Rolls MX422 Owner's manual

MX422
Field Mixer
Owner/Operator Manual
ROLLS CORPORATION
SALT LAKE CITY, UTAH
1/05
ROLLS CORPORATION
5968 South 350 West
Salt Lake City, UT 84107
Phone [phone]
FAX [phone]
www.rolls.com
NOTE: THIS MANUAL ASSUMES THE USER HAS A WORKING KNOWLEDGE OF
AUDIO ELECTRONICS, BALANCED AND UNBALANCED CONNECTIONS, AND
PROPER SIGNAL LEVEL SETTINGS.
LIMITED WARRANTY
This product is warranted to the original consumer purchaser to be free
from defects in materials and workmanship under normal installation, use and ser-
vice for a period of one (1) year from the date of purchase as shown on the purchas-
er’s receipt.
The obligation of Rolls Corporation under this warranty shall be limited to
repair or replacement (at our option), during the warranty period of any part which
proves defective in material or workmanship under normal installation, use and
service, provided the product is returned to Rolls Corporation, TRANSPORTATION
CHARGES PREPAID. Products returned to us or to an authorized Service Center
must be accompanied by a copy of the purchase receipt. In the absence of such pur-
chase receipt, the warranty period shall be one (1) year from the date of manufacture.
This warranty shall be invalid if the product is damaged as a result of
defacement, misuse, abuse, neglect, accident, destruction or alteration of the serial
number, improper electrical voltages or currents, repair, alteration or maintenance
by any person or party other than our own service facility or an authorized Service
Center, or any use violative of instructions furnished by us.
This one-year warranty is in lieu of all expressed warranties, obligations
or liabilities. ANY IMPLIED WARRANTIES, OBLIGATIONS, OR LIABILITIES,
INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MER-
CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, SHALL BE
LIMITED IN DURATION TO THE ONE YEAR DURATION OF THIS WRIT-
TEN LIMITED WARRANTY. Some states do not allow limitations on how long an
implied warranty lasts, so the above limitation may not apply to you.
IN NO EVENT SHALL WE BE LIABLE FOR ANY SPECIAL, INCI-
DENTAL OR CONSEQUENTIAL DAMAGES FOR BREACH OF THIS OR ANY
OTHER WARRANTY, EXPRESSED OR IMPLIED, WHATSOEVER. Some states
do not allow the exclusion or limitation of special, incidental or consequential dam-
ages so the above limitation or exclusion may not apply to you. This warranty gives
you specifi c legal rights, and you may also have other rights which vary from state to
state.

INTRODUCTION
Thank your for your purchase of the Rolls MX422 Field Mixer; Professional ENG
mixer. Please read and review this manual carefully as it contains important
information regarding the proper use and care of the MX422.
INSPECTION
1. Unpack and inspect the MX422 box and package.
If obvious physical damage is noticed, contact the carrier immediately to make a
damage claim. We suggest saving the shipping carton and packing materials for
safely transporting the unit in the future.
2. Please visit our website at
www.rolls.com
and click on the Register Your War-
ranty Here button, or complete the Warranty Registration Card and return it to the
factory.
TABLE OF CONTENTS
Introduction 1
Inspection
Table of Contents
Hearing Safety Warnings
Features 2
Specifications
Quick Start Guide 3
Description
Front Panel 4
Rear Panel 5
Connection 6
Rear Panel Connections
Front Panel Connections
Operation 7
Schematic 10
Warranty Back Pare
HEARING SAFETY WARNINGS:
While special attention has been given to your safety and hearing protection, the operator
determines proper and safe operating levels.
Please note the following:
- Always turn down the PHONES level control before plugging in your headphones.
- Always operate your headphones at the lowest practical level.
- Be especially cautious in unknown or widely varying environments.
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SCHEMATIC

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SPECIFICATIONS
Input Impedance: Mic: 10K Ohms XLR balanced
Source:
22K
Ohms
RCA
Limiter Threshold: -5 dB to off
fully clockwise: No Limiting
Setup Frequency: 1 kHz
Slate Frequency: 20 Hz
Output Attenuator: -30 dB
Self Noise: -57 dB maximum
-90 dB typical
Max Gain: +65 db
S/N Ratio: 115 dB
THD: .05%
Frequency Response: 20 Hz - 30 kHz | +0, -3 dB
Low Cut: 100 Hz
Trim Range: 0 to + 38 dB
Max Input: 0 dBV
Current Draw: 45 mA with no Phantom Power or Signal.
Phantom Power: +48 VDC
Typical Batery Life: 6 Hrs. (2 mics, phan on, 1 headphone)
Connectors: 4 ea. Female XLR, 2 ea. Male XLR, 3 ea. 1/4
”
,
1 ea. 1/8
”
(3.5mm), 1 Center Negative power jack.
