API 550A Discrete 3 Band EQ

3-band switchable EQ module for 500 Series format complete with switchable 12dB per octave 50Hz to 15KHz band pass filter and 2 x 2520 op amps on the output +4 balanced XLR I/O.


The API 550A is a three-band switchable EQ module for 500-Series format.
Since the late ’60s, the API 550A has been a staple of the American recording industry – included in both API and custom-made consoles. The original 550A modules have become so sought-after that they were the logical inclusion for the open-access 500-Series format that API invented.
A simple switchable three-band EQ, the API 550A has selectable shelving on the high and low bands with an independent band-pass filter. Proportional Q on the 550A allows smooth transition between the three frequency bands, gradually narrowing as more EQ is applied, up to 12dB.
The sound is unmistakably API – full of character and presence, with plenty of headroom and all the tonal sweetness that you need, to bring out the best in your instruments. Putting the API 550A into a Lunchbox, 500 Series gives you the power to use that fabled quality on the move.
API 550A Overview:

3 bands of classic API equalization
Each band offers 7 API selected frequency centres
Reciprocal and repeatable filtering
Maximum 12 dB of boost/cut per band
EQ Band 1 and 3 offer shelf/peak switching
“Proportional Q” narrows filter Q at extremes
Traditional API fully discrete circuit design
High headroom +30 dB clip level



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