TC Electronic LM2 User manual

LM2
STEREO LOUDNESS METER
USER’S MANUAL
English version

PAGE HEAD
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TC Electronic, Sindalsvej 34, DK-8240 Risskov – [email protected] Manual revision 1.11
Prod. No: 606150012
English Version
TABLE OF CONTENTS
Contents
Table Of Contents ......................................3
Introduction................................................4
Quick guide................................................8
Operating LM2.......................................... 10
Rear panel ............................................... 12
The Display - HOME page ......................... 13
The Display - HOME page ......................... 14
Edit Page................................................. 15
I/O Page .................................................. 20
Utility page .............................................. 22
Stats page ............................................... 23
Preset handling ........................................ 24
TC Icon & LM2 ....................................... 25
Logging ................................................... 36
Setup Examples - Production ..................... 39
Setup Examples - Production ..................... 40
Setup Examples - Ingest ........................... 41
Setup Examples - Master Control .............. 42
Setup Examples - Logging ......................... 43
Signal Flow Diagram ................................. 44
Technical Specifications............................ 45

INTRODUCTION
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The family of TC loudness and true-peak level meters represents a major improvement in how level is measured and
normalization is performed in the professional audio field.
The old quasi-peak and sample-peak meters are responsible for unacceptable level jumps in television, for music CDs
getting increasingly distorted, and for different audio formats and program genres becoming incompatible: Pristine music
tracks from the past don’t co-exist with new recordings, TV commercials don’t fit drama, classical music or film and
broadcast doesn’t match. The most fundamental audio issue of all – control of loudness – every day makes millions of
people adjust the volume control over and over again.
LM2 is part of a universal and globally standardized loudness control concept, whereby audio may easily and consistently
be measured and controlled at various stages of production and distribution. LM2 works coherently together with other
TC equipment, or with equipment of other brands adhering to the same loudness standards. Follow the guidelines given
in this manual to allow audio produced for different purposes to be mixed, without low dynamic range material such as
commercials or pop CD’s always emerging the loudest.
Loudness versus Level
Unlike level, loudness is subjective. Listeners weigh a number of contributing factors differently, leading to Between
Listener Variation (BLV) as well as Within Listener Variation (WLV). Coupled with deviations of the real world (equipment,
listening level etc.), loudness becomes an elusive measure and must be based on solid statistics. Together with the
academic community, TC Electronic has therefore performed numerous listening tests and evaluation of loudness models.
Today the company holds an extensive, Universal Database of loudness, based on ten thousands of assessments. Collection
of the database started in 1997, it is verified against other independent studies, and it covers all sorts of broadcast
material, music, commercials, feature film and experimental sounds. The Universal Database is authoritative from an
academic as well as a practical point of view. It has been indispensable when designing loudness meters because it
provided the missing link between short-term and long-term loudness, and helped develop the statistically founded
Universal Descriptors of LM2.
On the standardization of Loudness and True-peak level
Year 2000, the International Telecommunication Union, ITU, launched a research project that eventually became
recommendation BS.1770-2. The worthy goal of this project was to change the focus of the broadcast industry away from
sample peak and quasi-peak level to program loudness, thereby not automatically having commercials, promos and pop
music louder than other programming. Having studied the same phenomena for years, TC Electronic decided early on to
contribute to the diversified group of ITU researchers.
One of the reasons why BS.1770-2 today represents such a big leap forward for the entire audio industry is because of the
dedication and amount of expertise that research institutes, broadcasters and companies brought into the process: CRC,
IRT, USC, McGill University, numerous broadcasters, drive and film experience from Dolby Labs, research and music/post
experience from TC Electronic.