Power: 12VDC / 200 mA
Size: 9.5
”
W x 7.25
”
D x 2.375
”
H
Weight: 4 lbs
to remove your headphones or earphones when the Tone button is pressed in.
When levels are set, press the Tone button again to disengage the Tone oscilla-
tor.
HEADPHONE/EARPHONE MONITORING
HEADPHONE/EARPHONE MONITORING
PLEASE NOTE: The MX422 has very loud headphone and earphone circuitry.
Be sure to turn down the Phones level control before selecting the Source and
putting your headphones or earphones on to prevent accidental hearing damage.
HEADPHONE/EARPHONE SOURCE SELECT
HEADPHONE/EARPHONE SOURCE SELECT
When monitoring for recording, you typically will listen to the signal from the
Main Outputs. Leave the SOURCE button in the out position to monitor the Main
Output signal.
Occasionally, you’ll need to listen to an alternate signal - i.e. a remote truck or
recording engineer. Their signal is generally connected to the Monitor Input jack.
Press in the SOURCE button to listen to the signal on the Monitor Input.
OUTPUTS
The MX422 is a two-bus mixer with two individual balanced male XLR output
jacks. Each output is isolated providing excellent signal connectivity and noise
performance.
These outputs are generally connected to a recording device or other input look-
ing for a line-level signal. In the event you need to connect the MX422 output to a
mixer’s Microphone Input, press in the Output Level select switch to -30 dB. This
way the MX422 output is attenuated by 30 dB, and will be more compatible with
an input looking for a microphone level signal.
MASTER LEVEL CONTROL
The front panel Master Level control adjusts the overall output level of the Left
and Right outputs. The gain range of the Master Level is from complete attenua-
tion (no output signal) to +12 dB of gain. Ideally, the Master Level should be set
as close to the detent as possible, providing you with the maximum amount of
variance and headroom.
POWERING
The MX422 features a unique and useful battery scheme. Two separate bat-
tery compartments have been provided on each side of the unit. In the event of
battery voltage loss during recording, the rear panel BATTERY SELECT switch
may be moved to the other position to select the second set of batteries. This is
achieved without any signal loss!
We recommend using 9V alkaline type batteries, however Lithium or NiMH bat-
teries work as well. To check the status of the selected battery set, press and
hold the front panel BATT TEST button.
For AC power, Rolls provides the model # PS27 12 VDC supply to power the
MX422.
FEATURES
- Four servo-balanced XLR Inputs
- Two transformer-balanced XLR Outputs
- Switchable Output Level ( Line level, or -30 dB pad)
- 1/4
”
TRS Stereo Monitor Input and Auxiliary Input
- Switchable 48 Volt Phantom Power for each input
- Switchable 100 Hz Low Cut filters for each input
- Two sets of battery compartments, never lose power
- Level and Pan controls for each channel
- Built in Limiter with variable Threshold control
- 20 Hz Slate tone with Slate Microphone included
- Switchable 1 kHz setup Tone
- Calibrated VU meters
- 1/4
”
and 1/8
”
(3.5mm) Headphone/Earphone Outputs with selectable Source
Input (Main mix buss or Monitor input),and Level control
- Canvas case included
- 6 hour battery life (with 2 condenser mics using phantom power and head
phones attached, constant use).
- Rolls PS27 external power supply included

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low frequency signal and a low-cut filter is effective for reducing wind noise. For
several audio applications engaging the Low-Cut filter is beneficial since little us-
able audio information exists below 100 Hz - especially for speech recording.
PAN CONTROL
The Pan control routes an input channel signal anywhere between the Left and
Right outputs. The MX422 uses constant loudness pan controls, meaning that
the signal is 3 dB louder at the full right or full left position relative to the center
position. Usually, the channel is either panned full left, full right, or center.
The pan potentiometer has a detent in the center position for easy location, and
it is calibrated for a maximum difference of +/- 0.1 dB between the left and right
output in this position.
LIMITER
The MX422 Limiter acts as a
”
safety
”
limiter. During normal operation, with a
properly set gain structure, the threshold of the limiter will not be reached. If
extremely high input signal levels exist, such as in high SPL environments or with
misadjusted settings, the limiter will activate to prevent the channel from clipping.
Without a limiter, high signal conditions would overload the channel and cause
distortion.
Adjust the LIMITER THRESH control to a point above your normal operating
levels, but safely below levels causing distortion or “pegging” of the VU meters.
METERING
The MX422 features two calibrated, backlit VU meters. VU (Volume Units) meter
ballistics correspond closely to how the human ear perceives loudness and pro-
vides a good visual indication of how loud a signal will be. The attack and decay
of the meter signal is 300 mS. The indicated level on the meters is referenced to
+4 dB.
