Noise Engineering Loquelic Iteritas Percido User manual

Overview
Type VCO/ Voice
Size 20HP Eurorack
Depth
Power 2x8 Eurorack
+12 mA 150 / 80
-12 mA 5
Loquelic Iteritas Percido is an extension of the original Loquelic Iteritas.
Like Loquelic Iteritas, it is a digital VCO with interpretations of three
classic synthesis algorithms involving dual pitch control parameterized by
four tone controls. LIP adds an envelope that can be shaped and routed to
pitches and tone controls, making it into a free-standing voice.
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Noise Engineering
Loquelic Iteritas Percido
Complex Digital Voice
+5 mA 0 / 90 (optional)
1 Inch

Patch Tutorial
To get the sound of the original LI, do not route the envelope to any pitch or
tonal parameter (make sure all envelope sends are pointed to 12:00) and set
LIP to FREE.
e easiest way to get to know Loquelic Iteritas Percido is to set the mode to
Free, connect the output to your mixer, and start twiddling the knobs and
listen.
Switch mode to Loop and experiment with the envelope controls and sends.
LFOs and other CV sources can be hooked up to envelope controls to vary
sounds even more.
A good next step is to hook any LFO up to any of the four tone control inputs
(Morph, Fold, Modulate, Damp).
Other interesting effects can be created by controlling the pitches
independently (by default the 1v/8va inputs are normaled to each other). For
instance, using a Tonnetz Sequent to produce musical intervals produces
interesting results.
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Loquelic Iteritas Percido
Complex Digital Voice

Interface
controls the sync of the oscillators. When in the middle position both oscillators are free running. When A is
selected, oscillator B will sync to oscillator A; when B is selected, A syncs to B.
Master
Pitch A/B
e pitch of each oscillator can be controlled by pitch encoders. Tap encoders to alternate between coarse
and ne tuning. e 1v/8va input serves as an offset . e pitch inputs are cross normaled.
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Complex Digital Voice

Interface: Mode
In Trigger mode, LIP expects a trigger input to start the envelope. LIP triggers on the rising edge and expects
a voltage of about 3v.
Loop
In loop mode, the envelope will continually regenerate. A trigger in will hard reset it on the rising edge;
without a trigger in, it will regenerate based on the parameters set on LIP.
Free
Free-running mode is the original Loquelic Iteritas. Oscillators will continue to run. A trigger in will still reset
the envelope on the trigger rising edge, but will not affect the volume.
Trig
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Loquelic Iteritas Percido
Complex Digital Voice

Interface
controls the shape of the curve: CCW gives an exponential curve, while CW gives a logarithmic curve. In the
center, the shape is linear.
Shape
controls the attack and decay of the envelope. All the way CCW, the envelope is all decay; all the way CW,
attack dominates. Turning the knob transitions between these two extremes gradually.
Curve
controls the length of the envelope.
Time
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Loquelic Iteritas Percido
Complex Digital Voice
: Envelope

Interface
Envelope Controls
six attenuverters that route envelope to pitches and parameters. Positioned at 12:00, the envelope is off and
does not route to a parameter. Fully CCW results in an inverted envelope send. Fully CW yields full positive
send.
Input to trigger LIP. e envelope also resets (in any mode) when LIP receives a trigger.
Envelope Out
Trigger
Output to send envelope to other modules.
HIT
Momentary button to manually trigger LIP. When depressed, LIP behaves like it received a rising edge on a
trigger.
the AC-coupled audio output.
Audio Out
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Complex Digital Voice

Interface: Algo VO
FOLD - sets the wave fold threshold on the nal wave folder
As in Loquelic Iteritas, the VO algorithm is roughly based off of the VOSIM algorithm discussed in Curtis
Roads’s epic Microsounds. is algorithm amplitude modulates a carrier by an exponential to create a complex
harmonic structure. e simplest carrier is a sinusoid which produces a spectrum with a Gaussian
distribution centered on the carrier. More complicated waveforms produce Gaussians around each harmonic,
producing spectra similar to comb-ltered noise. Pitch A is the fundamental frequency of the carrier. Pitch B
is the retrigger frequency of the exponential decay.
DAMP - sets the decay constant on oscillator B relative to its period
MORPH - changes the waveform of oscillator A
MOD - phase modulates oscillator A by oscillator B
Controls
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Noise Engineering
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Complex Digital Voice

Interface: Algo SS
MORPH - changes the waveform of all oscillators
FOLD - sets the wave-fold threshold on the final wave folder
Controls
Algorithm SS is a highly modied version of summation synthesis originally developed by James Moorer. e
premise comes from a simple mathematical equality between an innite harmonic series and a relatively easy-
to-compute expression:
is equation allows a wide variety of musical spectra to be produced by only two parameters. LIP generalizes
the sinusoidal terms into multi-waveform oscillators: two of these track the two input pitches while the third
tracks the difference of the two pitches and adds a wave folder for more harmonics. In the equation oscillator
A is the le sinusoidal term in the numerator. Oscillator B is the sinusoidal term in the denominator. e
equation becomes
DAMP - sets the a parameter in the equality. This controls the generated spectra with higher values
producing higher power harmonics.
MOD - phase modulates oscillator A by oscillator B
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Loquelic Iteritas Percido
Complex Digital Voice
sin(θ β)
1+a−2a cos(β)
2
sin(Θ) − a sin(Θ−β)= ∑
∞
x=0
ax+x
sin(w t w t)
1+a−2a cos(w t)
2B
sin(w t) − a sin(w t−w t)
A A B = ∑
∞
x=0
ax
A+xB

