Xaoc Devices SARAJEWO User manual

SARAJEWO
syncable
analog delay
line
Model of 1984
operator’s manual rev. 1984/1.0

SAlut
Thank you for purchasing this Xaoc Devices
product. Sarajewo is an analog delay mod-
ule based on old school (but newly manufac-
tured) BBD (Bucket Brigade Delay) chips. It
features three delay taps, an external clock
input with various tempo sync factors, and a
wide range of settings controllable via CV. It is
based on high quality components with max-
imum effort put towards the highest sound
quality possible, while still preserving the
charm of the BBD technology. The module of-
fers a clean and warm analog sound with tons
of character and a comfortable user interface
with a tap tempo button, signal level indica-
tors, sync and CV inputs, four signal outputs,

inStAllAtiOn
The module requires 12hp worth of free space
in the Eurorack cabinet. The ribbon-type pow-
er 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
Sarajewo features an audio delay line consist-
ing of three BBD chips of 4096 stages each (see
   
clock, and are connected in series so that the
2
module
explained

block diagram
LP filter
LP filter
tilt filter expander
LP filter
expander expander
LP filter
bbd 1 bbd 2 bbd 3
crossfade
MIXED OUTPUT
T1T2T3
compressor
INPUT EXT FEEDBACK
LOOP

delayed signal is available after each chip. A
high signal–to–noise ratio is achieved thanks
to signal companding (dynamic compression
at the input matched with dynamic expansion


the outputs ensure optimal conditions for the
BBD chips to process the signal.
In general, the incoming signal must be band–
limited in order to prevent high frequency com-
ponents from interfering with the clock. Simi-

is processed helps to eliminate high frequency
artifacts introduced by the BBD chips. In Sara-

the current clock frequency, thus offering maxi-
mum bandwidth with minimal artifacts.
An internal feedback loop taken from the last
tap allows for the classic echo effect with ad-
ditional coloration offered by an adjustable tilt

externally while a crossfading circuit offers a
continuous mix of the input and the signal from
the last tap.
        
2. The signal you wish to process should be
patched to the input jack 1. The level knob
2above controls the amplitude with the in-
put indication multicolor LED 3providing
visual feedback. The outputs from individual
taps are labeled t1, t2, and t3, respectively:
4
,5 ,6 . The central large t3time dial 7
allows for precise setting of the overall delay
time of the three stages, from about 20ms to
over 1.5s. The delay time can be modulated
via CV patched into the corresponding jack
below 8or synchronized to an external clock
source via the sync input 9. Since all three
BBD chips share a common clock, using the t1
and t2outputs will provide signals delayed by
1/3 and 2/3 of the t3time, respectively. The
mixed output 10 delivers a continuous mix of
your input signal and the t3tap. The balance is
controlled both by the effect knob 11 and the
CV patched into the mix cv jack 12
. The sig-
nal from the ext feedback loop input 13 is
mixed with the input of the delay line. This jack
is normalized to the t3output, however, the
connection can be broken by sending one of the
tap outputs to an external processor (such as

via the ext feedback loop input. Regardless
of the actual feedback signal path (internal or
external), the signal always passes through

tone slider 14 . The amount of feedback is
controlled by the fbck slider 15
. The bbd off-
range led 16 indicates that the delay time set
by the combination of the t3time dial and the
incoming CV signal exceeds the time range of
the module. When the CV inputs are in use, the
corresponding knobs act as offsets.
inPut SiGnAl
Sarajewo is AC coupled and accepts modular
level audio signals (10Vpp and higher). The
level knob attenuates the input to prevent
distortion (indicated by the color of the input
indication LED). When it turns from green
to yellow and then to red, it means the signal
is too hot and the BBD chips may introduce
audible distortion.
3

