Hello and thank you for using the Shaka 3-Channel Audio Mixer for 4U modular. We hope you will find its
mix most pleasing!
Technical Specifications (4U, Loudest Warning standard)
Width: 1”
Depth: 25mm
Peak Current Draw (LF353): 13mA @ +12V, 13mA @ -12V
1. Connecting your Shaka
Connect a power cable to the MTA-156 header at the top of the Shaka pcb. The +12V side of the
connector must be aligned with the silkscreen indicator that says “+12V” for proper use. This module is
reverse diode protected, but it is still not recommended that you plug it in backwards to see what
happens.
2. Theory of Operation
At its core, the Shaka is a basic 3-channel summing mixer with a classic op amp-based topology which
will (more or less) cleanly and predictably sum any input voltages as long as that voltage sum doesn’t
exceed that of the power rails (+/-12V in standard 4U systems, a little lower after Schottky diode
protection). The taper of the controls is by default Exponential, providing increasingly more gain as the
knob is turned counterclockwise. This is ideal for Audio signals.
However, the two switches near the bottom provide a few performance features which are very useful in a
modular system, and with Serge systems in particular, which often blur the lines between Control and
Audio voltage and deal primarily in Unipolar signals as a result. The left switch provides easy Muting and
Phase Reversal for the third channel, an infinitely useful control for wrangling feedback or, of course,
muting the channel. The right switch will AC Couple the mix output, removing any offset voltages and
centering the audio signal around 0V, perfect for use as a main output or, again, limiting feedback to the
audio range.
With the Channel 3 Control switch set to “Ch 3 On” and the Coupling switch set to “DC,” the Shaka will
sum the three input voltages with no alteration before the output. Additionally, the six-pin header on the
back provides access to a Mix Node, to which a theoretically infinite number of channels may be
connected to expand the Shaka.
3. Summary of Functions
Level 1-3:
Controls the level of each corresponding Channel input before it is sent through the Mixer and
Coupling sections.
Channel 1-3:
Input for each of the three Channels. Ideal for use with Audio, but may also be used to sum
CV in a pinch.
Ch 3 On / Ø Switch
: Phase control switch for Channel 3 exclusively. In the upper position, Channel 3 will
behave as normal; in the middle position Channel 3 will be muted; and in the lower position it will be
flipped around 0V, producing Phase Reversal for audio signals or when AC Coupled.