5
INTRODUCTION
Once the relatively simple, yet accurate loudness model found by CRC had been independently verified through a number of
tests, the search began for a complementary and up-to-date measurement of peak level. To this end, the Audio Engineering
Society lent a helping hand. Consequently, our industry now holds a vastly improved and standardized way of measuring
peak level in the digital domain.
BS.1770-2 has recently been put to practical use in different recommended guidelines by BCAP, ATSC, EBU, as well
as Japanese and Australian broadcasters. In particular, EBU’s Expert Community on Audio, ECA, and its PLOUD group
has put great effort into standardizing important features of loudness measurement and normalization, building on top of
BS.1770-2, thereby specifying truly cross-genre, cross-platform solutions based entirely on open standards, the EBU R128.
A measurement standard with improved transparency and quality has finally arrived for the benefit of all music lovers,
cinema-goers and TV listeners. TC Electronic is proud to have contributed with research, verification, true-peak techniques
and new tools and descriptors to unleash the full potential of this global standard.
Introducing LM2
By itself, LM2 is a full-featured stereo loudness and true-peak level meter for use in post and live production, broadcast
ingest, linking and transmission. Either check the numbers you need to comply with on LM2’s front panel, or bring up the
Stats display for even more details. Connect to PC or Mac via USB and open the included Icon application to get the full
Radar screen picture.
Delivery Specs and Metadata
Global broadcast guidelines now recognize the need for keeping audio transmission easy and predictable, the main
facilitators being transparent normalization and fixed metadata. LM2 enables precision normalization and optimum use
of dialnorm metadata in AC3 transmission in order to avoid level jumps between regular programming and promos or
commercials.
Standard Compliance
LM2 comes pre-loaded with factory presets compliant with new ITU-R BS.1770-2, ATSC A/85, EBU R128, NABJ,
OP-59, BCAP and more guidelines. LM2 is field-upgradeable and will keep compliant with global practices as they refine.
Undoubtedly, standards will be updated within LM2’s warranty period – which is a whopping 5 years.
Connections
LM2 always offers a wide variety of 24-bit resolution audio inputs and outputs: AES/EBU, TOS, SPDIF / AES3id, ADAT and
Analog. Digital I/Os are fully synchronous while analog I/Os are scaled in the analog domain for max utilization of converter
dynamic range. Analog inputs can even be trimmed at 0.01 dB precision. LM2 may connect via USB to PC or Mac for
access to the Radar display, Logging, Remote Control, Preset Management and so on.

6
INTRODUCTION
24/7 Logging
As a standard feature LM2 comes with hindsight: the radar can show the past 24 hours, but LM2 actually includes so much
memory of its own that you can take a detailed look one week back in time, even if it has had no connection to a computer.
Dump log files routinely to PC or Mac, import files into Excel or Numbers and create line charts for better overview.
Ingest Normalization
The primary application for LM2 is as a loudness meter but it does one more thing very well: automatic level offset of
programs at a no-compromise resolution (synchronous, 48 bit, fixed point engine). LM2 therefore includes a precision
true-peak limiter to avoid output overload when positive gain normalization is required. For fans of speech normalization,
allow LM2 to measure some regular dialog and normalize to that. Otherwise, let its relative gate function automatically take
care of all sources. Presets are included, so the choice is yours…
Production Applications
In production, program duration and sliding window descriptors are indispensable tools for attaining a specific target.
When connected to PC or Mac, LM2 further provides access to TC’s unique radar display visualizing loudness history and
the loudness range to stay within. The radar color codes show loudness developments so it’s easy even for a person not
specialized in audio to identify target loudness (green), below the noisefloor (blue), and loud events (yellow), colors also
used to show these properties in Fig 1, and in numerous technical TC papers.

7
INTRODUCTION
Fig 1.
Left: Peak-level-normalization results in systematic loudness differences between genres.
Right: Loudness normalization is a better strategy and makes peak level vary instead.
When production engineers realize the boundaries they should generally stay within, less dynamics processing is needed
during distribution, and the requirement for maintaining time-consuming metadata at a broadcast station is minimized.
In broadcast, the general goal is to use the same loudness measure for:
- Production
- Delivery Specs
- Ingest
- Linking
- Master Control Processing
- Logging
thereby ensuring better audio quality not only in DTV audio, but across all broadcast platforms. LM2, other TC loudness
analyzers and TC processing are all based on the same standardized measurements and may therefore be used as bricks
in a transparent signal path ranging from production to delivery.
LM2 can also co-exist with PPM meters, VU meters or Dolby’s LM100 meter. LM2 greatly increases the usability of LM100
in production and transmission because it provides useful running status, and gives a standardized indication of much
more than the level of speech.

