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From Our Research Team:

A Great-Sounding Active Direct Box

Over the past quarter century, sound systems have evolved as have the instruments that are now used. The listener has also evolved. CD quality sound is no longer a luxury, but expected. Only now are we beginning to hear and appreciate the advantages of a good direct box. A good DI must provide a wide distortion-free frequency response and the dynamic range to handle today's powerful instruments.



Radial J48 at a Glance:

• Active 48-Volt phantom powered direct box.
  
• Minimal power draw with high rail voltage.
  
• Will not choke when driven hard.
  
• Low inter-modulation distortion.
  
• Innovative merge function.
  
• 80Hz high-pass roll-off filter reduces mud and increases headroom.

The Radial J48 is an active direct box that has been specifically designed to work around the limited current that is available with 48-Volt phantom power, and do so while delivering the pure and natural sound of the instrument. A unique switch-mode supply steps up the internal rails to allow an input signal of up to 10V without any noticeable distortion.

Will Not Choke When Driven Hard
The single most important development goal of the Radial J48 was increasing the headroom without compromising sound quality. To this end, every possible effort was made to deploy the limited energy resources of phantom power to the audio signal path. To begin, phantom power is converted using a super-efficient digital switch-mode power supply that steps up the internal rail voltage to an impressive 10 volts. This allows one to hit the J48 with as much as 9-Volts without choking! To further increase available horsepower, all non-essential devices such a power-hungry LEDs are turned off when the J48 is in use. A typical LED requires almost as much current as does the complete audio circuit!

Lower Harmonic Distortion
Open up the Radial J48 and you will see huge, over-sized capacitors that provide ample current storage to assure clean, unobstructed power for the signal. With added headroom comes improved performance in all areas: Less than half the phase distortion of competing DIs, significantly lower harmonic distortion and single-digit inter-modulation distortion are all realized. Paying attention to these basic details has the net result of better sound.

Innovative Merge Function
But great sound is not the only innovation: The Radial J48 introduces several new functions that improve functionality and open the doors for greater creativity. The input panel features the usual 1/4" instrument input and thru-put connections. An innovative Merge function converts the thru-put into a second input to sum stereo sources to mono such as stereo keyboards or CD players when mixer input channels may be of short supply. A -15dB pad may also be inserted when confronted with abnormally high signals.

Reduced Hum and Increased Headroom
To reduce low-end rumble and run-away acoustic resonance, an 80Hz high-pass roll-off filter is provided. As with any power system whether it is acoustic or electrical in nature, bass always contains significantly more 'RMS power' than high frequencies. This is why low-frequency drivers require anywhere from 10 to 20 times more power in PA system designs than high-frequency tweeters. By gently removing unnecessary lows, the J48's dynamic handling is increased by a full 3dB or twice the power handling. This innovative feature both reduces mud and increases headroom at the same time!

Like all Radial products, the J48 is built to handle the abuse on the road and features a unique welded I-beam construction for years of trouble free performance.


Radial J48 Features:

• Welded I-beam construction makes it impossible to torque the PC board. This virtually eliminates cold solder joints - the No.1 cause of system failure in the field.
  
• An innovative 'slide-in-place' XLR trace makes it possible to use I-Beam girder construction.
  
• A digital switching power supply steps-up the internal rail voltage to 9-Volts. The J48 will not choke like other DI's when hit with large transients.
  
• A military-grade PC board is employed for maximum wear and tear in abusive environments. Welded steel standoffs ensure the PC board will not shift.
  
• A -15dB pad allows super hot inputs such as that from a CD player to be connected and balanced for long runs.
  
• Momentary 48V Check LED will flash once when the 80Hz filter is depressed to tell you phantom power is present.
  
• The Merge function turns the input & thru into 'left & right' inputs to mono mix at the XLR output. This handy function saves valuable inputs on the mixer!
  
• The input is connected to the instrument.
  
• The thru-put is connected to the instrument amplifier. The JDI has a high input impedance to reduce loading.
  
• Our book-end design creates a protective zone around the switches & connectors for best protection!
  
• A heavy-duty baked enamel finish for excellent durability and great looks for years! 100% 14-gauge steel construction.
  
• The 600 Ohm balanced XLR out is mic level to properly match concert splitters - will drive 1000 feet without appreciable noise.
  
• A polarity reverse switch flips the polarity from the AES standard Pin-2 to Pin-3 on the XLR and is used when combining sounds that may be out of phase.
  
• An 80Hz low-cut (high-pass) filter gently reduces excessive bass for more headroom and clarity. Eliminates run-away resonant feedback from acoustics!
  
• The ground-lift disconnects the ground path to the transformer at the XLR output. This is used when a ground path is made at the input side such as with a keyboard.
  
• A no-slip full bottom pad reduces mechanical vibration, improves electrical isolation and keeps the JDI from moving around on busy stages!

The Radial J48 is a great sounding active direct box that is specifically designed to work with today's powerful active instruments. It provides a real-world solution to the limited headroom caused by inadequate current from 48V phantom powering. Plug-and-play and easy to use, the Radial J48 is ideally suited for studio, broadcast and stage use where high quality sound is required.

Specification Detail Type Active DI Channels 1 Inputs 1 x 1/4" Outputs 1 x XLR, 1 x 1/4" thru Height 2" Depth 5" Width 3.3" Weight 1.55 lbs. Manufacturer Part Number R800 3001