CEntrance MixerFace R4 User manual

MixerFace™ and CEntrance™ are trademarks or registered
trademarks of CEntrance LLC, All rights reserved. Other trademarks
are property of their respective holders. Rev 8.3. 2018-08-02
MixerFace R4
Mobile Recording Interface
User Manual

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Recording Studio, in Your Hand
These days, your smartphone or tablet is not
only your Digital Audio Workstation, but also
your means of sharing content with the world
online. MixerFace R4 takes advantage of this
environment by connecting your audio
sources with the digital ecosystem, making it
the ultimate mobile recording interface.
Modern location audio professionals demand
rechargeable batteries and field reliability.
Production crews, musicians, online
personalities, and field recording enthusiasts
alike share a need for a durable, portable
recording tool that delivers pristine audio
quality, available on-the-go, session after
session. MixerFace R4 is a modern,
sophisticated piece of recording equipment,
which allows you to create pro-level content
in any location.

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Table of Contents
FEATURES AT A GLANCE.........................3
TOP PANEL CONTROLS............................7
FRONT PANEL FEATURES......................16
BACK PANEL FEATURES........................18
TROUBLESHOOTING STEPS ..................26

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Features at a Glance
One of the most impressive features of
MixerFace R4 lies in its digital technology,
which connects the built-in pristine analog
preamplifiers to your phone and tablet’s
audio capturing app(s) for recording and
playback. While your phone or tablet
replaces the laptop, MixerFace R4 places the
entire production studio in the palm of your
hand.
Top Panel Adjustments
MixerFace lives up to its name—it’s part
audio mixer, part recording interface. The top
panel looks like a familiar music mixer,
offering an easy way to adjust signal and
monitoring levels. The controls are laid out
logically, making sure all audio adjustments
are right at your fingertips.

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Connectivity Options
Despite R4’s small footprint, its front and
back panels pack multiple connectors for
inputs and outputs. R4’s strength is in its
extensive connectivity options. There are a
total of four analog inputs and six analog
outputs, which allow routing your audio to
headphones, monitors, and line-level
devices. Digital input/output over micro USB
allows easy connections to computers,
tablets and smartphones.
Preamps and A/D Converters
Don’t let the small size fool you! MixerFace
R4 includes two boutique microphone
preamplifiers with custom Jasmine™
technology, which delivers clean, velvety-
smooth sound with the lowest noise and
distortion. It uses professional A/D and D/A
converters, which operate at sampling rates

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of up to 192kHz, and resolutions up to 24-bit,
meeting the most demanding needs of
today’s content producers.
Phantom Power
MixerFace R4 offers +48V phantom power on
channels 1 & 2, enabling you to use
professional condenser microphones. Unlike
other devices, it offers true +48V, which
means you can use it with any condenser
microphone in your mic locker. This feature
was previously found only in studio-level
products, but now MixerFace R4 makes it
available in a mobile package.
Signal Level LEDs
To ensure high-quality, distortion-free
recording, each channel features bright “SIG”
and “PK” LED indicators for monitoring
incoming signal strength. White LEDs

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indicate signal present (“SIG”) and Red LEDs
indicate overload or peak (“PK”).
• White LEDs turn on when the input
signal level is 40dB below clipping.
• Red LEDs turn on when the signal is
6dB below clipping.
• Once triggered, all LEDs remain on for
a little while to make sure you notice
them.

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Top Panel Controls
Top panel controls, as described below

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Channel Switches
All switches are active when the lever is
moved to the right. The levers are recessed
to prevent accidental adjustment. Use a thin,
sharp object, such as a paperclip, toothpick
or a pen tip to slide the lever to the right to
activate the feature.
Channel switches and the GAIN knob

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LINE / Hi-Z switch
These switches select between line input and
electric guitar (“Hi-Z”) input on the ¼” portion
of the Neutrik combo jack, per channel.
MixerFace R4 includes two professional,
electric guitar preamplifiers with high
impedance (“Hi-Z”) inputs. This means you
can connect MixerFace R4 directly to electric
guitar and bass to record anywhere.
Recording two different instruments or
signals is possible. For example, connect a
Microphone to Channel 1 and Guitar to
Channel 2, or record Guitar on one channel
and mono keyboard on the other. Each
channel works independently of the other,
offering diverse possibilities for recording.
Hi-Z switch operation is described below:

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• Slide the lever to the left to engage the
“Line” position. Hi-Z input is
disconnected and input gain is
reduced to accommodate line-level
sources on the ¼” jacks.
• Slide the lever to the right to engage
the “Hi-Z” feature per channel. Ideal
for connecting electric guitar and bass.
Low Cut Switch (HPF)
To simplify recording in noisy environments
and reduce wind or mic handling noise in
outdoor recordings, low cut switches are
available on each input channel. By design,
the low frequency rumble is cut early – right
at the input jack, long before the mic preamp
has a chance to overload and ruin your take.
The switches are labeled HPF, short for