8
QUICK GUIDE
Ingest Meter and Program Normalization
LM2 allows you check and level offset programs
transparently without connecting a computer. For a
detailed radar view, or to dump log files, attach a Mac or
a PC via USB and run the Icon application included.
1. Programs may either be measured only, or corrected
and ingested through LM2. For measurement only, refer
to items 1-5 in the Production and Live Meter section
above. For correction, connect one of LM2’s digital
outputs to route audio through the machine to the ingest
server.
2. Press the Recall key and use the dial to find an
“Ingest” preset, i.e. “EBU R128 Ingest” or “ATSC A/85
Ingest”.
3. LM2’s default input is AES/EBU. Change input if
needed using the I/O key, arrow keys and the dial.
4a. For EBU R128 compliance, run the full program (or
a representative part of it) and press the Set Gain key. If
the Range measurement is higher than recommended,
further actions may be required.
4b. For ATSC A/85 compliance, present LM2 with
“anchor elements” of the program, for example regular
dialog or music, and press the Set Gain key.
5. Ingest the program to the station server and observe
LM2 numbers to confirm that target level is now correct.
More info about the program may be found on the Stats
page by pushing the Home key.
Measurements may be paused and reset using the
keys next to the LCD display.
TC Electronic LM2
– Walk This Way
Getting started with the LM2 Loudness and True-peak
Meter.
LM2 enables compliance with the latest global broadcast
loudness standards straight out of the box. The ideal
settings depend on your application:
Production and Live Meter
LM2 lets you “mix by numbers” by only looking at the
numbers on its LCD display. For a detailed radar view,
or to dump log files, connect a Mac or a PC via USB and
run the Icon application included.
1. Press the Recall key and use the dial to find a “Meter”
preset, i.e. “EBU Mode R128” or “ATSC Mode A/85”
2. Press the Enter key to confirm recall of preset. Note: A
preset recall resets the meter history and the log.
3. LM2’s default input is AES/EBU. Change input if
needed using the I/O key, arrow keys and the dial.
4. You may choose which two descriptor numbers are
shown in LM2’s display. For live and mixing applications,
it is recommended to have one of them showing “Sliding
Loudness” which doesn’t need to be reset. To accomplish
this, push the Edit key and select “Sliding Loudn.” as
Descriptor 1.
5. The left number in the display now shows Sliding
Loudness (current loudness) while the right number
shows Program Loudness. Program Loudness is average
loudness since the meter was reset.

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5. To lock LM2’s front panel from log reset and
adjustments, press and hold the Utility key. Note: Extra
info about loudness and true-peak level may still be
accessed on Stats page by pushing the Home key.
Loudness Glossary
The many new standards, loudness and true-peak level
terms may be difficult to keep track of. Find an updated
glossary at the TC Electronic website at
www.tcelectronic.com/loudness
QUICK GUIDE
Master Control Logging
LM2 monitors loudness continuously 24/7. Dump log
files to a PC or a Mac or bring up the Radar view using
the Icon application. Note that a computer may monitor
multiple LM2 units, and that it is not necessary to
connect one, except for dumping log files every now and
then.
1. Press the Recall key and use the dial to find a “Meter”
preset, i.e. “EBU Mode R128” or “ATSC Mode A/85”
2. Press the Enter key to confirm recall of preset. Note: A
preset recall resets the meter history and the log.
3. LM2’s default input is AES/EBU. Change input if
needed using the I/O key, arrow keys and the dial.
4. To lock LM2’s front panel from log reset and
adjustments, press and hold the Utility key. Note: Extra
info about loudness and true-peak level may still be
accessed on Stats page by pushing the Home key.
Master Control Limiting
On top of 24/7 logging, LM2 can be used as a precision
true-peak limiter. Dump log files to a PC or a Mac or
bring up the Radar view using the Icon application. Note
that a computer may monitor multiple LM2 units, and that
it is not necessary to connect one, except for dumping
log files every now and then.
1. Press the Recall key and use the dial to find a “Limit”
preset, i.e. “EBU R128 Limit” or “ATSC A/85 Limit”
2. Press the Enter key to confirm recall of preset. Note: A
preset recall resets the meter history and the log.
3. LM2’s default input is AES/EBU. Change input if
needed using the I/O key, arrow keys and the dial.
4. To adjust the limit threshold of LM2, press the Edit key
and find the “Lim Thres TP” parameter.

