Sonifex Reference Monitor Meters Instruction Manual

Reference Monitor Meters
User Handbook
RM-M1F53 1 Stereo 53 Segment Meter, Free-Standing
RM-M1R53 1 Stereo 53 Segment Meter, Rack-Mount
RM-M2F53 2 Stereo 53 Segment Meters, Free-Standing
RM-M2R53 2 Stereo 53 Segment Meters, Rack-Mount
RM-M4R53 4 Stereo 53 Segment Meters, Rack-Mount
RM-M1F106 1 Stereo 106 Segment Meter, Free-Standing
RM-M1R106 1 Stereo 106 Segment Meter, Rack-Mount
RM-M2R106 2 Stereo 106 Segment Meters, Rack-Mount

bReference Monitor Meters User Handbook
This handbook is for use with the following product:
RM-M1F53 1 Stereo 53 Segment Meter, Free-Standing
RM-M1R53 1 Stereo 53 Segment Meter, Rack-Mount
RM-M2F53 2 Stereo 53 Segment Meters, Free-Standing
RM-M2R53 2 Stereo 53 Segment Meters, Rack-Mount
RM-M4R53 4 Stereo 53 Segment Meters, Rack-Mount
RM-M1F106 1 Stereo 106 Segment Meter, Free-Standing
RM-M1R106 1 Stereo 106 Segment Meter, Rack-Mount
RM-M2R106 2 Stereo 106 Segment Meters, Rack-Mount
©Sonifex Ltd, 2009-2012
All Rights Reserved
Revision 1.03, June 2012
Sonifex Ltd, 61, Station Road, Irthlingborough,
Northants, NN9 5QE, England.
Tel: [phone]
Fax: [phone]
Email: [email protected].uk
Website: http://www.sonifex.co.uk
Information in this document is subject to change without notice and does not represent a commitment on the part of
the vendor. Sonifex Ltd shall not be liable for any loss or damage whatsoever arising from the use of information or any
error contained in this manual.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying, recording, information storage and retrieval systems, for any purpose other than the purchaser’s
personal use, without the express written permission of Sonifex Ltd. Unless otherwise noted, all names of companies,
products and persons contained herein are part of a completely ctitious adaptation and are designed solely to
document the use of Sonifex product.
REFERENCE MONITOR METERS
USER HANDBOOK
REFERENCE MONITOR METERS USER HANDBOOK
Made in the UK by

Reference Monitor Meters User Handbook c
CONTENTS
CONTENTS
Warranty i
Warranty and Liability i
Unpacking the Reference Monitor Meter iii
Returning the Warranty Card iii
Safety Information iv
Safety of Mains Operated Equipment iv
Voltage Setting Checks iv
Fuse Rating iv
Power Cable and Connection iv
Ordering the Correct Mains Lead v
Installation Information v
Atmosphere v
Electromagnetic Radiation v
WEEE & RoHS Directives - Sonifex Statement vi
Reference Monitor Meters Introduction 1
System Block Diagram 2
Front Panel Indicators & Controls 3
Power LED 3
AES Lock LED 3
Level Alarm LED 4
Input Select Button (RM-M1-106 Only) 4
Main Meters 4
Table 1 – Meter Characteristic DIPSwitch settings 6
Meter Labelling 6
Brightness Control 7
Phase Meter 7
Reset Button 7
Rear Panel Connections & Operation 8
Mains Power 8
Audio Inputs 8
Digital Input Termination 8
Input Gain Adjustment 9
Table 2 – Input Gain DIPSwitch Settings 9
Remote Inputs and Outputs 10
Table 3 – Remote Input and Output Connection Details 11
RS232 Remote Control 11
Force Bootloader Mode 11
Serial Interface Commands & Responses Protocol 12
Serial Data Format 12
Error Messages 15
Reference Monitor Meters SCi Remote Control Software 16

