I have always been a fan of Radial's direct boxes and have gotten plenty of use out of their JD4 rackmount DI over the years, so I was excited to record some tracks with their latest 500-series unit. Radial's line of 500-series modules can now lay claim to a tube-based mic preamp - the PowerTube. Employing a high-voltage 12AX7 tube, a Jensen input transformer, and a balanced Class A output stage, it's capable of 60 dB of gain, offering enough level for pretty much any mic. It fits comfortably into one slot of your 500-series rack.
The layout on the front panel is economical and practical. I appreciate an actual VU meter for a change. Many of the other 500-series preamps in my rack lack meters, so it's nice to be able to spot check my gain staging. There are individual knobs for both the input trim and output gain. Although they're not detented, recall is pretty easy with the marked increments on the faceplate, and the knobs feel smooth and pro.
Pushbuttons are included on the front for polarity-reversal, an 80 Hz high-pass filter, and a gentle 5 kHz boost for "air." Switching on the latter can add a little something extra for vocals. There's also a pushbutton for phantom power that's recessed to prevent accidental engagement. If you're working with ribbon mics, this is a potential life-saver!
The front-panel input is XLR, but it's worth noting that if you have one of Radial's 500-series Workhorse racks [Tape Op #85, #92], you can also access DI capability via the rack's Omniport. If you don't have one of Radial's racks, no DI for you. Personally, I found that to be kind of a bummer, as I track a lot through DIs for bass, synths, etc.
This puppy promises "tube" magic, and apparently the folks at Radial found a way to deliver 140 volts to the tube, which gives the signal a flavor akin to that of a vintage tube amp. Retro tone and warmth is what they're going for, and I found that they succeeded in their goal; you won't find many options in this price point that deliver on this promise. I found that vocals sounded smooth, as did acoustic guitar tracks I captured for a scoring project. Driving the unit into the red provided a sweet overdrive that warmed up the resulting track, and the saturation that you get is very usable. If maniacal distortion is your thing, you'll want to look elsewhere. The PowerTube is a meat and potatoes, everyday workhorse mic preamp that's really musical, no matter what you throw at it. I would equate the PowerTube to the quiet, unassuming guy who gets s#@t done because that's his job. I should mention that if you track really quiet sources with ribbon mics, you might want a little more gain at your disposal, but I got some nice sounds using a Crowley & Tripp ribbon mic.
As with my previous experiences with Radial Engineering gear, I found the PowerTube to be totally reliable and ruggedly built. During my time with it, I never had a single issue. It's a straightforward piece of gear, and it does what it does very well. If you're in the market for a quality mic preamp that offers a little color (when you need it), I wouldn't hesitate to recommend the PowerTube. ($699 street; www.radialeng.com)
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