Interface: Algo PM
e PM algorithm is a naive time-domain two-oscillator phase-modulation implementation that combines
both oscillators with amplitude modulation.
Controls
MORPH - changes the waveform of both oscillators
FOLD - sets the wave-fold threshold on the final wave folder
DAMP - blends between oscillator A and B through their product (AM)
MOD - phase modulates the oscillators by each other
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Complex Digital Voice

Loquelic Iteritas Percido can run its processor on the 5V eurorack power rail
to reduce noise and load on the 12V bus. Gently push the switch tab in the
direction of the desired rail to use.
Calibration
Voltage Supply
Loquelic Iteritas Percido is best calibrated using a stroboscope and tuning
octaves across the pitch range. Each pitch input has as separate calibration.
e pitches can be isolated from each other by using the master switch to
force the base pitch to be determined by only one input.
Noise Engineering
Loquelic Iteritas Percido
Complex Digital Voice
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CV
Loquelic Iteritas Percido has a wealth of CV inputs. Each input,coresponds to
a parameter on LIP. e CV inputs are offset by the knobs, so the sum of the
knob position+the input CV gives each parameter its nal value. LIP’s CV
inputs respond to 0-5v, except the pitch inputs, which respond to 0-8v. Sync
and Trigger respond to a rising edge of around 3v. e envelope output is
around 0-6v.

Sample Rate
Loquelic Iteritas/Loquelic Iteritas Percido use a unique multisampling
technique to make aliasing more musical. By choosing a particular sample
rate for a waveform that has a harmonic structure (all overtones are integer
multiples of the fundamental) the alias power can be moved into frequencies
that are also multiples of the fundamental and therefore more musical.
is gets complicated when synthesizing two oscillators at different pitches
but using the same DAC. e compromise that LI/LIP make is to give up the
notion of a xed sample rate and compute a time delay between samples
based on both oscillators. For the single oscillator case, this delay is based
entirely on pitch. If this delay is computed based on each oscillator's pitch,
both sample rates can be interleaved by checking which oscillator's delay will
be up rst. is oscillator is then updated to its next timestep and an output
value is computed based on both oscillator's output state. is makes no
guarantees about exactly where the aliasing goes. It is an attempt to make the
aliasing related in some way to the fundamental pitch.
Osc A
Osc B
Out
Two independent sample
rates combine to form
one irregular sample
rate. Sample rate is not
a constant.
Time
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Complex Digital Voice
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Design Notes
My wife, Kris, however, had other ideas: her rst time playing with LI,
she said, “is should be a drum.” Pretty quickly, we realized that the
module was hugely versatile, and people used it in many ways, but Kris
was far from alone in recognizing the utility of an envelope and a
trigger for Loquelic Iteritas. And we got to work.
ere have, as always, been multiple revisions from the functional to
the mundane (people at Superbooth in 2017 were treated to a version
with one LED so bright it hurt to look at until we covered it with Noise
Engineering stickers!), but from the start, we were pretty excited about
the expansion of LI. It’s the largest module we’ve made so far, but we
think it packs a hell of a punch. We hope you agree, and we hope you
have as much fun playing with this one as we’ve had making it.
e original LI was just a simple implementation based on VOSIM but
I soon realized I could pack a lot more punch in this form factor and
found two additional algorithms. Loquelic Iteritas was designed to be a
functional oscillator for sound designers as well as for musicians. I
wanted to maximize the possible sound space given the input controls
going from simple calm sounds to extreme, even broken, sounds. e
priority of tonal variance led to some sacrices on the musical side such
as the total pitch range.
Noise Engineering
Loquelic Iteritas Percido
Complex Digital Voice
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Special Thanks
Shawn Jimmerson
Alex Anderson
Mickey Bakas
Tyler Thompson
References
Jolley, Leonard Benjamin William, ed. Summation of series. Courier Corporation,
2012.
Derrick Baseck
Kaegi, Werner, and Stan Tempelaars. "Vosim-a new sound synthesis system."
Journal of the Audio Engineering Society 26.6 (1978): 418-425.
Moorer, James A. "e synthesis of complex audio spectra by means of discrete
summation formulas." Journal of the Audio Engineering Society 24.9 (1976): 717-
727.
Roads, Curtis. Microsound. MIT press, 2004.
Anthony Baldino
Cyrus Makarechian & Black Line
William Mathewson
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Loquelic Iteritas Percido
Complex Digital Voice
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