API / 550A

This 3-band equalizer is made by API and is compatible with the API 500. It allows up to 12 dB of boost/cut on each band. The HF and LF bands can be switched between peak and shelving.

■ 3-Band Equalizer, API 500 Compatible

■ Faithfully reproduces the classic 3-band API equalization
■ Five-point center frequency selection for each band
■ Up to 12dB boost/cut for each band
■ Switchable peak/shelve settings for HF and LF
■ ""Proportional Q"" circuitry delivers steep, narrow equalization
■ Utilizes API's legendary original op amps
■ High headroom with a clipping level of 30dB

Few equalizers compare to the revived classic 550A. Designed by Saul Walker in the late '60s with all discrete stages, the 550A was first used as a modular OEM equalizer. The recording industry rapidly embraced the 550A's sound quality, leading to numerous custom console designs by Frank DeMedio and other leading engineers. Many of these consoles are still in production today. Forty years later, the 550A remains the gold standard for equalizer performance, and it has played a major role in the recording industry for decades. While there have been copies, they were merely copies. When the company began manufacturing consoles in 1971, the 550A became API's standard channel module equalizer. With all existing units still in use, the equalizer was finally reintroduced in 2004. The 550A features a 5-step, 15-point design, providing 12 dB of gain per band. The 15 points are divided among three overlapping bands. Peak or shelving is independently selectable for HF or LF. A bandpass filter is inserted regardless of all other settings. Frequency bands and boost/cut are selectable via three coaxial selector switches. The ""IN"" switch turns the equalizer on or off. A small toggle switch is used to insert a bandpass filter into the 550A. Utilizing Walker's unparalleled API 2520 op-amp and his ""Proportional Q"" circuitry, 550A users benefit from superior acoustic equalization. This long-awaited return of this unit marks a milestone in recording history, one that will continue to shape music for generations to come.