the VCO output with the Fine Tune knob.
• Select between Triangle and Saw waveforms using the waveform
  switch.

Filter Controls

• Set the desired cutoff frequency with the Cutoff knob.
• Adjust the resonance using the Resonance control.
• Select the filter type (Highpass, Bandpass, Lowpass) with the
  switch.

Input Options

The module offers an Accent input that can be used to modulate
the sound or accept external audio input for processing through the
filter and VCA.

Jumper Settings

There are jumpers available to configure the CV outputs to
either Frequency or Cutoff inputs for added flexibility in
modulation options.

FAQ

Q: Can I use external audio sources with the ADDAC107?

A: Yes, you can use the Accent input to route external audio
through the filter and VCA of the module.

Q: What power supply specifications are required for the

ADDAC107?

A: The module requires 80mA of power at both +12V and -12V.

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Instruments for Sonic Expression
Est.2009
INTRODUCING
ADDAC107 ACID SOURCE
USER’S GUIDE . REV02
June.2023
From Portugal with Love!

Welcome to:
ADDAC107 ACID SOURCE USER’S GUIDE
Revision.02Junea.2023

DESCRIPTION
We started this module with the idea of developing a complex drum source however, somewhere along the process, we noticed how much better it performed as a synth voice and simply embraced this lucky accident.
It features a VCO with a [FREQUENCY] and [FINE TUNE] knob plus a dedicated CV Input and Attenuator knob (tunable over 4 octaves).
The VCO waveform output is achieved by selecting either a Triangle or Saw through a switch. the selected waveform can then be mixed/balanced against the square wave. The resulting mix is then sent to the Filter through a jumper that can be removed disabling the VCO.
The Filter features a [CUTOFF] and [RESO] resonance knob plus a Cutoff CV Input and Attenuverter knob. A 3 position switch is used to select the filter type: Highpass, Bandpass or Lowpass. The resulting output is then sent to the VCA.
The VCA features an Input with [INPUT GAIN] knob which at maximum can amplify the incoming signal by a factor of 2. This is a very important control (more about it in the next page). It accepts any signal Trigger, Gate or CV. Whatever input is plugged in the signal is then fed through an AD with a very short attack and controllable decay through the [VCA DECAY] knob plus the CV Input and Attenuverter knob. A 3 position Decay Switch allows to change the decay ranges: Short / Off / Long The resulting slewed signal is then used to control the VCA gain. This signal is also sent to the CV OUTPUT as well as the LED monitor. The Accent input adds to the Input signal creating a different amplitude output
The CV OUTPUT is also normalled to the Frequency and Cutoff inputs.
This module will also be available as a full DIY kit.
ADDAC SYSTEM page 2

Tech Specs: 9HP 4 cm deep 80mA +12V 80mA -12V

ADDAC107 User’s Guide
INPUT GAIN
Usually Attack/Decay envelopes have a maximum voltage of +5v, no matter if the input gate is +5v or above the AD will clip at +5v. In this case we did not use this clipping method and instead allow the incoming voltage to determine the maximum AD voltage, meaning that if a +5v gate is present then the AD maximum voltage will be +5v but if a gate of +10v is sent then the AD maximum voltage will be +10v. This also means that with higher input voltages the decay, although falling at the same speed, will be longer than with lower voltages as it has a longer range to go back to 0v. As we mentioned before the [INPUT GAIN] knob can amplify the incoming input by a factor of 2, allowing to use a standard +5v gate or envelope and being able to make the resultant AD go up to +10v. The AD signal is responsible for opening the VCA. Up to +5v the VCA will open to unity gain above this value the VCA will start to amplify and eventually saturate and distort. This saturation will add harmonics to the signal which will change it’s gentle timbrical nature to a more unique and peculiar timbre that will make the module shine in Acid contexts. Adding high levels of Resonance or even filter self oscillation in combination with high VCA saturation will create even more harmonics that we highly encourage the user to explore.
ADDAC SYSTEM page 3

ADDAC107 User’s Guide
ACCENT / INPUT
The Accent input can be used in two ways: The default one is the Accent already described in previous pages. The second mode is to use it as an input straight into the filter and allow to use the filter vca combo with external vcos or other sound sources. The jumper on the panel allows to disable the internal VCO to use the external audio alone or mix both the external input with the internal VCO.
JUMPERS LOCATIONS
There are 3 jumpers on the side of the module. CV OUT > FREQ. CV ACCENT / INPUT
ADDAC SYSTEM page 4

CV OUT > CUTOFF. CV

ADDAC107 User’s Guide
SIGNAL FLOW DIAGRAM

FREQUENCY INITIAL

FREQUENCY

VCO

FINE TUNE

ON/OFF JUMPER

FREQUENCY CV IN

FREQUENCY – + ATTENUVERTER

TRIANGLE OR SAW

RECTANGLE /
TRI/SAW MIX

ON/OFF JUMPER

CUTTOFF CV IN
INPUT TRIG/GATE/CV IN DECAY CV IN

CUTOFF INITIAL CUTOFF – + ATTENUVERTER RESONANCE
HP / BP / LP SELECTOR
INPUT GAIN (MAX = *2)
DECAY INITIAL
DECAY – + ATTENUVERTER

FILTER VCA DECAY SLEW

ACCENT/INPUT

ACCENT / INPUT JUMPER

VCA

OUTPUT

LED MONITOR CV OUTPUT

NORMALLING (SELF-PATCHED)

ADDAC SYSTEM page 5

ADDAC107 User’s Guide
CONTROLS DESCRIPTION

VCO Frequency control VCO Fine Tune control VCO disabling jumper
Filter Cutoff control
Filter Resonance control
Input Gain Amplifier (*2) Filter Cutoff Attenuverter VCO Frequency Attenuator
VCO Frequency CV Input Filter Cutoff CV Input Excitation Input (Trigger, Gate or CV) Accent Input

Triangle Or Saw Selector
Square <> Tri/Saw Balance
HP, BP, LP Selector Envelope Monitor VCA Decay control VCA Decay range: Short/Off/Long Decay Attenuverter
Decay CV Input Audio Output CV Output

ADDAC SYSTEM page 6

For feedback, comments or problems please contact us at: addac@addacsystem.com
ADDAC107 USER’S GUIDE
Revision.02June.2023

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