Radial Engineering J48 Stereo Active Direct Box

The Radial J48 Stereo is a high performance active direct box designed for professional touring and studio recording. It features the same award-winning signal path that has made the single channel J48 the most specified active direct box on tour today. And with users as diverse as Paul McCartney, Tommy Emmanuel and Joe Chiccarelli, can be sure it will meet the most demanding qualifications. The design begins with a rugged 14 gauge steel construction and a bookend design that protects sensitive switches and connectors from damage. The internal I-beam construction ensures the fragile internal PC board will not torque, which in turn could lead to cold solder joints developing and premature failure. All connectors are made from glass-filled nylon and feature extra large nickel-silver contacts that will not tarnish over time. Inside, a unique switching power supply converts the 48 volt phantom to AC, increasing the headroom for improved signal handling and lower distortion. This results in an exceptionally linear frequency response that spans from 10Hz to 40kHz while being able to handle high output instruments without choking. In addition, a -15dB pad may be engaged for extreme signal handling. This is supplemented with a high-pass filter that gently rolls off low frequencies below 80Hz to clean up mud and excessive resonance. A side-access 180º polarity reverse aids when using the J48 Stereo with dual element pickups to either phase align the sources or eliminate acoustic hot spots that can cause feedback on stage. A unique aspect of the power supply is the way that the J48 handles buzz and hum caused by ground loops. The traditional solution is to lift the audio ground by disconnecting pin-1 at the XLR output. When this is done, the 48 volt phantom power from the console is shut off, forcing one to introduce a battery into the equation. Unfortunately, batteries are inconsistent, and when they begin to drop power, severely affect the available voltage and resulting headroom. Instead, the J48 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.