Sound Devices MixPre-3

More keenly priced than many Sound Devices products, the MixPre-3 nonetheless offers exceptional sound quality and functionality.

American pro-audio manufacturers Sound Devices are perhaps not so well known in the project studio marketplace, but in the broadcast and film sectors the company have built an almost legendary reputation over their 20-year history. Launched in 1998 by a trio of former Shure employees, Sound Devices initially produced very high-quality battery-powered mic preamps for location sound work. These were followed by a line of sophisticated and versatile over-the-shoulder location mixers, and then one of the earliest professional USB audio interfaces.

By 2004 the company were making a range of ultra-compact digital audio recorders and elaborate production mixers, and later introduced a variety of integrated location mixer/recorders. The company’s ethos has always been about manufacturing extremely robust and well-engineered products that are capable of providing decades of reliable service in the most hostile environments. Just as importantly, the company prides itself on meeting the demands and expectations of professional sound recordists, especially in terms of easy operation and appropriate facilities.

Overview

The latest offerings from this innovative company are the MixPre-3 and its slightly larger sibling, the MixPre-6. Both units combine the functions of a multichannel file-based audio recorder, a compact field mixer, and a USB interface, and they can be powered by a variety of different battery options or over USB-C from a computer or mains wall-wart supply.

Both models share exactly the same technology, of course, but the bigger one offers a bit more of everything — hence the 3040 percent price premium compared with its smaller sibling. The intended applications for these high-tech, high-performance products are wide-ranging, but include home-studio recording, location recording, videography (paired with DSLR or video cameras), podcasting... and anything else that requires seriously top-flight sound recording in a very compact format!

The MixPre-3 is a five-track machine that can ‘iso’ (short for isolated, as in not mixed) record its three input channels along with a live stereo mix, at sample rates up to 96kHz. In contrast, the MixPre-6 is an eight-track device, which records six iso input channels plus the stereo mix, and at sample rates up to 192kHz. When connected as a USB interface (it’s USB 2.0 class-compliant for OS X/iOS devices, and there is an ASIO driver for Windows systems) the MixPre-3 provides a total of five inputs to the computer and two outputs from it, whereas the MixPre-6 manages 8-in/4-out. Both machines record locally to a single SD memory card, but can also stream audio simultaneously over USB to a computer, if required.

I was sent a MixPre-3 to review, and that ships with an 18-page Quick Start Guide (a full 57-page manual can be downloaded from the company’s web site), a four-AA battery module, and a USB cable that splits the MixPre-3’s USB-C connector out to two USB-A plugs (since a single USB-A port can’t usually provide the necessary 7.5W of power).

That phrase I used above, “...in a very compact format”, doesn’t really do the MixPre-3 justice: this thing really is tiny, measuring just 110 x 114 x 36mm (WHD) and weighing 0.6kg complete with a fully loaded four-AA battery pack and a memory card. (The MixPre-6 measures 118 x 166 x 36mm.) Although ‘compact’ often means ‘fiddly’, that’s really not the case here at all; the front-panel knobs are sensibly sized and well-spaced, as are all the connectors on the side panels.

The MixPre-3 sports two XLR mic inputs on one end panel, and one on the other, and these are joined by dual USB ports, HDMI input for timecode, an aux/mic input, main stereo line output, and headphone output with volume control.Designed to be robust, the chassis is constructed from die-cast aluminium, while rubber inlay panels top and bottom provide secure mounting surfaces for cameras and tripods, of which more in a moment. The left-hand side panel carries two of the unit’s three transformerless balanced XLR inputs, which are switchable for mic or line sensitivity (both with a 4kΩ input impedance, and +48V phantom power is available). There’s also a configurable unbalanced stereo line output on a 3.5mm socket, USB-A and USB-C sockets, and a power on/off slide switch (which is slightly recessed to avoid accidental operation). The USB-A socket allows a standard keyboard to be connected for file titling and metadata entry, as well as for remote control functions and quick access to the configuration menus.

