CEntrance MixerFace R4 Mobile Recording Interface
Part audio mixer, part recording interface, and uncommonly mobile-friendly
by Phil O'Keefe
CEntrance was founded in 2000, and while they may not be a familiar brand name to some readers, in addition to developing their own products, they have also co-developed products with more well-known companies such as Lavry, Waves, Benchmark, and Mackie; when they decided to take on the challenges of making a truly mobile recording interface, they had plenty of know-how and experience to work from. And let's face it - mobile recording interfaces are a challenge. Weight and size are always issues, and so is durability. Power requirements are also a concern - you won't want something that drains the battery in your laptop or tablet, nor do you want to be tethered to an AC power outlet. CEntrance feel they've come up with a product that more than meets those challenges - the MixerFace R4 Mobile Recording Interface. Let's see how well it performs.
What You Need To Know
- The MixerFace R4 is a 2 x 2 audio interface. Designed for mobile use, it can also be used as your primary interface in your home studio if your input requirements are fairly modest. 16, 24 and even 32 bit recording are supported at sample rates of 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.2 kHz, and 192 kHz.
- The CEntrance MixerFace R4 is compact, measuring only 4.76" L x 2.76" W x 1.42" H. It weighs only 9.1 ounces, but its black aircraft grade anodized aluminum housing feels tough and sturdy and ready for the rigors of the road.
- The design of the MixerFace R4 takes a different, more mixer-like approach than most recording interfaces, making the process of setting recording and monitoring levels a bit more intuitive for the typical musician.
- There are six knobs on the top surface. Each of the two input channels has its own Gain control (labeled Gain 1 and 2) for the two built-in Jasmine mic preamps. Signal present and Peak LEDs on inputs 1 and 2 let you adjust the gain for the best signal to noise performance. The signal present LEDs light up when signals exceed -40dB below clipping, while the peak LEDs illuminate at -6dB before clipping.
- Each channel also has a small recessed switch for selecting high or low impedance for the 1/4" inputs on the main Neutrik combo XLR / 1/4" input jacks. Switchable high pass filters (6dB per octave at 130Hz) are also provided for each channel. The inclusion of the high impedance option for the 1/4" jacks makes the MixerFace R4 well suited for recording your guitar or bass "direct" by plugging straight into the MixerFace R4.
- Each channel also has its own individual Channel / USB or "Monitor blend" knob to let you adjust the amount of the input signal vs playback signal that you hear when monitoring your recordings.
- An Aux 3/4 knob lets you adjust how much signal from the unit's 1/8" TRS stereo Line Input is blended in with the signals from the two primary input channels, so you can record, mix and monitor from external sources. The built-in mixer inside the R4 mixes inputs 1/2 along with Aux 3/4, so both sets of inputs (main and aux) can be recorded simultaneously to either a stereo pair or two mono tracks if desired.
- The final knob is labeled Monitor, and it controls both the output level of the two main 1/8" TRS balanced line out jacks as well as the headphone volume level.
- You'll find the main line out jacks located at one end of the MixerFace R4, along with the main XLR / 1/4" combo input jacks; while you'll need 1/8" TRS to 1/4" TRS cables to connect the balanced output jacks to your powered studio monitors, the cables are not too difficult to find - CEntrance offers them for sale as an option if you don't already own a pair.
- While the MixerFace R4 is relatively small, it features an impressive amount of connectivity, with four analog inputs and six outputs (counting the headphone output), as well as the (micro) USB connectivity, which gives you digital I/O to and from your recording device of choice. And speaking of recording devices of choice, you get a lot of options - the MixerFace R4 is compatible with Macs and PCs (ASIO drivers are available for download on the CEntrance site), Linux, and most mobile devices are supported too, including iOS and Android.
- The other end of the MixerFace R4 is where you'll find the 1/8" TRS line input (Aux 3/4) jack. A second (pre-Monitor knob) line output jack (on an unbalanced 1/8" stereo TRS jack) is also provided, as well as a stereo headphone output on a 1/8" TRS jack. The MixerFace R4 has plenty of power in its built-in AmpExtreme headphone amp to power professional headphones (16 to 600 ohm) to very respectable levels, making the unit a good choice for headphone amp duties with your mobile devices too.
- This is also where you'll find the main power switch, along with three white LEDs that indicate battery strength. That's right - the MixerFace R4 contains an internal lithium polymer battery. This is recharged through a dedicated micro USB port (on the right side), which can be left connected while using the unit if you wish. A second micro USB port is used to connect the MixerFace R4 to your computer or mobile device.
- The onboard battery makes this a truly mobile interface - when paired with a laptop, smartphone or tablet, you have no need of an external AC power source, so you can record literally anywhere. You can typically expect to get a very respectable 7-8 hours of use from a single charge of the internal battery.
- The quality of the two Jasmine mic preamps is very good, especially by mobile interface standards. They're surprisingly clean and low-noise, and offer a very respectable gain range of +10 to +53 dB.
