Xaoc Devices HRAD User manual

HRAD
mixing
console
commander
Model of 1967
operator’s manual rev. 1967/X/1.0

sAlut
Thank you for purchasing this Xaoc Devices
product. Hrad is an expander for our Praga
four–channel stereo mixer that adds new func-
tionality and enhancements. Hrad features a
master section with stereo volume control over

indicator, a stereo sum output that is switch-
able between eurorack and line level, a head-
phone output with volume control that is inde-
pendent of the main attenuator, a special cue
input that can be auditioned with and without
the mix, four control inputs for automated
muting/unmuting of individual channels, four
inputs for voltage control over the aux send
levels, four insert points in the aux sends, and
two stereo attenuators for Praga's two AUX
return pairs.
Hrad may be used alongside a single Praga
unit. If you have more than one Praga chained,
it is best to pair with the last Praga in the chain.
Please bear in mind that all features related to
AUX channels and muting will refer to the Pra-
ga that is connected to Hrad. It is also possible
to connect a separate Hrad to every Praga in
the chain so as to have access to the extra func-
tionalities in every unit. However, please take
into account the substantial power require-
ments of such a complex setup.
instAllAtiOn & setuP
The module requires 10hp worth of free space in
the Eurorack cabinet and it is best located next to
your Praga. Hrad does not have its own separate
power connection as it draws power from Praga
and adds its own 50mA to what Praga consumes.
attention: never connect any power ca-
ble to any pin header on the back of your
hrad—it will destroy the unit!
Hrad connects to Praga using the two 16-pin
ribbon cables 12 
2). note: these cables are deliberately short and
should not be replaced with longer ones for the
sake of safety as well as keeping interference
and noise to a minimum. Prior to making the
connection, you must remove all jumpers from
the lower pin header 13 of your Praga (you will
have to put them back if you ever decide to use
your Praga without Hrad, otherwise the unit
will not work properly). Next, carefully connect
the cable going from the upper and lower head-
ers of Hrad to the upper and lower headers of
Praga paying attention to not mix them up or
rotate them as this would seriously dam-
age both units!
Locate the jumper labeled praga revision
16            
according to what is printed on the PCB of your
Praga. Improper setting of this jumper is not
dangerous, however, the AUX channels will not
work as designed. While you are there, you may
also decide to set the output level of your Hrad. If
Praga is the last stage of your Eurorack system,
it may be reasonable to switch the pair of out-
put level jumpers 17 from euro (default) to
line position.
Both Praga and Hrad should be fastened by
mounting the supplied screws before powering
up. To better understand the device, we strong-
ly advise the user to read through the entire
manual before using the module.
2
module
explained

7
3
3
5
8
9
11
1
10
6 4
front panel
overview
interface
2

4
mODule OVeRVieW

the master section of a small mixer. The main
level knob 1controls the stereo sum signal
at the main output 2

is shown by the 5-bar LED indicator 3. The
headphone volume at the phones output 4
is set by the phones level knob 5
. The cue
input 6allows auditioning of an additional
signal in your headphones, with or without the
main mix as selected by the cue solo button
7
. The four active inputs 8 offer remote
muting and unmuting of Praga's four individual
input channels. The two aux ret knobs 9offer
attenuation of signals plugged into Praga's aux
return pairs. The four aux cv inputs 10 offer
voltage control over Praga’s AUX send levels.
The four aux ins inputs 11 are insert points for
Praga's individual AUX sends.
VOlume cOntROl
The main level attenuator controls the stereo
signal at the output of Hrad without affecting
the stereo sum on Praga. note: it is possible
to overload the sum output in Praga when sev-
eral hot audio signals are mixed with high vol
settings. If this happens, you can simply lower
Hrad’s main level attenuator to achieve a clean
POWER
CONNECTOR
1967 VOLTAGE CONTROLLED MIXING SURFACE
REV. 03.2017
installation
Observe the cable
orientation!
Do not mistake
expander headers
with power
cord headers,
this would void
the module
warranty!
13
12

5
signal thanks to the additional 12dB of head-
room provided by Hrad’s internal connection
to Praga.
The default output level on Hrad can be switched
between the normal Eurorack (+20dBu) and
        