The third input XLR is on the right-hand panel, along with an unbalanced 3.5mm stereo auxiliary input. This can be used for a variety of functions, starting with connecting a stereo line input, or the monitoring return from a video camera. But it can also be used to accept a linear timecode signal for time-stamping the recorded audio files, or for connecting a mono or stereo consumer electret mic (plug-in power, or ‘PIP’, is provided).

Another 3.5mm socket on this side panel carries the stereo headphone output, and a small rotary encoder knob (with press-button action) serves primarily as the headphone volume control. However, when rummaging around the menus, this encoder can also be used to select and adjust various menu parameters. Finally on this side panel, a micro-HDMI socket accepts start-stop commands and timecode from compatible video cameras.

As you might expect, the MixPre-6’s connection panels are laid out in exactly the same way with all the same facilities. The only difference is that there are two XLR inputs on the right-hand side instead of one (making four in total), and these are all are combi-jack types which can accept TRS plugs for the line inputs.

Moving to the front panel, the MixPre-3 features three rotary controls, with a protruding pin on top of the knobs for tactile operation even when wearing gloves. Pressing any knob accesses the corresponding channel’s configuration menu and, cleverly, illuminated skirts at the base of each knob indicate the corresponding signal levels. Arranged above these controls are three transport buttons (play, stop, and record), while to the right is a 1.6-inch (320x240-pixel) colour LCD touchscreen, which can be made bright enough to read easily in sunlight.

This crisp screen defaults to showing bar-graph level meters, but also displays the project name and file number at the top, along with the recording duration, and a power-remaining meter. A virtual button in the top right-hand corner accesses the setup menus, whereupon the screen changes to show an array of virtual buttons. Three smaller buttons across the top access the headphone mode, select the menu level, and return to the home (meter) display, while most of the screen is given over to four sub-menu access buttons, each labelled for a specific sub-menu tree. It’s all pretty self-explanatory, and I had no trouble quickly finding the features and options I needed without referencing the manual — although I learned a lot more about what the machine can do when I did!

As you would expect, the MixPre-6 model is much the same in its control layout and operation, although it has four rotary channel controls instead of three, and a star (* ) button has been added in the transport group as a user-configurable shortcut to a selected menu function. The only other significant difference is that the larger model includes a couple of extra input channel signal-processing options — input-delay and polarity-reverse — which are absent from the MixPre-3.

Power Options

I haven’t yet mentioned the rear of the machine, where the battery unit attaches. As I said earlier, the unit ships with a rubberised clip-on battery holder for four AA cells (primary or rechargeable NiMH types are recommended) but, frustratingly, neither the Quick Start nor the full manuals give any indication of expected battery life. As a test, I fitted four new Duracell Plus-Power alkaline AA batteries and (while phantom powering a couple of Sennheiser MKH mics, recording all five tracks at 48kHz, and with the LED/LCD brightness at full), I managed not much over 40 minutes of recording before the batteries expired — although to be fair I subsequently discovered that dimming the LCD/LED displays would have helped to extend the time considerably. The recording duration would also be a lot longer with NiMH or Lithium cells of course (probably of the order of a couple of hours), or by using the optional eight-AA battery pack.

However, for serious portable applications requiring long recording times it would make a lot more sense to adopt either the optional ‘MX-LMount’ (which fits in place of the standard battery module and allows a couple of high-capacity, hot-swappable, Sony L-type batteries to be used), or to employ a high-capacity external battery pack connected via the USB-C socket. It’s a shame that Sound Devices haven’t fitted the industry-standard Hirose power socket for compatibility with existing external power sources, but that’s one of the compromises involved in aiming for such compactness. It’s also worth noting that total power loss also results in loss of any current audio recording, as the file doesn’t get properly saved until the recording is stopped manually.

