The two-channel BLUETUBE DP is the successor to the original BLUETUBE mic preamp. Each channel is fully independent and features 48 V phantom power, a 20 dB pad, an 80 Hz high-pass filter, polarity reversal, knobs for gain and tube drive, and VU meters that read from -20 dBu to +6 dBu. As the lowest-priced preamp in the PreSonus lineup, we were curious about two things: what did the DP preamps sound like, and was the tube gain a gimmick or a worthwhile feature?
On louder sound sources and with the tube gain turned off, the DP preamps were only a very slight improvement over the stock preamps on our Soundcraft Spirit 328 console. (We took care to fully bypass the board's preamp circuitry.) When we turned to quieter sources, the improvement was much more apparent. The PreSonus was very quiet at high gain, and exhibited none of the "graininess" that the Spirit's preamps show in a high-gain situation. The DP was particularly effective paired with low-output dynamic mics, and it helped improve the quality of our recordings of acoustic and singer-songwriter type bands.
The effect of the tube drive was quite dramatic. It could be varied from completely off to all-out distortion at its highest setting, and it proved to be amazingly useful for us. We engineer a huge variety of bands at WMBR Radio, and sometimes we need some analog "fuzz" to offset the sound of our digital console. That's something we couldn't readily obtain in the past (the 328's converters overload before its preamps do), but the DP's tube drive worked great for distorting vocals and drums when needed. We also found that, when used subtly, it could help an instrument poke out in a dense mix.
On the downside, using the tube drive liberally on louder, screamier vocals sometimes caused high-end artifacts that were just barely unpleasant. EQ and backing off the amount of drive were the solutions here.
Overall, the BLUETUBE DP is a very strong contender in the low-cost mic preamp space. Its best quality is versatility; it comes in handy in both quiet and loud situations. It should also be mentioned that PreSonus makes it possible to change the vacuum tube to vary the sound of the unit and even includes directions on how to do so. We wish that more manufacturers would adopt this philosophy, and the fact that PreSonus does so even with their low-end products makes us like both the BLUETUBE DP and PreSonus even more. ($229 MSRP; www.presonus.com)