This DIY 550A from Brian Horvitz is a clone of API’s classic, 3-band equalizer. Horvitz’ design departs slightly from the original in order to use commonly available, modern components. Kits and PCBs will most likely be offered within 2011.

Features:

• Accepts all standard-footprint discrete opamps
• Uses Ed Anderson’s replica of the API 2503 output transformer
• Does not require custom switches
• 500-series compatible
• Employs high-quality WIMA capacitors

Price: Not announced yet

More reading:

• Brian Horvitz’ GroupDIY thread
• API’s info on the 550A