RDL RUMX4T Quick Start Guide

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Model RU-MX4
Pro Audio Mic/Line Mixer

®

SERIES

ANYWHERE YOU NEED...

• Four Channel Audio Mixer

•

XLR Microphone Inputs, Phono Line Inputs

• Switchable Phantom for Each Mic Input

• Mic or Line XLR Output, Switchable

• Unbalanced Line Output and Direct Input

• Studio Quality, Low-Noise Performance

• Integral Compressor/Limiter, Switchable

• Expansion Bussing Capability

• Output Isolation Transformer (RU-MX4T)

You Need The RU-MX4(T)!

The RU-MX4 is part of the group of RDL RACK-UP products. The compact design permits high-density installations, with three
products mounted in a single rack unit. The RU-MX4 may be used alone, or mounted using a wide variety of RACK-UP series
options.

APPLICATION: The RU-MX4 is the ideal choice in many applications where a combination of balanced mic and/or unbalanced

line-level signals needs to be mixed. All balanced connections are made through XLR connectors. Unbalanced signals are coupled
through phono jacks.

Each of the four RU-MX4 inputs can accept either a balanced XLR mic or an unbalanced line-level phono input. Each MIC input
accepts either a dynamic or a condenser microphone. A PHANTOM switch is located below each microphone input. These

switches activate the phantom voltage and set the input preamplifier for the optimum gain range for the type of microphone. An
integral high-pass filter rolls off frequencies below 80 Hz.

A separate unbalanced DIRECT input allows an external audio source to be summed directly into the mix amplifier, bypassing the
front-panel input level controls. The unbalanced phono jack LINE OUTPUT from one RU-MX4 may connect to the unbalanced input
of other equipment, or may be connected to the DIRECT input of another RU-MX4 to expand mixing capabilities. Up to 3

RU-MX4 mixers may be rack mounted in a single rack unit using an RDL RU-RA3HD rack adapter. A power interconnect cable is
supplied with each RU-MX4 allowing the rack mounted mixers to run from a single 24 Vdc power supply.

The RU-MX4 provides one balanced output, switchable for mic or line level. The balanced XLR output and the unbalanced phono
jack output may be used at the same time.

Audio levels are adjustable on the front panel. A convenient label area is provided below each fader knob. A label tab included with
the mixer may be professionally labeled using a commercial lettering machine, or the user may write on the tab. The tabs lock into
a pocket behind the front panel laminate to produce a professionally labeled appearance.

Each input channel is equipped with a front-panel dual-LED VU meter that follows standard VU ballistics. A green LED illuminates
at 15 dB below the optimum input gain, becoming progressively brighter with increasing audio level. The adjacent red LED
illuminates when the input gain exceeds the correct operating level.

The final mix is displayed on an LED string VU meter featuring a visually comfortable arc motion. The outputs may be fed directly
from the final mix, or may be routed through the integral compressor/limiter. A rear-panel switch allows the soft-knee compressor to
be switched in or out. When active, the compressor/limiter begins acting as signals exceed 6 dB below the normal output level,
and maintain an average +4 dBu output level for excessive signal levels up to 20 dB. An optional security cover (RU-MX4SC) is
available to prevent user access to the rear panel switches. The RU-MX4 is electronically balanced. A factory installed output
isolation transformer is available by ordering the RU-MX4T.

Wherever a mixer is needed to provide superior audio clarity, user adjustments, reliability, compactness and unsurpassed
versatility, the RU-MX4 is the ideal choice. Use the RU-RA3HD rack-mount adapter to mount multiple mixers, or to combine related
products (such as audio or video distribution, or audio metering) into a single rack unit!

RDL • 659 N. 6th St. • Prescott, AZ., USA 86301 • [phone] • FAX [phone] • www.rdlnet.com

®

RACK-UP

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SERIES

Installation/Operation

Model RU-MX4
Professional Audio Mic/Line Mixer

CONNECT TO EXPAND
MIXING TO ANOTHER
RU-MX4

DIRECT

INPUTS

24V

PWR

SET XLR OUTPUT JACK FOR MIC OR LINE LEVEL

ADJUST EACH INPUT GAIN
FOR BRIGHTEST GREEN LED
WITH MINIMAL FLASHING
OF THE RED LED

TYPICAL PERFORMANCE

Microphone Inputs(4): 2 kΩ balanced, switchable 24 V phantom (IEC 1938: 1996-12)

Microphone Input Level: -58 to –20 dBu (PHANTOM OFF); -41 to –4 dBu (PHANTOM ON) for +4 dBu output

