API / 5500

This dual equalizer features the same EQ circuitry as the all-time popular API550 equalizer, balanced input, hardwired bypass function, built-in power supply with noiseless mute function, and various range controls.

■Dual 550 Equalizer with Range Switch
■Based on the legendary API 550B equalizer design
■Two-range gain selector switch with adjustable gain steps
■Functions also available as the 550B, 550D, or 550M
■Peak/Shelving switches on high and low sections
■Hardwire bypass function
■Balanced input/output via XLR connectors
■Unbalanced input via 1/4"" phone jack
■EQ IN/OUT switch

The equalizer circuit used in the 5500 is based on the legendary API The name originates from the 550 equalizer. The 550 was designed as an equalizer module for recording consoles, so its input specifications were unbalanced. As compact mixing console designs became more common, mixing modules presented numerous operational challenges. The 5500 was developed to overcome these limitations. Its balanced inputs, hardwired bypass function, built-in power supply with noiseless mute, and various range controls make it an ideal tool for mastering, which has become increasingly important in recent years. Like all API products, the 5500 uses no integrated circuits in its main path. Gain is handled by a hand-built, discrete 2520 op amp. The balanced input stage is handled by a 2510 discrete op amp, similar to the 2520 but capable of higher output. The signal passing through the 2520 is then further transformed by API's original output transformer. By passing through the 2503, a high output level of +30dBm is achieved. This ample headroom allows for sufficient gain in the main path without the need for additional preamps. The 5500's new range control allows for more precise sound adjustments, with a pre-set range between 1/4 and 1/2. This feature is important for complex 2-mix adjustments and final mastering. Another new feature in the 5500 is hardwired bypass. In this mode, the input and output are directly connected. This mode is ideal for broadcast use, as it ensures output even if the power is not initially turned on or if it goes out during operation. Of course, there is absolutely no noise when switching. The signal from the XLR input is connected to an active balanced circuit. The XLR output passes through an output transformer, allowing for final adjustment regardless of input impedance. The lack of a polarity switch also provides the advantage of consistent polarity control between devices connected before and after.