API Audio 5500

The lineage 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, due to the architecture of the recording console, uses an unbalanced input.

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 it versatility to mastering applications.

Like all API products, the 5500 contains no integrated circuits in its signal path. The gain comes from two hand-built 2520 operational amplifiers in each channel. The balanced input is handled by a 2510 discrete operational amplifier, which is similar to the 2520, but without the high current output stage. Besides being a key component of the API sound, the 2520 coupled with the API 2503 output transformer is capable of delivering +30dBm before clipping. With this much headroom, it is unlikely that the 5500 can be driven to distortion unless perhaps another API unit is driving the input!

      FEATURE

• Classic 550B Equalizer Design
• 2 Range Switches Individually Alter Gain Steps
• Useable as a 550B, 550D or 550M
• Peak/Shelf Switch on HI & Lo bands
• True Hardwire Bypass
• Balanced IN and OUT on XLR
• Unbalanced Input on 1/4"
• EQ In/Out Switch