XAOC Samara II Analog CV and Audio Processor for Ambitious Signal Manipulation User Manual
- October 30, 2023
- Xaoc
Table of Contents
XAOC Samara II Analog CV and Audio Processor for Ambitious Signal Manipulation User Manual
Module explained
SALUT
Thank you for purchasing this Xaoc Devices product. Samara II [samara] is both a flexible mixer and a multifunction utility that may be used for processing audio signals, control voltages, and modulation waveforms. It is a second, significantly extended version of Samara, originally introduced in 2016. It offers four channels of signal attenuation, conversion between unipolar and bipolar voltages (offsetting by either positive or negative value), mixing in various configurations, as well as a variety of useful signal transformations: clamping, minimum/maximum, sample & hold, and wave scanning.
INSTALLATION
The module requires 10hp worth of free space in the Eurorack cabinet. The
ribbon-type power cable must be plugged into the bus board, paying close
attention to polarity orientation. The red stripe indicates the negative 12V
rail and should point in the same direction on both the bus board and the
unit. The module itself is secured against reversed power connection, however
reversing the 16-pin header may cause serious damage to other components of
your system because it will short-circuit the +12V and +5V power rails.
The module should be fastened by mounting the supplied screws before powering
up. To better understand the device, we strongly advise the user to read
through the entire manual before using the module.
MODULE OVERVIEW
Samara features four channels–each with two inputs and an attenuator, plus two additional switchable (+5V/-5V) offset generators, four voltage level and polarity indicators, two adders with switchable scale, and a four-input/two output signal processor that performs a variety of transformations on the four attenuated difference signals, according to one of its five switchable modes.
ATTENUATION, INVERTING & OFFSET
Looking at the front panel layout (fig. 1), there are four channels. Each
channel features a regular in input 1 as well as an inverting inv in input 2
(note there are additional labels at some in inputs related to the signal
processing part of the module). Signals from these two inputs are subtracted,
and this difference signal is processed by an active linear attenuator. Each
unused input is normalized to 0V, hence this arrangement allows for normal
attenuation, or inversion followed by attenuation or computing an attenuated
difference between two voltages or signals.
Additionally, two sources of a switchable +5V or 5V offset are available in
channels 1 and 3, activated by pressing the corresponding illuminated offset
button 3 . A short press turns the offset on and off, while long press flips
the polarity, which is indicated by the button lit red (for +5V) or green (for
5V). This offset is added to the inputs before attenuation. Thus, if nothing
is patched to the inputs of channels 1
Front panel overview
and/or 3, they can be used as a source of variable constant voltage, from 0 to
+5V, or from 0 to 5V. On the other hand, combining the offset with a signal
fed to the corresponding inputs facilitates conversion from bipolar to
unipolar voltages (by using +5V offset), or converting from unipolar to
bipolar (by using 5V offset). The resulting signal or voltage, after being
manually attenuated by the level knob 5 , is available at the corresponding
out socket 6 .
A bi-color LED 7 indicates the value and polarity of the individual out
voltage via brightness and color, wherein red indicates positive and green
indicates negative. For audio signals, fast blinking of red and green yields a
yellow-orange mixture with intensity indicating signal level.
MIXING
A cascaded arrangement of summers allows for a multitude of mixing
configurations. First of all, note that patching a cable into an individual
output excludes the corresponding channel from further mixing (however, it
does not exclude it from taking part in additional processing for func
outputs). To mix four signals, feed them into inputs and adjust the level
knobs 4 . The resulting signal is available at the all socket 9 (make sure
that nothing is plugged into 1+2 output socket 8 ). Additionally, you can also
use the inverting inputs 2 to mix up to eight signals.
To use Samara as two independent 2:1 mixers, use both 1+2 8 and 3+4 9 outputs.
Patching a cable to 1+2 output breaks the internal connection, so that these
two channels are no longer mixed with channels 3 and 4 at the all output.
Again, using the inverting inputs allows for two four-component mixes.
Since mixing multiple hot signals with little attenuation usually yields
distortion (especially at the all output 8 ), Samara offers a soft-clipping
solution. It can be engaged by putting a jumper on the twopin header labeled
soft clip at the back of the unit.
Additionally, optional 6dB (2:1) attenuation is available independently for
1+2 and 3+4 summers by moving two jumpers marked atten from the upper to lower
position. Switching just one jumper does not affect the amplitude on the
second summer. Note that the mix at all will then have unequal proportions.
The jumpers do not affect the operation of the additional processing at the
multi-functional func outputs 10 11 .
WAVEFORM PROCESSING FUNCTIONS
In addition to linear mixing, Samara features a multifunction signal processing unit that operates on the four out signals from channels 14. The results of processing are delivered to func outputs 10 11 . These functions are implemented in a precise analog circuit under digital control. A small DSP chip monitors the signals and operates a number of analog CMOS switches that route them (or chop them into pieces) to the output buffers. There are five modes selectable by the small pushbutton 12 . Pressing it selects the desired mode in a cycle, indicated by a corresponding LED 13 .
