Recording - February 2015 - 17

diaphragms are activated and their
signals added. The U48, released
in 1957, was switchable between
cardioid and figure-8. The figure-8
pattern was achieved by subtracting
the back signal from the front, which
also results in signals arriving from
the back of the mic being output in
reverse polarity.
Around 1960 Neumann started
using the new K47 and K49 capsules, which used 6 micron polyester
diaphragms instead of PVC. The K49
capsules had more precise matching
of the tension between the front and
back diaphragms for more uniform omni or
figure-8 patterns. Nowadays the original
M7 capsules don't hold up very well due to
drying and deterioration of the PVC.
By the 1950s Neumann had taken over
distribution of the U47 and put its own
logo on it, but in the 1970s Telefunken
stopped making the mic's VF14M tube.
Neumann experimented with different
tubes but could not find one he liked, so he
discontinued the U47, saying, "Don't try to
bend the laws of physics in pursuit of a
particular sound. If people want the sound
of the U47, it's up to them to try to get hold
of one."
However he did introduce the solid-state
U47fet. This phantom-powered mic used a
Field Effect Transistor instead of a tube. The
U47fet was less expensive, and had only
a cardioid pattern. Those K47 capsules
that did not have the tighter matching
between the front and back were used.
Even though only the front diaphragm was
activated, it is a good thing that the back
diaphragm was there, because dual
diaphragm mics have better behaved
proximity effect up close. This is explained
in one of the most important papers you
will ever find on microphone technology:

Unique Directional Properties of DualDiaphragm Microphones by Guy
Torio and Jeff Segota, available on the
Shure website. Read it-it will change
how you do everything! The U47fet
sounded a bit different than the U47,
and didn't catch on for vocals in the
same way, but became very popular
for kick drum and upright bass. You'll
find a review of Neumann's brandnew U47fet reissue on Page 20.
The U47 has an instantly recognizable sound due to the combination of
the capsule, tube electronics, and output transformer. The cardioid frequency response exhibits a gradual bass rolloff
below 300 Hz and a 4 dB double camel
hump rise centered around 4 kHz and 10
kHz (easily seen in Figure 6). This makes
the U47 noticeably brighter than the ribbon mics that preceded it, and engineers
and listeners have remarked on the
enhanced "clarity" of the sound. A U47
has a more pronounced proximity effect
than later designs, which balances out the
high midrange clarity when you get close.
This combination of low end warmth and
high-high/mid clarity is the U47 sound!
The mic was expensive, about $3500 in
today's dollars, so only well heeled studios
could afford it. Capitol Records bought a
bunch, and it became Frank Sinatra's mic
of choice-he called it his "Telly". Pictures
show him a very consistent 1 foot or so
away, with no pop filter. At that distance
his voice sounds very well balanced, warm
but without a noticeable bass boost, but on
various songs you can clearly hear him
moving in and out. The album Songs for
Swingin' Lovers is a great example of
Sinatra at his best. On We'll Be Together
Again you hear him sing the first two low
quiet lines rather close, and then as he
goes into his higher register it is quite obvious that he backs up a bit. The sonic effect
is quite remarkable! Low, quiet passages
sung very close yield a blooming, intimate
warmth, and higher, louder passages at a
distance really bark at you in a way that
cuts without getting edgy.
Producer George Martin used the U47
and U48 on the Beatles from the very
beginning. During the recording of the
first few Beatles albums there were strict
rules at Abbey Road specifying just how
close to a mic you were allowed to get.
Some session photos show the Beatles
singing about 8 to 10 inches away for
solo vocals and up to a foot or two for trio
vocals.

6
RECORDING February 2015

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Recording - February 2015

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