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Audix SCX-25, April 2002

In a market awash with lowball Neumann wannabe lookalikes, the Audix SCX-25 is a refreshing sight and looks like no mic I've ever seen.

In a market awash with lowball Neumann wannabe lookalikes, the Audix
SCX-25 is a refreshing sight and looks like no mic I’ve ever seen. With
its two identical head grilles attached to either side of a central,
threaded brass ring, it has a distinctive, stylish look.

The Audix SCX-25 is a large-diaphragm, cardioidcondenser mic, priced at $799, with standard mic
clip in a padded wooden box. The mic does not have a pad or roll-off. As with all Audix dynamic mics, the SCX-25 is now manufactured and
built in the USA.

The smaller size of the SCX-25 allows it to be snugged into tight
spaces. I’d suggest using it around drum kits, but away from flailing
drumsticks. The SCX-25 head grille is single-ply metal mesh, thin
enough to be easily moved with the tip of a finger. A solid whack with
a drumstick could permanently dent the grille and possibly contact the
diaphragm. Should the head grille become dented, it can easily be
removed for repair or replacement.

These minimalist head grilles result in the SCX-25 having a very
open sound, because the capsule is more accessible to fragile
transients. Also, because sound doesn’t get trapped inside the housing
as much as with more formidable head grilles, the off-axis response is
nowhere near as phase-y as many other large-diameter condensers. The
head grilles are so light that they ping slightly when the mic body is
tapped, but having used the mic for a while, I doubt this amount of
resonance would cause a problem.

The 1-inch, gold-sputtered, center-tapped diaphragm is suspended by
elastic from four points around the inside of the central brass ring.
It’s a fairly effective suspension mount, but you might need additional
isolation if you presently have problems with mic boom resonance.

The SCX-25 has an output impedance of 200 ohms, shows a sensitivity of 29
mV (ref. 1 kHz @ 1 Pa), and has a 14dBA self-noise and an 80dB S/N ratio. The mic requires a 48VDC phantom
supply and handles 138dB max SPL. It’s pin #3 hot.

To get a sense of the 14dBA self-noise and sensitivity, I compared
the SCX-25 with a Neumann U89i (17 dBA). The SCX-25 is about 8 dB more
sensitive than the U89i. After I adjusted a pair of GML preamp levels
to achieve equal output, the self-noise levels were almost identical,
although slightly different in spectra. The U89i was flatter, and the
SCX-25 had a rise in the 5 to 7kHz range (by ear), giving it a brighter
sound. For another perspective on self-noise and sensitivity, I swapped
the U89i for a Neumann TLM103, which has a 7dBA self-noise. The SCX-25
was about 3 dB hotter than the TLM103. If you’ve had a TLM103 overdrive
your preamp, then you could expect the same with the SCX-25.

The SCX-25 had noticeably more self-noise when adjusted for equal
gain. At close range, the frequency responses of the SCX-25 and TLM103
were very similar, with the TLM103 having a bit more upper bass or low
mids. I could hear a bit more room with the SCX-25, although there were
times when I could only tell the two apart by the increased self-noise
of the SCX-25.

I plugged both mics into two channels of an Aphex 1100 preamp and
fed both via the AES/EBU digital output, through a Graham-Patten
110-to-75-ohm converter to the S/PDIF input of a Pro Tools Digi 001.
Carefully positioning the mics equidistantly about four inches from my
mouth, trimmed for equal level, I recorded narration with each mic on a
separate track. The TLM103 was smoother. Again, the SCX-25 seemed
brighter with less upper bass/low mids.

I moved the SCX-25 and TLM103 to a Mackie 1604 VLZ/XDR and found
that they, again, sounded similar at close range. Moving the mics back
about two feet, where the low-frequency increase from proximity effect was less of a factor, the SCX-25
was somewhat scooped in the upper bass/low mids and sounded a bit edgy.
Next, I used the Dreaded Key Jangle Test. Both mics
“splatted” about equally, and their frequency responses
remained consistent with my findings.

Audix also plans to build a double-mic mount, allowing a pair of
SCX-25s to be attached to the internal crossbars of a piano. The mount
will permit the piano lid to be open or closed. [Note: Although the
mic mount is not shipping yet, I tried the SCX-25s on a studio grand
with conventional stands. The mic’s slim side-profile simplified
placement even at half-stick, and their smooth pickup with a rising top
end and lack of off-axis coloration added a nice sparkle for a natural
piano sound that worked well in solo or ensemble tracks. — George

My next session was back at my studio with a D28S Martin, which has old
but not dead strings, and a Millennia Media STT-1 preamp. With the
SCX-25 at my usual spot—about six inches out from where the neck
meets the body—the fifth and sixth strings were too boomy. I was
surprised to find that aiming the mic at the lower bout, from slightly
below the center and up at the bridge about 10 to 14 inches away,
sounded much better. I’ve never put a mic there with good results, but
that’s where I liked the SCX-25.

I tried stereo-miking with a pair of SCX-25s, close-spacing the
capsules, with the lower mic angled slightly up and the upper angled
slightly down, both pointed at the rear bout. That worked! I found that
I could get the mics aimed at my original “off-the-neck”
position if I positioned the mics 16 to 18 inches from the body, with
capsules cross-aimed at the upper bout.

I took the pair of SCX-25s to Secret Sound near Baltimore for a drum
tracking session. Studio owner John Grant used the mic pre’s in a
Mackie D8B. His usual drum setup has an AKG D12 on kick, Beta 57 on
snare, two 421s on toms, Sony ECM10 for hi-hat, AKG 451s on overheads
and CAD E100 for room.

The studio has a fairly low hard ceiling, and the room is moderately
damped. We positioned an SCX-25 overhead next to each AKG 451, about
seven feet above the floor, and splayed them out slightly. Drummer
Jamie Wilson (drummer for Baltimore Mayor Martin O’Malley’s band)
played while we set levels.

The SCX-25s were 4 to 5 dB more sensitive than the 451s. The 451s
were very smooth with a more conservative bottom, to the degree that
the kick and snare sounded as though they were further away. The
SCX-25s were brighter on top, less midrange-y, with a more present kick
and snare. Grant felt that the SCX-25s also had a tighter pattern than
the AKG 451s. Moving the SCX-25s a little more than a foot higher to
just below the ceiling made their stereo spread similar to that of the
lower 451s. I felt that the 451s sounded drier, flatter and more
isolated, while the SCX-25s sounded brighter, without being harsh, and
with a wider stereo spectrum.

On harsh sources like banjo, fiddle or sax, the SCX-25 may be too
bright, but the pair of SCX-25s worked nicely as drum overheads. While
the Audix SCX-25 is not as quiet as a Neumann TLM 103, the proximity
effect makes the two mics more similar in sound when used close-in. The
SCX-25 would also be a good choice on louder vocals with darker voices
or other darker sources, especially in the din of a small practice
space or club where everyone is playing, and where there’s frequently
too much upper bass/low-mid energy. Try ’em there as well.