Radial Engineering OX8-r, OX8-j User's Guide

True to the Music

OX8

User Guide

Eight Channel • Transformer Isolated • Microphone Splitters

Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5
tel: [phone] • fax: [phone]

www.radialeng.com

email: [e-mail] • web: www.radialeng.com

Specications and appearance are subject to change without notice.
© Copyright 2009, all rights reserved.

www.radialeng.com

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True to the Music

OX8

User Guide

Eight Channel • Transformer Isolated • Microphone Splitters

Table of Contents Page

OX8 Introduction......................................................1

OX8 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

CX8 Introduction ......................................................8

CX8 Installation .......................................................9

INTRODUCTION

Congratulations on your purchase of a Radial microphone splitter. This manual covers installation and operation of the OX8 micro­phone splitter. 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.

Should you have questions or applications not covered in this manual, we invite you to log onto the Radial web site at www.radialeng.
com to check the FAQ section for the latest updates. Of course, you can also send us an email at [e-mail].

OX8 DESIGN CONCEPT

The Radial OX8 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 on­stage 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 produce buzz and hum. To avoid these pitfalls, sound reinforcement com­panies have been building custom “splitter-snakes” for many years.

The OX8 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.

Radial Engineering Ltd. OX8™ User Guide

1

BASICS

What is a Mic Splitter

In modern concert production there are often two separate sound sys­tems. The main PA covers the audience or “house” while a monitor sys­tem covers the stage so the performers can hear. A third system may be
added if the concert is to be recorded. Each system requires it’s own mix­ing console because the mix that sounds good in the house simply won’t
work for the monitors or be suitable for a recording. A mic 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.

True to the Music

Stage Microphone

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 OX8 uses high performance audio isola-

Isolation

Transformer

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). A transformer 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 eld
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

Main PA Recorder

Monitors

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.

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.

Transformer Isolation

Ground Loop Path

Earth

Earth

Once the loop is complete there is the electrical potential for DC voltage to ow through it. This potential is caused by the interaction
between devices with different ground voltage references and allows unwanted spurious current to ow through the shields of the
signal cables. This ow 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 ow 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 Eclipse® and
Jensen® transformers apart. Designed for pro-audio applications, they include a host of features not found in general purpose audio
transformers. A core 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 inside a mu-metal can which provides enhanced shielding from electromagnetic interference. The built-in Bessel
low pass lter removes ultrasonic distortion that can mask natural sound and cause ear-fatigue.

2

Radial Engineering Ltd.

OX8

™

User Guide