Experience the simplicity and acoustic superiority of a legendary EQ with the API Audio 550A, a 3-band EQ module for 500-series racks with ±12 dB of boost/cut per band. With switchable shelf/peak operation on the low and high bands and proportional Q circuitry for narrowing the filter bandwidth at the extremes, the 550A is a versatile and intuitive EQ module.
Each band provides seven selectable frequency centers and 21 steps of EQ adjustment. The 550A sports high-headroom discrete circuitry, offering up to 30 dB of input gain before clipping. A small toggle switch can be used to inset a bandpass filter to the 550A signal path, and the bandpass filter can be inserted independently of all other EQ settings.
As the industry rapidly embraced the sonic quality of the 550A, it quickly found its way into many custom console designs by Frank DeMedio and other leading engineers. Many of these consoles are still in use today. Forty years later, the 550A remains the standard against which other EQs are measured, and it has played a major role in the recording industry for decades.
Frequency ranges and boost/cut are selected by three dual-concentric switches, and a push button in switch allows the EQ to be silently introduced to the signal path. A small toggle switch is used to insert the bandpass filter into the 550A.