The API 550b is a four-band EQ based on the classic 1960s API 550, featuring additional frequencies and one extra band. Built with the original 2520 Op Amp and “Proportional Q” design, it offers musical, phase-friendly EQ curves with high headroom and precision. Trusted by engineers worldwide, it remains a powerful and flexible tool for both corrective and creative applications.
The API 550b is a modern evolution of the original API 550 equaliser introduced in the late 1960s. While preserving the core character that made the original so influential in recording history, the API 550b adds a fourth band and a broader range of selectable frequencies.
Built with API’s proprietary components, including the renowned 2520 Op Amp, the API 550b faithfully reflects the design and sonic integrity of the original, using actual blueprints and spec control drawings from API’s archives. Its distinctive tone has been a staple on countless hit records, earning it a permanent place in professional studios worldwide.
Designed with practicality and musicality in mind, the API 550b avoids unnecessary complexity. It offers four overlapping bands of EQ, each with seven carefully chosen switchable frequencies spanning up to five octaves. These frequencies were not selected at random or purely by measurement, but through consultation with some of the most respected engineers in the industry, resulting in an EQ that is as musical as it is effective.
A key feature of the API 550b is API’s proprietary “Proportional Q” design, originally created by API founder Saul Walker. This system automatically adjusts the filter bandwidth depending on the amount of boost or cut applied: wider at subtle levels, narrower at more extreme settings.
This approach reduces the phase shift artefacts common in many equalisers, helping to retain clarity and focus. Additionally, its reciprocal EQ curves allow for precise correction or reversal of previous adjustments without introducing coloration.
The API 550b stands out for its high headroom and consistent analogue performance, even during demanding tonal shaping. Whether used for surgical correction or creative tone enhancement, it remains a highly flexible and reliable tool that continues to meet the needs of today’s professional audio engineers.
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$2,349 Inc GST
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