Radial Engineering 8ox User manual

www.radialeng.com
RADIAL ENGINEERING LTD.
3 YEAR TRANSFERABLE WARRANTY
RADIAL ENGINEERING LTD. (“Radial”) warrants this product to be free from defects in material and workman-
ship and will remedy any such defects free of charge according to the terms of this warranty. Radial will repair
or replace (at its option) any defective component(s) of this product (excluding finish and wear and tear on com-
ponents under normal use) for a period of three (3) years from the original date of purchase. In the event that a
particular product is no longer available, Radial reserves the right to replace the product with a similar product
of equal or greater value. To make a request or claim under this limited warranty, the product must be returned
prepaid in the original shipping container (or equivalent) to Radial or to an authorized Radial repair center and you
must assume the risk of loss or damage. A copy of the original invoice showing date of purchase and the dealer
name must accompany any request for work to be performed under this limited warranty. This limited warranty
shall not apply if the product has been damaged due to abuse, misuse, misapplication, accident or as a result of
service or modification by any other than an authorized Radial repair center.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE FACE HEREOF AND DE-
SCRIBED ABOVE. NO WARRANTIES WHETHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIM-
ITED TO,ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FORAPARTICULAR PURPOSE
SHALLEXTEND BEYOND THE RESPECTIVE WARRANTYPERIOD DESCRIBEDABOVE OF THREE YEARS.
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CIFIC LEGAL RIGHTS, AND YOU MAY ALSO HAVE OTHER RIGHTS, WHICH MAY VARY DEPENDING ON
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Radial 8ox and 8cx Owner’s Manual - Part #R870 1185 • V1.0
Specifications and appearance are subject to change without notice.
Radial Engineering Ltd.
1638 Kebet Way, Port Coquitlam BC V3C 5W9
tel: [phone] • fax: [phone]
email: [email protected] • web: www.radialeng.com

www.radialeng.com
8ox and 8cx
Owner’sManual
EightChannel•TransformerIsolated•MicrophoneSplitters
8oxRackmount
Specifications and appearance are subject to change without notice.
Radial Engineering Ltd.
1638 Kebet Way, Port Coquitlam BC V3C 5W9
tel: [phone] • fax: [phone]
email: [email protected] • web: www.radialeng.com
www.radialeng.com
TruetotheMusic
R800 8003 - Radial Transformers
R800 8004 - Jensen Transformers
8cxInstall
R800 8002 - Radial Transformers
R800 8001 - Jensen Transformers

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
INTRODUCTION
Congratulations on your purchase of a Radial microphone splitter. This manual covers installation and operation for both 8ox and 8cx
microphone splitters. We recommend that you take a few minutes to read through this manual in order to familiarize yourself with the
many innovative features that are built in.
Shouldyouhavequestionsorapplicationsnotcoveredinthismanual,weinviteyoutologontotheRadialwebsiteatwww.radialeng.com
to check the FAQ section for the latest updates. Of course, you can also send us an email at [email protected].
8ox DESIGN CONCEPT
The Radial 8ox is an eight channel, balanced microphone splitter in a compact 1RU package that divides the mic signals three ways; to
a direct output; a direct output with ground lift; and an isolated output.A high performance bridging transformer is used on the isolated
output to eliminate hum and buzz caused by ground loops.
Splitting microphone signals is a straight forward concept. It’s most common in sound reinforcement and live recording when the on-
stage microphones must be split to feed two mixing consoles. When done improperly, splitting a signal can dull frequency response,
lower the output, and worst of all, cause ground loops that product buzz and hum. To avoid these pitfalls, sound reinforcement com-
panies have been building custom “splitter-snakes” for many years.
The 8ox is an off-the-shelf splitter for the rest of us allowing virtually anyone to design and assemble a splitter-snake with plug-n-play
simplicity and professional audio quality without the need for custom metal work or complex soldering.
Table of Contents Page
8ox Introduction...................................................... 1
8ox Design Concept............................................... 2
Basics - What is a Splitter ...................................... 2
How a Transformer Works...................................... 2
What is a Ground Loop .......................................... 2
Signal Flow Block Diagram .................................... 3
Feature Set............................................................. 4
Applications............................................................ 6
Grounding Options ................................................. 7
8cx Introduction...................................................... 8
8cx Installation........................................................ 9
Radial 8ox
Rack Mount Splitter
Specifications and appearance are subject to change without notice.
Radial Engineering Ltd.
1638 Kebet Way, Port Coquitlam BC V3C 5W9
tel: [phone] • fax: [phone]
email: [email protected] • web: www.radialeng.com
www.radialeng.com
1
8ox and 8cx
Owner’sManual
EightChannel•TransformerIsolated•MicrophoneSplitters