Assuming the unit is receiving sufficient power via its USB-C port, this automatically takes priority over the rear battery pack, as you’d expect. However, in situations where the USB-C power doesn’t reach the machine’s full requirements various facilities are automatically disabled to maintain the machine’s ability to record. For example, phantom power is no longer available on the third (and fourth, in the MixPre-6) mic channel(s), although they may still be used with dynamic or self-powered mics. Also, the brightness of the LED/LCD displays is dimmed, and the USB-A and HDMI ports are disabled.

On Camera

Removing the battery pack from the rear provides access to the single memory card slot, which accepts SD, SDHC, or SDXC cards of up to 512GB capacity (formatted as FAT32 below 32GB and exFAT above). This compartment also reveals more of the smart thinking that characterises Sound Devices products: set into a recessed space and secured safely with a small embedded magnet are an Allen wrench and a small screw-in pin — both are required when using the built-in tripod/camera mounts.

An Allen key, which secures to the body via a magnet, is used to attach the MixPre-3 to the underside of a camera — a neat arrangement which avoids the screw-thread protruding when not in use.The base of the MixPre-3 has two holes (as does that of the MixPre-6): one is threaded for a standard 1/4-inch camera tripod attachment, while the other accepts an anti-rotation pin (if present). However, that threaded socket actually reaches right through the machine to a captive quarter-inch threaded stud, which is spring-loaded to reside just below the top plate. The stored Allen wrench is used to push that mounting stud proud of the top plate and to screw it into a camera’s tripod socket while, for cameras with an anti-rotation recess, the small screw-in pin can optionally be fitted to the MixPre-3’s top plate to serve that function. Of course, this arrangement requires the MixPre-3 to be attached to the camera before mounting on the tripod, but I found it quite practical to bolt the mixer/recorder to the bottom of my camera (a Canon 5Diii) and just leave it there, as it’s not too large or heavy. All in all, this is a very elegant and versatile solution; tripod mounting instantly available when needed, but hidden safely away when not!

Operation

As shipped, the MixPre-3 starts up in a ‘Basic’ mode recording just the stereo mix. A large stereo bar-graph meter dominates the display, with project/file name and recording time and the menu-access soft button at the top. Remaining storage time is shown at the bottom of the display along with the current headphone mode (stereo, mono, and so forth). Although small, the meters are very easy to read, aided by sensible colour-coding (green up to -20dBFS at the midpoint of the bar-graph, yellow up to -12dBFS, and then red to 0dBFS). This arrangement naturally encourages sensible headroom margins, and I wish more manufacturers would adopt a similar scheme.

Pressing any fader knob accesses the corresponding channel’s menu, offering selection of the pan position (restricted to hard left, centre, or hard right), input source (off, mic, line, aux 1/2, or USB 1/2), phantom power on/off, and low-cut filter on/off. When working in this Basic mode, the channel knobs are configured as simple gain controls spanning a massive 110dB range from -14 to +96 dB for the mic input (or -60 to + 50dB for the line input). The superbly good preamps are Sound Devices’ latest bespoke ‘Kashmir’ design, which uses discrete components, coupled with the latest 32-bit A-D converter technology — and I suspect part of the gain range is analogue, while some is performed digitally.

When in the Basic mode, peak limiters are automatically engaged to prevent overloads, with analogue stages for the channel inputs and digital processing for the stereo mix. Although perfectly effective, I found these a little more obvious in operation than I expected (the release time seems a little long for a transient limiter). I was also surprised that the MixPre-3 doesn’t offer a pre-record buffer — capturing a few seconds before the record button was pressed — as this is a standard (and much valued) facility on most of the competition. Having said that, future firmware updates might well bring additional functions like this, and some extra features were added through a firmware revision during the review period.

For simple applications such as recording interviews, blogging, making scratch music recordings, and so on, the Basic mode does a great job, and makes using the MixPre-3 very straightforward indeed. However, for more demanding situations an Advanced mode allows access to the unit’s full capabilities. Selected through the System menu, the Advanced mode reconfigures the machine quite significantly. For a start, the input channels acquire separate input gain and fader controls, with the gain being set as a static menu function (+6 to +76 dB for mic inputs, or -20 to +30 dB for line inputs), while the rotary knobs become mix faders, with a range of -50 to +20 dB (plus Off, and with unity gain at the 12 o’clock position).

