TC Electronic LM2 User Manual

USER’S MANUAL

English version

LM2

STEREO LOUDNESS METER

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

TABLE OF CONTENTS

PAGE HEAD

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

TC Electronic, Sindalsvej 34, DK-8240 Risskov – [e-mail] Manual revision 1.11

English Version

Prod. No: 606150012

3

INTRODUCTION

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.

4

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.

5

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.

6

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.

INTRODUCTION

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.

7

QUICK GUIDE

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.

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.

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.

8

Measurements may be paused and reset using the
keys next to the LCD display.

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.

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

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.

9

OVERVIEWOPERATING LM2

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.

10

OVERVIEW

OPERATING LM2

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.

11

OVERVIEWREAR PANEL

...continued

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.

Rear Panel

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.

Power Input
100 - 240V

Power Switch

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.

Balanced
Analog
Inputs
XLR

Balanced
Analog
Outputs
XLR

Optical
SPDIF
& ADAT

Sync In
BNC

12

AES/EBU
Input/
Output

Coax
SPDIF
Input/
Output &
AES3id

Through

USBCOM IN/OUT

OVERVIEWTHE DISPLAY - HOME PAGE

Descriptor 1 Descriptor 2

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.

13

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 “-”.

14