Recording - December 2013 - 60

B Y PA U L V N U K J R .

PreSonus RC 500 Solid State Channel Strip
A new preamp design heads up a channel strip that's a real revelation
In our August 2013 issue we took a look
at the PreSonus ADL 700 channel strip, built
around a single channel of the Anthony
Demaria-designed ADL 600 stereo tube
microphone preamp, also built by PreSonus
and reviewed back in October 2006. The
ADL 700 married Mr. Demaria's high-gain
tube preamp with an FET compressor and a
solid-state 4-band equalizer designed by
PreSonus in-house designer Robert Creel,
the inventor of PreSonus' popular XMAX
preamps (used in many of the company's
interfaces and mixers, etc.). In that review I
found the ADL 700 to be "an incredibly
powerful tool, capable of a wide range of
sonic sculpting."
This month we have another new mono
channel strip from PreSonus, the RC 500. It
keeps the FET compressor and equalizer from
the ADL 700 and replaces the ADL 600's
tube preamp with a new solid-state design,
also created by Robert Creel. This is where
the RC in the product name comes from.
The RC500 looks like a single-rackspace version of the ADL 700, with a similar look and layout, although the big blue
lights (aside from the power light) and
chunky toggle switches are gone and the
backlit VU meter has been miniaturized.
Front and rear panel layouts
The newly designed preamp in the RC
500 is a Class-A hybrid design with discrete
transistors and new, low-distortion op amps.
It has a 1/4" instrument input, and a switch
for selecting between that or the rear-panel
XLR microphone input. It offers the usual preamp functions: polarity invert, phantom
power, 80 Hz highpass filter and a -20 dB
pad. Like the ADL 700, it has a variablegain knob offering 20 to 70 dB of clean
gain, which lets it handle low-output ribbon
and dynamic mics with no problem.
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RECORDING December 2013

The compressor employs the same FETbased VCA-style compression circuit as the
ADL 700, but simplified. The RC 500 whittles down the ADL 700's controls to three,
by removing the knobs for ratio selection
and makeup gain. In the RC 500 the ratio
is fixed at 3:1 with a soft-knee curve. It has
a -25 to 20 dB Threshold control, Attack
(0.05 ms-10 ms) and Release (30 ms to
500 ms). The compressor can be switched
in or out of the circuit with a hard bypass,
and its VU meter can be set to show gain
reduction or output level.
The EQ on the RC 500 is also simplified from its predecessor, being a 3-band
rather than a 4-band semi-parametric
with each band offering a fixed Q of 0.5.
The Low band can be switched between
peak or shelving with a range of 20 Hz
to 400 Hz, ±16 dB. The Mid band goes
from 400 Hz to 5 kHz, ±16 dB, and the
High band is switchable between peak or
shelving with a range of 2 kHz to 20
kHz, ±16 dB. The EQ, like the compressor, can be hard-bypassed out of the circuit, although unlike on the ADL 700 the
order of the two cannot be changed.
The last control on the RC 500 is a master output knob with a throw of -80 dB to
+10 dB.
On the rear of the RC 500 there is a
choice of XLR microphone or balanced
XLR line input. It has a pair of TRS 1/4"
insert points for patching in external gear,
and it's rounded out by a choice of XLR or
balanced 1/4" connections for output.
In use: the new preamp
As a huge fan of the ADL 600 preamp,
I was a tad worried when I found out
PreSonus was adding a new channel strip
alongside the ADL 700, but one that put
in a solid-state design in place of the tube

pre I knew and loved... and using words
like "vintage flavored" to describe it. I put
the new Creel-designed microphone preamp through its paces, alongside two
other solid-state mic preamps I know well,
the Millennia Media HV-3D and the
Chandler TG-2. It turns out that I didn't
have much to worry about.
The sound of the new RC 500 preamp
is clean, solid, and has a positively huge
low-end presence. Compared to the ADL
600/700 tube pre, which I found bold
with an opulent top end, the preamp in
the RC 500 is thicker and punchier with a
more focused top.
While it was too sonically different from
the straight-wire-with-gain sound of the
Millennia for any useful comparison (other
than to say, "wow, it's really different"), the
RC 500 shared a mid-forward punch and
tightness with the TG-2 but was fuller in the
lows. I should clarify that I am not implying
that the low end is fat and pillowy, but
rather that it has a boldness and weight to
it that sits really nicely.
Overall the RC 500's preamp is a nice
console-style preamp with a sound that
layers well on any sound and source, be
it vocals, acoustic instruments, drums, or
electric guitars. Its low-end weight makes
it really nice on DI'd bass as well.
This is easily the best solid-state mic pre
that PreSonus has built since the classic
original Jensen-equipped MP20! In fact, I
would love to see this preamp available
without channel strip as a two-channel
unit... it's that nice.
Simpler can be better
Moving on to the rest of the channel
strip, my thoughts on the RC 500 remain
similar to those from my ADL 700 review,
especially concerning the EQ which, just

Recording - December 2013

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