Two modules of API 512C and two modules of 550B bundled in an API Lunchbox 500-6B.
The API 512c is a discrete mic / line / instrument preamp designed to provide a low noise, unusually good sounding front end for all types of audio systems.
Sonically, it offers the distinct API sound at an extremely affordable price. Offering low noise (-129 EIN) and 65 dB of gain, the 512c includes phantom power, and switchable polarity, -20 dB pad and Mic or Instrument/Line selector. Front panel XLR and 1/4 inch connectors combined with rear panel mic access allows for additional flexibility when installed into an API lunchbox, API's 10 position 500V vertical rack, or an API console.
The API 512c remains faithful to the circuit designs of API's founder, Saul Walker. Fully featured and still hand assembled, the 512c carefully preserves the original sound character that made it so much a part of the early days of recording. Offering high headroom and a wide variety of inputs and input access points, it is equally at home in the commercial recording studio as it is in the home project studio.
The 512c Mic/Line Preamp makes use of the 2520 op-amp and therefore exhibits the reliability, long life, and uniformity which are characteristic of all API products.
Based on the original API 550, the API 550b is a continuation of the EQ but with an additional filter band and several new frequencies.
Incorporating API's exclusive circuitry and proprietary components (such as the legendary API 2520 Op Amp),
the 550b artfully blends the past with the present. So many hit records still depend on the unique 550 sound that engineers around the world find it to be an invaluable tool. In fact, the 550b design has been taken from the original blue prints and spec control drawings from the API archives. It is unlike any other EQ you will ever use.
Rather than offer a huge assortment of complex features, the API 550b provides exactly the right number of controls. Its four EQ bands are overlapped significantly to aid in dual roles as problem solver and sweetening device with each band offering seven switchable filter frequencies that span four-to-five octaves. These frequencies, purposely selected to be musical rather than numeric, were selected by an experienced "who's who" list of the industry's most proficient engineers.
Making use of API's "Proportional Q," an innovation designed by Saul Walker in the '60s, the 550b intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings without the need for additional bandwidth controls. This unique feature minimizes the "phase-shift" sound found in many equalizers. In addition, the reciprocal nature of the 550b enables the user to "undo" what has been done previously with exact precision.
The benefits of the API 550b are most obvious to those who work with EQ on a continuous basis. If major tonal restructuring is required, the extraordinary headroom made possible with API's 2520 Op Amp offers the predictable and warm analog performance, even under duress. With a surprisingly wide range of tonal variations, the 500b is an invaluable and professional audio tool with great flexibility and excellent sonic
The API 500-6B, also commonly called "lunchbox" is a 6-slot rack designed to accept all API standard 5.25" X 1.5" modules.