Xaoc Devices ODESSA User manual
ODESSA
variable
spectrum har-
monic cluster
oscillator
Model of 1975
operator’s manual rev. 1975/1.2
2
SALUT
Thank you for purchasing this Xaoc Devices
product. Odessa is an additive oscil-
lator, which means the output signal is syn-
thesized by adding a multitude of sinusoidal
components (up to 2560 harmonic partials).
By manipulating their parameters it is possible
to obtain a broad range of unearthly sounds as
well as classic saw, square, and pure sine. Odes-
sa offers a set of controls for shaping harmonic
spectra based on number of partials and their
distribution in frequency and amplitude; all
of which is illustrated by a spectrum analyzer
comprising 12 multicolor LEDs. The series of
harmonics can be squeezed or spread apart,
tilted, or pruned by a comb-like frequency re-
sponse, resulting in a huge variety of spectra.
Animating the comb response yields radical
partials are frequency-related to a common
fundamental and controlled by a single volt/
octave input. Additionally, the signal can be fre-
quency modulated by exponential and linear
voices can be spread apart for a fat and dense
cluster, or a powerful chord.
INSTALLATION & SETUP
The module requires 24hp worth of free space
in the eurorack cabinet. Always turn the pow-
er off before plugging the module into the bus
board using the supplied ribbon cable. Pay
close attention to power cable pinout and
orientation. The red stripe indicates the neg-
ative rail and should match the dot or –12V
mark on both the bus board and the unit.
Odessa is internally secured against reversed
power connection, however, rotating the 16-
pin header may cause serious damage to
other components of your system because
it will short circuit the +12V and +5V power
lines. Always pay particularly close attention
to the proper orientation of your ribbon cable
on both sides! Also, observe that there are sev-
eral pin headers on the board. connecting
the power cable to an incorrect head-
er will destroy your odessa! The unit
should be fastened by mounting the supplied
screws before powering up. To better under-
stand the device, we strongly advise the user
to read through the entire manual before use.
MODULE OVERVIEW
-
rect access to all parameters in a one-knob-
per-function arrangement. Observe that it
also follows the traditional synthesis layout,
wherein pitch and voicing are controlled on
the left side, the main timbral features are
centrally located, and additional effects are
controlled at the right. Signal outputs are
located in the bottom array of jacks. The arc
of multicolor LEDs offers a rough overview of
the spectrum of the signal, from very low to
the highest audible frequencies.
Pitch frequency is controlled via the pitch
cv v/oct input 1which accepts voltages
in –5V…+10V range. The coarse 2and
fine 3pair of potentiometers set the pitch
throughout the entire audible range (16Hz to
20kHz) without the need for external voltage.
Additionally, pitch can be modulated from the
exp fm input 4that accepts ±5V, with depth
controlled by the dedicated attenuator above
5. As with other Xaoc Devices products, the
slider LED illuminates to show the absolute
degree of modulation by lighting up for both
negative and positive voltages. Bear in mind
that while the pitch knobs alone cover the
entire frequency range, at extreme knob po-
sitions modulation from the exp fm input will
module
explained
3
not change the pitch any further. This limita-
tion does not include the pitch cv v/oct in-
put which is handled by a separate precision
A/D converter.
The big, central partials knob 6limits the
harmonic partials, from 1 to 512 per voice.
This limit can also be controlled by CV using
the jack below 7. Note that the response
appears to be stepped, especially at the be-
ginning of the range, because it causes con-
secutive partials to be turned on and off. At
the minimum position, only the fundamental
frequency is audible. Also note that due to au-
tomatic volume compensation, lower frequen-
cies become quieter as higher components are
added to the spectrum.
The red spectral tilt knob 8controls how
quickly the amplitudes of consecutive partials
decrease with frequency. At the middle posi-
tion, partials decrease slowly, similar to the
spectrum of a saw wave. At the minimum po-
sition, the decrease is so rapid that mostly the
fundamental is audible. At the maximum posi-
additional comb response is engaged), which
results in a buzzy, narrow pulse waveform.
This parameter can be also controlled by ex-
ternal CV (±5V) via the dedicated jack 9.
