A robust portable recorder, tested with supercars at 14,000 feet
Review by Alex Hawley
Based in Reedsburg, WI, Sound Devices specializes in location and field recording solutions—wireless receivers, portable mixers, preamps and audio recorders. Each one is engineered to be reliable in the harshest conditions in the most remote locations. On review today is the MixPre-6 II, which is positioned in the middle of the portable MixPre series between the MixPre-3 II and the flagship MixPre-10 II.
All three models in the long-standing MixPre line are built around the renowned Sound Devices Kashmir preamps. The MixPre-3 features 3 preamps and 5 total inputs; the MixPre-6 has 4 preamps and 8 total inputs; and the MixPre-10 offers 8 preamps and 12 total inputs. The 6 and 10 models feature combo XLR-1/4” jacks, while the MixPre-3 is XLR-only.
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Since version II, the MixPre series can record 32-bit floating point at up to 192 kHz. 32-bit floating point is quite useful in a field recorder; I can imagine many scenarios where capturing unpredictable sources and sound effects on location would benefit from the extended dynamic range. When you’re recording gunshots, explosions or fast cars (more on that later), 32-bit floating point is a lifesaver for the unexpected peaks that occur.
32-bit floating point is available in the Advanced operating mode, accessible through the integrated 1.6″ LCD touchscreen. Advanced mode also changes a few workflow aspects, such as reassigning knob functions. Everything is nicely customizable within the menus, and you can tweak the operating modes between advanced and basic to develop a hybrid that works best for you.
Save Your Work
Like most mobile recorders, the MixPre units record directly onto an SD, SDXC or SDHC card. Plus, the MixPre-6 II update introduced the ability to automatically copy data to an external USB thumb drive inserted on the unit’s USB-A port in real-time—an extra safety blanket for peace of mind on mission-critical recordings.
There are several ways to power the unit, including an AC adapter or four AA batteries on an included sled. Assuming most users will use the MixPre away from AC power and require more run time than four AA batteries will provide, the back panel sled is detachable. A variety of other power options may be employed, such as an 8x AA battery sled or 2x hot-swappable Sony L-type battery sled.
I opted to power the unit via USB. The MixPre-6 II can receive power via USB-C—it also doubles as a bus-powered USB interface. I purchased a 40,000mAh portable USB power bank to use in the field and I was able to record about 10 hours of audio with one channel of phantom power running all day. The power bank had roughly 40% charge left over. No complaints there!
The Kashmir preamps in the MixPre-6 II have a clean, transparent sound with high headroom and very low noise. They have a whopping 76dB of gain on tap with a potential of 96dB of maximum gain and a respectable EIN rating of -130 dBV. The extended frequency response (10 Hz–80 kHz) is handy for sound effects capture at higher sample rates. The preamps can be paired with an onboard analog limiter for extra protection, though it’s a global on/off compression and cannot be applied per channel.
While the MixPre series primarily focuses on audio paired with video (evidenced by its native polyWAV format), it also serves as a robust USB interface for general music recording or location podcasting.
You can even download and install plugins to aid in these other tasks. The optional Musician Plugin reconfigures MixPre to operate as a 12-track multitrack recorder, complete with overdubbing, track bouncing, punch-in, metronome, reverb, EQ and more.
The Ambisonic plugin enables first-order ambisonic recording (up to 192 kHz). It includes gain-linking, stereo down-mixing and full binaural decoding to monitor through headphones in real time (due to the processing needed for binaural decoding, this feature is only available at 44.1/48 kHz sample rates).
The four mic inputs on the MixPre-6 II easily lend themselves to any A-Format mic array, such as the Sennheiser AMBEO (reviewed on page 30). The MixPre-10 II can even record B-Format via FuMa or AmbiX channel configurations.
Performance at Pikes Peak
There are only so many pieces of gear suitable for a full day of recording 14,115 feet in the clouds at the summit of Pikes Peak in Colorado. Last June, I had the opportunity to capture sound effects for “King of the Mountain,” an upcoming documentary about the Pikes Peak International Hill Climb.
One of North America’s most historic and dangerous races, drivers are challenged with unpredictable conditions at high altitudes on a road full of hairpin turns and dramatic cliffs. As a field recordist, stakes are high in the sense that each racer only gets one run (so there’s only one shot at capturing the sound of each car), and positioning on the side of the road is limited (and dangerous).
The violent dynamics from car to car made setting gain a unique challenge. By the time I heard the cars coming, it was already too late to reach for the gain knob. I needed enough juice to capture whisper-quiet electric vehicles and enough headroom for the deafening combustion-based supercars.
This is where 32-bit floating point paired with high-end preamps on the mountainside thrived! Theoretically, 32-bit floating point has infinite headroom, but the real-world dynamic range for the MixPre 6-II is 142dB (based on what the converters can handle without distorting on the way in). This proved to be plenty of headroom to capture these incredibly loud cars ripping up the road.
In between racers, I recorded ambiances and crowd walla. The few moments of quiet I had allowed me to stretch the preamps with more gain, and I was able to record calm mountain wind and other gentle nature ambiance. Loud or soft, the Kashmir preamps sounded great—I didn’t detect any preamp noise in the recordings.
Pikes Peak International Hill Climb was an ideal event to truly test the capabilities of the MixPre-6 II for anytime, anywhere audio—fully remote (and constantly moving locations throughout the day), a 12+ hour day with no power or charging opportunities, and dramatic source material with only one shot to capture each car.
The results were genuinely inspiring. The Sound Devices MixPre-6 II captured every car and mountain breeze cleanly with detail and headroom. If you’re in the market for a mobile recorder with top-shelf preamps and flexible modes of operation that can double as a portable studio-grade music interface, the trio of MixPre models will not disappoint.
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