Recording - June 2013 - 56

Many years ago, while I was a student at a recording school, an instructor
strictly prohibited the class from mixing on headphones. This moment is still
poignant to me today, as it reflects the duality of using headphones to produce
audio content. On the one hand, mixes created on phones can result in compatibility issues on many playback systems. Loudspeakers are still the most
common way to experience music, and translation from headphones to speakers is always imperfect. On the other hand, working on headphones gives an
engineer a variety of tools that can greatly aid the mixing process. Mixing with
headphones is essential, but care must be taken to avoid complications.

if you know where to look). Aimed specifically
at engineers who have no choice but to mix on
headphones only, these software-based products emulate the phase, frequency, and level
changes caused when opposite channels of different path lengths mix in our ears.
Perhaps the biggest disadvantage to mixing
solely on headphones is one of vibe, not science. This may be a personal experience only,
but I find myself less picky about balance on
headphones than I do when listening to loudspeakers. To me, listening to music on headphones is a very enjoyable experience. Maybe
it’s the artificial “world” headphones create, or
the fact that it is easier to hear things when isolated from outside distractions. Whatever the
reason, headphones do not force me to work
as hard to make a mix be “glued” together,
and thus headphone-only mixes are more likely
to fall apart when transferred to less-than-ideal
loudspeakers.
Coincidentally, this is similar to the phenomenon many engineers experience when switching between pleasing sounding studio monitors, such as an expensive pair of Genelecs,
and more “difficult sounding” sets of speakers
such as Yamaha NS10s. The harsher speakers
inevitably make the mix less likable and challenge the engineer to keep working until the
mix sounds great through both sets of monitors.
By Eric Ferguson

Chapter 18: Headphones—Part 1
So why was my instructor so severe in her prohibition of cans (headphones)
while mixing? The answer to this question is rhetorical. Headphones simply don’t
sound like speakers, and mixes produced solely on cans often disintegrate when
played back on loudspeakers for several reasons, one being frequency
response. Due to driver size and other physical limitations, bass is often light in
headphones, and mixes produced only on phones can sometimes end up heavy
or cloudy in the low end when played back later on speakers. Mixing through
monitors, however, typically alerts the engineer to these issues, and forces him
or her to spend more time defining the balance and eq of bottom-heavy sources.
Imaging and balance
Another distinction between headphone and loudspeaker monitoring is the
intermixing of information between the left and right channels. When listening to
speakers, both ears hear both monitors. Differences in level, high-frequency content, and arrival time help our brains decipher between the left and right. Of
course, intermixing does not occur on headphones and therefore panning and
imaging decisions are sometimes influenced.
This is not to say that one should shy away from panning on headphones. On
the contrary, the very nature of headphones allows for finer analysis of the stereo
field than what is possible with monitors. In fact, I use headphones to make many
of my most detailed panning decisions, such as deciding the location of tom and
hat mics, setting auto-panning effects, and placing layered background vocals
throughout the stereo field. This said, I always return to speakers to double-check
balance after panning.
As a side note, plug-ins like 112 dB Redline Monitor and ToneBoosters TB
Isone process a mix output to sound more speaker-like even when monitored on
headphones (and there are audio interfaces with this sort of thing built in as well,
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RECORDING June 2013

Goodbye cruel room
Criticisms aside, headphones are very useful in
the mix process, and isolation from room acoustics
is by far the biggest reason. Every room suffers frequency response issues, and mix tonality varies
with listening position. (This column spent the last
several months covering control-room acoustics,
well worth a re-read in the context of what we’re
discussing here.) Headphones, by their very
nature, completely eliminate standing waves,
reverb, and other acoustic issues from the decision-making process. Phones let you hear what is
really there without room-induced coloration.
It is for this reason that many professional engineers travel with at least their own trusted set of
cans. Working in new rooms can be challenging, and bringing your own set of headphones
to sessions can greatly increase consistency from
studio to studio. Expanding this approach, some
engineers even bring along their own high-quality headphone amp. A surefire way to ensure a
dependable critical listening environment, this
approach is no different from bringing your own
powered monitors to a foreign studio, a practice
that heavyweight mix engineers have maintained for decades. Mixing is difficult, and anything to make the job easier is welcome.

Recording - June 2013

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