The three knobs near the right edge of the
panel control a comb-like frequency response
that is imposed on the spectrum. Note there is
certain settings), instead, a frequency-domain
shaping function is applied to the amplitude
of each harmonic partial. The density knob
10 controls how dense the notches of the comb
are: from zero (no notches at all) through
moderate (just a few notches) to a maximum
-
tered out (assuming minimum warp setting).
This parameter can be controlled by external
CV via the dedicated jack 11 that accepts
±5V, and is scaled by the slider potentiometer
above 12 . The warp knob 13 controls the
uniformity of the comb response: from linear,
where notches are equidistant in frequency
-
ear response, where notches are very dense
at the bottom of the spectrum and become
more distant for higher overtones (similar to
a phaser effect). This parameter can also be
controlled by CV via the dedicated jack 14
that accepts ±5V, and is scaled by the slider
potentiometer above 15 . The peaking knob
16 controls the shape of the comb response:
from narrow notches (at the minimum posi-
tion) through moderate up to wide notches
with narrow peaks in the response (at the
maximum position). This parameter can be
controlled by a ±5V CV via the jack below 17 .
tension 18 is a very important and sensitive
parameter that determines whether the sinu-
soidal partials generated by Odessa adhere to
a harmonic pattern wherein frequencies are
strictly integer multiples of the fundamental
frequency. There is a little dead zone in the
central position of this knob that helps to set
it to zero. With tension set to sharp (above
the middle), partials are more spread apart so
that their frequencies increase more quickly
than with a linear law (e.g. the harmonic se-
ries) and the spectrum becomes sparse. With
tension
are more condensed so that their frequencies
increase slowly and create a dense non-har-
monic cluster that may resemble noise. This
parameter can be controlled by a ±5V CV via
the jack below 19 .
4
Odessa features two main outputs of the
synthesized signal: odd partials 20 and
even partials 21 . It is possible to split the
harmonic spectrum so that even and odd
numbered partials are separately present at
those outputs yet always mixed with the fun-
damental partial. An additional fundamen-
tal output 22 offers a simple signal of the
fundamental frequency: either a sinusoid or a
square wave that can be employed for syncing
selects one of these two options.
The two knobs at the top ( 23 and 24 ) to-
gether with their associated CV inputs
25 and 26
address the distribution of spectral compo-
nents between the odd partials and even
partials outputs. When the bank length
parameter is set to 0, both outputs offer the
same full signal. If set to +1, each output of-
fers the same fundamental (1st partial) plus its
even (2nd, 4th, 6th, etc) and odd (3rd, 5th, 7th, etc)
overtones, respectively. With different lengths,
odd and even sequences of partials are split
between the two jacks. Additionally, all par-
tials except the fundamental may be frequen-
cy-scaled by an integer factor: from simple
fractions (1:2, 1:3 down to 1:8) to multiples
(2, 3… up to 8), selected by harmonic fac-
tor. The direction of bank length (either
turned left or right) selects which of the two
unless bank length is 0, which means the
harmonic factor affects both outputs.
Odessa is capable of delivering 1, 3, or 5 stacked
voices of its synthesized signal, selectable by the
voices button 27 . When a single voice is select-
ed (button lit green), the spread knob 28 and
its corresponding CV jack below 29 have no
effect. With 3 or 5 voices (button lit orange or
front panel
overview
2
19
2518
3
28
31
6
1
4
30
29
5
5
the interface
13
10
14
15
12
16
9
2623 2432 8
27
20 1122721
17
6
red), the spread parameter controls the de-
gree of symmetric detuning of the additional
voices around the central voice.
The lin fm input 30 together with the associ-
ated slider 31 offers a deep through-zero fre-
quency modulation of the signal. The modula-
tor input is AC coupled (cut below 20Hz) and
accepts full-bandwidth signals up to 10Vpp.
Bear in mind that while the fundamental fre-
quency is modulated to the degree you set, the
overtones are modulated much wider because
the depth scales with their relative frequen-
cy. With a wideband carrier, the spectrum of
an FM’d signal explodes into MHz range and
most of it will be removed by the anti-aliasing
protection. Classic clangorous FM sounds are
obtained with just a few harmonic partials.
note: Place the slider at minimum when no
modulation is applied in order to prevent am-
converter which could impact pitch stability.
