Using the J+4

Connections & Powering Up
Before making connections, start by making sure all audio system levels are either turned off or volume down to avoid any connection popping that could harm your speakers. Connect the 15VDC power supply. Note that the J+4 comes equipped with its own power supply. If yours 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.

Connect the desired source device (ie: a CD player, i-Pod, computer sound card, DJ mixer) to the stereo input jacks. Connect the XLR outputs to your mixing console. Keep in mind that the J+4 produces a line level output. This means that you can bypass the preamp stage on your mixer or even drive a power amplifier directly from the J+4.

It is always a good idea to test the audio at low levels to make sure all your connections are working. Set the level control on the J+4 to zero or all the way counter-clockwise to 7 o’clock. Turn on the source device (example: CD player). Bring up the level on your audio system and slowly increase the level on the J+4. Listen. If you hear distortion, check to make sure the J+4 is not overdriving your console. If you hear hum or buzz, try lifting the ground switch this lifts the ground on both XLR outputs. You should be ready to go.

High Pass Filter
The Radial J+4 is equipped with a handy high-pass filter that is used to cut low frequencies below 100Hz. This provides several important benefits. First and foremost, when playing back audio tracks through a PA system, excessive bottom end can produce low frequency resonance which in turn can cause run-away feedback. It is also important to note that bass frequencies contain significantly more energy than higher frequencies. Reducing bass content can dramatically increase your system’s dynamic range. Finally, by reducing unneeded low frequencies, it really helps clean up the mix.

J+4 Specifications

Frequency response:	10Hz ~ 20kHz (+/- 1dB … -3dB at 40kHz)
Signal to noise:	100dB
Input level:	-10dBu typical
Maximum input level:	+17dBu
Maximum output level:	+15dBu
Dynamic range:	100dBu
Total harmonic distortion + noise:	0.004% (-10dBu input, +4dBu output)
Channel separation:	>90dB
Self noise:	-95dBu
Input impedance:	10k-Ohms
Output impedance:	600-Ohms typical
High pass filter (low cut):	-3dB at 100Hz
XLR configuration:	AES standard… pin-1 ground, pin-2 hot
Power Requirement:	15VDC 400mA center positive - 30mA draw power supply included
Construction:	14 gauge steel chassis and outer shell, baked enamel finish
Size:	3.3" x 5.0" x 2" (84 x 127 x 48mm)
Weight:	1.55 lb (720 g)
Warranty:	Radial 3-year, transferable