OVERVIEWOPERATING LM2
10
1 - POWER key
Power on/off. Press to turn the unit on. Press and hold to
turn the unit off.
2 - PCMCIA Card Slot
A PCMCIA card can be used for backing up settings and
for system updates. LM2 handles PCMCIA cards from
512 kb to 2 MB.
3 - METERS
These meters indicate the true-peak level as defined
in ITU-R BS.1770-2. The range is from -60 dB to -1
dB. Meters may be switched between pre and post the
true-peak limiter.
4 - LED indicators
ERROR
The Error LED indicates a serious system or setup error,
for instance the lack of selected digital input or the lack
of selected input clock.
AES, SPDIF and ADAT/TOS
Indicates which digital input source that is currently
selected in the I/O menu.
48 kHz and 44.1
A steady LED indicates the current sample rate. If a
digital input is the audio source and Clock Select is set
to internal 44.1 or 48 kHz the LED’s show the incoming
clock rate - not the selected internal rate.
48 kHz lock is indicated with a green LED
44.1 kHz lock is indicated with a yellow LED, - as this is
not standard sample rate in broadcast.
If a digital input is selected and not available, 48 and
44.1 kHz LEDs start blinking. This also happens if the
selected input clock is lost.
COM/REM
The LED is lit when commands are received through the
remote COM port.
EDITED
Indicates that settings have been changed compared to
the currently recalled preset.
5 - Display
On the Home page, Loudness Descriptors are displayed
in the lower corners. The display may also show
parameters and store/recall parameters.

OVERVIEW
6 - PAUSE key
Pauses the loudness measurements. When engaged,
the Home page reads “PAUSE” in the upper right-hand
corner.
7 - HOME key
Press Home to toggle between the Home page and the
Stats page. LM2 defaults to the Home page with the
large Loudness Descriptors when not touched for 30
seconds.
When pressed together with neighbor keys, Home
invokes these functions:
HOME + PAUSE: Resets all Loudness Descriptors and
the Loudness Log.
HOME + SET GAIN: Reverts LM2 to unity gain, resets
the Loudness Descriptors and the Loudness Log.
The SET GAIN functions can be disabled on the
I/O page. Factory presets with “Meter” in the title
have SET GAIN functions disabled. Factory
presets with “Ingest” in their title have SET GAIN
functions enabled.
8 - SET GAIN
Additional to metering, LM2 may perform static gain
offsets in order for a program to comply with a certain
Target level. Once a program has been measured, press
the Set Gain key to have LM2 automatically apply the
static gain required to make the program arrive precisely
at Target level.
The Set Gain key also resets the Loudness
descriptors and the Loudness log.
The Set Gain key may be enabled or disabled in
the I/O menu.
The key is disabled in all factory preset banks
called “Meter” while it is enabled in all preset
factory banks called “Ingest”.
9 - RECALL key
The RECALL key recalls presets. Turn the ENCODER to
select a preset, - then press ENTER.
10 - STORE key
Press STORE once to access Store mode.
Then select store location using the ENCODER.
Press ENTER to confirm.
OPERATING LM2
11

OVERVIEWREAR PANEL
12
11 - EDIT key
Press to enter preset Edit mode. Use the CURSOR UP/
DOWN keys to navigate and the ENCODER to change
values.
12 - ENTER key
ENTER is used for confirmation of various operations.
13/14 - CURSOR UP/DOWN
These keys are used for navigating in menus.
15 - ENCODER
The encoder is used to change values.
16 - I/O key
Press to enter the I/O menu providing access to
parameters such as In/Out selection, level, clock, dither
etc. I/O parameters are stored and recalled with presets.
Balanced
Analog
Inputs
XLR
AES/EBU
Input/
Output
Balanced
Analog
Outputs
XLR
Coax
SPDIF
Input/
Output &
AES3id
Power Input
100 - 240V
Power Switch
USBCOM IN/OUT
Through
Optical
SPDIF
& ADAT
Note: The USB connection may be used for parameter control and radar display via the
Icon application. This is also the interface used to dump logging data from the LM2 unit to a
Mac or PC.
Sync In
BNC
Rear Panel
...continued 17 - UTILITY
Press UTILITY to access the Utility page. The Utility page
holds the following parameters:
- Display viewing angle
- Analog trim.
- Auto Info on/off
Utility parameters are global and unit specific. These
parameters do not change with a preset recall.
Lock function
Hold the UTILITY key for three seconds to lock or unlock
the LM2 frontpanel. In Lock mode it is only possible to
switch between the Home and Stats pages.
Use the lock mode to prevent unintended operation.
18 - BYPASS key
Press to bypass gain normalization and true-peak
limiting.

