API 550B 4 Band EQ
Many EQ's today offer a huge assortment of complex features, but the API 550B provides exactly the right number of controls to the professional engineer. Deceptively simple at first glance, the 550B's four EQ bands are overlapped significantly to aid in dual roles as problem solver and sweetening device. Each band offers 7 switchable filter frequencies spanning 4 to 5 octaves, selected through experience by a "who's who" list of the industry's most proficient engineers. This re-issue design has been taken from the original blue prints and spec control drawings from the API archives.
Making use of "API Proportional-Q", a design introduced by API in the 60's, the 550B intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings—without the need for additional bandwidth controls. This feature minimizes the "phase-shift" sound found in many equalizers. The reciprocal nature of the 550B enables the user to "undo" what has been done previously.
The benefits of the API 550B are most obvious to those who work with EQ on a continuous basis. The 550B's ability to affect or reverse tonal modifications is perhaps the most important feature. If major tonal restructuring is required, the extraordinary headroom made possible with API's 2520 op-amp offers predictable and gentle "analog" performance under duress. With a surprisingly wide range of tonal variations, you can do no better than the API 550B.
- 4 bands of our famous sounding equalization
- Each band offers 7 API selected frequency centers
- Reciprocal and repeatable filtering
- 12 dB of boost/cut per band
- EQ Band 1 and 4 offer shelf/peak switching
- "Proportional Q" narrows filter Q at extremes
- Traditional API fully discrete circuit design
- High headroom +30 dB clip level
- Re-issue of 1967 API 550 EQ with an extra band