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
BASICS
What is a Mic Splitter
In modern concert production there are often two separate sound sys-
tems. The main PA covers the audience or “house” while a monitor sys-
tem covers the stage so the performers can hear. Athird system may be
added if the concert is to be recorded. Each system requires it’s own mix-
ing console because the mix that sounds good in the house simply won’t
work for the monitors or be suitable for a recording. Amic splitter provides
the means to split the original signal from the on-stage microphones and
send it to the various systems, main PA, monitors, and recording, so that
each can get a clean, unaffected signal directly from the mic.
However, splitting microphone signals is not as simple as just wiring the
microphones to all the consoles. Issues such as impedance loading,
ground loops and phantom power can degrade the signal and introduce
noise. To solve these issues the 8ox uses high performance audio isola-
tion transformers to decouple the signal passing through it and eliminate
ground loops that cause hum and buzz in audio systems.
Inside A Transformer
A transformer consists of two coils of wire in close proximity to one
another wound around a metal core. One coil is the transformers input
(primary), the other coil is the output (secondary). Atransformer is said to
electrically isolate, or decouple, the input from the output because there
is no physical connection between the primary and secondary windings.
When the primary winding is energized by the mic signal a magnetic field
is produced and the lines of force cut across the turns of the secondary
winding. Alternating current (AC) which makes up the audio program is
transduced from one winding to another through induction. Direct current
(DC) which is responsible for buzz and hum in sound systems, is blocked
by the transformer eliminating noise caused by ground loops.
Once the loop is complete there is the electrical potential for DC voltage to flow through it. This potential is caused by the interaction
between devices with different ground voltage references and allows unwanted spurious current to flow through the shields of the
signal cables. This flow of DC voltage creates noise in the signal wires through induction and capacitance at the base frequency of 50
or 60 Hz (hum) and the upper harmonics of 120 Hz, 240 Hz, etc. (buzz). Isolating or decoupling the audio signal with a transformer at
a point between the two devices is the best way to block the unwanted flow of ground-potential currents and eliminate hum and buzz
in audio systems.
Sound Quality
Besides isolation to prevent hum and buzz, audio transformers must sound brilliant and sound quality is what sets Radial transform-
ers apart. Designed for pro-audio applications they include a host of features not found in general purpose audio transformers. Acore
material of nickel-iron allows ultra high input levels before saturation, linear frequency response, excellent bandwidth and near zero
phase distortion. Consistent unit-to-unit performance is achieved through precision computer controlled winding. The core is sealed in-
side a mu-metal can which provides enhanced shielding from electromagnetic interference. The built in Bessel low pass filter removes
ultrasonic distortion that can mask natural sound and cause ear-fatigue.
Main PA Recorder
Monitors
Those Darn Ground Loops
A ground loop is created when an audio system has multiple paths to ground, often called earth. This situation can occur when two
AC powered audio devices, such as two mixing consoles, are plugged into different power circuits and connected together via a signal
cable. Both audio devices have a path to ground through the third prong on the AC-mains cable. The signal cable completes the loop
by connecting the devices together through the signal cable’s shield.
Stage Microphone
Isolation
Transformer
2
Earth
Earth
Ground Loop Path
Transformer Isolation

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
SIGNAL FLOW
Take a moment to follow the signal path through the block diagram below.
Parallel Inputs
For flexibility, the 8ox has three paralleled inputs.
• Female XLR connectors on the front panel
• 25 pin D-SUB (DB-25) on the rear panel
• Euroblocks screw terminals on the rear panel (Set of eight
Euroblocks terminals sold separately, Order # R800 8050).
Direct Output
The DIRECT output is the primary “straight through” output
and provides a return path for 48V phantom power for con-
denser microphones and active direct boxes. In the diagrams
we refer to the Main FOH console as connected to the DI-
RECT output. In fact it doesn’t’ matter which console, main or
monitor, is connected to DIRECT as long as it is the sole con-
sole which will supply phantom power. The DIRECT output is
paralleled to DB-25 and Euroblocks terminals for flexibility.
Auxiliary Direct Output with Ground Lift
The DIRECT OUT WITH GROUND LIFT is a auxiliary output
that uses eight front panel switches to lift the ground. This
output may be patched to another audio system that may or
may not be transformer isolated itself. The DIRECT WITH
GROUND LIFT output is paralleled to DB-25 and Euroblocks
terminals.
Isolated Output
The ISOLATED outputs uses eight precision audio isolation
transformers to decouple the mic signals from the DIRECT
outputs. This output may be patched to a separate audio sys-
tem without creating ground loops. The ISOLATED output is
paralleled to DB-25 and Euroblocks terminals.
-20dB PAD
The front panel PAD switch can prevent transformer over-
load when connecting high output devices like synthesizers
and drum machines. Engaging the PAD reduces the level by
-20dB for that particular channel at the ISOLATED output.
Radial Transformer
After the PAD the signal is fed to the isolation transformer
where the mic signal is decoupled to eliminate noise from
ground loops. For the most flexibility when designing techni-
cal ground systems, each transformer features an internal
switch allowing the signal ground to connect around the
transformer.
RF Filter (not shown in the diagram)
The three paralleled inputs employ a RF network filter on their
ground paths to prevent unused inputs from acting like anten-
nas when the ground is lifted.Any radio frequencies picked up
by an open pin will be shunted to ground.
Inputs 1-8
DB-25 Front Panel XLR x 8 Inputs 1-8 Euroblock
Direct Output and
Return Path for 48V Auxiliary Direct Output with Ground Lift Transformer Isolated Output
-20dB
PAD
Internal
Ground
Lift
DB-25
Euro
Block
Front Panel
Ground Lift
DB-25 DB-25
Euro
Block Euro Block
Isolation
Transformer
1
2 3 4
1
2
3
4
3

