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Sound Devices 664 Field Mixer

Lightweight, Powerful Mobile Unit Includes Multitrack Recorder

Sound Devices creates portable recording products that are sturdy, rugged and loaded with connectors, switches and functions. With all features offered in a small, portable and lightweight frame, each of the company’s releases seems to instantly fill a role as a new standard in field recording. The new 664 production sound mixer combines features from two of their most popular products, the 552 production sound mixer and the 788T production recorder; it supports SD cards or CompactFlash drives.


The 664 is a 6-input portable mixer featuring six full-size XLR inputs that accept mic or line signals. The stereo mix can be output to a pair of full-size XLR connectors, while redundantly feeding a pair of TA3 mini-XLR connectors, and feeding the stereo audio legs of each of the two Hirose 10-pin connectors (which can be broken out to XLRs using the XL-10 breakout cable). While all of these stereo outputs are being fed the main mix bus, two mono mix buses are also provided, each having its own TA3 connector for output. Additionally, each microphone has a direct output via TA3 connector, which can run at mic level as well as pre- or post-fader line level. All of these analog outputs, from the bus outputs to the direct outputs, are transformer-balanced to keep them as clean and noise-free as possible. Typical of Sound Devices, this goal is successfully accomplished, as noise is not a consideration at any point in the circuitry of the unit.

The 664 also has eight possible digital outputs. Each of the XLR outputs can pass two channels of AES3, and each of the 10-pin Hirose connectors can pass a pair of AES3 signals. The digital sends don’t merely mirror the analog outputs. In the menu, there is a routing matrix page, where any of the eight digital outputs can be fed a mix that includes the left and/or right outputs, either or both of two aux outputs, and any or all of the direct outputs. With that, the possibilities of feeding different recording decks, DAWs or digital inputs of cameras are pretty vast.

The input section also provides a healthy complement of options. In addition to accepting mic or line signals, input connectors 1 and 6 double as AES inputs, which can accept AES3 or AES42 signals. For those unfamiliar with AES42, it is a digital protocol designed to work with microphones that convert A/D signal directly from the capsule, before even boosting them to mic level. The idea is to preserve a cleaner signal by avoiding long analog cable runs, while a secondary purpose is to allow remote control of microphone functions like filtering or built-in limiters. While the 664 provides the standard 10-volt AES42 phantom power and a remote gain control, there is not a comprehensive AES42 remote control system to address additional mic functions. If the six inputs provided on the 664 are not enough to accommodate larger setups, like reality TV shows that use many radio mics, an additional six inputs can be added by connecting an optional CL-6 expansion unit.

Mic pre’s on the 664 are not exactly the same as those found in the 302 and 552 mixers. They are a new design, more closely related to the transformerless, transistorized mic pre’s found in the 744T, or the USBPre 2. They are clean and essentially colorless, with a very wide dynamic range. Considering the lack of transformers, and that the pre and power supply are housed in such close proximity, I heard no noticeable noise. Likewise, the limiters, which can be engaged across inputs, did an excellent job of preventing distortion without imparting a great deal of color or character. When engaged, they worked at a preset 20:1 ratio with a 1ms attack and 500ms release, perfect for speech.


Besides being an able mixer, the 664 is also a full-featured multitrack production sound recorder. Each of the mix buses can be recorded to its own track, while each of the six inputs can be recorded separately, as well. When adding the CL-6, its inputs can be summed to each mix bus and recorded separately, expanding the track count to 16. Both the SD recorder and the CF recorder can be used at the same time, and every available track can be recorded to both simultaneously. Alternatively, you can adjust which tracks will feed which media with some degree of discretion. Each card can record everything—just the individual tracks (ISO tracks), just the stereo mix, or just the auxes. This could be very convenient, as an SD card could be used to record the live mix throughout the day and given to the editor to sync dailies, while a large CF drive collects all ISO tracks and reference mixes throughout the day, to be given directly to the post-production audio department.

Each track is recorded with a wealth of metadata. From track names to scene and take numbers to timecode, it’s all there, making it very easy to sync the multitracked audio to edited clips during post. When recording, all tracks for a take are stored together in one convenient file. The free Wave Agent software (which you can download from the Sound Devices Website) can take the single file and break it out to individual tracks, which can then be panned, leveled and auditioned within the software. From there, the required tracks can be exported while preserving all metadata.

The 664 can record 16-bit or 24-bit files at either 44.1 kHz, or all-standard, pulled-up and pulled-down versions of 48 kHz necessary to work with film, video or hybrid workflows. The unit can record BWF files or MP3 files. The one thing it can’t do is record sample rates higher than 48 kHz. Because of this, it is important to note that this is a great all-in-one tool for production dialog, but will probably struggle to gain favor for sound effects gathering. The ability to pitch and stretch audio without producing artifacts is much desired today, and requires audio recorded at higher sample rates.


