The API 550 introduced visionary EQ curves. Q varies with gain, so boosting adds a more focused musical quality—while reducing gain provides natural, subtle-to-steep tone shaping. Developed in close collaboration with API, the 550A/B are loving re-creations of these late-60s legends.
Expertly selected frequencies lift instruments up, or place them further back—just as easily as they can sweetly shape a mix’s contour. For individual tracks, buses, or full masters, the 550 defines musical transparency.
550A: 5 selectable frequencies for 3 bands, and 50 Hz – 15kHz filter
550B: 4 overlapping EQ bands with multi-octave ranges
Ideal for general problem-solving or sweetening
High/low bands for 550A and B switch between peak and shelving
Switchable analog harmonic distortion and hiss
Convenience features like phase switch, output trim, and metering