Waveform processing
MIN/MAX OF FOUR
None of the LEDs are lit. This is the default mode and is the same as the original Samara. In this mode, the minimum voltage of all four inputs is determined and delivered to the min jack 10 , and the maximum of all four inputs is delivered to the max output 11 . Note that all inputs always take part in the equation (fig. 2). If there is nothing plugged in, the corresponding value is zero, which in certain situations may be selected as the minimum or the maximum value.
MIN/MAX OF TWO
Indicated by the LED labeled mm2. In this mode, only channels 1 and 2 take part in the calculation of minimum and maximum. This mode is more useful if you only need to operate on two signals. Also, it spares half of your Samara for other uses.
CLAMP
Indicated by the LED labeled clp. This mode limits the range of two
independent signals or voltages by two voltage controlled clamps (fig. 3).
Channels 1 and 3 define interchangeably the minimum and maximum voltage the
signals are clamped within. These two limits can be set manually (by engaging
positive or negative offsets and adjusting attenuators) or dynamically, by
applying control voltages to the inputs of channel 1 and 3. Signal fed to
input 2 is then clamped by these two limits and the resulting signal is
available at the func a 10 output. Similarly, signal from channel 4 is clamped
by the same two limits and appears at func b output 11 .
SCAN
Indicated by the LED labeled scn. Three input signals from channels 2, 3 and 4
are scanned (or selected) by the voltage in channel 1 (fig. 4). This scanning
voltage may be set manually (by engaging offset in channel 1 and adjusting the
attenuator), or it may be an external signal plugged into the inputs of
channel 1, labeled scan. Two orders of scanning are implemented.
The func a output offers the result of scanning in a pendulum-like order,
while func b output delivers signals being selected in a circular arrangement,
see the table (fig. 5).
SAMPLE AND HOLD
Indicated by the LED labeled s&h. This mode offers two independent channels of full sample and hold operation. In this mode, channels 2 and 4 are the control channels (as indicated by the shtrg panel labels), while signals or voltages in channels 1 and 3 are being sampled, and the result of this sampling (a stepped voltage) is available at the func a and func b outputs, respectively (fig. 6).
The motivation of this setup is that besides typical processing of external signals, it allows sampling of manually controlled voltages when offsets (either positive or negative) in channel 1 and 3 are engaged.
Block Diagram
Note that this is an analog sample and hold implementation where output
voltages are not processed by any digital converter. Even though special low-
leakage foil capacitors are used to hold the sampled value, there will be a
noticeable droop after a longer period of time.
Actually, you do not have to use a trigger-like signal for the control inputs.
Any analog signal will fire a new sample at the instant it crosses the 1V
threshold. Note, however, that slowly changing signals may produce a series of
multiple samples due to the presence of noise and multiple crossing of the
threshold. In order to prevent this, there is a small hysteresis near the
threshold.
ACCESSORY
Our Coal Mine black panels are available for all of Xaoc Devices modules. Sold separately. Ask your favourite retailer. ·
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 US ANYTHING, PLEASE CONTACT US AT
SUPPORT@XAOCDEVICES.COM. NOTE THAT ANY UNSOLICITED PARCEL WILL BE REJECTED AND
RETURNED!
GENERAL INQUIRIES
FOR USER FEEDBACK SUGGESTIONS, DISTRIBUTION TERMS, AND JOB POSITIONS, FEEL
FREE TO CONTACT XAOC DEVICES AT INFO@XAOCDEVICES.COM. PLEASE VISIT
XAOCDEVICES.COM FOR INFORMATION ABOUT THE CURRENT PRODUCT LINE, USER MANUALS,
FIRMWARE UPDATES, TUTORIALS, AND MERCHANDISE.
EASTERN BLOC TECHNOLOGIES
MADE IN THE EUROPEAN UNION
MAIN FEATURES
Four attenuation channels
Two offset channels
Four inverters
One fourchannel mixer
Two double channel mixers
Mixing of up to eight signals when using inverted inputs
Two modes of min/max calculation
Clamp, scan, sample and hold waveform processing modes
TECHNICAL DETAILS
Eurorack synth compatible
10hp, skiff friendly
Current draw: +50mA/-20mA
Reverse power protection
ALL RIGHTS RESERVED. CONTENT COPYRIGHT ©2022 XAOC DEVICES. COPYING, DISTRIBUTION OR ANY COMMERCIAL USE IN ANY WAY IS STRICTLY PROHIBITED AND REQUIRES THE WRITTEN PERMISSION BY XAOC DEVICES. SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT PRIOR NOTICE. EDITING BY BRYAN NOLL.