dReference Monitor Meters User Handbook
FIGURES
FIGURES
Contents (Continued)...
Connecting the RS232 Serial Port 16
Using SCI for the First Time 16
Loaded Launcher 17
SCi for Reference Monitor Meters – Main Screen 17
SCi for Reference Monitor Meters – Options Screen 18
Firmware Updates 20
The Misc screen shows the Update Firmware option. 20
Technical Specication 21
Figures
Fig A: Packing List iii
Fig B: Power Connections iv
Fig C: Mains Lead Table v
Fig 1-1: Reference Monitor Meters Block Diagram 2
Fig 1-2: RM-M1-53 Front Panel 3
Fig 1-3: RM-M2-53 Front Panel 3
Fig 1-4: RM-M1-106 Front Panel 3
Fig 1-5: Meter Labelling Options – 53 Segment Display 6
Fig 1-6: Meter Labelling Options – 106 Segment Display 6
Fig 1-7: Brightness Control 7
Fig 1-8: Phase Meter 7
Fig 1-9: Reset Button 7
Fig 1-10: RM-M2-53 Rear Panel 8
Fig 3-1: SCi Launcher 16
Fig 3-2: SCi Device Discovery Panel 16
Fig 3-3: SCi Launcher Loaded 17
Fig 3-4: SCi Main Status Screen for RM-M2-53 17
Fig 3-5: SCi Main Status Screen for RM-M1-106 18
Fig 3-6: SCi Options Screen 18
Fig 3-7: SCi Misc Screen 20

Reference Monitor Meters User Handbook i
Warranty
Warranty and Liability
Important: the purchaser is advised to read this clause
(a) The Company agrees to repair or (at its discretion) replace Goods which are found to
be defective (fair wear and tear excepted) and which are returned to the Company
within 12 months of the date of despatch provided that each of the following
are satised:
(i) notication of any defect is given to the Company immediately upon its
becoming apparent to the Purchaser;
(ii) the Goods have only been operated under normal operating conditions and
have only been subject to normal use (and in particular the Goods must have
been correctly connected and must not have been subject to high voltage or
to ionising radiation and must not have been used contrary to the Company’s
technical recommendations);
(iii) the Goods are returned to the Company’s premises at the Purchaser’s expense;
(iv) any Goods or parts of Goods replaced shall become the property of
the Company;
(v) no work whatsoever (other than normal and proper maintenance) has been
carried out to the Goods or any part of the Goods without the Company’s prior
written consent;
(vi) the defect has not arisen from a design made, furnished or specied by
the Purchaser;
(vii) the Goods have been assembled or incorporated into other goods only in
accordance with any instructions issued by the Company;
(viii) the defect has not arisen from a design modied by the Purchaser;
(ix) the defect has not arisen from an item manufactured by a person other than
the Company.
In respect of any item manufactured by a person other than the Company, the Purchaser
shall only be entitled to the benet of any warranty or guarantee provided by such
manufacturer to the Company.
(b) In respect of computer software supplied by the Company the Company does not
warrant that the use of the software will be uninterrupted or error free.
(c) The Company accepts liability:
(i) for death or personal injury to the extent that it results from the negligence of
the Company, its employees (whilst in the course of their employment) or its
agents (in the course of the agency);
(ii) for any breach by the Company of any statutory undertaking as to title, quiet
possession and freedom from encumbrance.
WARRANTY
WARRANTY

ii Reference Monitor Meters User Handbook
(d) Subject to conditions (a) and (c) from the time of despatch of the Goods from the
Company’s premises the Purchaser shall be responsible for any defect in the Goods
or loss, damage, nuisance or interference whatsoever consequential economic or
otherwise or wastage of material resulting from or caused by or to the Goods. In
particular the Company shall not be liable for any loss of prots or other economic
losses. The Company accordingly excludes all liability for the same.
(e) At the request and expense of the Purchaser the Company will test the Goods to
ascertain performance levels and provide a report of the results of that test. The
report will be accurate at the time of the test, to the best of the belief and knowledge
of the Company, and the Company accepts no liability in respect of its accuracy
beyond that set out in Condition (a).
(f) Subject to Condition (e) no representation, condition, warranty or other term,
express or implied (by statute or otherwise) is given by the Company that the Goods
are of any particular quality or standard or will enable the Purchaser to attain any
particular performance or result, or will be suitable for any particular purpose or use
under specic conditions or will provide any particular capacity, notwithstanding
that the requirement for such performance, result or capacity or that such particular
purpose or conditions may have been known (or ought to have been known) to the
Company, its employees or agents.
(g) (i) To the extent that the Company is held legally liable to the Purchaser for any
single breach of contract, tort, representation or other act or default, the
Company’s liability for the same shall not exceed the Price of the Goods.
(ii) The restriction of liability in Condition (g)(i) shall not apply to any liability
accepted by the Seller in Condition (c).
(h) Where the Goods are sold under a consumer transaction (as dened by the
Consumer Transactions (Restrictions on Statements) Order 1976) the statutory
rights of the Purchaser are not aected by these Conditions of Sale.
WARRANTY
WARRANTY

