Recording - May 2015 - 49

as "liquid". What does that mean? It's something I find hard to put into words, but this
mic seems to make the notes played on an
acoustic guitar flow into one another more
smoothly than other microphones. It's something more readily heard than described;
perhaps the most accessible example is the
studio recording of the song "Suite: Judy Blue
Eyes" from the first Crosby, Stills and Nash
recording, way back when. Listen to the
acoustic guitar part, which was recorded

of a Martin, and you get a sound you can
almost reach out and massage: a palpable,
real sound that blends with voices and
other instruments like butter. The C451
doesn't have the liquid character of the U
87, but its sound on an acoustic guitar is
just as beguiling, in a totally different way.
Last example: sometimes a mic/instrument partnership is particular to a specific
combination. I usually mike a mandolin with
a Neumann KM 84; it's a nice combination.

With nothing in the specs to predict
the ephemera of how mics and sources interact,
how does the poor engineer choose the right mic?
entirely with a single U 87. (According to
legend, it was done in a single take.) You
can hear the U 87's liquid quality on this
track; I've also used the U 87 on mandolin,
and can testify that the liquid character
applies to that instrument too.
Why does this mic sound like that? I
don't know; I once posed the question to
a well-known microphone designer, and
he confessed that he didn't know either,
but we agreed that (a) it was there, (b) the
microphone was adding it, and (c) we'd
only heard the effect from multipattern
large-diaphragm condenser mics.
This liquid quality is definitely a coloration, but a pleasing one, and I suspect
that's another reason the U 87 is a perennial studio favorite, despite its high price.

One time, though, when I was setting up
with Paul Ovaitt of the Augusta Bottoms
Consort, I'd run out of KM 84s, and put up
an Oktava MK012. Well, sir-on that mandolin (Paul plays a Flatiron), the MK012
knocked the socks off the KM 84. I've used
Oktavas on Paul's instrument ever since.
All three examples have one thing in common: there's nothing in the microphones'
specifications or frequency response charts
that predicts the effects. Not the liquid character of the U 87, nor the palpable character of the C451B on acoustic guitar, nor the
particular synergy between the MK012 and
Paul Ovaitt's mandolin.
With nothing in the specs to predict
these phenomena, how does the poor
engineer choose the right mic? The

The answer is that, in the end,
there is no real substitute for experience:
knowing what your mics will do.
But whatever causes that liquid sound doesn't show up on frequency response charts.
Here's another example. Take a look at
Figure 7, a frequency response plot for the
AKG C451B small-diaphragm cardioid
condenser mic. The chart has the usual
"drumhead, etc." resonance around 10
kHz. You can see a couple of dotted lines
on the left for two selectable highpass filters, which compensate for proximity effect.
In short, there's nothing particularly striking or unusual about the C451B's specified
frequency response. The chart doesn't tell
you (or even hint) that this mic, like the U
87, has a particular affinity for acoustic guitars-but it does. Aim a 451 at the 14th fret

answer is that, in the end, there is no real
substitute for experience: knowing what
your mics will do. That experience doesn't have a shortcut route; you only get
there by trying different mics in different
applications, and hearing what works.
Enough with the philosophizing. In next
month's article I'll go into detail about
which microphones I used in our clip, why
I chose them, and where I put them. See
you then!
Paul J. Stamler (stamler@recordingmag
.com) is a recording musician, engineer,
educator, and collector of bizarre vintage
recordings, living in St. Louis.
RECORDING May 2015

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Recording - May 2015

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