Klavis
Logica
XT
user manual V1.0
Page
5
of
11
Logic voltages
Logic signals are represented by a voltage or lack of it. In the modular world, any gate, trigger,
clock and even square output from an LFO or VCO can be considered a logic signal.
Logic functions are the interaction of logic signals. Logic functions do not respond to amplitude
nuances in the way analog signals do. Nevertheless they obey to electrical ranges and levels.
Logic signals are normally positive only; negative voltages are ignored and interpreted as zero.
Typically, a voltage close to zero volts will be considered logic 0 (off) and a voltage of at least a
few volts will be seen as logic 1 (on). Incoming voltages can go beyond or below what are valid
one and zero without any problem. In other words, you can’t go beyond On when it’s already On!
Therefore, it is perfectly valid to drive this module with almost anything, including analog signals
from any source. Moreover, you are not limited to “squary” type signals; any wave shape can be
used as a logic source signal. For example, passing the saw wave output of an oscillator through
an OR function will create pulses since only the positive half of the wave will be accepted, and
within that half, only levels high enough will produce a logic one on the output. So, changing the
amplitude or the voltage offset of the saw will change the width of the resulting pulse: saw to
PWM !
Simple logic functions
These are also known as combinatorial logic, or Boolean logic.
They are listed on the panel’s left column and indicated by a single white LED being lit.
Forced On & OFF states
When the potentiometer (or CV in) pushes the setting at the top and bottom of the logic options
offered in the column, the output is forced to a static level: To one when pushed full up, to zero
when pushed full down.
The On state has a dedicated LED at the top of the column; the Off state is indicated by all LEDs
of the column being off. With forced states, the input jacks are disabled; only the manual button
can be used to invert the output.
And & Nand
The main output goes on when all inputs plus the button are on. The manual button defaults to
ON. AND is somehow the logic equivalent of a VCA where one input has to be ON for the other to
pass through. The difference being that, contrarily to a VCA, all inputs are simultaneously
controlling and controlled.
Or & Nor
The main output goes On when at least one input or the button is on. OR is the logic equivalent
of a mixer: if there is something being on at any input there’s something coming out.
The manual push button defaults to Off.