OVERVIEWTHE DISPLAY - HOME PAGE
13
The HOME page is the default operation page and the
page LM2 defaults to from several of the sub-menus,
when left untouched for 30 seconds.
To access the HOME page from any menu press HOME.
1 - Preset Name
This is the name of the current preset.
To recall presets press RECALL, scroll using the encoder
and press ENTER to confirm recall.
2 + 3 - Descriptors
LM2 measures Program Loudness, Loudness Range,
Loudness Max and Sliding Loudness permanently. You
may pick one or two of these measurements to be shown
in big numbers on the Home page. Descriptors are
assigned to the Home page from the Edit page.
Which parameter is most relevant to display depends
on your application: For Post Production and Quality
Control, Program Loudness and Loudness Range
are prime candidates. For Live Production, it is more
informative to display Loudness Range alongside Sliding
Loudness. For Ingest of commercials, Loudness Max is
a useful probe in combination with Program Loudness.
Please find more information in the Application section of
this manual.
Regardless of which descriptors are shown on the
Home page, they are all updated and available on
the Stats page, accessed by pressing the Home
key one or two times.
4 - Upper line of the Home Page
In this area, various notes and alerts may appear.
When gain normalization is applied using the SET GAIN
function, the upper left hand corner of the Home page
indicates the gain offset, while the upper right hand
corner shows if the loudness measurement has been
paused.
Descriptor 1 Descriptor 2

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THE DISPLAY - HOME PAGE
Set Gain
Reset Meter
Pause
Set Gain
Press Set Gain to insert a gain offset before the loudness
meter. This function is used for easy normalization of
programs, and under the protection of LM2’s true-peak
limiter. Set Gain may be disabled on the I/O page. Only
Factory “Ingest” presets have the function enabled.
Example
- Loudness Target level has been set to -23 LUFS
(EBU standard)
- LM2 has measured a program to -35.8 LUFS
- Press Set Gain and a gain of +12.8 dB is applied
When SET GAIN is active the applied gain, negative or
positive is indicated in the upper left corner.
Attention - the Set Gain function resets
measurement and logging
Set Gain may be used during transmission by an
experienced operator, and pressed more than
once. Each time Get Gain is pressed, output
loudness will be re-aligned to match Target
loudness. This may create level-jumps, but at a
time of the operator’s choosing.
Reset Meter
Press both the HOME and PAUSE buttons to reset
metering. The display briefly indicates reset.
Pause
For easy reading at a specific time the metering can be
paused by pressing the PAUSE button.
Pause can also be used to exclude certain program
material such as commercials from measurement , or to
only measure, for instance, regular speech if so desired.
Start of a new measurement
When LM2’s meter is reset by pressing Home and Pause,
instead of numbers it shows “-” markings in the display.
Two lines, “- -”, indicates that the measurement has been
reset, and that no audio above the safety gate threshold
(-70 LUFS) has yet been detected. One line, “-”, indicates
that audio level above the safety gate has been detected
and that it will influence the measurement. Once enough
audio has been registered for it to be of statistical value,
descriptor numbers appear.
Sliding Loudness does not show “- -” when the
meter is reset. This is because Sliding Loudness is
defined as a running measure without safety gate.
If the level drops to -100 LUFS or lower, Sliding
Loudness displays “-”.

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OVERVIEW EDIT PAGE
Navigating the Edit page
- press the EDIT key to enter the page
- press CURSOR UP/DOWN keys to move cursor and use the ADJUST wheel to change parameter values
- to access Edit page 2, place cursor at the parameter in the bottom of the display and press the CURSOR DOWN key
- to exit the EDIT pages, press EDIT or HOME - or press e.g. UTILITY or I/O keys to navigate directly to those menus.
LM2 automatically returns to the Home page after 30 sec if no key has been touched.
Parameters and settings
Descriptor 1 Loudn. Range, Prog.
Loudn., Sliding Loudn.,
Loudn. Max, Off
Descriptor 2
Sliding Loudness From 3 sec to 8 min
Loudness Max 0.4 sec to 10 sec
Lim Threshold TP -18 dB to off
Lim Profile Dynamic, AC3 Codec,
UniversalLoud, Voice
Lim Link Off, On
Target -6 to -36.0 LUFS (if LUFS)
Norm. Gain +/- 24 dB
Loudness Unit LUFS, LU, LU/LUFS
Loudness Std. EBU R128, ATSC A/85,
Cnt of Grav.
Page 1
Page 2
Page 3
The Edit page is used for selecting the Loudness Descriptors shown on the Home page, measurement standard,
adjustment of normalizing gain, true-peak limiting etc. Note: Edit page parameters are stored and recalled with presets.

