Radial Engineering has earned an enviable reputation for the performance of its high quality direct boxes, Now from Radial comes the JDX Reactor™, a guitar amplifier direct box that takes a new slant to capturing guitar tones onstage.
Something Completely Different
Radial offers a full line of direct boxes, both active—solid-state and tube—as well as a few passive designs. But the JDX Reactor takes a completely different approach. Unlike your typical DI, a ¼-inch speaker input on the JDX accepts the output of a guitar (or bass) amplifier, while a second ¼-inch jack routes the signal back to the speaker cabinet. The output of the JDX’s Reactive Amp Emulation process is intended to mimic the sound of a Shure SM57 on a Marshall 4×12 cab—familiar territory for most working engineers.
Radial Engineering is very clear about the fact that the JDX is not a “load box” and does not replace a speaker cabinet. In fact, the JDX relies upon the interaction between the amplifier and the speaker to derive its sound. The benefits of the JDX are that it maintains consistency of sound regardless of microphone placement or selection, and the output provides total isolation from the rest of the stage.
Features, Functions
In addition to the ¼-inch jacks previously mentioned, the JDX features a balanced XLR output at microphone level for connection to a mixing console, an input for the supplied 15 VDC power supply, an LED power indicator and switches for the ground lift and polarity reverse functions. The JDX’s solid case is flanged to protect the connectors and switches, and the power supply connector is recessed to further protect it from damage. There is no on/off switch and the JDX cannot be battery or phantom powered.
Setup for the JDX requires that the guitar or bass amp provides access to the connection between amp and speaker. This is certainly not an issue with most amps, but it might require some creative thinking or fabrication of cables on older combo amps. Radial recommends making all connections prior to turning on the gear—always a good idea, anyway—although powering up the JDX last created no noise bursts, whumps or artifacts.
On Test, On the Road
I patched the output of two Marshall JCM900 heads into two JDXs on the way to their respective Marshall 1960A cabinets. In this particular situation, I was using Shure SM57s to mike the amps, one per cabinet (the guitar rig was stereo) so there were a total of four channels going to the mixing desk: mic left, mic right, JDX left, JDX right. At the console the mics were hard-panned left/right, as were the JDX units.
Sound coming from the JDX feed was surprisingly close to the sound of the SM57s on the speaker cabinets—most listeners would be hard-pressed to tell them apart. Differences were subtle enough that a bit of EQ could make them nearly identical.
On heavily distorted timbres, the JDX sounded slightly “closed” in the upper mids, almost is if there was a slight loss of “air.” In this particular case, I used all four channels in the mix and rode the JDX channels up for solos. Of course soloing the microphones revealed bleed from the stage while the JDX channels were 100 percent isolated—always a good thing especially when loud bass amps are nearby.
I also used the JDXs on Peavey Classic 30/112 and Fender Twin Reverb combo amplifiers (with Shure SM57 and Audix i5 microphones). Both of these amps allow their speakers to be disconnected from their respective heads. In both cases, clean fingerpicked sounds were warmer coming from the JDX and I preferred them over the mic/speaker combos.
Of course moving the microphone changes the tone—a double-edged sword. The good news is that you can tweak the sound by moving the mic. The bad news is that an overzealous musician can bump or knock into the mic stand and change the tone you worked so hard to achieve. This would never be an issue with the JDX; in fact, you could certainly fly without the mics. Any changes made to the tone or drive controls on the amp were clearly heard in the JDX output and there was no loss of dynamics through the JDX.
When using the Fender amp to create crunchy overdriven tones, the JDX sounded better than the speakers, capturing the sound of the speaker thumping back and forth on palm muted parts. It was interesting to connect the amp heads to different speaker cabinets and observe changes in the sound of the JDX. Clearly, the JDX is somehow “monitoring” changes in the interactive relationship between the amp head and the speaker and translating this to the balanced output signal.
The Bottom Line
At a street price of around $200, the JDX is a highly useful tool that effectively solves the issue of day-to-day consistency, while maintaining complete isolation of a guitar or bass amp from loud nearby instruments that otherwise cause leakage. Even if you aren’t experiencing onstage leakage issues, it’d be worth checking out the JDX as an optional sound for your mix, especially in situations where performers are using in-ears.
More information at www.radialeng.com.
