How many times can you reinvent the wheel? A direct box may seem like a simple piece of gear — and some are, such as Radial’s acclaimed JDI line of passive direct boxes. But when active processing enters the picture, Radial has been known to break out of that “just a direct box” mold with some creative designs and features that redefine the modern direct box. In fact, Radial seems to do this on a regular basis and improves on it every time. The Mk5, the latest version (and fifth generation) of the company’s popular JDV active direct box, features some interesting and useful innovations that take it well beyond the norm.
Features & Functions
The user guide is well put together, informative and useful. It even has a block diagram so you can see the routing of the electronics.
But let’s begin with a look at the JDV Mk5’s front panel. There two input channels with separate level adjustment knobs for channel A and B. Both channels also have individual knobs for high pass filters ranging from 5 Hz to 500 Hz.
There is also a channel select button and LED indicator to switch between channels A and B. A Phazer (phase adjustment) knob to fine-tune the relative phase (time alignment) between channels A and B. But this is no simple polarity reverse: A switch changes your adjustment option from 1 to 180 degrees to 181 to 360 degrees — an essential touch, particularly on combined miked/direct bass feeds.
LEDs on each channel show if you are receiving signal or you are overloading. Channel A has a “10M” switch sets the load to 10 Mohms for piezo or variable drag for magnetic pickups. A “drag” adjustment knob for matching the load of passive pickups is one of the recent innovations that Radial has broken new ground with. Also on channel A is a phantom power LED to let you know 48V phantom power is active on the mic input.
The actual phantom power switch is on the side of the box, along with a button to blend channels A and B, and an Aux out/direct switch that lets you introduce an isolation transformer into a stage amp output signal path to reduce ground hum or buzz.
I have to say that these switches, as well as the load switches on the front are all recessed inset switches, which I think are great for keeping them safe from getting bumped by accident, but I had trouble visually telling if they were active or not. The phantom has a front panel LED, so that is identifiable, although I had trouble turning the phantom off. I thought I had released the switch, but the LED remained lit.
To continue with the front panel, in addition to the level and high pass filter adjustment, channel B has a load switch that the input impedance from 10M ohms for piezo transducers to 220k ohms for magnetic pickups. On the back panel we’ve got a locking 4-pin XLR power connection, a standard 3-pin XLR output that is transformer isolated to address ground loops.
Slick Input Tricks
There are also two unbalanced 1⁄4” input jacks used to connect instruments to either channel A or B. There is a balanced 1⁄4” TRS microphone input. And as the unit has phantom power, you can use a condenser or dynamic microphone. One slick trick comes from the “Blend” switch, which makes both the A and B inputs active at the same time. Using the Blend switch, you can easily combine an instrument’s Hi-Z pickup output (going into channel B) with a mic input (such as a miniature clip-on mic) going into channel A. This opens up a lot of tonal variations with a rotary pot on each controlling the blended sound. The downside here is that the mic input is TRS, so you will have to come up with an appropriate adapter to connect to your mic.
An unbalanced 1⁄4” thru output can be used to feed a stage amp. There is also a 1⁄4” tuner output and an input for an optional JR2 remote footswitch. When connected, this lets you select the input channel or mute the JDV for silent tuning. There are also a series of inset switches to adjust the XLR output. The first is a polarity reverse that inverts the signal polarity by flipping pin-2 and pin-3 on the XLR output. The second is a ground lift that disconnects pin-1 at the XLR out to reduce hum or buzz that might be caused by ground loops. Switch three adds a transformer into the XLR signal path to help eliminate noise — or simply add another tonal variation. Switch four increases the XLR output from mic level to +20 dB line level for direct connection to a console.
The Bottom Line
I tried the JDV Mk5 out with a variety of instruments to see how it handled them. I tried guitars, keyboards and bass and the JDV did not color their sound in any way, which is what I look for in a direct box — that is, unless I wanted more coloration and here, the unit delivers a wide palette of possibilities.
From an audio perspective, the JDV Mk5 rocked, taking full advantage of the clarity of its discrete Class-A electronics, feed-forward design and 30-volt rails providing headroom for days — exactly what you want when capturing the percussive transients of hard rhythm guitar strums.
Is this the perfect direct box for every situation? Hardly. The JDV Mk5 is a precision instrument and would not be my first choice when plugging into a bass rig from band #11 while doing sound for an all-day street fair. But for use with players that are willing to make a relatively small investment in time to create the optimal sound from their instrument, the JDV Mk5 is an ideal tool for some serious sounds. Radial Engineering refers to this flagship model as a “Super Direct Box” and I believe you’d be hard pressed to find a more versatile, great sounding tool in your sonic arsenal.
JJ Jenkins is a live sound and studio engineer based in the San Francisco Bay Area.
At a Glance
The Super Direct Box?
Radial Engineering’s flexible and versatile JDV Mk5 direct box combines a non-compromised approach to audio purity with an advanced feature set for sonic tweaking — and a host of functions that redefine the notion of a “simple” D.I.
PROS
- Transparent, but full featured
- Tough, near-indestructible construction
- Unit can output at mic or line level
- Jensen Transformer isolated outputs
CONS
- Uses external power supply
- It can be difficult to determine which position the inset switches are in (particularly on the side of the unit).
Radial Engineering JDV Mk 5
SPECS
- Frequency Response: 20 Hz to 20k Hz
- Dynamic Range: 107 dB
- Equivalent Input Noise: -90 dBu
- Weight: 2.8 pounds
- Price: $449/street
Manufacturer: Radial Engineering
More Info: www.radialeng.com