SPECTRUM ANALYZER
The arc of 12 multicolor LEDs 32 shows the
power density spectrum which is the
name of the power contribution of differ-
ent frequency components of the signal in a
number of disjoint bands. Here, the 12 bands
cover the entire audible frequency range in
exponentially spaced intervals (0.8 octave
per band): below 35Hz, 35 to 63Hz, 63Hz to
113Hz, 113Hz to 204Hz, 204Hz to 367Hz,
367Hz to 661Hz, 661Hz to 1.19kHz, 1.19kHz
to 2.14kHz, 2.14kHz to 3.85kHz, 3.85kHz to
6.94kHz, 6.94kHz to 12.5kHz, above 12.5kHz.
Certainly, with only 12 bands it offers only a
crude overview of what is going on. note: the
color temperature is mapped from dB scale.
Although the LEDs turn off below a certain
level, this does not mean there are no spectral
components in a given band, but rather that
they are too quiet to show.
THE MEANING OF SPECTRUM
PARAMETERS
The various parameters offered by Odessa
have been selected by observing how spectra
of different sounds vary, and how these differ-
ences could be generalized to a set of global
features without losing the ability to syn-
thesize a broad range of sounds. The default
most common waveform in synthesizers: the
sawtooth wave. It became so popular because
it is quite easy to generate in analog circuits,
and also because it’s a good starting point for
many synthetic timbres.
The partials parameter controls the num-
ber of harmonic components in a signal, from
1 to 512. Turning it down limits the spectrum
to the initial N partials, until the signal resem-
note: you can’t
turn off the fundamental. However, since it is
separately available on a dedicated output,
you can subtract it from your signal using a
simple patch. So as to avoid aliasing, Odessa
does not produce partials whose frequencies
would exceed the maximum frequency of
fundamental output
configuration jumper
21kHz. Therefore, the usable range of the big
knob depends on pitch frequency. For high-
pitched sounds, the frequency of most of the
overtones would be too high, hence increasing
this parameter above a certain number will
not create any audible effect.
There is a fundamental problem with additive
synthesis as it relates to dynamic range: a sum
of many sinusoids may be much louder than
just a single sinusoid (or a few). For example,
50dB. For practical reasons, Odessa applies a
perceptually optimized volume compensation
to the output signal. You may notice that the
low-frequency partials become quieter when
the energy of higher partials increases. The
result is similar to what you hear when com-
paring the loudness of different waves from a
traditional VCO.
The tilt parameter determines how quickly
the spectrum decays (how quickly the ampli-
tudesofpartialsdecrease withfrequency).This
-
in the partial amplitude formula: An=A1/n.
7
The spectrum of a saw wave contains all overtones in a naturally decaying harmonic series: the am-
plitude of each harmonic partial is inversely proportional to its number: An=A1/n (A1is the amplitude
-
ic partials missing because their spectra are shaped by a Sinc function which introduces a series of
notches: An=A1
spectrum
parameters
0 0.5 1 1.5 2
1
0.5
0
-0.5
Time
AmplitudeAmplitude
0 0.5 1 1.5 2
1
0.5
0
-0.5
-1
Time
5 10 15 20 25 30
1
0.8
0.6
0.4
0.2
Partial number
0
05 10 15 20 25 30
1
0.8
0.6
0.4
0.2
Partial number
AmplitudeAmplitude AmplitudeAmplitude
sawtooth and pulse waveforms and their respective harmonic spectra (truncated for clarity).
AmplitudeAmplitude
8
This parameter can change from 3 (very
quick decay, dull sound), through 1 (like in
the sawtooth wave) down to nearly 0 (almost
impact on the resulting energy of the signal.
Together, the density, warp, and peaking
parameters control the comb-like frequency
response imposed on the spectrum. The notch-
es of the comb are produced by a warped Sinc
Bear in mind the response refers to the rela-
tive frequencies of partials, so it scales with
pitch. Depending on the density parame-
ter, there may be zero to 256 notches, hence
at minimum, the spectrum is smooth, and at
(only odd-numbered partials remain), provid-
ed there is no warp. Thus, with all other pa-
rameters set to default, turning the density
knob morphs the signal from a sawtooth to
simple crossfade!