Reference Monitor Meters User Handbook iii
Unpacking the Reference Monitor Meter
The Reference Monitor Meter is shipped with the following equipment. Please check your
packaging to ensure that you have all of the items below. If anything is missing, please
contact the supplier of your equipment immediately.
Quantity
Product Type IEC leads Handbook, CD &
warranty card
Meter scale overlay
sheet
RM-M1F53 1 1 1
RM-M1R53 1 1 1
RM-M2F53 1 1 2
RM-M2R53 1 1 2
RM-M4R53 2 1 4
RM-M1F106 1 1 1
RM-M1R106 1 1 1
RM-M2R106 2 1 2
Fig A: Packing List
Each Reference Monitor Meter is shipped in protective packaging and should be inspected
for damage before use. Where an item is found to have transit damage, notify the carrier
immediately with all the relevant details of the shipment. Packing materials should be kept
for inspection and also for if the product needs to be returned.
Returning the Warranty Card
In order to register the date of purchase so that we can keep you informed of any design
improvements or modications, it is important to complete the warranty registration
document that is enclosed and return it to Sonifex Ltd in the UK.
For your own records you should write down the serial number (which can be found on the
rear of the Reference Monitor Meter.
Serial Number ………………………………………
WARRANTY
WARRANTY

iv Reference Monitor Meters User Handbook
Safety Information
Safety of Mains Operated Equipment
This equipment has been designed to meet the safety regulations currently
advised in the country of purchase and it conforms to the safety regulations
specied by use of the CE Mark.
Warning : There are no user serviceable parts inside the equipment. If you should ever
need to look inside the unit, always disconnect the mains supply before removing the
equipment covers.
Voltage Setting Checks
Ensure that the machine operating voltage is correct for your mains power supply by
checking the box in which your Reference Monitor Meter was supplied. The voltage is
shown on the box label. Please note that all Reference Monitor Meters have a universal
power supply, 85-264V AC, 47-63Hz.
Fuse Rating
The Reference Monitor Meter is supplied with a single fuse in the live conducting path
of the mains power input. For reasons of safety it is important that the correct rating and
type of fuse is used. Incorrectly rated fuses could present a possible re hazard, under
equipment fault conditions. The fuse rating for the Reference Monitor Meter is:
1A 5 x 20mm SB
The active fuse is tted on the outside rear panel of the unit.
Power Cable and Connection
An IEC power connector is supplied with the Reference Monitor Meter which has a
moulded plug attached – this is a legal requirement. If no moulded plug has been supplied
with your Reference Monitor Meter, please contact your supplier, because an IEC connector
is always supplied from the Sonifex factory.
If for any reason, you need to use the Reference Monitor Meter with a dierent power
cable, you should use the following wiring guidelines.
Wire Colour Connection
Green, or green and yellow Earth (E)
Blue, or black Neutral (N)
Brown, or red Live (L)
Fig B: Power Connections
Connect the equipment in accordance with the connection details and before applying
power to the unit, check that the machine has the correct operating voltage for your mains
power supply.
Important Note : The terminal marked on the rear panel must be earthed.
SAFETY INFORMATION
SAFETY INFORMATION

Reference Monitor Meters User Handbook v
Ordering the Correct Mains Lead
When ordering a Reference Monitor Meter from Sonifex, it is helpful if you can specify your
required operating voltage and mains lead. After the product code add:
UK, for 230V, UK 3 pin to IEC lead
EC, for 230V, European Schuko 2 pin to IEC lead
US, for 115V, 3 pin to IEC lead
AU for 230V, Australasian 3 pin to IEC lead
Fig C: Mains Lead Table
E.g. order RM-M1R53 UK for a UK IEC lead to be supplied.
Installation Information
Atmosphere
The units should be installed in an area that is not subject to excessive temperature
variation (<0°C, >50°C), moisture, dust or vibration.
Electromagnetic Radiation
The cover is connected to earth by means of the xing screws. It is essential to maintain
this earth ground connection to ensure a safe operating environment and provide
electromagnetic shielding.
SAFETY INFORMATION
SAFETY INFORMATION

