bEFACO Octaves VCO Sound Sources Eurorack Modular User Manual

: June 14, 2024
: BEFACO

Table of Contents

POWER & INTRO
INTRODUCTION
CONTROLS
BLOCK DIAGRAM
MISCELLANEA
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OCTAVES VCO
USER MANUAL

POWER & INTRO

POWERING THE MODULE
THANKS FOR PURCHASING A MODULE FROM BEFACO!
BEFORE YOU PLUG THIS MODULE IN…

Disconnect your cabinet from the mains.
Triple check the power cord polarity. The coloured line on the cable (pin number one) is the -12V rail.
If you plug the module backwards you might burn it out and unfortunately this is not covered by the warranty.
If you have any questions about this product feel free to contact us support@befaco.org

INTRODUCTION

WHAT IS OCTAVES VCO?

A harsh and funky take of an additive Oscillator. Pile up multiplications of your frequency to get six pulses on consecutive octaves, with common PWM and volume control for each.
At the core is a triangle oscillator whose frequency is doubled several times to obtain 2x frequency triangles.
Then these triangles are passed through comparators to convert them to pulses of variable width.
This octave generation method differs from the classic pulse divider method in two ways:

Pulse With Modulation on all the resulting pulses. This PWM Is symmetrical, so both flanks of the pulse expand at the same time.
All octaves are centered on each other so the sum of them always produces symmetrical “castell-like” shapes. This generates a different timbre than the classic divide-down methods where all octaves are summe at 0º phase producing a “staircase-like” wave shape.
Six VCAs (one for each pulse) let you play with the volume of each octave. This can be done manually or via CV. When a CV is pach to the Volume INs the manual controls become attenuators.
On top of that, octaves VCO has a multi-mix feature. That means each octave is summed in cascade to the next one. You can either have one output with all frequencies or break the chain and get different submixes.

CONTROLS

TUNE
Sets the pitch of the VCO. C At the center position.
TUNE RANGE
Select the precision of the TUNE control [1]. Full range at the left position, one octave at the center, and one semitone at the right position.
OCTAVE SELECTOR
Select the base Octave of the core oscillator.
PULSE WIDTH
Controls the proportion of the period in which all the pulses are UP or DOWN.
PITCH CV CONTROL
“Volt per octave” control voltage INs. Both INs are summed together.
HARD SYNC IN
Resets to zero the core oscillator, when a pulse is received (usually from another oscillator), generating extra harmonics.
PWM CV IN & ATTENUATOR
CV is passed through the manual attenuator. The resulting CV is added to the PWM MANUAL CONTROL [4]
MANUAL LEVEL CONTROLS
Adjust the volume of the OUTs. When a CV is present at the LEVEL CV INs [9] they become attenuators of the incoming voltage.
LEVEL CV INS
SIGNAL OUTS
Output of the different octaves. Each one is summed to the one on the right. When connecting a jack, all the signals from all the jacks that are not connected further to the left come out through it. This makes it possible to have different mixes.
For example, If only the rightmost jack is connected this jack will act as “Master out” with all the Octaves.
Also, If another jack is connected on the third out, you get two mixes; one with the first three and one with the last three.