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New JDV Mk3 from Radial Engineering

Oct 21, 2002

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Radial Engineering announced the release of the Radial JDV Mk3 direct box. A departure from regular DI's, the JDV combines multiple inputs and outputs for signal routing, with greater interface facilities while at the same time, featuring a high-voltage, feed-forward Class-A circuit topology.

According to Radial President Peter Janis: "For 30 years, direct boxes have followed the same basic design whereby one connects the source instrument to the input, the thru-put goes to the musician's amplifier, and the balanced output is connected to the mixing console. When we set bout redesigning the JDV, we cleared the slate and rethought the whole DI process. We looked at how tracks are being recorded and what musicians are using on stage. We then looked at how instruments have changed in the past 10 years and found that for the most part, direct boxes have simply been left out of the evolutionary process."

"Consider this: Most bass players today use more than one bass on stage and many players are running stereo rigs. Furthermore, when recording in the studio, combining sounds from a direct feed, stereo effect feeds and multiple amplifiers, is not rare; it has become the norm."

"More importantly, acoustic and bass guitars have pretty much all shifted from being passive to active with built in pre-amps. These pre-amps are putting out anywhere from 3 volts to 7 volts and in some cases, dual 9V batteries are employed. Considering that most DI's use phantom power, there is a hidden problem that many are completely oblivious to: Phantom may have 48 Volts, but it only has 5 milliamps of current. This means that the maximum voltage available is 2.4 volts peak. The result is predictable: subject a 5 Volt peak from a guitar to the 2.4 Volts available in a traditional DI and you get square wave clipping."

"For years, I have been going to concerts wondering why the acoustic guitar always seemed to sound thin with tons of peaks and no body or sustain. The player was using a high quality guitar and the console world class... Then it hit me... could the DI be overloading? We tested regular DI's and found that our hypothesis was correct: Once the capacitors get charged up, there is nowhere left to go. The dynamic range and headroom is squashed, the DI chokes, and as expected, the sound is awful. We are pleased to announce the new Radial JDV Mk3 addresses all of this and more!"

The JDV Mk3 direct box features a 100% discrete, feed-forward Class-A circuit, that one can best equate to the way a tube is utilized in a traditional amplifier. This is combined with a 30 Volt internal rail voltage for headroom. As a unity gain device, the JDV will handle almost any input level and send it out at full capacity. A -15dB PAD has been positioned at the output to avoid overloading the console. Input functions include an on-board high-pass filter to reduce low-frequency mud and run-away resonance from acoustic guitars. A low-pass (hi-cut) is also included to reduce hiss from older guitar preamps and other noisy electronic devices. Two selectable inputs are provided to allow two instruments to be connected at one time. A selector switch on the control panel provides switching without having to mute the amplifier or PA. These are monitored with both signal present and overload LED indicators.

To further enhance performance a two-stage impedance-matching system is provided. A 3.9 meg-ohm input allows proper interface to piezo style pick-ups such as those used on stand-up bases. The JDV also features Drag Control , a feature that was developed for the Radial JD7 Injector.

Janis continues: "When we developed the JD7, we noticed a very subtle problem that caught our attention when using old vintage guitars. We developed a circuit that was so good at reproducing the original sound; it actually ended up being too good! Here's the crux: As soon as a signal goes through an active pre-amp such as a direct box, it gets buffered or effectively changes from being passive to active. The natural relationship between the instrument and the amplifier is lost. This natural loading is essential if one wants to retain the original character of the instrument. Drag Control is an impedance-resistance network that allows the user to dial-in the natural loading for a natural sound. In fact, after a while, the subtleties become addictive! We have noticed that producers and engineers use Drag all the time."

The JDV is equipped with four different instrument outputs for added hook-up flexibility. These include a direct output such as found on a typical direct box, two Class-A instrument outputs designated as AUX-A and AUX-B to drive alternate amplifiers, effect boxes, or stereo rigs. A tuner output is also provided that allows constant monitoring without interfering or adding additional load to the original signal.

The output panel features a standard XLR-male for balanced Class-A output to the console. This is coupled with a polarity reverse that flips pin 2 and 3 adding yet another creative and electrical dimension. A ground lift switch decouples the XLR ground pin to reduce ground loop noise. The JDV is also equipped with two pads: a -30dB pad allows a signal to be tapped from a speaker cabinet for a post-amplifier sound while a -15dB pad is on the output to tame down the JDV's high level potential.

The JDV features a 'bookend' design that creates a protective zone around switches, Drag control and jacks. A full bottom no-slip rubber pad provides both mechanical and electrical isolation while ensuring the JDV not slide off the amplifier during performance. Construction is welded 14-gauge steel with a durable baked enamel coat to ensure that outside stress from abuse will never see the double-sided military grade PC board.

For more information, visit their web site at www.radialeng.com.
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