ART's Tube MP mic preamp line has been around for some time, but a recent evolution of the series gave us the opportunity to review this unit. The stock preamps on our mixer here at WMBR radio (a Soundcraft Spirit 328 digital board) suffer from both a weak low end and a high noise floor, so external mic preamps come in handy; the budget price of the Tube MP Project Series ($65 street) definitely appeals to us as well. We put the unit through its paces in our usual fashion, using it to record live-to-2-track sets for radio broadcast as well as some multitrack work to Pro Tools.
The Tube MP Project Series includes the usual range of controls (input and output gain knobs; polarity, phantom- power, and high-pass filter buttons) as well as buttons for input impedance, limiter, and an additional 20 dB of gain. According to the manual, the impedance button selects between 4.7k and 600 Ohms. As expected, the condensers that we tried were unaffected by the impedance selector, but dynamics (such as the SM58) exhibited a bit of high-end rolloff at the lower impedance setting, and although we don't have a ribbon mic at WMBR, we can guess that the change in sound would be less subtle with a ribbon. We had little use for the limiter, preferring to drive the unit hard instead (see below).
We do, however, need to single out the gain knob. On most other preamps, the gain pot has logarithmic taper, and therefore, the amount of gain is distributed evenly in units of dB across the travel of the input knob. However, on this unit, the first half-turn results in 9 dB of gain while the second half-turn adds 36 dB on top of that. The unfortunate consequence is that the first 75% of the knob's travel was useless to us, and tiny adjustments in the last 25% would make huge differences in level.
As for the sound of the unit, the Tube MP Project Series shone, but in a way that we didn't expect. Under normal conditions, the preamp was quiet and well-behaved; used with our SE Electronics Z3300A condenser mic in omni mode, sounds from a banjo, tambourine, and a smattering of percussion instruments came through clear and smooth. The preamp also exhibited a strong, tight low end, which was ideal when used with kick drum or bass, but was a little too much when used on vocals with mics that have exaggerated proximity effect.
When we drove this unit hard, however, the real usefulness came out. Cranking the input gain produces a distortion and compression effect that sounds good, is easily-controlled, and is really handy. It's also very different in character from our PreSonus BlueTube DP, another mic preamp that includes a tube drive and is similar in price per channel. When recording a bass amp with our Earthworks SR69, we were able to dial in an aggressive, compressed sound, over and above the sound of the amp alone. It's good on drums, too. We used our AKG D 112 on kick drum and ran it through the ART really hot, mangling the sound; in the mix with our Shure SM81 drum overheads and other drum mics, the kick sounded great, and we could vary the amount of attack by simply adjusting the preamp's gain. In addition, snare and toms sounded good when given a similar, if less extreme, treatment.
Ultimately, we found that the real value of the Tube MP Project Series is that it's not only a mic preamp with solid low end, but it's also a good effect/compressor. Given the low price, we'd definitely recommend it to anyone recording a rhythm section on a budget, with the knowledge that it's plenty useful in other situations as well. ($79 MSRP; www.artproaudio.com)