Dual VCA / Mixer for CV and Audio with chaining

Description
The t03 VCA from Thonk Synth is a 6HP Eurorack dual voltage controlled amplifier module. This compact VCA has some clever signal normalisation allowing for it to be used as CV macro controller and expandable VC mixer as well.

Each channel has a button for switching between linear and exponential response curves. Linear is typically best suited for CV/modulation signals while exponential is better suited for audio signals.

The input signal level of each channel is set by the sliders, which work as attenuators for the CV inputs. CV input A is normalled to +5V and CV input B is normalled to CV input A. This allows the level sliders to function as simple level/volume controls when no CV signals are plugged in.

There is also normalisation on the signal inputs. Input A is normalled to +5V, and Input B is normalled to input A when unpatched. This allows for using each channel as a manual offset/macro control with no signal patched to the inputs. Each channel also has a dedicated bias/offset control that’s summed with the respective channel’s CV input. There are bi-colour LEDs at each output for visualising the voltage level – with orange for positive voltages and white for negative voltage.

Module Chaining
Multiple t03 VCAs can be chained behind the panel to create multi-channel VC mixers. All normalisation is chained across, as well as all outputs being mixed and available at the last output jack. For example when 2 modules are chained, INPUT 1 will be normalled to INPUT 2, 3 & 4, CV 1 will be normalled to CV 2, 3 & 4, and OUTPUTS 1, 2, 3 & 4 will be mixed and output at the last output jack. This allows for processing one input signal with four different modulation sources, or for one modulation source to control four different inputs, or any combination of each! See the User Manual for more details and patch examples.

The VCA core is based on the reliable SSI2164 chip from Sound Semiconductor. This module is part of a new range of DIY Eurorack designed in house at Thonk HQ.

Features:

• 2 x VCA channels using the SSI2164 chip
• Linear / Exponential mode button
• Level sliders for amplification
• 0-5V bias/offset control per channel
• VCA in A and CV in A normalled to +5V
• VCA in B and CV in B normalled to A when unpatched.
• Multiple VCAs can be chained via the back of the module.
• Designed in-house at Thonk

Specs:

• Width: 6HP
• Depth: 25mm (including power connector)
• Power: +12V 22mA, -12V 20mA

Build Document | User Manual