vi Reference Monitor Meters User Handbook
WEEE & RoHS Directives - Sonifex Statement
The Waste Electrical and Electronic Equipment (WEEE) Directive was agreed on
13 February 2003, along with the related Directive 2002/95/EC on Restrictions
of the use of certain Hazardous Substances in electrical and electronic
equipment (RoHS).
The Waste Electrical and Electronic Equipment Directive (WEEE) aims to minimise the
impacts of electrical and electronic equipment on the environment during their life times
and when they become waste. It applies to a huge spectrum of products. It encourages
and sets criteria for the collection, treatment, recycling and recovery of waste electrical and
electronic equipment. All products manufactured by Sonifex Ltd have the WEEE directive
label placed on the case. It gives a contact for individuals who are unsure about the correct
procedure when the product has reached its “end of use”.
Sonifex Ltd will be happy to give you information about local organisations that can
reprocess the products, or alternatively all products that have reached “end of use”can be
returned to Sonifex and will be reprocessed correctly free of charge.
Sonifex Ltd has phased out the use of certain hazardous substances identied in the
European Union’s Restriction of Hazardous Substances (RoHS) directive. The RoHS
directive limits the use of certain hazardous substances currently used in EEE manufacture,
including lead, mercury, cadmium, hexavalent chromium, and halide-containing
compounds PBB (polybrominated biphenyl) and PBDE (polybrominated diphenyl ether).
Elimination of these substances will result in more environmentally friendly recycling
of electronic equipment. For the products which Sonifex manufacture, the main area
where products were aected was in the use of lead for manufacturing and assembling
electronics circuit boards.
Sonifex Ltd practices lead-free (LF) manufacturing processes. LF solder is used on the
surface-mount PCB manufacturing processes and for hand soldering. The printed circuit
boards (PCBs) used are either gold plated, or immersion tin plated, both of which use no
lead. Historically the PCBs were hot air solder levelled (HASL) PCBs which used tin/lead
based solder.
The manufacturing processes include the assembly of purchased components from
various sources. Product is oered as RoHS compliant, or LF, only after sucient evidence
is received from the component manufacturers that their components are RoHS compliant.
Sonifex Ltd relies solely on the distributor, or manufacturer, of the components for
identication of RoHS compliance. Thus whilst every eort is made to ensure compliance,
Sonifex Ltd makes no warranty, or certication, or declaration of compliance concerning
said components.
Sonifex Ltd denes “Lead Free”as pertaining to any product, which has been manufactured
by Sonifex Ltd using components which have been declared by the manufacturers as
“Lead Free”. All statements by Sonifex Ltd of RoHS compliance are based on component
manufacturer documentation.
WEEE & ROHS DIRECTIVE
WEEE & ROHS DIRECTIVE

Reference Monitor Meters User Handbook 1
INTRODUCTION
INTRODUCTION
Reference Monitor Meters Introduction
The Reference Monitor Meters oer accurate, high resolution metering of up to
2 stereo audio sources in a compact 1U freestanding or rack mount package. All
stereo sources are auto-switching between either analogue or digital AES/EBU
formats with sample rates up to 192kHz accepted.
The level of each stereo source is displayed on a pair of bright, multi-coloured
bar graph meters, with a choice nine accurately modelled scales/responses to
suit dierent applications and local preferences. Separate phase meters indicate
channel correlation or phase error conditions, and additional LEDs show digital
input lock and audio level alarm status.
On the rear panel, open-collector alarm outputs provide hardware indication of
audio under-level or silence, audio over-level, sustained phase errors above 90
degrees and digital source lock.
Alarm audio threshold levels and time-out durations are all fully congurable via a
RS232 connection in conjunction with Sonifex SCi Windows-based remote control
software. Status monitoring and unit identication, plus rmware updates to
add extra functionality are also supported by the Sonifex SCi software. The open
control protocol also allows operation with terminal programs or customised
applications.
There are 3 models in the Reference Monitor Meters range which can be supplied in rack-
mount, freestanding and twin versions to provide eight dierent products.
The RM-M1F53 has a single stereo audio input and a pair of 53-segment bar graph meters.
The RM-M2F53 is a dual stereo input version with a pair of 53-segment bar graph meters for
each audio input. Separate phase and status LEDs for each audio input are also provided
The RM-M1F106 is a dual stereo audio input version, with a pair of 106-segment bar graph
meters for greater display accuracy. A front panel mounted input select switch selects the