The MixPre-3’s standard battery holder accommodates four AA batteries, but it can also be powered via USB-C. For those working longer hours on location, there’s an optional eight-AA-battery holder, and another option which accepts high-capacity, hot-swappable, Sony L-type batteries.This separation of input gain and fader functions allows each channel’s pre-fader signal to be recorded to an individual iso track, while the output from the fader is combined with the other channels and recorded as the stereo mix. Tapping the meter display changes the screen to show five narrow bar graphs for the stereo mix and three input channels, and the recorded audio is stored as a polyphonic WAV file (16 or 24 bits), with the stereo mix on tracks 1-2, and the iso tracks as 3-5. Sound Devices offer their free WaveAgent utility software for file manipulation, if required (converting between poly and mono Wavs, editing metadata, previewing tracks, batch-editing and so on).

Switching to the Advanced mode also brings additional channel menu options, such as solo monitoring, individual track arming, continuous panning, and selectable low-cut filter frequencies (40, 80, 120, or 160 Hz). Channel 1’s menu options also feature three stereo linking modes: unlinked, channels 1 and 2 ganged (channel 1’s knob adjusts the level of both channels, while channel 2’s alters the stereo balance), or M-S decoding. This last option assumes a Mid microphone is attached to channel 1 and a Sides mic to channel 2, such that the channel 1 knob adjusts the overall level while channel 2’s alters the stereo width. In the MixPre-6, both stereo ganging and M-S decoding is available for channel pairs 1-2 and 3-4, while channel 5-6 doesn’t have an M-S decode option. I mentioned earlier that the MixPre-6 included a channel polarity-invert function, but the MixPre-3 doesn’t, and that’s a great shame because this is a much-needed facility when working with an M-S stereo mic (to correct the stereo image if the mic is inverted).

Usefully, the MixPre-3 features user presets to allow specific machine-wide configurations to be stored and recalled instantly. Four presets are stored internally, but an unlimited number can be saved to the memory card, and this makes reconfiguring for different regular setups very fast and simple, recalling channel gains, signal routing, track arming, sample rates, and so on. The very powerful headphone output also has its own set of four configuration presets, too, with options for listening in stereo or mono, and to different sources within the machine.

Verdict

In the MixPre-3 and MixPre-6, Sound Devices have introduced a pair of mixer/recorder/interfaces that are deliberately designed to appeal to a market sector which is quite different from the company’s usual professional broadcast/film user base. I’m sure some experienced Sound Devices customers will consider these MixPre products as inferior in various ways, but while they might lack some features expected by high-end professional users for some specific applications, these products are also considerably less expensive than much of the Sound Devices catalogue. And, importantly, they maintain the highest sound and build quality which people have come to expect from this brand.

In fact, there’s so much about the MixPre-3 that is extremely impressive, starting with the quality and astonishing gain range of the mic preamps, and continuing with its delightfully straightforward operation, its configurable versatility, its scarily powerful headphone amp and its amazingly compact form — and let’s not forget the very competitive price. It also works superbly as a USB interface, and I have to say that I really enjoyed using the MixPre-3 in a wide variety of applications.

Inevitably, there are a few aspects of this new technology that might benefit from a firmware update (a pre-record option being one, and the absence of a polarity-invert option on the Sides channel in M-S mode another) but Sound Devices have always been a very responsive company, and I’m sure the MixPre-3 and MixPre-6 will see useful further enhancements very quickly.

Overall, the MixPre-3 and MixPre-6 are brilliantly thought-out mixer/recorder/interfaces. They’re easy to use, they capture sound at the highest possible quality, and they’re remarkably versatile. Moreover, they offer very serious alternatives to the Zoom F4 and F8, which have dominated this sector of the market unchallenged for some time now. If you are considering a compact audio recorder that offers so much more, I thoroughly recommend checking out these new Sound Devices offerings.