Jim Williams has been making his Audio Upgrades High Speed Microphone Preamp since 1994, but largely on the down low-no advertising, no reviews, just a page on his audioupgrades.com website. The first thing you notice about the two-channel preamp is how simple it is. It's one rackspace of light-blue, brushed metal with two power knobs, two switches for phantom power, and a power switch. In the back, there are two XLR inputs, two XLR outputs, a toggle switch for American and European voltage, a fuse, and a removable heavy-duty cord for the built-in power supply. The slew rate is 400 volts per microsecond with a flat frequency response of 2 Hz to 200 kHz, so it's a clean machine. For my initial tests, I decided to recruit Austin acoustic guitarist extraordinaire Mark Viator to play his hand-made Gurian guitar through the unit. Not only did I want to hear him through the preamp, I wanted him to hear the result himself, since the last time I had a clean preamp in the studio, he didn't like it at all. Too brittle, he said, too bland. I set up Mark's guitar with a lone Neumann KM 84 aimed at the 12th fret. We experimented with different distances, and settled on a close mic'ing approach about 5" away from the guitar, perfect for his finger-picking style. He played a song we were both familiar with, and it was obvious-the Audio Upgrades just sounded right. It sounded exactly as you'd expect his guitar to sound on a record if you were listening to him in a coffee house. Perfectly clear and rich. For contrast, we ran his guitar through a Great River MP-2NV preamp as well, and even though I had it set at the cleanest setting possible-loading button in, output cranked, input set as low as possible-it definitely sounded colored in comparison. Not to say it's bad at all, but the acoustic guitar went from sounding like it belongs on an Alison Krause album to more of a Cat Stevens sound. The Great River had more balls, the Audio Upgrades more sparkle. The Great River was chocolate, the Audio Upgrades... not vanilla, really-more like sparkling water. I tried some strong strumming and let Mark engineer. I was surprised how good it sounded on the Audio Upgrades preamp. Nothing lacking on the low end here. A couple of days after this session, I tried out some vocals. One test was on a full-blown production I was working on, the other just acoustic guitar and vocals. I decided to try vocals with three mics: Neumann U 87, Gefell UM70, and a vintage Neumann CMV 563. The Audio Upgrades preamp really brought out the sound of my mics, and there was more contrast between the three than I'd ever heard before. The CMV 563 tube mic really shined through the preamp on both songs-clean but rich. The U 87 cut through well on the multitracked production, while the UM70 sounded nice and transparent on the vocal/acoustic guitar arrangement. Next, I tried some electric guitar through the preamp-a Fender Strat into a Mark III Boogie and mic'ed by a Brauner Phantom C. I kept the guitar sounds fairly clean-perfect for jazz, country and classic rock-but I didn't even bother with anything approaching a heavy metal sound, as it was obvious that you'd want something more colored, such as the Great River or Germanium preamp. I didn't try out bass either, but my feeling is that mic'ing a standup bass would work great, while you might want to go with something else for electric bass. There aren't any 1/4" inputs in the preamp, so going direct with bass would require an external DI. I kept coming back to acoustic guitar with this preamp and tried out several tests using my Collings D1A-finger picked, flat picked, and strummed. Although the Collings sounds great on other preamps, with the Audio Upgrades, I seem to be hearing the entire guitar, and it's very hard to stop playing. It just sounds... right. Anybody who records acoustic music specifically-and acoustic guitar especially-deserves a listen to this preamp. A 500-series lunchbox version of the Audio Upgrades preamp is also under development. ($1500 direct; www.audioupgrades.com)

Tape Op is a bi-monthly magazine devoted to the art of record making.

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