2Reference Monitor Meters User Handbook
1
INTRODUCTION
INTRODUCTION
audio source to be monitored, from either of the 2 stereo inputs, or from a mono mix of
each channel with channel 1 shown on the left meter and channel 2 shown on the right
meter.
The Reference Monitor Meters are available in 1U rack mount versions:
RM-M1R53 Rack mount version of RM-M1F53.
RM-M2R53 Rack mount version of RM-M2F53.
RM-M4R53 Dual rack mount version combining 2xRM-M2R53 units providing 4 stereo
inputs.
RM-M1R106 Rack mount version of RM-M1F106.
RM-M2R106 Dual rack mount version combining 2xRM-M1R106 units providing
4 stereo inputs.
In this document, generic model references are used to refer to features that are relevant to
all versions of that particular model, for example:
RM-M1-53 refers to the RM-M1F53 and the RM-M1R53,
RM-M2-53 refers to the RM-M2F53 and the RM-M2R53 and
RM-M1-106 refers to the RM-M1F106 and the RM-M1R106.
All Reference Monitor Meters products operate from global mains voltages (85-264V AC,
47-63Hz) without adjustment.
System Block Diagram
Analogue
or Digital
Input
AES/EBU
Receiver
AES/EBUTermination
A/D
Converter A/D Auto
Switch
Analogue
or Digital
Input
(Select Switch
on RM-M1F06,
RM-M1R106 &
RM-M2R106 Only)
Global
Mains
Power
Global
Mains
Power
AES/EBU
Receiver
Display
Driver
Phase
Metering
Level
Metering
AES/EBUTermination
A/D
Converter A/D Auto
Switch
RS232
Remote Control
Alarms &
Logic I/O
Configuration
Switches
Indicators Metering Display
Input 1
Input 2 (Input 2 not on RM-M1F53 or RM-M1R53)
Micro Controller
I/P Gain
Front Panel

Reference Monitor Meters User Handbook 3
1
FRONT PANEL INDICATORS & CONTROLS
FRONT PANEL INDICATORS & CONTROLS
Fig 1-1: Reference Monitor Meters Block Diagram
Front Panel Indicators & Controls
Fig 1-2: RM-M1F53 Front Panel
Fig 1-3: RM-M2F53 Front Panel
Fig 1-4: RM-M1F106 Front Panel
Power LED
The Power LED illuminates whilst internal power is present within the unit. If this indicator
is not on, the most likely reason is simply the absence of mains power, but under fault
conditions it may also indicate a ruptured mains fuse or a problem with the internal power
supply module.
AES Lock LED
The AES Lock LED illuminates when the corresponding audio input is connected to a valid
digital AES/EBU audio signal. It will not illuminate if the audio input is an analogue signal, or
if a digital audio signal is applied which has a sample rate outside the acceptable range of
the unit, contains invalid/non-audio data or is too weak for the receiver to lock on to.

4Reference Monitor Meters User Handbook
1
FRONT PANEL INDICATORS & CONTROLS
FRONT PANEL INDICATORS & CONTROLS
Level Alarm LED
The Level Alarm LED illuminates when the alarm condition setting for the corresponding
audio input has been met. By default, the alarm condition is set to Input Clip. With this
setting, the Level Alarm LED will illuminate when the input signal level (taking into account
any input gain applied) has either exceeded or come within 0.5dB of the maximum
acceptable input level. See the section “Reference Monitor Meters SCi Remote Control
Software” for further details on additional alarm settings.
Input Select Button (RM-M1-106 Only)
The Input Select Button determines which source is currently routed to the metering.
Pressing the button selects the next available source, and the button illumination indicates
the current selection. With input 1 selected, the button is not illuminated. When the button
illuminates green, the left meter shows a mono mix of input 1 and the right meter shows a
mono mix of input 2. When the button illuminates red, input 2 is selected.
When mains power is removed, the currently selected input is stored in non-volatile
memory and recalled once power is restored.
Main Meters
Fig 1-5: RM-M2-53 53 Segment Meter & RM-M1-106 106 Segment Meter
The main meters are made up of 53 or 106 segment, multicoloured LED bar graphs
(dependent on model). Units with 53 segment displays will have a pair of bar graphs for
each input channel. On all units, the top bar graph is the left channel and the lower bar
graph is the right channel.
Several dierent meter characteristics are available to suit dierent applications and
regional preferences, and each available input channel can be individually set to the
required setting. The active meter characteristic is selected using the DIPSwitches in the
“Settings 2” bank (found on the rear panel of the unit), according to the following table.

