The beginnings of the 5500 circuit can be traced back to the original 550 equalizer designed by Saul Walker, the founder of Automated Processes Inc. The 550 was designed as a console equalizer, which uses an unbalanced input due to the architecture of the recording console. Because the ergonomics of a console dictate that the controls take up little space, sometimes the number of included functions can be limited. The 5500 is specifically designed to address these limitations; it has a balanced input, a true straight-wire bypass, an integrated power supply with noiseless muting and a range control that expands its versatility to mastering applications.

The 5500's input XLR is connected to an active balanced circuit. The unit's output XLR is driven from a transformer coupled output and can drive any load from 600 ohms or more to full output capability. There is no change from input to output in the unit's polarity, so it is suitable in studios using either pin 2 or pin 3 as the "hot" connection. Additionally, the 5500 has a 1/4 inch input connector that interrupts any present signal on the input XLR. It is balanced and can be driven from either balanced or unbalanced sources. A positive signal on the tip will deliver a positive signal on pin 2 of the output XLR. Using the 1/4 inch input does not bypass any internal circuitry and does not change the gain or operating levels.

Features:
    Classic 550b Equalizer design
    Two range switches to individually alter gain steps
    Useable as a 550b, 550D or 550M
    Peak/shelf switch on Hi and Lo bands
    True hardwire bypass
    Balanced In and Out on XLR
    Unbalanced input on 1/4"
    EQ In/Out switch

Technical Specifications:
    Power Consumption, Quiescent:     .66 Watts
    Size:     19" X 1.75" (1U) X 11.25" Deep
    Size (Boxed for Shipping):     23.25" X 6.5" X 16"
    Actual Weight:     9.68 lbs.
    Shipping Weight:     13.51 lbs.