TC Electronic LM2, User Manual

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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.