SLATE TONE AND MICROPHONE
The Slate Tone and Microphone circuit is used to notate scenes at the mixer lo-
cation. The Slate circuit uses the front panel momentary button. When this button
is pressed, a 20Hz tone is sent to the Main Outputs, and the Slate Microphone
becomes active. When notating a scene - press and hold the Slate button, speak
into the four-holed Slate microphone, and release.
1kHz TONE
This oscillator is provided to set the gain structure between the MX422 and the
next device in your signal chain. The Tone oscillator is set to output a 1 kHz sine
wave to the Main Right and Left outputs (with the Output Level switch set in the
out or LINE position). Note this tone is also sent to the Headphone outputs when
the Headphone SOURCE button is in the MAIN position. It would be a good idea
QUICK START GUIDE
For those familiar with ENG or field mixers, this guide highlights basic functionality to
begin operating your MX422.
POWERING
To power the MX422 and get it ready for operation:
1. Insert four 9-Volt alkaline batteries into the battery compartments. Insert with the cor-
rect polarity. NOTE: Only one pair of batteries is being used at a time. The other pair is a
backup. More on that later.
2. Or, connect external DC power (the Rolls PS27) 12 VDC to the MX422 DC Input con-
nector.
3. Press in the POWER button.
4. Check battery life by pressing the BATT button.
INPUT CHANNEL SETUP
To set up a gain level for an input channel:
1. Connect a signal source (microphone or line level signal) to a channel input connector.
2. Set the rear panel trim control at the 12 O’clock position (this is just a starting point).
3. If you’re using a condenser microphone, activate the Phantom Power by pressing in
the
phan
button.
4. Set the LEVEL Control at the 12 O’clock position (again - just a starting point).
5. Set the channel PAN control for the desired signal position in the stereo field.
6. Press in the rear panel “low cut” switch if needed.
7. Verify there is signal present on the output meter(s).
OUTPUT CONNECTION
To connect to the MX422 main Outputs
1. Connect an XLR cable to the LEFT and RIGHT Outputs of the MX422.
2. Set the output level switch to either LINE (switch out), or -30 dB (switch in).
3. Verify that the next device in the signal chain is receiving signal from the MX422.
HEADPHONE MONITORING
1. Connect stereo headphones or earphones to the HEADPHONE outputs on the front
panel. NOTE: THESE MUST BE STEREO HEADPHONES OR EARPHONES - USING
MONO PHONES WILL DAMAGE THE MX422.
2. Select the Phones signal SOURCE (monitor either the Main signal; switch out, or Moni-
tor Input; switch in).
3. Set the PHONES level to 0.
4. Verify signal in the phones by slowly bringing up the PHONES level control.
5. Set the PHONES level control for a comfortable level.
METERING
1. View the Main RIGHT and LEFT output signal levels on the ref. +4 dB VU meters.
2. To check the available battery voltage - press the BATT TEST button.
LIMITING
1. For no limiting at all, turn the LIMITER THRESH control completely clockwise.
2. To set a limiting point, send signal through the MX422 and slowly turn the LIMITER
THRESH control counter-clockwise until the desired amount of limiting is acheived.

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DESCRIPTION
FRONT PANEL
LEVEL 1, 2, 3, and 4: Adjust the level of signal from the corresponding Mic Input.
PAN 1, 2, 3, and 4: Adjusts the relative Right/Left signal level to the mix bus.
SLATE MIC: When the Slate Button is pressed and held in, the sound at this
microphone is sent to the main outputs, along with a 20Hz sine wave signal.
SLATE BUTTON: Engages the Slate Mic.
COMP THRESH: Sets the level at which the compressor will
“
compress
”
or lower
the signal level.
1 kHz TONE: When pressed, this button sends a 1 kHz signal to the main out-
puts.
BATT TEST: When pressed, this button will indicate the approximate battery volt-
age on the VU meters. Proper battery voltage will be indicated with the meters
moving to the red region of the field. If the meters are below the red region, bat-
tery replacement is necessary.
HEADPHONE LEVEL: Adjusts the level of signal from the Headphone Outputs.
HEADPHONE SOURCE SELECT SWITCH: When this button is OUT, the sound
heard at the Headphone Outputs will be that of the Main Output, when it is
pressed IN, the sound heard will be that of the Monitor Input.
HEADPHONE/EARPHONE OUTPUTS: 1/4
”
Tip-Ring-Sleeve and 1/8
”
(3.5 mm)
Tip-Ring-Sleeve jacks containing either the Main Output signal or Monitor Output
signal depending on the setting of the Headphone Source Select Switch.
OPERATION
INPUT CHANNELS
The inputs to the MX422 consist of four, full-featured microphone preamplifiers.
