In the world of audio mastering, there's none more esteemed than
Bob Ludwig. Bob was a classically trained trumpet player before becoming a mastering engineer for producer
Phil Ramone's A&R Recording, then eventually worked his way up to chief engineer at
Masterdisk. In 1993 he built his own
Gateway Mastering in Portland, Maine, which even though it's not in a main media center, still has a who's-who list of celebrity clients.
Recently Bob did an interview with the
Huffington Post regarding separate "
iPod mixes" and the loudness wars. You can
read the entire interview here, as well as find the link for the second part of the interview.
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"Given how many people listen to music on portable digital
players, do you find that producers are mixing for earbuds? Is it common
to find an "iPod mix" that you master separately?
Bob Ludwig: No it isn't.
Dr. Floyd Toole (of
Harman
International, the makers of
JBL speakers) showed that averaging all the
different consumer speakers (some bright, some with too much bass or
midrange etc.) one ends up with a very flat curve which is empirical
proof that mastering with an extremely accurate and flat playback system
yields a product that sounds correct on more systems.
Like speakers,
earbuds run the gamut from the old stock
Apple earbuds that sounded
tinny and lacking warmth to top-of-the-line
Shure earbuds that are
extremely accurate, to "hip-hop" earbuds that are overly bass heavy. One
must master to sound as good as possible on all systems.
Almost all pop mixes are mixed with the bass and kick drum panned to
the center which is proper as many people will be listening on boom
boxes which have limited power and having a powerful center channel bass
available to both speakers is ideal. Very early recordings of
The
Rolling Stones and
The Beatles (to name two groups) were totally
intended for mono and were recorded on 2-channel or 3-channel tape decks
solely for creating a mono-only mix. When stereo became popular these
early multi-track tapes were re-purposed for stereo and the bass and
kick drum were typically locked into either the right or left channel.
With earbuds and headphones, this is very unnatural sounding and
sometimes it is decided to filter the low bass into the center by
mono-ing the signal somewhat. This sounds much better. This is
definitely a decision based on current widespread use of earbuds, and it
remains an important philosophical question when doing re-issues of old
recordings with this problem.
Can you explain how the "loudness" of a mix becomes a factor
in mastering? Can you explain compression and how it affects you at the
mastering stage?
Bob Ludwig: Compression uses a piece of hardware or
software plug in which either enhances or most often limits the dynamic
range of the music being fed into it. Compression is crucial to pop
music. Live pop music is almost always performed at hearing damaging
levels, way above the 85dB SPL
OSHA threshold for start of possible
hearing loss. In order for this immense power to be even somewhat
realistically reproduced on consumer systems the pop sound pipeline must
be compressed so that musically the performance has the extra energy
that the live performance had. For pop music, this translates as a very
musical thing. ("
The Loudness Wars" video illustrates.)
This problem starts from the fact that human beings, when hearing two
examples of the exact same musical program but with one turned up only
+0.5 or 1dB, almost all listeners who don't know exactly what they are
hearing choose the louder one as "sounding best." Fair enough.
So through the years, the louder example is eclipsed by a yet louder
example winning the hearts and minds of the artist, the engineer and the
A&R person. At some point, the music is so loud and unnaturally
compressed that the aural assault on the ear, while very impressively
loud, has sucked the life out of the music and makes the listener
subconsciously not want to hear the music again.
At an
Audio Engineering Society
workshop I was recently in about loudness,
Susan Rogers from
Berklee
College talked about the hair cells in our ears that receive music and
she pointed out that loud compressed music does not "change" as much as
dynamic music and notes that "we habituate to a stimulus if it stops
changing. Change 'wakes up' certain cells that have stopped firing. This
is cognitively efficient and therefore automatic."
In other words,
there are very physical reasons why too much compression turns off our
music receptors. Every playback system ever manufactured comes with a
playback level control. If one is listening to an album, one should be
able to turn that control anywhere you want and the absolute level on
the CD should not make a difference. Another place level on a CD does
not
make the difference one would think is on radio broadcast. It can be
shown that in general, loud CDs sound worse and less powerful on
commercial FM radio than a CD with a moderate level that lets the radio
station compressors handle the loudness problem. Non-classical radio
station compressors make soft things loud and loud things soft.
Two areas where producers get upset about not having enough level is
the
iTunes Shuffle, or even comparing songs on the iTunes software
itself, and that moment at the radio station where the PD is going
through the week's new releases and deciding which two or three songs
will be added to his playlist. Here, sometimes having a little extra
level can make a lesser song seem a little more impressive, at least at
first listen.
A great example of a contemporary recording that has full dynamic range is the
Guns N' Roses Chinese Democracy CD where
Axl Rose wanted all the textures of the original mixes to come
through and he got his wish! A good example of one of the loudest most
distorted CDs is the
Metallica Death Magnetic CD where apparently
10,000 fans signed a web petition to have the album remixed because
they got to hear how good it sounded on
Guitar Hero which did not have
all the digital limiters the final CD mix had."
Read more of the interview here. You can also
read an interview excerpt that Bob did for The Audio Mastering Handbook here.
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