Line Inputs (4): 2 kΩ unbalanced
Line Input Level: -25 dBV to +20 dBV for +4 dBu output; -10 dBV nominal

Gain Adjustments (5): Mic: Off to 62 dB gain (PHANTOM OFF); Off to 62 dB gain (PHAN TOM ON HI GAIN);
Off to 46 dB gain (PHANTOM ON LO GAIN)

Line: Off to 27 dB gain
Output Attenuator: 0 dB to infinity
Frequency Response:
Mic: 80 Hz to 30 kHz (+/- 1.5 dB), <-10 dB @ 20 Hz (integral high-pass filter)
Line: 20 Hz to 30 kHz (+/- 0.25 dB)
THD+N:
Mic: < 0.1% (80 Hz to 20 kHz)
Line: < 0.02%
Residual Noise (below +4dBu output): 4 line level sources (unity gain): < -82 dB (wideband)

40dB Gain, LO GAIN: Mic: -79 dB; all 4 mic level sources: < -73 dB (wideband); < -76 dB (“A” weighted)
50dB Gain, HI GAIN: Mic: -79 dB; all 4 mic level sources: < -73 dB (wideband); < -76 dB (“A” weighted)
60dB Gain, HI GAIN: Mic: -70 dB; all 4 mic level sources: < -64 dB (wideband); < -66 dB (“A” weighted)
Outputs (2): +4 dBu 150 Ω balanced (switchable MIC or LINE); -10 dBV unbalanced

Indicators (18): Dual-LED VU meter for each input

COMPRESSION/LIMITING active LED
POWER LED

8-segment bar mode string LED audio mix level meter, 0 dB = +4 dBu
VU ballistic: -20 dB, -10 dB, -6 dB, -2 dB, 0 dB, +3 dB; Peak reading: +8 dB,+12 dB
Power Requirement: 24 Vdc @ 150 mA, Ground-referenced

Overall Dimensions: Height: 1.7 in. 4.3 cm
Length: 5.8 in. 15.0 cm
Depth: 4.8 in. 12.2 cm

891-3190F

Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287

SWITCH COMPRESSOR
ON IF DESIRED

LINE

OUTPUTS

ON
COMP/LIM

24VDC PWR

RDL

1

4

PHANTOM

ONOFF

HI

LO

MICLINE

MIC GAIN

TURN PHANTOM ON FOR CONDENSER, OFF FOR DYNAMIC
SELECT HI OR LO GAIN AS APPROPRIATE WITH PHANTOM ON

234

Radio Design Labs Technical Support Centers

U.S.A. [phone], [phone]; Fax: [phone]

3

MIC

PHANTOM

ONOFF

HI

LO

MIC GAIN

LINE

ADJUST LEVELS FOR LED
ACTIVITY IN THIS RANGE

IF COMPRESSOR IS TURNED ON, LED
FLASHES WHEN COMPRESSOR IS ACTIVE

2

MIC

PHANTOM

HI

MIC GAIN

LINE

60

40

20

-3

-6

-7

-10

-20

AUDIO COMPRESSION / LIMITING

METERING

MIC

ONOFF

LO

LINE

80

-1 0-2

1.5
3

5

8

10

PHANTOM

MIC GAIN

12

1

ONOFF

HI

LO

POWERINPUT LEVEL

T
T
E
N

OUTPUT

EN55103-1 E1-E5; EN55103-2 E1-E4

Typical Performance reflects product at publication time
exclusive of EMC data, if any, supplied with product.
Specifications are subject to change without notice.

CONNECT LINE LEVEL

DIRECT

INPUTS

MIC

LINE

CONNECT 24 VDC
SUPPLY CURRENT MUST
BE SUFFICIENT TO POWER
ADDITIONAL MIXERS, IF ANY

NA
O
R
M
A
L

SET TO NORMAL UNLESS
OUTPUT NEEDS TO BE TURNED DOWN

TO PHONO JACK
OR MIC TO XLR (EACH INPUT)

24V

PWR

INPUT SWITCH SETTINGS

PHANTOM

ONOFF

LEFT POSITION FOR DYNAMIC MICS
(HIGH GAIN)

HI

LO

MIC GAIN

PHANTOM

ONOFF

CENTER POSITION FOR CONDENSER
MICS WITH LOW LEVEL OUTPUTS

LO

HI

(HIGH GAIN)

MIC GAIN

PHANTOM

ONOFF

RIGHT POSITION FOR CONDENSER
MICS WITH HIGH LEVEL OUTPUTS

LO

HI

(LOW GAIN)

MIC GAIN