Recording - January 2016 - 27

Threshold: as mentioned above, this
large central knob offers 41 full stepped
positions from 0 to 40 dB. It has a tight,
springy resistance that feels great.
Attack/Release: Here is where the unit
becomes a "feel" device. Both Attack
and Release have settings of Slow to
Fast with no numeric labels in between.
Why not? Because it would be pointless;
the attack and release speeds are entirely affected by Iron's other functions and
change quite drastically with each.
Bottom line-you set the Attack and
Release by feel and by ear.
Tube Bias: This setting, controlled by a
3-position toggle switch labeled
Low/Medium/High, changes the bias of
the tube. The higher the bias, the more
the compression digs in.
Rectifier: This is perhaps the single
most timbrally wide-ranging parameter
on Iron. Paraphrased from the manual,
the rectifier produces the bias voltage
that controls the parallel tubes. There are
six different choices, and each one has
a direct and noticeable effect on the
attack and release time. There are two
initial Germanium choices (1 mF, 2 mF),
LED (3.3 mF), Silicon (330 nF), a 3rd
Germanium (220 nF) and a combination
of Germanium and Silicon (100 nF). The
only other compressor I have seen that
offers a similar feature is Chandler's
Germanium Compressor (reviewed
March 2008), which also uses multiple
choices of Germanium, Silicon, and
Zener settings.

Side Chain EQ: This control, while
common on modern compressors, is usually a highpass filter that allows low frequencies to pass through the compressor
without it clamping down. On Iron you
get 4 choices of preset EQ curves that
are quite complex, as well as traditional
external control. Note that like all
sidechain signals, this does not add EQ
or filtering to the signal path; instead, it
controls which frequencies trigger the
threshold and compression. Of all the
functions on Iron, this one is the biggest
"taste and feel" control, but the printed
RECORDING January 2016

manual does offer a graph with each
curve on it so you can make an
informed choice.
Hard Bypass: The last control for each
channel is an individual backlit hard
bypass button.
Controls and features: global
In addition to the individual channel
settings and the link function, there are a
few unique global settings as well. The
first one is a global EQ of sorts with two
available choices.
The first is labeled AirBass. As its
name implies, it adds a thick 2 dB boost
in the low end, centering on 40 Hz,
while the upper frequencies are similarly
boosted 2 dB in the 10-20 kHz range.

Flipping the toggle switch in the other
direction engages Tape Roll-Off, which
rolls off the high end steeply, starting at
5-6 kHz. The extreme low end is also
gently attenuated. As its name implies,
this is of course set to mimic the rolloff
characteristics of hitting analog tape.
The last feature of Iron is Auto-Bypass,
which allows you to dial in an interval via
a small variable knob that will engage
and disengage the unit. This allows you
to sit back in the sweet spot and audition
Iron's affect on the music. This may seem
like a novelty or a gimmick, but it works
well and allows for better decisionmaking by just listening rather than
pushing buttons and allowing said button
presses to influence your decisions.

http://www.dpamicrophones.com

Table of Contents for the Digital Edition of Recording - January 2016