API Audio 550A Discrete 3 Band EQ

Features 3 bands of classic API equalization Each band offers 7 API selected frequency centers Reciprocal and repeatable filtering Maximum 12 dB of boost/cut per band EQ Band 1 and 3 offer shelf/peak switching “Proportional Q” narrows filter Q at […]

2-year warranty on all products!

Colour

Black

Features

3 bands of classic API equalization
Each band offers 7 API selected frequency centers
Reciprocal and repeatable filtering
Maximum 12 dB of boost/cut per band
EQ Band 1 and 3 offer shelf/peak switching
“Proportional Q” narrows filter Q at extremes
Traditional API fully discrete circuit design
High headroom +30 dB clip level

Few equalizers enjoy the respect and admiration of the coveted API 550A. Designed by the now-legendary Saul Walker in the late ’60s, the discrete 550A was first used as a modular OEM equalizer. As the industry rapidly embraced the sonic quality of the 550A, it quickly found its way into many custom console designs by Frank DeMedio and other leading engineers. Many of these consoles are still in use today.Forty years later, the 550A remains the standard against which other EQs are measured, and it has played a major role in the recording industry for decades. Still copied but never duplicated, the 550A became API’s standard channel module EQ when the company began manufacturing consoles in 1971. With virtually all existing units spoken for, popular demand for this EQ resulted in API finally resuming production in 2004.The 550A provides reciprocal equalization at 21 points in 5 steps of boost to a maximum of 12dB of gain at each point. The fifteen equalization points are divided into three overlapping ranges. The high and low frequency ranges are individually selectable as either peaking or shelving, and a band-pass filter may be inserted independently of all other selected equalization settings. Frequency ranges and boost/cut are selected by three dual-concentric switches, and a pushbutton “in” switch allows the EQ to be silently introduced to the signal path. A small toggle switch is used to insert the band-pass filter into the 550A.The combination of Walker’s incomparable 2520 op amp and his “Proportional Q” circuitry gives the 550A user an uncomplicated way to generate acoustically superior equalization.With the long-awaited reissue of this unit, an EQ that has had such a part in the history of recording is continuing to make history in today’s music.

Specifications
	66 kΩ high level 17 kΩ low level
	Less than 85Ω (transformer isolated)
	–15 dBm to +12 dBm
	None (bridging)
	±0.5 dB 30 Hz to 20 kHz
	Unequalized, output noise of –90 dBm, high level strapping and –98 dBm, low level strapping, 20 Hz to 20 kHz unweighted
	.05% THD max, 30 Hz to 20 kHz @ +4 dBm .07% THD max, 30 Hz to 20 kHz @ +18 dBm
	+30 dBm
	±15 volts to ±18 volts @ 70 ma
	Dual Concentric Rotary: LF select: 30, 40, 50, 100, 200, 300, 400 Hz and stepped degree of equalization –12dB to +12 dBDual Concentric Rotary: MF select: 200, 400, 600, 800, 1500, 3000, 5000 Hz and stepped degree of equalization –12dB to +12 dBDual Concentric Rotary: HF select: 2500, 5000, 7000, 10,000, 12,500, 15,000, 20,000 Hz and stepped degree of equalization –12 dB to + 12 dBAll equalization is in steps of 2, 4, 6, 9 and 12 dB either plus or minus
	50 Hz to 15 kHz band-pass filter In or out Push Button: LF range Peak or Shelf Push Button: HF range Peak or Shelf Push Button: Equalization In or Out Tally light when In
	30 pin PC connector supplied
	1.5″ X 5.25″ X 7.75″ Deep
	4.5″ X 6.25″ X 10.25″
	2 lbs.
	2.53 lbs.