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This EQ Has Royal API Blood Lines!

Incorporating API's legendary circuitry, the API 550b 4-band equalizer exudes that royal API blood line in every ounce of its sonic character. Artfully blending the past with the present, the API 550b carries the torch from the now-classic API 550EQ — delivering just the right amount of controls to solve problems and sweeten the sound. On each of the API 550b's bands, there are seven carefully selected, switchable filter frequencies. It's packed with surprisingly surgeon-like capabilities — but it's all about musicality — you'll find out why top engineers depend on the API 550bB everyday.

API 550b 500 Series Modular 4-band Equalizer at a Glance:

• A modern relative of a music-history favorite
  
• API's "Proportional-Q" Control
  
• Excellent at affecting or reversing tonal modifications
  
• API's 500 Series: Long-term flexibility, lasting value

A modern relative of a music-history favorite
The API 550 EQ played a major part in the history of music recording in the USA during the 60s and 70s. Originally conceived for use in API's consoles, this latest 550"B" version, the API 550b, is a continuation of the original 1967 550 through the 550A with one additional filter band and several new frequencies. Incorporating API's exclusive circuitry and proprietary components (such as the legendary API 2520 op-amp), the 550b blends the past with the present. So many hit records still depend on the unique 550 sound — and you'll find that the 550b will be an invaluable tool you'll turn to again and again.

API's "Proportional-Q" Control
Making use of "API Proportional-Q", a design introduced by API in the 60s, the 550b intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings — without the need for additional bandwidth controls. This feature minimizes the "phase-shift" sound found in many equalizers.

Excellent at affecting or reversing tonal modifications
You'll be surprised by the possibilities the API 550b 4-band equalizer opens up. One of the 550b's most compelling features is its ability to affect or reverse tonal modifications. If major tonal restructuring is required, the extraordinary headroom made possible with API's 2520 op-amp offers predictable and gentle "analog" performance under duress. You've got a surprisingly wide range of tonal variations, just a few knobs away.

API's 500 Series: Long-term flexibility, lasting value
The beauty of the entire API 500 Series is its long-term flexibility and lasting value — especially when you consider that needs change over time. With a range of mounting frame options, the API 550b will be a valuable asset to your ever-changing studio rigs. It's also ruggedly designed with sound you just won't outgrow — crafted to be your sonic partner for year after year after year.

API 550b 500 Series Modular 4-band Equalizer Features:

• 4 bands of their famous-sounding equalization
  
• Each band offers 7 API-selected frequency centers
  
• Reciprocal and repeatable filtering
  
• 12dB of boost/cut per band
  
• EQ Band 1 and 4 offer shelf/peak switching
  
• "Proportional Q" narrows filter Q at extremes
  
• Traditional API fully discrete circuit design
  
• High-headroom +30dB clip level
  
• Reissue of 1967 API 550 EQ with an extra band

API 550B 500 Series Modular 4-band Equalizer Specifications:

• Modular 4-band Equalizer
  
• Filter Type:"Low" and "High" bands are Peak/Shelf switchable. Low-Mid and Mid-High are peaking type
  
• Low Filter Frequency Center: 30, 40, 50, 100, 200, 300, 400Hz
  
• Low-Mid Filter Frequency Center: 75, 150, 180, 240, 500, 700, 1Khz
  
• Mid-High Filter Frequency Center: 800, 1.5K, 3K, 5K, 8K, 10K, 12.5K
  
• High Filter Frequency Center: 2.5K, 5K, 7K, 10K, 12.5K, 15K, 20K
  
• Filter Boost/Cut: +/- 12dB
  
• Filter Slope: 12dB per Octave
  
• Input Impedance: 18.5 K +4 in, 7.5 K -2 in
  
• Output Impedance:Less than 75 Ohms
  
• Nominal Levels: -15 to +15 dBu
  
• Clipping Level: +30 dBu at ±16 V
  
• Frequency Response:+0, -.3, 30 to 20 kHz
  
• Noise:Actual, unw noise, <-98 dBu, 20-20 kHz
  
• Distortion:.07% max, at +18 dBu Output
  
• Connectors:15 position .156sp edge connector
  
• Size: 1.5" X 5.25" X 6" Deep
  
• Weight: 2.5 lbs

The API 550b 4-band equalizer artfully blends classic API sound with modern features!

Specification Detail Manufacturer Part Number 550B

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