4
front panel
overview

the interface
1415
7
2
8
4
1
11
6
5
12
10
17
16
139
3

cOntinuOuS And tAP-tEmPO
dElAY cOntROl
Sarajewo can operate as a continuously variable
delay or in one of two synced modes in which the
delay follows a given time base. The illuminat-
ed tap tempo button 17 always blinks with a
period equal to the current delay time, while its
color indicates the current mode. Please note that
unlike digital delay effects which vary the length
of their memory buffer, each change of the delay


will inevitably cause pitch variation similar to the
sound of a tape-based machine.
fREE mOdE
When Sarajewo operates in free mode, the
tap tempo button blinks green and delay
time is continuously adjustable from 20 to
1560ms via with the central dial.
The external CV input adds an offset to the cur-
rent value, extending the delay time up to 4x
(with negative CV) as well as shortening down

cannot exceed the limits mentioned above. Val-
ues beyond the range will be clamped and the
bbd off-range LED will appear red.
tAP-tEmPO mOdE
Pressing the tap tempo button at least two
times switches Sarajewo to tap-tempo mode,
indicated by a yellow tap tempo button back-
light. The period of your recent taps is mea-
sured and used as the current time base (unless
it is slower than the longest delay setting, i.e.
1560ms). In this mode, both the t3time knob
and the corresponding CV input are still active,
but their function changes so that the t3time
knob allows for multiplication or division of the

the factors from the scale: 1:6, 1:4, 1:3 1:2, 2:3,
1:1, 3:2, 2, 3, 4, 6. Turning the dial will switch
these factors in discrete steps. Turning the dial
left will shorten the delay time (from 1:1 ratio
to 1:6 ratio). Turning the dial right will length-
en the delay time (from 1:1 ratio to 6:1).
A long press of the tap tempo button brings
you back to free mode.
SYnc mOdE
Patching an external clock source to the sync
input switches Sarajewo to external sync
mode, indicated by a red tap tempo button
backlight. The delay now follows the tempo
of the external clock while applying the same
   
of the factor as in tap-tempo mode. Please
note that you cannot exit this mode as long
100 1000 10000
10
5
0
-5
-10
-15
-20
-25
-30
tilt filter response
5

as a cable is patched and new impulses ar-
rive. When you unplug the cable, the module
returns to the free mode, with the delay time
t3time
knob.
Again, you cannot exceed the BBD clocking lim-
its by turning the knob to the extremes and/or
applying a high amplitude CV signal. However,
instead of clamping the delay time at the upper
or lower limit, the time factor is automatically
reduced to the nearest synced value, so that
your echoes remain in sync.
tAP-tEmPO & SYnc mOdE
timE cV inPut BEhAViOR
The time CV input acts as an offset, and pro-
vides two user-selectable options. The default
behavior is that CV is added to knob position
which yields quantized switching between
time factors. The alternative option is that the
CV value is unquantized which allows for subtle
modulation of the delay time. In order to acti-
vate the second option, power up your system
while holding the tap tempo button.
OPERAtinG thE fEEdBAcK
The fbck slider potentiometer determines how
much of the delayed signal is returned to the
input of the BBD line and mixed with the input
signal. Obviously, the stronger the feedback,
the more the echoes repeat, thus sustaining the
sound to the point where self-oscillation builds
up a wall of saturated sound and noise. Please
note that the buildup or decay rate depends

is the number of audible repetitions. The illumi-
nated fbck slider shows the amplitude of the
feedback signal by blinking green and turning
to red to warn that the signal is too hot and
close to the clipping level of the BBD chip.
Besides the depth of feedback, you can also
shape the frequency content of your signal
by adjusting the tone
mind that with a deep feedback your sound

the effect will be more and more pronounced.
In the middle position of the slider, it introduc-
es very little coloration. At the lower position
-
cies while attenuating higher frequencies.
Please note that amplifying low frequencies
may accelerate the self-oscillation effect and
increase distortion. At the higher position of
       -
quencies and amplify middle and higher fre-
quencies, hence the echoes will sound bright-
er. Again, note that exaggerating this effect
may affect feedback depth. The illuminated
tone slider blinks in color, showing which
frequencies are dominating in your feedback
signal with red indicating highs and green
indicating lows.
EffEct miXinG
The effect knob in Sarajewo controls the
wet/dry balance in a distinct manner. In the
middle position, both the original and delayed
sounds are delivered to the mixed output at
their original amplitudes. Unlike a traditional
crossfader, turning this control left and right
attenuates one of the signals without am-
plifying the other. This balance can also be
6

