API Reissues the 550A Three-Band EQ Module
 October 11, 2004
After 20 years, the API 550A discrete, three-band
equalizer will start rolling off the production line.
API's Saul Walker designed the 550A in the late 60s.
Originally a modular OEM equalizer, the 550A quickly found it's way into
many custom console designs by Frank DeMedio and other leading engineers,
many of which are still in use today. This often-copied
equalizer became API's standard channel module EQ when they started
manufacturing consoles in 1971.
Providing a true replica of the famed API 550A equalizer was no small
undertaking for API. Jeffrey Bork, head API engineer, comments: "We've gone
to great lengths to ensure that the new 550As are exactly (and I mean
exactly) the same as the original. For starters, API constructed exact
duplicates of the metal work and circuit boards from the original artwork.
We made silk screens from the same original artwork for the new front
panels. The 550A uses the same output transformer that API has used
throughout the years. And to keep everything exactly the same, we went to
the original manufacturer for the exact same rotary switches and the same
Schadow switches for the bypass. What you end up with is an exact replica
even down to the gauge of the wiring and the harnessing- even the original
documentation is included. Everything is so exact that people with older
550A EQs will now be able to buy matching units or purchase parts to
refurbish and fix their older units."
"It's basically the next production run of API units from the early
eighties. And its worth mentioning that we never even considered trying to
make the 550A 'better,'" added Bork.
The 550A uses bridge-T filters (RC networks), two of API's 2520 discrete
amplifier modules, a 1:3 output transformer, and provides up to +28dBm
output level. All three of the frequency bands overlap and there is up to
+/-12dB of boost or cut in 2dB steps available for each band. There are
choices of shelving and peaking for the Hi and Lo Band and a switchable,
12dB/octave, 50Hz to 15kHz bandpass filter.
A feature important to the classic sound is the
proportional Q design where the bandwidth (or Q) of the equalizer narrows as
boost or cut is increased. The Q is three octaves wide at 2dB of boost/cut
and narrows down to one octave with 12dB of boost/cut.
MSRP: $1,695.00
For more information, visit their web site at www.apiaudio.com. | 