OVERVIEWEDIT PAGE
16
Descriptor 1-2
Loudn. Range
Loudness Range, standardized in EBU R128 and
abbreviated “LRA”, displays the loudness range of a
program, a film or a music track. The unit is LU, which
can be thought of as “dB on the average”.
The Loudness Range descriptor quantifies the variation of
the loudness measurement of a program. It is based on
the statistical distribution of loudness within a programme,
thereby excluding the extremes. Thus, for example, a
single gunshot is not able to bias the LRA number.
EBU R128 does not specify a maximum permitted LRA.
R128 does, however, strongly encourage the use of LRA
to determine if dynamic treatment of an audio signal is
needed and to match the signal with the requirements of
a particular transmission channel or platform.
Consequently, if a program has LRA measured at 10
LU, you would need to move the master fader +- 5 dB to
make loudness stay generally the same over the duration
of the program. (Not that you would want that).
In production, Loudness Range may serve as a guide to
how well balancing has been performed, and if too much
or too little compression has been applied. If a journalist
or video editor isn’t capable of arriving at a suitable LRA,
he could be instructed to call an audio expert for help.
This may be regarded as initial production guidelines:
HDTV and digital radio: Stay below LRA of 20 LU.
SDTV: Stay below LRA of 12 LU.
Mobile TV and car radio: Stay below LRA of 8 LU.
Remember to use LRA the other way around too: If there
is an ideal for a certain genre, check its LRA measure,
and don’t try go below it. LRA should not be used for
Limbo. Allow programs or music tracks the loudness
range they need, but not more than they need.
Loudness Range may also be measured on a broadcast
server to predict if a program is suitable for broadcast
without further processing. LRA is even a fingerprint of a
program and stays the same downstream of production
if no dynamics processing has been applied. You may
even check the number out of a consumer’s set-top box
to verify that distribution processing and Dolby DRC has
been disabled.
Like with Program Loudness and Loudness Max, the
meter should be reset before measuring LRA.
Prog. Loudn.
Program Loudness returns one loudness number for
an entire program, film or music track. Its unit is LUFS.
Some vendors and countries use the unit “LKFS” or
“LFS”, but all three are the same: An absolute measure of
loudness in the digital domain, where the region around
“0” is overly loud and not relevant for measuring anything
but test signals. Expect readings of broadcast programs
in the range between -28 and -20 LUFS.
Program Loudness is used as a production guideline, for
transparent normalizing of programs and commercials,
and to set loudness metadata in delivery if so required.
For delivery or transmission of AC3 format, the metadata
parameter “dialnorm” should reflect Program Loudness.
The easiest way to handle multiple broadcast platforms
is to normalize programs at the station to a certain value,
thereby being able to take advantage of the normalization
benefits across platforms, at the same time enabling
static metadata.
Loudness measurements in LM2 are all rooted in ITU-R
BS.1770-2. However, subtle differences exist between
different regions of the world. Therefore LM2 also
includes the “Loudness Standard” parameter. Be sure to
set this parameter correctly for compliance in your region.
The Program Loudness target is more or less the same
for broadcasters around the world, especially when

17
EDIT PAGE
17
taking the measurement differences into account. Target
numbers range between -24 and -22 LUFS.
Like with Loudness Range and Loudness Max, the meter
should be reset before measuring Program Loudness.
Sliding Loudn.
Sliding Loudness, unlike Program Loudness, Loudness
Range and Loudness Max, is a continuously updated
measure that doesn’t need to be reset. This type of
descriptor is especially useful when “mixing by numbers”,
i.e. when there is no access to the extremely informative
radar display. When mixing by numbers, having Program
Loudness as one descriptor and Sliding Loudness as
the other displays simultaneous information about the
full program side by side with the most recent loudness
history.
The Edit menu includes a separate parameter where the
width of the sliding window may be defined. For typical
broadcast production, a starting point between 6 and 15
seconds is suggested. For production of commercials
or promos, 3 or 6 seconds would should be considered,
while longer duration wide loudness range production
(drama, acoustic music) might give more relevant
numbers with a duration of 30 seconds or longer.
Note 1: Because the Sliding Loudness measurement
is completely un-gated, it may also be used to spot
check sections of a program complying to “raw” ITU-R
BS.1770-2 and the first revision of ATSC A/85.
Note 2: LM2 makes use of optimized statistics processing
in order to display a sliding loudness value (a prognosis)
as quickly as possible after a reset. Until the sliding
window has been filled, a spinning line symbol is shown
next to the descriptor title.
Loudness Max
Loudness Max displays the maximum loudness
registered since the meter was last reset. Loudness Max
is an especially useful parameter when checking and
normalizing short duration programs such as promos and
commercials. BCAP rules from the UK is an example of
using Loudness Max as an efficient instrument to reduce
listener complaints regarding loud commercials. While
Program Loudness is adequate to normalize a consistent
mix, Loudness Max may be used as a second line of
transparent defense against overly short and loud event.
The Edit menu includes a separate parameter where
the width of the Loudness Max window may be defined.
Experience from the UK indicates that a Loudness
Max width of 3 or 4 seconds should be used for such a
purpose.
Target
Range: -36 LUFS to -6 LUFS
The parameter specifies the loudness level to generally
aim at. It affects a number of functions and displays in
LM2, and must be set according to the standard you
need to comply with. Current broadcast standards require
Target to be in the range between -26 and -20 LUFS. For
instance, EBU R128 calls for -23 LUFS while ATSC A/85
specifies -24 LUFS.
The Target parameter affects these LM2 functions and
displays:
1. Target sets the reference point for loudness
measurements in LU. If the Loudness Unit parameter
is set to LU, Program Loudness, Sliding Loudness and
Loudness Max will be shown in LU relative to Target. On
Target measurements will consequently read “0.0 LU”.
2. Target defines the aim for LM2’s normalization
functions. When the Set Gain key is pushed, LM2
inserts a gain equalling the difference between Program
Loudness and Target. For instance, if Target is set to
-23.0 LUFS and Program Loudness measures -21.5
LUFS, LM2 inserts a gain of -1.5 dB.

