Sound Devices has been known for years as a manufacturer of audio gear for the field recording engineer, with compact and rugged field mixers and solid-state recorders making up most of its product line. It was one of the first companies, if not the first, to offer a really high-quality bus-powered audio interface in the form of the USBPre, which we reviewed all the way back in November 2002. In that review, the USBPre handled itself with aplomb in an era of IRQ conflicts, driver mismatches, audio-hostile operating systems, and computers that were just becoming fast enough to routinely handle native audio.
A lot has happened in the world of computer music since then, and we're due for an upgraded USBPre. The question is, in an era where high-resolution USB audio is now commonplace, does Sound Devices have anything left up its sleeve to make the USBPre 2 stand out? See for yourself.
The USBPre 2 is a portable bus-powered USB 2.0 audio interface that can also function as a standalone 2-channel mic preamp with analog and digital outputs. It handles audio at up to 24-bit resolution and 192 kHz sample rate. It operates as a Core Audio compliant interface with any Mac running OS X 10.4 or better (some issues with OS X 10.6.5 were resolved in 10.6.6, which is where we did our OS X tests); ASIO drivers are available for Windows XP SP3, Vista, or 7; and with the appropriate ALSA snd-usb-audio module in place, it supports Linux Kernel 2.6 or greater. I didn't get to test the USBPre under Linux, but I had no issues with our Mac or Windows test machines.
The USBPre 2 is built into a tough extruded-aluminum box with bolted end plates, a recessed front panel, high-quality connectors, knurled metal knobs, Neutrik jacks... first class all the way. The front panel has three Big Knobs -- two for channel input gain, one for headphone output level -- and two Small Knobs that retract into the case to keep them from being accidentally turned -- one for output gain control and one for zero-latency monitor mix of analog inputs vs. computer. Four tiny but positive-feeling buttons select source for inputs 1 and 2 (separately, huzzah!), metering of input vs. computer audio return, and mono monitoring on the headphones. Last and certainly not least, there's a gloriously high-resolution 23-segment LED stereo level meter, 2 dB steps from -44 dBFS to 0 dBFS, plus indicators for when the onboard limiter kicks in on each channel.
The left end panel has all the inputs: two XLR (Mic), two 1/4" TRS balanced (Line), and two unbalanced RCA (Aux). The right panel has 1/4" and 1/8" TRS headphone output jacks, RCA Aux outputs, coaxial S/PDIF input and output, and the USB port; the rear panel has the balanced XLR outputs, optical Toslink S/PDIF in and out, and a rubber cover that hides two sets of DIP switches for assorted device settings (see below). Note the absence of a multipin connector and breakout cable, a common way to add I/O with minimal hardware cost but one that isn't designed for rough use in the field. Good choice.
There's no power supply jack; in standalone mode the USBPre 2 is still powered over USB. You can do this with a powered hub or USB power supply of 500 mA capacity. Even a computer can act as a power supply if need be; the USBPre 2 can be told to enter standalone mode on powerup, even if it sees a computer at the other end of the cable.
Taking a DIP
What about those DIP switches, anyhow? They let you set up a wide variety of functions that are vital to flexible operation but don't need to be fiddled with on the fly. This is where you set your sample rate for standalone mode, and toggle the 48V phantom power, low cut filter (12 dB/octave, 3 dB down at 80 Hz), 15 dB pad, and built-in limiter (the threshold's fixed at -4 dBFS) for each input. You can also:
- set dual mono operation with Input 1 routed to both tracks;
- set the XLR outs to mic or line level (-40 dBu or 0 dBu);
- set the headphone mono button to sum only the inputs, or audio from the computer as well;
- set whether the meter automatically switches to show computer audio levels when the interface senses audio playback;
- swap the functions of the small lockable output gain knob and large headphone level knob;
- set the outputs to only take audio from the computer, or to share the headphone signal that's affected by the Monitor Mix control; and
- lock out the input select buttons.
These settings cover a lot of functions and really let you tailor the USBPre 2 to work the way you need it to during a gig. This design also reflects the unit's partly-interface, partly-standalone nature by being completely independent of a computer. There's no control panel application and no software-switchable features.
The USBPre 2's stated frequency response is flat (±0.5 dB) out to 40 kHz, 3 dB down at 65 kHz. From my listening tests with high-resolution audio files, I see no reason to doubt these claims; the D/A conversion on this box is just gorgeous, and really takes things up a level from budget-grade converters. While the overall quality of D/A continues to improve every year, the USBPre 2 really is something special.
In practical terms, I found the preamps to be very clear and honest, providing good results from condenser and dynamic mics on a variety of acoustic instruments and on my vocals. I would recommend being a little cautious when using these pres with mics that require a lot of really clean gain, such as vintage passive ribbons; while the spec sheet claims 80 dB of available gain, to my ears the pres get audibly noisy when you crank them all the way up. In an early test, my noise floor measurement with the gain set to minimum was about -70 dB, whether with nothing plugged in at all or with a 150 ohm dummy load; this turned out to be a DC offset problem, and a firmware update (version 4.01 in a prerelease version) fixed it handily, bringing the noise floor below -90 dB. Sound Devices earns major points for a fast and helpful followup here!
Once that one question mark was sorted out, everything else worked as advertised. The Loop function that brings an audio channel out of the computer and sends it back into the interface for use with reference tones worked like a treat, the ability to configure output levels and routing was delightful, and those meters... oh, those meters... they reminded me of why we use meters in the first place, and why good ones are so fantastic while bad ones can be worse than no meters at all. They pretty much spoiled me after years of reviewing interfaces with two- or three-step LED ladders that barely do more than show "signal present" or "clipping".
The USBPre 2 is designed with performance in mind -- it offers a whole slate of features that most entry-level recording musicians don't yet know enough to ask for but which experienced engineers adore, especially in field work. Being able to quickly check your inputs in mono, control routing of zero-latency monitor signal vs. what goes to your DAW, and see what's going on with real meters... those are things the field recording expert expects not as luxuries but as necessities, and the USBPre 2 delivers.
All in all, this is a timely update to a well-respected device, with its capabilities as a standalone preamp and converter (especially its luscious D/A) just adding value to a very rugged and feature-rich interface. If you're going to be doing a lot of remote recording and want an interface that works with you rather than making you figure out ways to work around it, give the USBPre 2 a listen.
More from: Sound Devices, www.sounddevices.com.