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
8OX FEATURE SET
1. XLR Inputs - Front panel female XLR jacks allow easy
connection of individual signals. Rugged, glass-reinforced
nylon construction for reliable connections.
2. PAD -20dB - Prevents transformer overload when con-
necting high output devices. Only the ISOLATED output is
affected by the PAD.
3. Front panel Lift switch - Disconnects the ground path at
the DIRECT WITH GROUND LIFT auxiliary output. Using
the front panel ground lift can eliminate ground loop noise
between equipment connected to the 8ox direct outputs.
4. Easy ID label zones - For dry-erase markers or wax pencil
identification. Handy when using several 8ox at a time.
5. Military Grade PCB - The dual layer circuit board is
manufactured with plated through holes and secured with
8 standoffs.
6. Transformers - Each transformer is mounted directly on
the PCB in close proximity to the input for the shortest
possible signal path. Choice of standard Radial or optional
Jensen transformers.
7. Heavy-duty Switches - Front panel switches are metal
encased and rated at 20,000 operations.
8. Internal Ground Lift - Each channel features an internal
switch that, by default, is set to “lifted” so the transformer
can isolate ground potential voltages. It may be used by
system designers to accommodate specific grounding
schemes when desired.
9. Internal Chassis Ground Lift - Input connectors are
100% isolated from the chassis, but an internal switch is
provided to connect signal ground (pin-1) to the chassis
without modifying the 8ox. By default, this switch is factory
set to “lifted” allowing the chassis to “float” ungrounded and
should remain this way unless a specific grounding scheme
requires the signal ground to be tied to the chassis.
10. 14-Gauge Chassis - Made extra tough with heavy gauge
steel and welded corners to provide excellent shielding
and durability. Finished in baked enamel.
11. Isolated Output - This output is transformer isolated
to block noise caused by ground loops and is wired in
parallel to DB-25 and Euroblocks terminals.
12. Direct With Ground Lift - This is an auxiliary output
wired in parallel with the DIRECT output. The signal
grounds may be disconnected using the front panel LIFT
switch. This output is wired parallel to the DB-25 and Eu-
roblocks terminals.
13. DB-25 Pin-out Diagram - The pin-out for the female DB-
25 connector is diagramed on the rear panel. All DB-25
connectors follow the Tascam standard for eight channel
analog signal interface.
14. Euroblock Sockets - These panel sockets receive 12-pin
Euroblock screw terminals. Each Euroblock connects four
channels with bare wire termination and facilitate custom
options like interfacing a connector panel or multi-pin
disconnect. Euroblocks screw terminals are optional and
must be ordered separately. (Radial order # R800 8050)
15. Direct Output - This output passes signal through the
8ox and provides the return path for phantom power.
This output is wired parallel to the DB-25 and Euroblocks
terminals.
16. Rear Inputs - The rear panel DB-25 and Euroblock inputs
connect all eight channels and are wired parallel to the
front XLR connectors.
17. Chassis Ground - Ground screw connection point used
in conjunction with the internal chassis lift switch to bond
the 8ox to earth.
1234
56 7 8 9 10
11 12 13 15 16 1714
4