Warping the comb response results in a
non-uniform distribution of the notches in
frequency. As warp increases from zero,
0 0.5 1 1.5 2
Time
1
0.5
0
-0.5
-1
AmplitudeAmplitude
0 0.5 1 1.5 2
Time
1
0.5
0
-0.5
-1
AmplitudeAmplitude
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
sawtooth wave after limiting the spectrum
to the initial 5 partials
sawtooth wave after limiting the spectrum
to the initial 10 partials
the notches become more concentrated in
low frequencies. note: at high density and
warp values, notches may be so dense in low
frequencies that they interfere with the har-
monic pattern which may lead to unexpected
holes in the spectrum. At low peaking values,
notches of the comb response are very narrow.
At high peaking values, the notches become
wider and peaks become more narrow and
The tension parameter has a crucial impact
on the harmonicity of the signal. At the neutral
(middle) position, frequencies of all sinusoidal
partials are integer multiples of the fundamen-
tal: Fn=n×F1, which is a necessary condition for
obtaining a periodic waveform. This results in
equidistant partials throughout the spectrum.
With tension above 0, the upper partials are
spread apart (the frequencies increase quicker
than the partial numbers) which yields an in-
harmonic, metallic timbre with an often more
tension below
0, the distances between upper partials be-
come smaller and smaller (the frequencies in-
crease slower than the partial numbers) which
yields a dense, rough, inharmonic cluster that
resembles noise. Large negative values of ten-
sion may even result in the spectrum folding
over itself to a degree where certain partials
have lower frequencies than the fundamental.
caution: Pitch and intonation behaves par-
adoxically with these inharmonic sounds and
-
tional sounds. Furthermore, these sounds can
cause ear fatigue and are best used sparingly
in musical contexts.
Bear in mind that inharmonic spectra yield
aperiodic waves due to individual sinusoids
being no longer synchronized in phase. When
you turn the tension parameter off the
central (zero) position, the relative phases
of all signal components begin to drift away
from each other. Thus the original waveform
becomes more distorted and will remain as
such, even after returning tension to zero. It
is possible to re-synchronize the phase and re-
store the waveform, however, this produces an
audible click in the signal due to discontinuity,
therefore it is not done automatically. To do
so, press the voices button. Besides selecting
the number of unison voices, this re-syncs the
individual voices and also restarts all sinu-
soids within each voice.
9
AmplitudeAmplitudeAmplitudeAmplitude
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
comparison of tilted spectra in extreme and middle
positions of the tilt knob
10
signal, the sinusoidal partials generated by
Odessa may be organized into harmonic
banks and split between the odd partials
and even partials outputs. bank length
above the fundamental that belong to even
and odd banks, respectively. harmonic fac-
tor -
in one of the banks. note: the fundamental
(1st partial) is excluded from the banks and is
always present on both outputs with its orig-
inal frequency unaffected. For example, with
length set to 3, the odd partials output
contains the fundamental mixed with 5th, 6th,
7th, 11th, 12th, 13th ... etc, while the even par-
tials output contains the fundamental mixed
with 2nd, 3rd, 4th, 8th, 9th, 10th… etc. Additionally,
if factor is set to 2, all partials (except the
fundamental) on the even partials output
EXPANDABILITY: HEL
The shrouded header is dedicated to the uni-
versal Xaoc Hel module which offers paraphon-
ic generation of 3-voice and 5-voice chords.
Please refer to the manual of Hel for details.
0100 200 300 400 500
Relative frequency
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
0100 200 300 400 500
Relative frequency
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
0100 200 300 400 500
Relative frequency
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
0100 200 300 400 500
Relative frequency
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
warped comb response with minimum peaking (upper)
and maximum peaking values
tilt + comb frequency response for low (upper)
and high (lower) density values
11
05000 10000 15000 20000
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
05000 10000 15000 20000
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
EXPANDABILITY: LEIBNIZ SUBSYSTEM
Odessa also offers integration with the Leib-
niz Binary Subsystem via another expansion
header at the back of the unit.
Connecting an expander like Xaoc Lipsk, al-
lows one to enable and disable the individu-
bank
length parameter. To engage this control,
press and hold the voices button for 1 second
until it starts to blink. At this point, a high
state of each binary line (for example, a but-
ton activated on Lipsk) turns one group on.