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EDIT PAGE
3. Target defines the “12 o’clock” value of the Radar
meter when LM2 is connected to a Mac or a PC running
the Icon application.
Loudness Unit
LUFS
All measurements of program loudness and sliding
loudness are shown in units of LUFS, that is, in Loudness
Units on the absolute scale. This is the normal setting
for the Loudness Unit parameter, that we recommend for
most applications.
Loudness Range is always shown in units of LU, because
it is basically a measurement of ‘range’ or of the distance
between a high and a low loudness level.
LUFS/LU
This setting is similar to the ‘LUFS’ setting, except that
the Radar display uses an LU scale rather than an LUFS
scale, on the Icon. There is no difference between the
LUFS and LU/LUFS settings, when the LM2 is used in
stand-alone mode.
LU
In this setting, measurements of program loudness
and sliding loudness are shown in units of LU, that is,
in Loudness Units on a relative scale. The 0 LU is by
definition the target loudness level, such as -23.0 LUFS.
So by selecting ‘LU’, one can immediately see if a
loudness level is above the target level (e.g. +1.2 LU) or
below (e.g. -3.4 LU).
Loudness Std.
Options: BS.1770-2, Leq(K) or Cnt of Grav.
The Program Loudness measure is always rooted in
the ITU-R BS.1770 loudness model. This parameter
sets measurement gating. Note that the parameter only
influences Program Loudness, and not Sliding Loudness
or Loudness Max.
BS.1770-2
This setting reflects the latest revision of ITU-R BS.1770.
Relative gate at -10 LU, safety gate at -70 LUFS.
Leq(K)
This setting reflects the original version of ITU-R
BS.1770.
No measurement gate besides from at safety gate at -70
LUFS, so the user doesn’t need to precisely start and
stop a measurement in order to avoid bias from complete
silence.
Cnt of Grav.
The standard setting from early versions of TC radar
meters.
Relative gate at -20 LU, safety gate at -70 LUFS.
International Standards
Note how the three Loudness Standard settings generally
return the same Program Loudness result for Narrow
Loudness Range (“NLR”) programs, such as commercials
and pop music, but can differ significantly with Wide
Loudness Range (“WLR”) programs such as film, drama,
acoustical music etc.
For an update on international standards, check for
new versions of this manual, or download the Loudness
Glossary available at www.tcelectronic.com/loudness
This is the situation as of August, 2011:
Japan, Canada, Brazil, China, Europe and most other
countries specify the use of BS.1770-2 to make Program
Loudness perform well across genres. BS.1770-2 enables
the meter reliably to focus on foreground sound, and to
transparently control loud commercials. ARIB (Japan)
specifies BS.1770-2 in TR-B32. EBU (Europe) specifies
BS.1770-2 in EBU R128 and in associated Tech Doc
3341.