Each channel has a wide gain range to accommodate nearly all signal types.
The unit accepts signals ranging from low-sensitivity ribbon and dynamic micro-
phones to medium level wireless and condenser mic outputs, up to the “hot” line
levels.
The MX422 input channels can be used as wither balanced or unbalanced con-
nections. When unbalancing - ground pin-3 to pin-1. There is no change in gain
between unbalanced and balanced connections into the MX422.
The AUX INPUT jack is provided for recording stereo sources such as CD play-
ers, MP3, players, DVD, etc.
TRIM CONTROL
Like traditional mixing consoles, the MX422 microphone preamp gains are set via
the trim control. This control adjusts the input sensitivity of the channel input so
that the channel fader can be set to operate in a usable range. Once set, the trim
is typically kept at the set level and all mixing is done on the channel front panel
Level control.
INDIVIDUAL CHANNEL LEVEL CONTROLS
While both the trim and channel Level controls adjust the gain of a given channel,
the Level is the primary channel volume control. The trim can be thought of as a
“
course
”
gain adjustment to be adjusted during setup, and the Level control is a
“fine” gain adjustment used while recording. With a properly set up trim control,
the Level can be set to a nominal level (around 12 O’clock) providing the maxi-
mum amount of variance and headroom.
PHANTOM POWERING
The MX422 can provide up to 10 mA of current to each input at 48 Volts, suf-
ficient for the most power-hungry condenser microphones. The MX422 Phantom
Power utilizes a fixed 48 Volts DC which is resistively applied to pin-2 and pin-3
of an XLR input connector relative to pin-1 (there is no voltage difference be-
tween the signal on pins -2 and - 3; a dynamic microphone may or may not oper-
ate normally in the presence of phantom power).
It is generally a good practice to turn off phantom powering when not using a
condenser microphone as it can capacitively couple noise into the mic inputs
with poor mic cables.
Also, be sure to turn off phantom powering when using rib-
Also, be sure to turn off phantom powering when using rib-
bon microphones since an improperly wired cable can permanently damage the
bon microphones since an improperly wired cable can permanently damage the
microphone
microphone
.
LOW-CUT FILTERS
Each channel of the MX422 features a switchable Low-Cut filter set at 100Hz.
These Low-Cut (sometimes called “High Pass”) filters are useful for removing ex-
cess low frequency energy in audio signals. Wind noise is a common unwanted

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CONNECTION
REAR PANEL CONNECTIONS
Connect your microphones
to the MX422 using bal-
anced XLR cables. Connect
the MX422 Outputs to the
next device in your signal
chain (usually a recording
device of some kind), also
via balanced XLR cables.
For monitoring external
signal sources, connect a
stereo (Tip-Ring-Sleeve)
plug to the Monitor Input
FRONT PANEL CONNECTIONS
Connect your headphones or earphones to the MX422 front panel as shown
below.
IMPORTANT NOTICE: DO NOT PLUG MONO (Tip-Sleeve)
PLUGS INTO EITHER PHONES JACK. DOING SO WILL
DAMAGE THE MX422.
Carefully adjust the Phones Level
control for a comfortable listening
level.
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REAR PANEL
12VDC / 100 mA: Power input connector. Connects to the optional Rolls PS27
Power Adapter.
POWER: Button - turns the MX422 on and off.
MONITOR INPUT: 1/4
”
Tip-Ring-Sleeve jack for connection to a stereo signal
source to be monitored. This signal connects directly to the Phone Level control,
and the Headphone Outputs.
LEFT/RIGHT OUTPUT: Balanced XLR jacks containing the main mix signal. Pin
2 is configured
”
hot
”
, pin 3 is neutral, and pin 1 is conntected to chassis ground.
OUTPUT LEVEL (-30 dB / LINE): When pressed in, this button pads the Output
signal by 30 dB.
BATTERY SELECT: This switch selects which set of battery compartments are
being used. When the switch is to the left, the left side (with the back panel facing
you) battery compatments are being used. When the switch is to the right, the
right side battery compartments are being used.
AUX INPUT: 1/4
”
Tip-Ring-Sleeve jack for connection to an auxiliary line-level
stereo signal such as the output of another mixer, AM/FM tuner, CD player, etc.
INPUTS 1 - 4: Balanced XLR jacks for connection to dynamic or condenser mi-
crophones - or, to a balanced line-level signal.
TRIM: Adjusts the input signal gain to the corresponding channel.
PHAN 1 - 4: When pressed in, this button applies 48 volts of phantom power to
the corresponding Input.
LOW CUT 1 - 4: When pressed in, this button reduces the low frequency (100Hz
and below) of the corresponding Input signal.
DESCRIPTION CONT.
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