A black API 550b 500 Series equalizer module shown vertically, with four large round aluminum rotary knobs stacked down the center, concentric frequency and boost/cut markings around each knob, API branding and the "550b" label at the top, and an IN switch at the bottom.

API 550b 500 Series 4-Band Equalizer Module

$1,300.12
$1,300.12
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A black API 550b 500 Series equalizer module shown vertically, with four large round aluminum rotary knobs stacked down the center, concentric frequency and boost/cut markings around each knob, API branding and the "550b" label at the top, and an IN switch at the bottom.
  • A black API 550b 500 Series equalizer module shown vertically, with four large round aluminum rotary knobs stacked down the center, concentric frequency and boost/cut markings around each knob, API branding and the "550b" label at the top, and an IN switch at the bottom.
  • A black API 550b 500 Series equalizer module shown vertically, with four large round aluminum rotary knobs stacked down the center, concentric frequency and boost/cut markings around each knob, API branding and the "550b" label at the top, and an IN switch at the bottom.
API 550b 500 Series 4-Band Equalizer Module

API 550b 500 Series 4-Band Equalizer Module

API 550b 500 Series 4-Band Equalizer Module — sourced facts: Low: 30, 40, 50, 100, 200, 300, 400Hz; Audio resolution: 1Khz; Connectivity: USB; {"handle": "550b", "classification": {"lane": "studio", "action": "keep", "reason": "retailer taxonomy"}, "catalogListingId": "studio_economik:10123020796223"}.

$1,300.12
$1,300.12
Condition Mint
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Specifications

“Low” and “High” bands are Peak/Shelf switchable. Low-Mid and Mid-High are peaking type · 16 V Frequency Response: +0, -
Low 30, 40, 50, 100, 200, 300, 400Hz
Audio resolution 1Khz
Connectivity USB
{"handle" "550b", "classification": {"lane": "studio", "action": "keep", "reason": "retailer taxonomy"}, "catalogListingId": "studio_economik:10123020796223"}
Specifications Number of Bands Four
Filter Type “Low” and “High” bands are Peak/Shelf switchable. Low-Mid and Mid-High are peaking type
Filter Frequency Centers Low: 30, 40, 50, 100, 200, 300, 400Hz Low-Mid: 75, 150, 180, 240, 500, 700, 1Khz Mid-High: 800, 1.5K, 3K, 5K, 8K, 10K, 12.5K High: 2.5K, 5K, 7K, 10K, 12.5K, 15K, 20K
Filter Boost/Cut ±12 dB
Filter Slope 12 dB 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
Dimensions note 4 in, 7
Size 1.5″ X 5.25″ X 7.5″ Deep
Size (Boxed for Shipping) 4.5″ X 6.25″ X 10″
Actual Weight 2.02 lbs.
Shipping Weight 2.43 lbs.
Power 16 V Frequency Response: +0, -
Power Consumption ±12/18 Volts/DC,@ 40 ma.

Fit and constraints

16 V Frequency Response: +0, -

Intended use

Not for Anyone needing fully sweepable, continuously variable parametric control or user-adjustable Q, since the 550b switches between seven fixed frequencies per band and its Q is fixed by the Proportional Q design. Also skip if you have no 500 Series frame and power supply, if you need more than +/-12 dB of boost/cut, or if you need stereo from a single unit (this is a one-channel module).

Constraints

Power16 V Frequency Response: +0, -

To use it

Description

Product details

The API 550b is a four-band equalizer module in the 500 Series format. Each band offers seven selectable center frequencies and up to plus or minus 12 dB of stepped boost or cut, with the low and high bands switchable between peaking and shelving response while the two mid bands are peaking only. It uses API's Proportional Q, which widens the filter bandwidth at small settings and narrows it at larger settings, together with the company's discrete 2520 op-amp. It is a reissue of API's original 1967 550 equalizer with an added fourth band.

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