The lowest bit (B0
2nd, 3rd, and 4th), the next higher bit (B1) affects
the second group (5th, 6th, and 7th), and so on.
The highest bit (B7) affects all remaining par-
tials (from 23rd up). note: the result of switch-
ing individual partials may be subtle. For a
more radical effect use longer bank lengths.
ACCESSORY
Our Coal Mine black panels are available for
all of Xaoc Devices modules. Sold separately.
Ask your favourite retailer. •
AmplitudeAmplitude
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
AmplitudeAmplitude
5 10 15 20 25 30
Partial number
0
1
0.8
0.6
0.4
0.2
signal spectra at the odd partials and even partials
outputs for length=3 and factor=2
inharmonic spectra resulting from positive (upper)
and negative (lower) values of tension
MAIN
FEATURES
Powerful additive
synthesis engine
with up to 2560
sinusoidal
partials
0.5Hz to 21kHz
frequency range
with resolution
of 0.006Hz
Harmonic
or inharmonic
spectra shaped
by tilt and
warped comb
response
Volt/octave
pitch control
Through-zero
linear FM input
Up to 5 unison
and detuneable
voices
Three signal
outputs
TECHNICAL
DETAILS
Eurorack synth
compatible
24hp, skiff friendly
Current draw:
+110mA/ -80mA
Reverse power
protection
EASTERN BLOC TECHNOLOGIES MADE IN THE EUROPEAN UNION
ALL RIGHTS RESERVED. CONTENT COPYRIGHT ©2022 XAOC DEVICES. COPYING, DISTRIBUTION OR ANY
COMMERCIALUSEINANYWAYISSTRICTLYPROHIBITEDANDREQUIRESTHEWRITTENPERMISSIONBYXAOC
DEVICES. SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT PRIOR NOTICE. EDITING BY BRYAN NOLL.
WARRANTY TERMS
XAOC DEVICES WARRANTS THIS PRODUCT TO BE FREE OF DEFECTS IN MATERIALS OR WORKMANSHIP
AND TO CONFORM WITH THE SPECIFICATIONS AT THE TIME OF SHIPMENT FOR ONE YEAR FROM THE
DATE OF PURCHASE. DURING THAT PERIOD, ANY MALFUNCTIONING OR DAMAGED UNITS WILL BE
REPAIRED, SERVICED, AND CALIBRATED ON A RETURN-TO-FACTORY BASIS. THIS WARRANTY DOES NOT
COVER ANY PROBLEMS RESULTING FROM DAMAGES DURING SHIPPING, INCORRECT INSTALLATION OR
POWER SUPPLY, IMPROPER WORKING ENVIRONMENT, ABUSIVE TREATMENT, OR ANY OTHER OBVIOUS
USER-INFLICTED FAULT.
LEGACY SUPPORT
IF SOMETHING GOES WRONG WITH A XAOC PRODUCT AFTER THE WARRANTY PERIOD IS OVER, THERE IS
NO NEED TO WORRY, AS WE’RE STILL HAPPY TO HELP! THIS APPLIES TO ANY DEVICE, WHEREVER AND
WHENEVER ORIGINALLY ACQUIRED. HOWEVER, IN SPECIFIC CASES, WE RESERVE THE RIGHT TO CHARGE
FOR LABOR, PARTS, AND TRANSIT EXPENSES WHERE APPLICABLE.
RETURN POLICY
THE DEVICE INTENDED FOR REPAIR OR REPLACEMENT UNDER WARRANTY NEEDS TO BE SHIPPED IN
THE ORIGINAL PACKAGING ONLY AND MUST INCLUDE A COMPLETED RMA FORM. XAOC DEVICES CAN
NOT TAKE ANY RESPONSIBILITY FOR DAMAGES CAUSED DURING TRANSPORT. SO BEFORE SENDING
UNSOLICITED PARCEL WILL BE REJECTED AND RETURNED!
GENERAL INQUIRIES
FOR USER FEEDBACK SUGGESTIONS, DISTRIBUTION TERMS, AND JOB POSITIONS, FEEL FREE TO CON-
FORMATION ABOUT THE CURRENT PRODUCT LINE, USER MANUALS, FIRMWARE UPDATES, TUTORIALS,
AND MERCHANDISE.
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