Reference Monitor Meters User Handbook 5
1
FRONT PANEL INDICATORS & CONTROLS
FRONT PANEL INDICATORS & CONTROLS
Meter
Characteristics Scale Range* 0dBFS Reference
Amber Section
Starts at*
Red Section
Starts at*
Dual PPM + Standard
VU -13 to +13dBu +18dBu 0dBu +8dBu
BBC PPM or EBU
PPM** -13 to +13dBu +18dBu 0dBu +8dBu
Nordic PPM -40 to +12dBu +18dBu 0dBu +6dBu
AES Digital PPM -52 to 0dBFS +18dBu -18dBFS 0dBFS
DIN PPM -54 to +5dBu +18dBu 0dBu +4dBu
Standard VU -24 to +3VU +18dBu -4VU 0VU
Extended VU -59 to +15VU +18dBu -4VU 0VU
German PPM -54 to +15dBu #+15dBu -54dBu +7dBu
AES Digital PPM
(SMPTE RP.0155) -52 to 0dBFS +18dBu -20dBFS 0dBFS
Meter
Characteristics
Audio Input 1 Audio Input 2
SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8
Dual PPM +
Standard VU OFF OFF OFF OFF OFF OFF OFF OFF
BBC PPM or EBU
PPM** ON OFF OFF OFF ON OFF OFF OFF
Nordic PPM OFF ON OFF OFF OFF ON OFF OFF
AES Digital PPM ON ON OFF OFF ON ON OFF OFF
DIN PPM OFF OFF ON OFF OFF OFF ON OFF
Standard VU ON OFF ON OFF ON OFF ON OFF
Extended VU OFF ON ON OFF OFF ON ON OFF
German PPM ON ON ON OFF ON ON ON OFF
AES Digital PPM
(SMPTE RP.0155) OFF OFF OFF ON OFF OFF OFF ON
* With 0dB of input gain selected # With 0dB input gain (SW6 and SW7 o)
**May be BBC or EBU PPM depending on the choice of scale plate.
Table 1 – Meter Characteristic DIPSwitch settings

6Reference Monitor Meters User Handbook
1FRONT PANEL INDICATORS & CONTROLS
FRONT PANEL INDICATORS & CONTROLS
The meter characteristics can be changed at any time, without the need to remove power
from the unit. A total of sixteen meter characteristics can be supported for each audio input,
allowing additional settings to be added in future rmware versions.
Meter Labelling
Each meter characteristic possesses dierent scaling, range and ballistics according to
the relevant British or International standards and self-adhesive scales for each of the
characteristics are supplied with the unit.
Fig 1-5: Meter Labelling Options – 53 Segment Display
Fig 1-6: Meter Labelling Options – 106 Segment Display

Reference Monitor Meters User Handbook 7
1
FRONT PANEL INDICATORS & CONTROLS
FRONT PANEL INDICATORS & CONTROLS
Once the desired meter characteristic has been chosen, proper scale labelling may be
ensured by removing the appropriate scale from the backing paper and applying it to the
recess provided between the meter bar graphs.
Brightness Control
The brightness of the bar graph meters and all other front panel indicators may be adjusted
to suit user preference or to match similar units nearby.
Fig 1-7: Brightness Control
A miniature at-bladed screwdriver inserted into the hole next to the brightness symbol
should be turned clockwise to increase the brightness or anti-clockwise to decrease it.
Phase Meter
Fig 1-8: Phase Meter
The ve-segment LED phase meter indicates the average phase correlation between the left
and right channels of the corresponding stereo audio input. It is labelled in both degrees
of phase shift and amount of correlation. A monophonic signal fed to both channels of the
corresponding audio input will have a correlation of 1.0, while inverting one such channel –
making it perfectly out of phase – gives a correlation of -1.0. True stereo signals will produce
a uctuating phase correlation.
Reset Button
In the unlikely event that the Reference Monitor Meters unit fails to respond, press the
recessed reset button via the small hole in the front panel.
Fig 1-9: Reset Button