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EDIT PAGE
Target Level in these countries is -23 LUFS or -24 LUFS,
measurement gating at -10 LU.
United States. Page 11 of ATSC A/85 (May 25, 2011)
references ITU-R BS.1770-1, even though BS.1770-2
was in effect at that time. The same page also says that
“All referenced documents are subject to revision”. The
wording is ambiguous and it’s up to the reader to decide
whether or not a relative gate (the difference between
BS.1770-1 and BS.1770-2) is applied when measuring
Program Loudness. The “Leq(K)” setting in LM2 disables
the relative gate, while the setting “BS.1770-2” includes
a relative gate at -10 LU. The BS.1770-2 setting is better
across genres and for controlling loud commercials.
Check in at www.atsc.org to see if the CALM act has
forced ATSC to make up their mind.
Target Level in United States is -24 LUFS, measurement
gating not clearly defined.
Limiter
LM2 includes a true-peak limiter and 48 bit internal
precision. Limiter Threshold sets the max true-peak
level on LM2’s outputs. In case positive normalization is
invoked, the limiter comes into action when the peak level
could otherwise have created an overload.
Profiles: Dynamic, AC3 Codec, Universal, Loud, Voice.
The adaptive Profiles allow you to tell The Limiter what
your intentions are.
Several internal variables are dynamically updated based
on the Profile chosen, so distortion is perceived (and
measured) to be as low as possible for a given loudness,
and reduction in average/peak ratio. Maximum perceived
distortion tolerated is different from Profile to Profile. The
multi-dimensional parameter-space is fully continuos to
avoid situations where distortion could occur, or where
processing is suddenly altered without a detectable
cause. Acquaintance yourself with the different Profiles
to have them at hand when called for by a specific
application.
The Dynamic Profile offers gentle processing with
minimum static and dynamic distortion. It’s a first choice
for audiophile limiting, for instance with classical music,
choir etc.
The AC3 Codec profile has been optimized for protecting
the relatively sensitive AC3 codec, which was invented
before squeeze-box techniques in production had
proliferated. When used for stereo, there are no down-mix
issues with the codec, and the threshold of the true-peak
limiter can safely be set to -2 dBFS or -1 dBFS.
The Universal Profile has a higher tolerance for
perceived distortion than Dynamic. It is still magnitudes
better than analog designs, but may be on the aggressive
side for sensitive music. It is a good choice for starters,
and in production where you don’t know what to expect.
The Loud Profile again has a higher tolerance for
perceived distortion, and is therefore better suited for
production and mastering rather than live applications.
The Voice Profile is targeted human voice, and adapts
well to asymmetrical signals. Used on composite material,
perceivable distortion is to be expected with large ratios
of limiting.
Limiter Threshold
Range: -18 dB to off
LM2’s limiter employs a look-ahead delay of 0.6 ms and
complies with ITU-R BS.1770-2 true-peak specifications.
Because true-peak limiting is a better strategy from an
audio quality point of view than sample-peak limiting, and
because LM2 has an immense internal headroom, there
is generally no need to set the limiter threshold lower than
-1 dBFS. However, if the downstream path contains low
bit-rate codecs or emphasis/de-emphasis circuitry, the
limiter threshold may need to be set considerably lower.
To enable pristine audio quality, the limiter threshold
should not be set lower than needed for a certain
broadcast platform. Also notice how you may be able to
lift the limiter threshold over time as a distribution path
improves.

20
I/O PAGE
Navigating the I/O page
- press the I/O key to enter the page
- press CURSOR UP/DOWN keys to move cursor and use the ADJUST wheel to change parameter values
- to access I/O page 2, place cursor at the parameter in the bottom of the display and press the CURSOR DOWN key
- to exit the EDIT pages, press EDIT - or press UTILITY or EDIT keys to navigate directly to those menus.
LM2 automatically returns to the Main page after 30 sec if no key has been touched.
The I/O page is used for selecting I/O formats, clock conditions, scaling of AD and DA converts, disabling of the Set Gain
function etc. Note: I/O page parameters are stored and recalled with presets.
Parameters and settings
Input Select AES, SPDIF, TOS, ADAT
Analog
Clock Select Intern. 44.1/48 kHz
Digital In, Word Clock,
ADAT Input ADAT 1/2, 3/4, 5/6, 7/8
Optical Output TOS, ADAT 1/2, 3/4, 5/6, 7/8 Set Gain Disabled/Enabled
TP Meter Pre Lim/Post Lim
Ana In, FS@ +6 to +21 dBu
Ana Out, FS@ +6 to +21 dBu
Ana Fader Off, -119 dB to +12 dB
Dither Off, 24, 20,16 bit
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