Radial Engineering J48 Stereo User's Guide

j48 stereo user guide
jensen transformer equipped
active 48v phantom powered direct box

Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5

Tel: [phone] • Fax: [phone] • Email: [e-mail]

j48 stereo direct box
user guide

Introduction ........................................................................ 1

J48 Stereo Features .......................................................... 2

Making Connections .......................................................... 3

Using the PAD ...................................................................4

Using the Ground Lift......................................................... 4

Using Various Instruments ................................................. 5

Examples ........................................................................... 6

Using the High-pass Filter ................................................. 7

Using the Polarity Reverse ................................................ 7

Optional mounting accessories ......................................... 8

Specications .................................................................... 9

Block diagram .................................................................. 10

Radial Limited Warranty ....................................Back Cover

Thank you for purchasing the Radial J48 Stereo. This wonderful active direct box employs a unique internal switching
supply that employs 48 volt phantom power and steps it up to increase the signal handling while it lowers distortion of all
types. Part of the magic behind the design is that it enables the user to lift the audio ground connection to eliminate noise

without disconnecting the 48V phantom power source. This means that you can enjoy the benets of an active direct box

without having to resort to batteries or some form of external power supply. This makes the J48 Stereo a very effective DI
box for all types of instruments in both live stage and studio recording applications.

The J48 Stereo is in fact a very easy to use direct box that is purpose-made to be compact and quick to deploy. You simply
plug it in, turn on the phantom power and it goes to work. There are however a number of features built in that should be
understood in order to get the most out of your J48. So please take a few minutes to go through this user guide to ensure

you get the most out of it. If after you have read it, you nd yourself asking questions; please visit the FAQ section of the
web page. This is where we post updates and questions from users. If you still do not nd the answer or need further
clarication, we invite you to send us an email at [e-mail] and we will do our very best to reply in short order.

Now get ready to enjoy the world’s nest phantom powered active direct box!

Radial Engineering Ltd. J48 Stereo™ User Guide

1

FEATURES

1. ¼” THRU-PUTS: Left and right parallel outputs used to

connect the hi-Z instrument signal to an amplier, tuner or

personal monitoring system.

2. ¼” INPUTS: Left and right unbalanced, hi-Z inputs used to
connect instruments.

3. -15dB PAD: Reduces the input sensitivity to prevent overload.

4. +48V: LED indicator will glow when the J48 Stereo is
receiving phantom power.

5. HPF: High-pass lter switch gently rolls off bass to remove

rumble and resonant feedback (-3dB @ 80Hz).

6. BOOKEND DESIGN: Creates a protective zone around the
switches and connectors.

7. 180° POLARITY (side panel): Reverses the polarity of the
RIGHT XLR output by toggling pins-2 and 3.

8. I-BEAM REINFORCED: 14-gauge steel enclosure with rigid
I-beam construction makes it impossible to torque the PC
board and cause solder joints to go cold.

9. XLR OUT: Left and right balanced, low impedance mic level

output. Wired to AES standard (pin-2 hot).

10. GROUND LIFT: Disconnects the ground from the audio

signal path and helps eliminate hum and buzz caused by

ground loops.

11. NO SLIP PAD: Provides electrical and mechanical isolation
and keeps the J48 Stereo from sliding around.

12. POWDER COAT FINISH: Durable nish keeps your J48
Stereo looking great for years.

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Radial Engineering Ltd. J48 Stereo™ User Guide

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OVERVIEW

The Radial J48 Stereo is an active direct box that derives its power from the 48 volt phantom supply from the mixing
console or mic preamp. You simply plug in and it will quietly go to work.

MAKING CONNECTIONS

As with all audio gear, always ensure audio system levels are turned down or equipment turned off before making connec­tions. This will avoid plug-in or turn-on transients from damaging more sensitive components such as tweeters.

There are two channels on the J48. These are identical and feature a ¼” INPUT, a ¼” THRU-put and a balanced XLR out.
Connect your source instrument to the input and the balanced XLR out to the PA system or recorder. The THRU connec­tor output provides the means for connecting the signal to a stage amp or personal monitor system. Simply connect the
THRU to your amp or monitor. Unbalanced cables are much more susceptible to noise than their balanced counterparts.

Keeping unbalanced cables under 8 meters (25’) in length is good practice while balanced cables can easily extend 100
meters (300’). The balanced output of the J48 Stereo is mic level, meaning that it should be connected to the mic input

of a mixing console or mic preamp. Once connected, make sure phantom power is activated. The green LED on the J48
Stereo will illuminate to let you know phantom power is present.

MonitorsSub-Mixer

ThruThru

InputsInputs

J48 Stereo with a keyboard, mixer and powered speaker.J48 Stereo with an acoustic guitar and stage amp.

Radial Engineering Ltd. J48 Stereo™ User Guide

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Balanced OutsBalanced Out