Selling a matched pair of API 550B four-band equalizers in excellent, barely-used condition.

The API 550B is a discrete Class A four-band EQ — an expanded version of the legendary API 550 with a fourth band added for even more tonal control. It features proportional-Q EQ across low (30Hz–400Hz), low-mid (75Hz–1kHz), high-mid (800Hz–12.5kHz), and high (2.5kHz–20kHz) bands, each on fixed-point selector switches for repeatable, precise settings, plus switchable high-pass and low-pass filters. This is the punchy, musical, larger-than-life API sound — a staple on drums, bass, vocals, and full mixes in studios worldwide.

Condition: Excellent. Both units have seen very light use and function flawlessly — every knob, switch, and pot moves smoothly with no scratchiness or issues. Electronically and sonically, both modules are 100% identical and perform exactly as they should.

Please note: One of the two units is missing its serial number plate and ID stickers (see photos). This is purely cosmetic — it does not affect operation, sound, or performance in any way.

Sold as a matched pair. Shipping from Belgium — message me for an accurate shipping quote to your country.

Specs:

• Brand: API (Automated Processes, Inc.)
• Model: 550B
• Type: Discrete Class A 4-Band Parametric/Fixed-Point EQ
• Format: 500 Series module
• Low band: 30Hz–400Hz
• Low-mid band: 75Hz–1kHz
• High-mid band: 800Hz–12.5kHz
• High band: 2.5kHz–20kHz
• Filters: Switchable High-Pass & Low-Pass per band
• Quantity: Sold as a matched pair
• Condition: Excellent, light use, fully functional
• Note: 1 unit missing serial plate/stickers (cosmetic only)
• Ships from: Belgium