voltage–controlled by a bipolar (±5V) signal
patched into the mix cv input.
dElAY timE VS BAndWidth
Just like any other BBD-based effect, Sarajewo
achieves long delays by reducing the clock
rate, which inevitably limits the usable band-
width. At the end of the scale, the (normally
ultrasonic) clock is slowed enough to become
an audible whine. Also, it produces some
aliasing and imaging artifacts, as well as in-
creased background noise. Sarajewo handles
this problem by automatically adjusting its

components just before they become audible.
That is why the signal becomes dark when the
delay is set beyond 500ms, and even darker
the further the scale. Each unit comes factory
calibrated to achieve the optimal balance be-
tween the bandwidth and artifacts.
uSAGE tiPS
Sarajewo is intended as a long delay effect
unit, and as such, it excels at longer delay
settings. For best results at the shortest delay
settings you are advised to use the t1output
and combine it with moderate, but not mini-
mum delay time settings of the t3time dial.
To make Sarajewo work as expected in that
-
t1
output to the ext feedback loop input. To
mix the dry signal with the wet signal from
the t1output, an external mixer is needed, as
the internal effect mixer always crossfades
between the dry and the t3
7
BBD
TECHNOLOGY
Bucket Brigade Delay is an
analog technology used in
vintage integrated circuits
that were popular in the 1970s,
long before digital signal converters
and digital memory were affordable. Each BBD chip contains thousands of
small capacitors and pMOS or nMOS transistors that act as analog switches. The signal is transferred as

(hence the name). A clock signal governs the speed of charge transmission, and directly controls the delay
time: the faster the clock, the shorter the delay (and vice versa). Due to the limitations of vintage technol-

transistors. Even though contemporary digital delay effects offer a much cleaner signal, BBD delays are
still sought after due to their desirable sonic characteristics. Furthermore, the range of delay time offered
by just a single BBD chip is limited to 20–300 ms, which is much less than what is commonly expected
from modern delay effects. In order to achieve more attractive delay times, several chips must be used and
-
tion at extreme delay time settings due to the accumulation of noise and distortion from multiple stages.

mAin
fEAtuRES
BBD-based analog
delay unit
Up to 1560ms of
analog delay times
Three delay taps
with individual
outputs
External clock
synchronization
Manual tap tempo
function
Variable tempo
divisions and
multiplications
Automatic band-
width control

feedback loop
External feedback
loop input
tEchnicAl
dEtAilS
Eurorack synth
compatible
12hp, skiff
friendly
Current draw:
+180mA/-120mA
Reverse power
protection
EASTERN BLOC TECHNOLOGIES MADE IN THE EUROPEAN UNION
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 A PERIOD OF 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 INSTAL-
LATION OR POWER SUPPLY, IMPROPER WORKING ENVIRONMENT, ABUSIVE TREATMENT OR ANY OTHER
OBVIOUS USER-INFLICTED FAULT.
lEGAcY SuPPORt
IF SOMETHING WENT WRONG WITH A XAOC PRODUCT AFTER THE WARRANTY PERIOD IS OVER, 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, SO PLEASE KEEP IT JUST IN CASE. ALSO, A FILLED RMA FORM MUST
BE INCLUDED. XAOC DEVICES CAN NOT TAKE ANY RESPONSIBILITY FOR DAMAGES CAUSED DURING
TRANSPORT. PRIOR TO SENDING US ANYTHING, PLEASE CONTACT US AT SuPPORt@XAOcdE-
VicES.cOm. NOTE THAT ANY UNSOLICITED PARCEL WILL BE REJECTED AND RETURNED!
GEnERAl inQuiRiES
FOR USER FEEDBACK SUGGESTIONS AND DISTRIBUTION TERMS, FEEL FREE TO CONTACT XAOC DEVICES
AT [email protected]. PLEASE VISIT THE XAOCDEVICES.COM FOR INFORMATION ABOUT
THE CURRENT PRODUCT LINE, USER MANUALS, FIRMWARE UPDATES, TUTORIALS, AND MERCHANDISE.
WRITTEN BY M. BARTKOWIAK, EDITED BY Ł. KACPERCzYK AND M. ŁOJEK. PROOfREADINg AND EDITINg BY
B. NOLL. DESIgNED BY M. ŁOJEK. ALL RIgHTS RESERVED. CONTENT COPYRIgHT ©2020 XAOC DEVICES. COP-
YING, 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.