Recording - July 2015 - 25

compression. Feedback compression is
where the RMS (Root-Mean-Square) detector gets its signal from the output of the
VCA. This is how most vintage VCA-style
compressors like the UA1176LN, older
dbx units, and API's classic 525 design
work. API describe it as "smoother, softer
and more transparent." In the New mode,
the RMS detector gets its signal direct from
the input or from a sidechain signal. This
offers a faster, tighter, more aggressive
compression style. Both can still be punchy,
pumpy and forward, but each in its own
way.
The last button on the 527 is labeled
Thrust®. It's a patented process, found previously on API's 2500 compressor and the

Home run: the 325
The 325 Line Driver is not an individually available module, but is found on the
output of many API consoles. Think of this
and its large black detented knob (-∞ to
+10 dB ) as the master fader. This section
has its own 2520 op amp and a 3:1 output transformer. It has a 10-segment VU
meter that can be switched to show the
512c's input or the unit's full output. There
is a large CUT button, better thought of as
a master mute, which can be remote controlled via a rear-panel 9-pin connector.
In addition to a front-mounted power button, the last button on the unit engages a
send and return should you want to patch
in an external processor. The return has its

R22 compressor from API's sister company
JDK (Reviewed April 2011). The original
Thrust circuit was taken from the compressors found on the ATI Paragon series of live
consoles in the 1980s. This circuit gives the
compressor a forward, focused punch by
allowing bass signals to pass through the
detector circuit without clamping down.
There is a 1/4" balanced sidechain input
on the back, as well as the 1/4" DC Link out
for linking two units. The rear panel also
has 1/4" balanced Ins and Outs for First
and Second Effects (the compressor and
EQ, depending on selected order).

own 1/4" input on the rear panel; the
Second Effect Out is used as a send.

Third base: the 550A
And speaking of EQ, next is the 550A.
It's one of the company's oldest and
arguably best-known modules, essentially
unchanged from Saul Walker's original
discrete 2520 op amp-based design.
The 550A is a 3-band EQ which uses
a trio of stepped, dual concentric pots for
frequency (inner pot) and gain/attenuation (outer pot). The 550A offers no Q
control; its Q is proportional, narrowing
with more boost or cut.
The 550A offers ±12 dB at 30-400 Hz,
400-5000 Hz, and 5-20 kHz. Unlike
many other modern and vintage equalizers, the 550A has minimal overlapping of
the bands, especially when pushed hard,
due to the proportional Q. This makes the
550A a very precise focused EQ rather
than a general tone-blender.
Both the high and low bands can be set to
shelving or peaking EQ settings, and there is
also a button labeled B.P. Filter which
engages a band pass filter fixed at -3dB @
50 Hz and 15 kHz. The EQ can be either
hard or soft bypassed, the latter meaning
that audio passes through the 550A's op
amps without the EQ being engaged.

Working the strip
Despite what may look at first to be complicated routing options, this device is about
as plug-and-play as it gets, if all you want to
do is run it as is from input to output.
Integrating it into a good patchbay to access
the intermediary signal patch points only
heightens the fun. As to the sound, what can
I say that tens of thousands of albums have
not already said? API has proven time and
time again that they are masters of sonic consistency across all of their products.
Despite having some differing components between the 200 and 500 Series
and even consoles, the sonic signature of
API remains distinctive. It is a sound that is
often thought of as punchy and aggressive,
"the sound of rock'n'roll," but there is also
a cleanliness, headroom, and a solid fullness that makes this channel strip a great
jack of all trades for many musical styles.
Conclusion
API has done a great job of bringing the
API console sound into a 19" rackmount
box, thanks in no small part to the 325 line
driver. It's a significant purchase for any
home or project studio, but if you purchase
just the first three modules in their 500
Series format, you'd pay more... and still
be minus the 325 and a rack enclosure.
As I said at the start, this is the API Sound
for users who aren't into module racks or buying a full-on console. If there's a downside to
The Channel Strip, it's that you're probably
going to end up wanting two of them.
Price: $2995 ($2545 street)
More from: API, www.apiaudio.com
RECORDING July 2015

http://www.royerlabs.com http://www.apiaudio.com

Table of Contents for the Digital Edition of Recording - July 2015