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
CONNECTING THE 8ox
8ox Inputs
You can connect mics and direct boxes to the 8ox using the front panel XLR inputs, or the rear panel DB-25 and Euroblocks terminals.
Which input you choose to use will depend where the 8ox is located and what you are connecting to it. For instance, individual micro-
phones may be connected directly via the front panel XLRs (X), or a multi-channel snake may be used to connect to the DB-25 inputs
(Y). Finally, a wall-mounted panel of XLRs may be connected to the Euroblock inputs with a multi-channel snake cable (Z).
Connecting the Euroblock Terminals
Euroblock, or European style terminal blocks, also called Phoenix blocks, are removable screw terminal connectors. The Euroblock
connector requires no soldering to terminate. Instead, the wire is stripped, inserted into slots in the connector, and locked into place
with a standard screwdriver. The connector then mates with the socket. Pin termination for the Euroblock terminals are clearly marked
on the rear panel.
Referring to the pins on an XLR connector:
12
3
+-G+-G+-G+-G
Connecting the DB-25 I/O
The DB-25 connectors on the rear panel use the TASCAM pin-out standard for analog audio. Connecting the 8ox to devices equipped
with DB-25 connectors like digital multi-track recorders and mic preamps is simply a matter of using compatible DB-25 audio cables.
Radial balanced DB-25 cables are a perfect match for the 8ox and can be ordered in standard or custom lengths.
The pin-out diagram is silk-screened on the rear panel for reference and represents the panel-mount female pin-out. To make your
own interface DB-25 cables follow the pin-outs below for male and female connectors.
1
-
+
G
-
+
G2
3
-
+
G
-
+
G
4
5
-
+
G
-
+
G
6
7
-
+
G
-
+
G
8
13
12
3
Female DB-25 Pin-out (Panel View) Male DB-25 Pin-out (Cable View)
1
-
+
G
-
+
G23
-
+
G
-
+
G45
-
+
G
-
+
G67
-
+
G
-
+
G88
13
12
3
XYZ
• Connect pin-1 (GROUND) to the G terminal.
• Connect pin-2 (HOT) to the + terminal.
• Connect pin-3 (COLD) to the - terminal.
NOTE: Euroblocks are optional equipment and must be ordered
separately (Radial order number R800 8050).
5

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
Connecting Two Mixing Consoles
This is the most basic 8ox set up and allows the
MAIN PA and MONITOR consoles to have ac-
cess to the stage microphone signals.
The MAIN PA console connects to the DIRECT
output and supplies 48V phantom power to the
mics and active direct boxes.
The MONITOR console uses the ISOLATED out-
put and is therefore electrically decoupled from
the first console. The MONITOR console may be
powered from a separate AC-mains circuit with-
out creating ground loops.
Connecting Three Mixing Consoles
This advanced setup connects three consoles
to an 8ox.
The MAIN PA console connects to the DIRECT
output and the MONITOR console to the auxil-
iary DIRECT with LIFT output. In order to avoid
hum and buzz from ground loops these consoles
should be powered from the same AC main cir-
cuit or a power distribution system designed to
prevent ground loops from forming.
A third RECORDING console connects to the
isolated output and is therefore electrically
decoupled from the MAIN PA and MONITOR
consoles. The RECORDING console may be
powered from a separate AC mains circuit with-
out creating ground loops.
Main PA
Direct Output
Monitors
Isolated Output
Main PA
Direct Output
Recorder
Isolated Output Monitors
Direct with Lift
AC Mains
Circuit 1
AC Mains
Circuit 2
AC Mains
Circuit 2
Earth Earth
EarthEarth
AC Mains
Circuit 1 AC Mains Circuit 1
6

TruetotheMusic
Radial Engineering Ltd. 8ox & 8cx Owner’s Manual
The Radial 8ox features two internal grounding options that
will be of interest to system engineers when integrating the
8ox into complex audio-visual systems. Most users will not
need these options and can accept the factory default set-
tings.
Internal Ground Lift - Each Channel
Each channel’s transformer features an internal ground
switch that re-connects the ground around the transformer.
It may be used on a per-channel basis to accommodate
specific grounding needs. For example, it may be neces-
sary to set this switch to closed for devices that have a
floating ground like battery powered laptop computers or
devices powered with an AC to DC adaptor.
By default this switch is set to open, or lifted (out position)
so the transformer can decouple equipment connected to
the ISOLATED outputs. Pushing the switch in (closed) will
connected the input signal ground to the output ground at
the ISOLATED output for that channel.
Internal Chassis Ground Lift - All Channels
All tconnectors are 100% isolated from the steel chassis
allowing chassis and signal ground to be kept separate.
However, an single internal switch is provided to connect
the pin-1 cable shields to the chassis without modifying the
8ox. By default, this switch is factory set to open or “lifted”
allowing the chassis to “float” ungrounded.
Should a specific grounding scheme require the cable
shields to be bonded to the chassis simply set this switch
to closed (pushed in position). The switch may be accessed
through a small hole in the side of the steel chassis or by
removing the top cover. The chassis ground switch does
not effect the isolation provided by the transformer at the
ISOLATED output.
On the rear panel a ground screw provides a convenient
point to bond the chassis. Use a heavy gauge solid copper
wire to bond the 8ox chassis to your technical ground.
Each channel has a lift switch
directly below the transformer.
Access the internal chassis ground
lift switch through a small hole
in the side of the chassis.
Rear panel chassis screw used
for bonding to technical ground.
7