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JDX 48™ Reactor™ Development

One of the most significant changes to occur on live stages has been the advent of in-ear monitors. 'In-ears' have largely replaced wedge monitors on major tours as they provide the artist with a more controlled listening environment, improved hearing protection and benefit by a cleaner looking stage.

Along with this technological advancement, a stark reality has come to bare: In the past, the guitarist would hear his amp and assume that what he heard on stage was the same sound going to the PA. But with in-ears, he is no longer hearing his amp - he is hearing the microphone. And he's not happy. Just put your ear right up close to a Marshall stack and give it a listen. Not only will you find it to sound harsh, you will wonder how the sound engineer ever managed to make the guitar amp sound good.

When a guitarist is playing (and listening) to his amp, the tone changes as he moves around. This is caused by the phase shift between the individual speakers, the sound reflecting off the stage floor and the room acoustics. With in-ears, the sound becomes static. It is merely a snap shot of the sound generated by the microphone. Ask any engineer and they will tell you… move the mic ever so slightly and the tone will be different - depending on where it is pointed and how far away it is from the loudspeaker.

Enter the JDX Reactor
Just like a microphone, the Radial JDX delivers a snapshot. In other words, it is designed to replicate the type of sound that one would get using a Shure SM57 positioned 2" away from a loudspeaker mounted in a 4x12 Marshall half-stack cabinet. The signal is then sculpted using a multi-stage EQ to sound good. Is the JDX 48 perfect? No. But it provides the engineer with a tone that is both very usable and consistent – show after show.

The real magic with the JDX is the reactive load. Other guitar amp interfaces merely take the signal from the head, filter it and send it along the way. Some companies have even tried to replicate the 'effect' of a loudspeaker by using light bulbs and resistor banks. But a loudspeaker is a motor and it generates an impulse as it moves and this is part of the very fabric that makes a guitar amplifier sound the way it does.

When developing the JDX, we asked ourselves a simple question: Why try to replicate the effect of a loudspeaker? Why not simply use the loudspeaker itself and capture the effect? The JDX is wired in such a way to capture both the signal coming from the guitar amplifier head and the back-electromotive impulse from the loudspeaker. It is this combination that sounds realistic.

At first this may sound confusing, but it is in fact quite simple. To create a circuit, you need two wires. Think of a light bulb connected to a battery. In other words, the circuit is created when the signal flows from the source, through the load and back to the source. The source in this case is a guitar amplifier and the load is a loudspeaker. The JDX is basically wired in parallel with the 'guitar amp circuit' and the sound is captured using a reactive load. In the JDX, the magic (reactive load) is the combination of a transformer and the loudspeaker itself.

The JDX 48 Advantage

  • Consistency
    When the artist is equipped with in-ear monitors, he or she quickly becomes familiar with the tone and comfortable once it is dialed in. With today's digital mixers, it is easy to set up a snap shot of what the artist expects and you can deliver the exact tone night after night. That is… unless someone moves the mic or changes the room acoustics. The Radial JDX 48 eliminates the variables, the tone is more consistent and the artist is happy. Happy artist = better performance.
  • Stage acoustics
    Problems that are rarely considered are the variables introduced by the room acoustics and stage resonance. If you are surrounded by highly reflective surfaces, the sound echoing off the walls and floor will interfere with the signal causing a phase canceling effect known as comb-filtering. To make matters even more abstract, one stage may be hard, the next hollow, causing a different resonance to enter into the mic each night. By eliminating the microphone, you eliminate many of the unknowns. Get these out of the way and you get a more consistent sound.
  • Improved sound
    By eliminating the variables such as mic placement and acoustics, you get a more consistent tone. This makes it a whole lot easier for the monitor engineer to provide great sound to the artist and allows the front-of-house engineer (FOH) to spend more time mixing the band, not searching for on the fly solutions to problems that he may have little or no control over. Better sound = happier audience.
  • Added features
    During the JDX 500 development, we decided toad a couple of features to add more flexibility in the studio. The first was extra power handling for high-output 300 watt guitar and bass amps. Although the original JDX could handle plenty of power, we felt that adding this extra safety net could be valuable for some. We also added a bass extension to enhance the low frequency output of the JDX 48 for 5 and 6 string basses. This is of particular benefit in the studio where sculpting the tone can be done in post-production.

Now with phantom power

The Radial JDX 48 is in fact the latest in our never ending search to improve Radial products. Many sound engineers have hesitated to use the original JDX as it required an external power supply. The new JDX 48 gives you the option to power it using standard phantom power from the mixing console or by using the included power supply. This means that you have one less headache to worry about on stage… and in the studio, you have the freedom to use local DC power if you are sending the JDX 48 output to a device that is not equipped with phantom.

So how does it sound?

Radial president Peter Janis relays the following experiences: "I first heard the JDX on tour with Radiohead. I was at front of house during the sound check and FOH engineer Jim Warren had set up two channels on the guitar amp. He was toggling between a Shure SM57 and the Radial JDX and asked: 'do you hear that?' Hear what? I could not hear any difference. He said: 'Exactly. Neither can I… In fact I am not sure which channel is the mic and which one is the JDX."

"The next big show was Chickenfoot. I had gone to the venue that afternoon to show Joe Satriani the Radial JX44 guitar and amp switcher. During sound check, the band struck up a tune and I was immediately impressed by the tone of Michael Anthony's bass system. It was as if listening to an SVT but loud. Really loud! Yet the tone was clear and punchy. I went to FOH engineer Russ Giroux and asked him what mic he was using? He said I am using the JDX. I said 'You can't do that! It's not for bass, it is designed for guitars… you will blow it up!' He said 'I've been using it on bass for months… it works great!' Since then, bass players around the globe soon followed suit."

More recently, session superstar Michael Thompson – known for his work with David Foster has this to say about the JDX:"I've used the Radial JDX as my main direct recording box for 8 years and although I own all the top speaker emulators the JDX is still the most natural sounding one. Whenever I perform live I always send the feed from the JDX to the house (instead of mic'ing my cabs) and I'm always really happy with the results. On the "Michael Bolton Live at the Royal Albert Hall" CD I'm using the JDX exclusively. I'm using the JDX on the new Bryan Adams album (due out soon on Verve Records) and I've used it on all the records that I've done since I got it including Shania Twain's "UP" album that I did with Mutt Lange. I also used it a bunch on Nathan East's new release on Yamaha Records."

Today, the JDX 48 is used by all kinds of bands from all types of musical genres. This includes heavy metal guitar bands like Slayer, Megadeth, System of a Down and Dimu Borgir; country acts like Rascall Flatts and Grand Ole Opre house band; rock artists like Lucinda Williams, Aerosmith, Whitesnake, Evanescence and Radiohead, and you can hear it on bass with Queen, Chickenfoot and the Prodigy.

Janis continues: "Queen's bass player Danny Miranda said it best: For the first time, I can hear my bass through the PA like it sounds on stage. I love it!"