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.
¼” INPUTS: Left and right unbalanced, hi-Z inputs used to connect instruments. -15dB PAD: Reduces the input sensitivity to prevent overload. +48V: LED indicator will glow when the J48 Stereo is receiving phantom power. HPF: High-pass filter switch gently rolls off bass to remove rumble and resonant feedback (-3dB @ 80Hz).
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 connec- tions.
USIng THE -15dB PAD Inside the J48 Stereo is a unique switching power supply that is designed to provide plenty of headroom even when pushed very hard. There are however, instances when the output from an in- strument can be extreme. To prevent distortion, the J48 Stereo has a -15dB input pad that reduces the input sensitivity.
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The image above shows an audio source and a destination with a common electrical ground. As the audio also has a ground, these combine to create a ground loop. The transformer and ground lift work together to eliminate the ground loop and potential noise. Radial Engineering Ltd. J48 Stereo™ User Guide...
USIng VARIOUS InSTRUMEnTS The J48 Stereo is active. This means that it has a built-in preamp or buffer circuit that drives the signal. This is the benefit of an active direct box over a passive counterpart. In other words, if you have a passive source such as an old Fender bass, the J48 Stereo presents a very effective interface.
USIng THE HIgH-PASS FILTER A very handy feature that is built into the J48 Stereo is the high-pass filter. When activated, it gently rolls off low frequencies below 80Hz and helps eliminate resonance and feed- back. This handy feature is particularly effective at cleaning up the low registers, making it easier to mix.
OPTIOnAL RAck MOUnTIng kITS The J-Rak 8 and J-Rak 4 are an innovative rack mount chassis. The J-Rak 8 has eight vertical slots for Radial J48 Stereo direct boxes or the other Radial J-Class products. The J-Rak 4 has four horizontal slots.
Weight: ................................1.55 lb (720 g) FCC approval: ....................Complies with section 15 of the FCC Rules Conditions:..................For use in dry locations only between 5°C and 40°C Warranty: ............................ Radial 3-year, transferable Radial Engineering Ltd. J48 Stereo™ User Guide...
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