- Unlike some other mobile interfaces, the MixerFace R4 has true 48V (±1%) phantom power, making it fully compatible with the vast majority of phantom powered microphones on the market. The switch for turning phantom power on and off is located near the USB jacks at one end of the unit. You'll also find switches for selecting stereo / mono monitoring, and low / high output levels for the aux (pre-monitor) line output. The low setting pads the output down far enough that it can be used to feed the mic-level inputs on a DSLR camera without overloading them.
- There are two internal mil-spec clocks with 10ppm precision and a low 1 ps jitter spec. Translation - the clocking is quite good.
- The back of the MixerFace R4 has a built-in tripod threads so you can easily mount it to a tripod or (with an adapter) a mic stand. You'll also find a handy quick start guide located there, as well as a somewhat more comprehensive one printed on a card that comes with the unit. A full PDF manual is available for download from the CEntrance website.
- A felt bag is provided to store your MixerFace R4 in, as well as a 3 foot USB A to micro USB cable for charging the battery and for interfacing with your recording device.
- A protective carrying case, USB fast charger (each priced at $19.95 "street"), and even a model that's well suited for use with your DSLR (the MixerFace R4R) with an internal SD card recorder (an additional $100.00 "street" over the basic R4) are available as options.
- The recessed switches require the use of an improvised tool to adjust their settings. A paper clip is ideal, but in a pinch you can use the tip of a ball point pen to get the job done. While this is a minor hassle, being recessed means they're less likely to break or be accidentally repositioned during travel.
- The MixerFace R4 is a 2 x 2 audio interface only - the line inputs feeding Aux 3/4 can not be routed to separate tracks in your DAW software for four input / four track recording - they are always mixed internally with inputs 1/2 and will be recorded to the same tracks as the main inputs.
- iOS users will need to purchase an Apple Lightning to USB 3 Camera Adapter ($39.00 "street") in order to connect the MixerFace R4 to their devices.
CEntrance really have done a great job of balancing the sometimes contradictory requirements (weight vs durability, size vs features) of a good mobile interface. The MixerFace R4 is both compact and light, yet surprisingly rugged, with a wealth of connectivity that some other ultra-compact mobile interfaces lack. True, some of it is on mini jacks, which means you'll need to use adapter cables to connect to things like your powered studio monitors, but that's really a minor inconvenience and something you can easily, uh, adapt to. Besides, I suspect most buyers won't be purchasing this for use as their primary home / studio interface, but as a highly capable mobile partner for it. The fact that you can use it as your home interface is a sweet bonus that will definitely appeal to some owners.
Best of all, the sound quality of the MixerFace R4 is very impressive for a product of this type, with sweet and clean sounding Jasmine mic preamps and high bit / sample rate capabilities. And you're truly mobile with the CEntrance MixerFace R4 - I was able to record for over seven hours on a single charge of its internal lithium-polymer battery, and you can easily extend the amount of time by bringing a USB power bank along with you, which can also be used to recharge your tablet or smartphone too. And there's no limits on what mics you'll be able to use - unlike some other bus-powered mobile interfaces that hobble you with lower voltage for phantom power, the MixerFace R4 lets you use all your microphones - including the ones that need a full 48V to operate properly.
While I wasn't able to test it with all of the supported platforms, CEntrance says it will work with not only your Mac and PC, but iPads and iPhones, as well as Android devices too, making it compatible with just about anything you're likely to want to record to. I had no problem using it with my Macs and iOS devices, and it was trouble-free throughout the evaluation period. My only complaint was the recessed switches, but many people will set and forget those, and even if you need to adjust them regularly, the tip of a paper clip can easily get the job done.
If you use a DSLR or video camera, smartphone or tablet to do product demo or instructional videos, adding a MixerFace R4 to your setup can help you get much better audio quality than you can from its built-in microphone, leaving it clear to handle the video while the MixerFace R4 feeds it high quality audio. This also gives you the ability to use two input sources, such as putting a mic right in front of an amp or instrument and another on a narrator or singer, while still leaving the camera free to be positioned for the best video angles. These features also make it a great choice for live streaming duties. The self-powered R4 will also be appreciated by samplers and field recordists, ENG journalists, podcasters, concert recordists, songwriters, home recordists and multitrack enthusiasts, and anyone who values mobility and who can't always rely on having a AC outlet nearby. It's a surprisingly sweet-sounding and capable recording interface with uncommon flexibility and mobility, and it deserves to be a big hit with a wide variety of musicians and recording professionals. -HC-
Want to discuss the CEntrance MixerFace R4 or have questions or comments about this review? Then head over to this thread in the Studio Trenches forum right here on Harmony Central and join the discussion!
CEntrance MixerFace R4 Mobile Recording Interface™ ($349.95 "street")
CEntrance product web page
CEntrance MixerFace R4 downloads, including drivers for Windows and GigaStudio and the AxePort Pro Mac Control panel
CEntrance MixerFace R4 user manual (PDF file)
You can purchase the CEntrance MixerFace R4 Mobile Recording Interface from:
Direct from CEntrance
CEntrance Demo and Instructional Videos:
Charging and turning it on
Using the MixerFace R4 for multitrack recording or as a headphone amp for jamming with a backing track
Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.