8Reference Monitor Meters User Handbook
1
REAR PANEL CONNECTIONS & OPERATION
REAR PANEL CONNECTIONS & OPERATION
Rear Panel Connections & Operation
Fig 1-10: RM-M2-53 Rear Panel
Mains Power
Power is applied via a standard three-pin IEC male socket. Mains voltages between 85V and
264V AC at frequencies between 47 and 63Hz are accepted without adjustment. A 1A, 5 x
20mm SB fuse is used. The Earth pin MUST be connected to ensure safety.
Audio Inputs
Three-pin female XLR connectors are provided for the connection of up to two stereo audio
sources (dependent on model). The pin assignations are as follows:
Pin 1: Ground
Pin 2: In-phase signal (“hot”)
Pin 3: Out-of-phase signal (“cold”)
Unbalanced signals may also be used by linking pins 1 and 3 and applying the unbalanced
signal to pin 2. Each of the audio inputs accepts either a pair of analogue line-level signals
(using both input XLRs) or a single AES/EBU digital signal (attach to the left-hand XLR of
the pair and leave the right-hand XLR unconnected). The unit automatically detects digital
audio signals and re-congures the input accordingly. A full-scale digital input signal
(0dBFS) corresponds to the maximum analogue input signal level as shown in Table 1 (with
no extra input gain applied).
Digital Input Termination
Switchable termination is provided to allow the Reference Monitor Meters inputs to be
bridged across an existing AES/EBU connection without double-termination, but this should
only be attempted with the terminating equipment mounted adjacent to the Reference
Monitor unit and with connections kept as short as possible. It is strongly recommended
that the digital input termination is set to ON at all times. Failure to do so may result in
unreliable reception of digital input signals and/or crosstalk between sources.
The 110Ω input termination for the AES/EBU digital inputs is controlled by the settings of
DIPSwitches 1 and 2 in the“Settings 1” bank (found on the rear panel of the unit) as follows:
SW1: When set to ON, digital input 1 is terminated with 110Ω.
SW2: When set to ON, digital input 2 is terminated with 110Ω (valid on 2 channel units only)

Reference Monitor Meters User Handbook 9
1
REAR PANEL CONNECTIONS & OPERATION
REAR PANEL CONNECTIONS & OPERATION
Input Gain Adjustment
For both analogue and digital sources the default input gain is zero, i.e. an input of 0dBu
results in a reading of 0dBu on the meters. However, to accommodate lower level sources it
is possible to introduce extra input gain in 6dB steps. This gain can be applied to each input
channel independently, and it is controlled by the settings of DIPSwitches 3, 4, 5 and 6 in
bank “Settings 1”(found on the rear panel of the unit), according to the following table.
Input Gain Maximum Signal Level
(Analogue Sources)
Maximum
Signal Level
(Digital
Sources)
Audio Input 1 Audio Input 2
SW3 SW4 SW5 SW6
0dB
+18dBu
(+15dBu for German PPM
meter setting)
0dBFS OFF OFF OFF OFF
+6dB
+12dBu
(+9dBu for German PPM
meter setting)
-6dBFS ON OFF ON OFF
+12dB
+6dBu
(+3dBu for German PPM
meter setting)
-12dBFS OFF ON OFF ON
+18dB
0dBu
(-3dBu for German PPM
meter setting)
-18dBFS ON ON ON ON
Table 2 – Input Gain DIPSwitch settings
The input gain setting can be changed at any time, without the need to remove power from
the unit.
Note that the application of extra input gain reduces the maximum signal level permitted
before signal clipping occurs. When the Level Alarm LED is congured to Input Clip, this
indicator illuminates at the onset of clipping, with extended illumination indicating that the
input gain should be reduced and/or the input signal levels attenuated.

10 Reference Monitor Meters User Handbook
1
REAR PANEL CONNECTIONS & OPERATION
REAR PANEL CONNECTIONS & OPERATION
Remote Inputs and Outputs
A 15-way female D-type connector carries eight open-collector status outputs and four
logic-level control inputs. The pin assignments are as follows:
Pin Number I/O Function
1 - Ground
9O
Audio input 1 under-level alarm – open collector with latching
capability
2O
Audio input 1 over-level alarm – open collector with latching
capability
10 O Audio input 1 sustained phase error alarm – open collector with
latching capability
3 O Audio input 1 AES/EBU lock output – non-latching open collector
11 O Audio input 2 under-level alarm – open collector with latching
capability
4O
Audio input 2 over-level alarm – open collector with latching
capability
12 O Audio input 2 sustained phase error alarm – open collector with
latching capability
5 O Audio input 2 AES/EBU lock output – non-latching open collector
13 - Ground
6 - Ground
14 I Audio Input 1 alarm reset – pull low to activate
7 I Audio Input 2 alarm reset – pull low to activate
15 I Reserved for future use
8 I Reserved for future use
Table 3 – Remote Input and Output Connection Details