Recording - May 2017 - 10

TalkBack
Headphone impedance: what's it mean?
Hi Mike Metlay: In your March 2017 issue you feature
new Fostex headphones. My question inspired by the review
is about impedance. Why the wide variation in impedance
amongst the different headphone offerings?
With these Fostex phones, you stated you thought there
would be little difference between the 250 ohm and 80 ohm
as far as audio quality is concerned. It seems that the
manufacturers must believe some value exists in their choice
of one impedance over another for a particular headphone
they design, and of course they know that some will require
headphone amps. I would like to have a better understanding
of this headphone impedance thing. Thanks,
James Wirth
Heber, AZ
Hi James, thanks for your letter. Headphone impedance
isn't that hard to understand; let me see if I can shed a little
light on the subject.
It is possible to build a brilliant-sounding headphone with a
high or low impedance; some people claim that high impedance
always sounds better, other things being equal, but the real
motivation to choose one or the other comes down to the pairing
of the headphone and the headphone amplifier.
Traditionally, high-impedance headphones were used in
pro audio applications where multiple headphones were used
in parallel on the same circuit (e.g. a rock band or even a full
orchestra in a tracking room). Because of how impedance
behaves in parallel circuits, two 200 ohm headphones in
parallel present a combined load of 100 ohms; similarly, the
more headphones are added to the circuit, the lower the load
will become. When the load drops low enough, the amp will
risk damage, so starting with a very high impedance means
that many headphones can be run at once before the load
drops to where it's a concern. As a very general rule, highimpedance headphones sound their best when driven by a
robust headphone amp with plenty of power to draw upon.
Low-impedance headphones are optimized for use with amp
circuits that don't have a lot of power available-think of any
sound source that runs on batteries or similarly low voltages,
like a smartphone, bus-powered USB interface, or laptop computer.
In this case, a low impedance presents a load that the amplifier
can easily handle, providing a loud and clear signal.
Fostex isn't the only maker of headphones with multiple
impedances; beyerdynamic offers some of its models in low, medium,
and high impedance versions. My usual recommendation is that
if you're working in a home studio situation, where your headphones
will likely be used anywhere from your smartphone to your audio

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interface or in a powered headphone amp, leaning toward a
lower impedance will cover the most bases.
You could get high and low impedance versions of the
same headphone to A/B test, I suppose, but remember that
the human brain is incapable of retaining fine details about
subjective audio quality for more than a few seconds, and
the simple act of taking off one pair of phones and putting on
another is enough to muddy the waters. First and foremost, the
sound of the headphone itself should be the strongest consideration.
If it sounds good, it is good!-MM

Copyrights: C vs. P
Near the end of the First Steps column for November
2016, Paul Stamler mentions that one might need two
copyrights: one to cover authorship, and another to cover
production. I have been assured several times by employees
of the Registrar's Office that Form SR (Sound Recording) is
sufficient for everything on the CD/tape/whatever, including
authorship, arrangements, performance, etc. Please correct
me if this hard-won information is in error.
You and your colleagues have been very helpful to me.
Thank you.
Dan Randall
via email
Hi Dan: This is a very good point. I have doublechecked
on copyright.gov and have determined that after many years,
the Copyright Office has indeed cleaned up and simplified its
language describing the differentiation between the two types
of registration.
A "visually perceptible copy" of the original work (e.g.
sheet music of a song you've written) is protected by the familiar
"C in a circle" copyright like you'd see on a book or magazine.
However, all necessary legal protections for a phonorecord
(the music on a CD, vinyl record, cassette, or download)
are covered by the less familiar "P in a circle" phonorecord
copyright. This protection includes the writing of the songs
themselves, assuming they weren't previously copyrighted by
another songwriter.
Because so many people don't recognize the "P in a circle",
it's a common practice to also include a "C in a circle" right
next to it. Technically the circle-C doesn't apply, but it serves
as a flag to the uninitiated that the work is indeed under copyright.
If you've filed your paperwork properly, and if a valid circle-P
is present, I doubt that a spurious circle-C will damage the validity
of the copyright in court. I hope this helps clarify things. Thanks
for your letter, and thanks for reading!-MM

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RECORDING May 2017

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Table of Contents for the Digital Edition of Recording - May 2017