The J48 Stereo active direct box is the first stereo direct box manufactured by Radial Engineering.
‘Since the Radial J48’s release in 2001, it has become the world’s most popular active direct box for live touring,’ says Radial President, Peter Janis. ‘What makes the J48 unique is the internal switching power supply. This elevates the internal rail voltage for greater headroom and less distortion, while providing a method to lift the audio ground without losing phantom power. This produces a wider frequency response, a higher output level over a passive DI and eliminates having to deal with batteries going dead in the middle of a show. For years, we have been asked to come up with a stereo version.’
The J48 Stereo is housed in a 14-gauge steel book-end case with an internal I-beam to ensure that the internal PC board will not torque – which could cause ‘cold solder joints’. All connectors are made from glass-filled nylon and are insulated from each other. Extra duty nickel-silver contacts are employed that will not tarnish over time.
The power supply converts the 48V phantom, increasing the headroom for improved signal handling and lower distortion. This results in a linear frequency response that spans from 10Hz to 40kHz while being able to handle high output instruments such as a digital piano or active bass without choking. An additional -15dB pad may be engaged should the need arise. A built-in high-pass filter gently rolls off low frequencies below 80Hz to clean up mud and excessive resonance. This is augmented with a side-access 180° polarity reverse that can be handy when using the J48 Stereo with dual element pickups to either phase align the sources or eliminate hot-spots on stage that can cause feedback.
The other benefit of this unique design is the way the J48 Stereo handles hum and While traditional designs eliminating ground loops by disconnecting Pin-1 at the XLR output and some manufacturers use a battery solution, the J48 Stereo employs a DC-to-DC converter with a high-frequency transformer that enables the audio ground to be lifted at the power supply. This does not shut off the phantom power and is invisible to the user.
With very low crosstalk, the J48 Stereo is suited to stereo instruments or may be used with two different instruments at the same time.