HeADPHOne OutPut
The dedicated stereo phones output on Hrad
can drive a wide range of studio and con-
sumer grade headphones with a dual high–
      
maximum loudness and low–frequency range
may vary with impedance. The recommended
headphone impedance is 80 to 300 Ohm.
The phones level knob is independent of the
main level attenuator, hence you can hear
your mix before your audience does. The cue
input allows you to audition an additional
center–panned mono signal in the context
of your mix or alone (after pressing the cue
solo button). Note the amplitude of this input
is attenuated for your listening comfort.
mute/ActiVitY cOntROl inPuts
By feeding gate signals to the four active in-
puts in Hrad it is possible to remotely control
the opening/closing of each individual chan-
nel in Praga exactly in the same way as click-
ing its front panel buttons. A gate–on signal

while gate–off (0V) mutes it (in a clickless
way). Note that even with the gate signal
plugged in, the panel buttons still remain op-
erational, however unplugging the signal will
leave your channel muted.
siGnAl PAtH Of AuX cHAnnels
The pair of Praga and Hrad features an un-
     -
      
the diagram of a single AUX path from a single
input channel in Praga.
The signal passes through the three VCA cores
in parallel—two of them form the stereo pair
that is mixed at the summing bus. The third
core forms the direct signal which is delivered
POWER
CONNECTOR 1967 VOLTAGE CONTROLLED MIXING SURFACE
REV. 03.2017
16
15
jumpers

6
to the vca out socket in Praga. This same sig-
nal is used for the auxiliary send (post fader).
However, before the a/b knob on Praga, it
may be replaced by its processed version (or
any other signal) thanks to the aux ins inputs
in Hrad. It then goes through one of the four
additional VCA cores (one per Praga channel)
where the send level can be controlled by the
external CV plugged into the corresponding
aux cv input.
The voltage response of this VCA is the same
as in Praga (please refer to its manual for de-
tails). The CV inputs are internally normalized
to 8V.
From the VCA, the signal passes through the
bipolar aux attenuator on Praga where one
of the auxiliary channels (aor b) may be
selected, and the amount of send may be set
manually. The mixed aux send signal from all
four channels is available at the aux send
socket in Praga.
When a return signal from external process-
ing is plugged into the stereo aux return
pair in Praga, it goes again to Hrad, where
it may be attenuated with the corresponding
aux ret (aor b) knob. From the attenuator,
the signal is routed to the stereo summing bus
in Praga.
block
diagram
signal flow
Praga Hrad
aux
vu
vu
control
AUX
sends
cue
solo
AUX
insert
stereo
output
signal
input
mute
AUX
return A
AUX
return B
VCA
output
chain
output cue input
phones
output
main
output
chain
input
pan vol



AUX
CV input

7
PAtcH eXAmPles
Standard (post–fader) operation: When
using your Praga and Hrad in a traditional
setup, you can add two external effects (e.g.
a reverb and delay) with the auxiliary chan-
nels (post–fader). Patch the aux send signal
to your effect processor input, and patch its
outputs back to the aux return pair. Now,
you can decide on the amount of the effect
being mixed to your audio via the correspond-
ing aux ret attenuator. By using additional
modulation plugged into the aux cv you can
dynamically control which parts of the audio
will have the reverb or delay added to them.
Pre–fader operation: Split the signal going
to an input in Praga, and feed a copy of it to
the corresponding aux ins    
5). This will bypass the vol and VCA controls
on Praga for your auxiliary send, which allows
for pre–fader operation. In other words, you
can have an effected portion of the signal au-
dible while the separate dry signal is turned
down. You can even plug any other signal into
that socket, and have additional sounds add-
ed (under CV control) to your effect bus.
AUX channel inserts: Take the vca out sig-
nal from a channel in Praga and process it
      
or bit crusher), and plug the result into the
corresponding aux ins
With this patch, you could have a reverb on
high frequencies only, or distorted echos of the
sounds that are clean in the main mix.
Extra stereo input: Sometimes you run out of
input channels in Praga but don’t need more
than one send effect. You can plug a mono or
a stereo pair into the unused aux return
sockets, and its volume will be controlled by
the aux ret
 
fx unit reverb
multiple filter

mAin
feAtuRes
Expander for
Xaoc Praga
mixer module
CV inputs for
controlling AUX
sends
Two stereo AUX
return attenuators
Four insert points
for AUX sends
Main volume
control with level
indicator
Switchable
Euro/line level
outputs
Headphone driver
with additional
cue input
Gate inputs for
channel muting
control
tecHnicAl
DetAils
Eurorack synth
compatible
10hp, skiff
friendly
Current drawn
from Praga:
+50mA/-35mA
No 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, 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. PROOfREADINg AND EDITINg BY B. NOLL. DESIgNED BY M. ŁOJEK.
ALL RIGHTS RESERVED. CONTENT COPYRIGHT © 2019 XAOC DEVICES. COPYING, DISTRIBUTION OR
ANY COMMERCIAL USE IN ANY WAY IS STRICTLY PROHIBITED AND REQUIRES THE WRITTEN PER-
MISSION BY XAOC DEVICES. SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT PRIOR NOTICE.