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“High Pass Filter”, which is a more
appropriate name, if you want to get technical
about it. The 6dB/octave cut is below 130Hz.
GAIN Control
MixerFace preamplifiers have a wide gain
adjustment range of over 55dB. This covers a
variety of applications – from on-the-mic
narration, to recording nature sounds from a
distance, using X-Y stereo microphones.
The two gain controls let you adjust the levels
of the individual input channels for minimum
noise and distortion. A common guideline
when adjusting input levels is to let the red
“peak” LED blink occasionally, but not stay
illuminated all the time. The white “signal
present” LED is useful to check signal level
during quieter packages.

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Signal Peak & Present LEDs
The White LED labeled “SIG” illuminates to
indicate “signal present”. This happens when
the audio level at the input of the A/D
converter reaches -40dB. The white LED
stays illuminated until the signal drops below
the -40dB threshold.
The Red LED labeled “PK” illuminates to
indicate “signal peak”. This happens when
the audio level at the input of the A/D
converter reaches -6dB. The red LED stays
illuminated until the signal drops below the –
6dB threshold.
As these bright, sunlight-visible lights blink
with the audio, they attract attention, offering
a simple way to see signal levels at a glance,
and make gain adjustments as necessary.

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Blend Controls (CH — USB)
Blend controls adjust the mix between the
zero latency input signal and USB playback.
This allows you to strike a balance between
the inputs on Ch 1 or 2 (CCW) and the stereo
signal coming back from your computer or
smartphone (CW), as seen below:
Blend, Aux3/4 and MONITOR controls

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You will find this knob useful when playing
your instrument over a backing track fed from
the computer. Another use of this feature is in
Voiceover, where you need to narrate over a
music bed streaming from the computer. In
both cases you can adjust the blend to taste.
This knob also comes in handy when you are
using your computer or smartphone as an
effects processor and need to dial in just the
right amount of direct signal vs. effects return
(AKA dry/wet control).
When monitoring the inputs, rotate the dials
counter-clockwise to silence the signal from
USB. When playing back from the computer,
smart phone or tablet, rotate the dials
clockwise to silence the input channels.
Note: The blend you create in your monitors
is for monitoring only. It will not be recorded.
Channels 1…4 are recorded as a stereo mix.

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AUX 3/4 Control
The Aux 3/4 knob adjusts the level of the
stereo signal fed into the Auxiliary input (line
input) located on the back panel. You can
connect an MP3 player or another source to
this input in order to play along with a click
track, a prerecorded track or to overdub.
Note: The stereo mix of CH 1&2 and Aux ¾
in your monitors will be exactly the way it will
be captured in your recording software.
MONITOR Control
The MONITOR volume knob controls the
level of the entire mix as monitored through
the headphones or balanced outputs.
Note: If the MONITOR knob is turned all the
way up and your monitor level is still too low,
adjust the blend controls counter-clockwise.

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Front Panel Features
The Front panel contains combo input and
balanced output connectors.
Inputs 1 and 2
MixerFace R4 features Neutrik combo XLR
jacks for connecting mic, line-level sources,
electric guitar, bass, etc.

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Balanced Outputs (TRS)
While you may do most of your monitoring
with headphones, sometimes it’s good to
listen to the mix on larger studio monitors.
We have provided two 1/8” (3.5mm)
balanced outputs on the front panel. Use
these outputs to connect MixerFace R4 to
external powered monitors. The 3.5mm
outputs use industry-standard TRS pinout,
with “Hot” connected to the left (tip), “Cold”
connected to the right (ring) and “Common”
connected to the ground (sleeve) pin. A
special cable may be required. Consult the
CEntrance website for recommendations.
The top panel MONITOR knob adjusts the
level at both balanced outputs. This allows
you to control the level of your monitor mix
right from the MixerFace. No need to get up
and walk to adjust the monitors.

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Back Panel Features
Back panel controls are explained below.
Power Button
The power button turns the power on/off.

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• To turn on, press and hold for three
seconds until the battery level LEDs
light up.
• To turn off, press and hold for three
seconds until the battery level LEDs
rapidly blink to indicate: “bye-bye”.
Charger Connection
MixerFace R4 will charge from any standard
5V charger by connecting a USB cable to the
right hand side micro USB jack, located next
to the battery LED indicators. For best
results, use a charger that offers at least 2A
of output current.
Note: There is no danger in leaving the
charger plugged in indefinitely – the battery
will stop charging when full and will only top
off as needed, automatically.