Using The J+4 - Radial Engineering J+4 User Manual

USING THE J+4

Before connecting, make sure all audio system levels are turned off to avoid any
transient popping noise that could harm your speakers. Connect the 15VDC power
supply included with the J+4. If your power supply gets lost or damaged, make sure
you replace it with an original Radial power supply as the output and polarity are
properly matched. Once the power is connected, the front panel power-on LED will
illuminate indicating the J+4 is ready to use.
Connect the desired source device (ie: a CD player, smartphone, computer sound
card, DJ mixer) to the stereo input jacks on the J+4 using a ¼" phone, RCA or 3.5mm
stereo cable. Since this part of the signal chain is unbalanced it is a good idea to
keep these cables under 8 meters (25 feet) to reduce the chance of inducted noise.
Connect the XLR outputs to your mixing console using balanced, twisted pair mic
cables. The length of the XLR cables is only limited by the quality of the cable but
typical lengths from 100 to 600 meters (300 to 2000ft) are usually not a problem.
The J+4 produces a balanced +4dB line-level output allowing you to bypass the
mic-preamp stage on your mixer and connect directly to a line input or even drive
a power amplifi er directly from the J+4.
If your mixer uses ¼" TRS phone jacks for balanced line inputs you can follow
the diagram below to make a TRS to XLR cable that will maintain the balanced
connection.
Tip
It is always a good idea to test the audio at low levels to make sure all your
connections are working properly. Set your audio system to a low level and the level
control on the J+4 to zero by turning the level control fully counter-clockwise. Turn
on the source device (example: CD player) and slowly turn up the level control on
the J+4. If you hear distortion, check to make sure the J+4 is not overloading the
input of your console.
Ground Lift
The J+4 is equipped with a dual ground lift switch that disconnects the pin-1 ground
connection on both XLR outputs and prevents ground loops. If you hear hum or
buzz, try toggling the recessed 'set & forget' ground lift switch on the side of the
J+4 using a tweaker tool.
Level Control
The LEVEL control sets the output level for both XLR
outputs. With a -10dB input signal this level control ranges
from infi nity to +10dB. The J+4 will produce a +4dB signal
level when the control is at the 12 o'clock position.
High Pass Filter
The Radial J+4 is equipped with a high-pass fi lter that is used to roll-off low
frequencies below 100Hz. Bass frequencies contain signifi cantly more energy
than higher frequencies. When playing audio tracks through a PA system, reducing
bass content with the high pass fi lter can increase the dynamic range of your audio
system. When recording a -10dB source signal, the high pass fi lter can help clean
up a muddy mix by reducing low frequencies.
Radial Engineering Ltd.
Ring Sleeve
Sleeve
Tip
Ring
Shield
Output Level Calibration
Female XLR
Pin-1
Pin-2
Pin-3
with -10dB input
J+4 ™ User Guide