The main controls and meters for the 664 are presented in a menu system on a sunlight-viewable LCD screen. In a departure from the multi-segmented LED meters found on every other Sound Devices product, including the CL-6 expansion unit for the 664, this device uses graphic meters on the display. This new technology offers the same peak and VU ballistics, color coding and indicators for clipping and limiting as the traditional LED meters, but they just felt a little different. I think it was the fact that the tracks were tightly crowded together and the meters weren’t broken up into segments that made it take a little getting used to. The software metering, however, made it easy to switch meter functionality between different signals.

The menus were very easy to navigate, with clear names for main headings and consistent formatting and navigation throughout. As usual with Sound Devices, to fit all controls into a small space, many of the knobs, switches and buttons perform a multitude of functions. For example, after pushing a button to get into the system menu, the headphone control became the control for scrolling through menus and provided the push-button for selecting things. The PFL switches, when flipped in the opposite direction, pulled up that input’s menu on the display, granting access to functions like output routing, input type or phantom power. That is slick because rather than feeling around the surface and encountering a thousand switches when looking for the right one, having a handful of hot spots made it easy to feel at home all the time. In the menus there is also a cheat sheet of control combinations that perform routine functions like dimming the display, for example.

Each channel has physical controls for input gain, highpass filter and panning. All of these knobs pop up out of the unit and can recess flush with the surface when not needed. Because of this, the fact that one channel’s filter is nearly touching the next channel’s gain controls is not terribly problematic. Both of these controls are located within close proximity to the fader, however, making it very easy to bump one control when adjusting the other. This layout is no different than that found on the already popular 552 mixer, so it obviously has not proven a deal-breaker in the past. The faders are really fast, which, once mastered, made it very easy to do quick crossfades from one actor’s mic to another’s.

Advanced Workflows

Because the 664 is designed to be the central nervous system of large multi-camera, multi-miked shoots, advanced monitoring and communication functionality is also provided. The 10-pin connectors are each designed to run to a different camera. Six of the pins are used to send the two balanced signals to be recorded in stereo to the camera. This leaves four more wires on the multi-wire cable, and three of them are used to return an unbalanced stereo signal from the camera. A third unbalanced stereo camera return is also provided using a 1/8-inch TRS connector.

The metering section can be toggled to display meters for the three return paths, and each of them can be soloed and monitored through headphones. A pair of TA-3 connectors for communication send and return are also provided, and the comm return can also be monitored through the headphones. A built-in slate mic, or a mic connected to the TA3 “Slate Mic In” jack, can feed any or all of the outputs so that it can be used to mark all cameras and recorders with a voice slate.

In Use

I used the 664 for a small interview-style shoot using a boom mic and a couple of handhelds. For my purposes, it was perfect. All sound was captured directly to the internal SD card, with a reference printed to the camera’s audio track. Mastering the unit took only a few minutes. Everything was so intuitive and was exactly where you would expect it to be. The sound of the mic pre’s was fantastic, and with unpredictable spikes being tamed by the limiters, level setting was as comfortable as could be.

I ran the unit off of the power supply, as the shoot was indoor and stationary. The 664 can run off of five AA batteries, but this seems to be a backup only. I tried NiMh batteries as recommended and the battery meter drained quickly, started flashing and an alarm bell began to sound. I turned off the alarm through the menus but the batteries only lasted about an hour while only phantom powering one mic. Also worth noting is that the unit does not recharge your NiMh batteries when connected to the power supply. A firmware update to Version 1.3 is supposed to offset the low battery indicator to a lower level.

As an alternative, the 664 can run off of an NP-type battery and the XL-NPH battery enclosure would be a recommended accessory if you want to use this unit portably. When switching between packs, or switching between an external battery pack and the power supply, the unit can switch to the internal AAs without powering down the unit, so fast power changes can be made on the fly without cutting out audio or communication. That, I thought, was very handy.

A New Standard

The 664 is like a 788T with a slightly reduced track count and an integrated fader-based mixer, all for under $5k. As good as it sounds, and easy as it is to use, with the market already established, the 664 is sure to be an instant classic.

Brandon Hickey works as an independent production sound and Foley jockey, educator, and audio engineer.


When recording production sound, the expectation is that some audio from the set will be unusable. Because of this, recording dialog in a studio, a process known as ADR is required. Blending the sound of ADR recorded in a completely different environment than the production sound takes isn’t always easy. Because of this, it can be quite helpful to record impulse responses on sets or locations where shooting takes place, right to the production sound recorder. These sonic snapshots of spaces can be loaded into a convolution reverb, which can re-create the original ambience and be applied to ADR lines.