API 560 (1969–)

Name: API 560
Brand: API

Ten sliders, one octave apart. The sound is surgical and musical, and it still cuts through modern mixes.

Overview

You don't so much dial in the API 560 as work on a track with it. Fingers hover over chunky, stepped sliders, making tiny 1 dB nudges that turn a lifeless snare into something that bites, or carve the wooliness out of a bass guitar without turning it into a toothpick. It's not subtle, but it's not blunt either. This is a graphic EQ, a breed often dismissed as crude or clinical, yet the 560 feels alive, even when doing nothing. Credit the 2520 opamp and API's proprietary proportional-Q design. Plug in a vocal that's flatlining, hit the 2 kHz or 4 kHz band with a gentle lift, and it leans forward in the conversation. It's not louder, just present.

API built the 560 for its console lines in the late '60s and early '70s, and it was never meant to be a standalone star. It was a utility, a precise tool for tonal correction on mix buses, drum subgroups, or problem tracks that refused to sit. It outgrew that role. Engineers started grabbing them for tracking, then for mastering, then for anything that needed a little more authority. Unlike the 550A's three broad bands, the 560 gives you ten fixed frequencies, spaced one octave apart from 31 Hz to 16 kHz. That spacing sounds limiting next to modern parametric EQs, but it forces decisions. You can't dither around at 837 Hz. You pick 500 or 1k and commit. Each band uses the same proportional-Q behavior as the 550 series, so the more you cut or boost, the narrower the bandwidth gets. A 2 dB bump is wide and musical. A 10 dB carve is surgical. That's why it works so well on drums, electric guitars, and anything with harmonic complexity - you can emphasize or remove resonances without collapsing the entire sound.

It's also built like a bunker. The original units were console modules, so they had to survive daily abuse in high-end studios. The sliders are not faders in the traditional sense. They're stepped switches with detents, mechanically precise and nearly indestructible. You won't find smooth analog sweeps here. Each slider clicks into place at 1 dB increments, from -12 to +12 dB. That frustrates anyone used to infinite resolution, but it makes settings repeatable, which helps when you're recalling mixes years later. The front panel is stark, just sliders and a bypass switch.

Specifications

Manufacturer	Automated Processes, Inc. (API)
Production Years	1969–present (original and reissue)
Original Price	$495 (module, early 1970s)
Form Factor	500 Series / Console Module
Equalization Type	10-band graphic EQ
Frequency Bands	31 Hz, 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, 16 kHz
Boost/Cut Range	±12 dB per band
Adjustment Steps	1 dB detented sliders
Q Characteristics	Proportional Q (bandwidth narrows with boost/cut)
Opamp	API 2520 discrete opamp
Input Impedance	600 ohms
Output Impedance	600 ohms
Maximum Input Level	+30 dBu
THD	0.02% at +20 dBu output
Frequency Response	10 Hz – 20 kHz, ±0.1 dB
Signal-to-Noise Ratio	100 dB (A-weighted)
Power Requirements	±16V DC, 250 mA (500 Series)
Weight	2.2 lbs (1 kg)
Dimensions	1.5" H x 1.75" W x 6.5" D (module only)
Bypass	Hardwire relay bypass

Key Features

The 2520 Opamp: The Heartbeat of the API Sound

The real secret of the 560 is the 2520 discrete opamp. This isn't an off-the-shelf chip. It's API's own design, hand-built with discrete transistors, and it can swing voltages up to ±16V and handle transients like a champ. It's fast, clean, and forgiving. Even when you're slamming 10 dB cuts or boosts, the 2520 keeps its composure. There's no harshness, no fizz, no sense of strain. What you get is a firm low end that stays thick without getting muddy, mids that punch without splintering, and highs that air out without turning brittle. That's why even flat settings on the 560 change the sound. Just routing a signal through the 2520 adds a subtle saturation, a kind of tonal glue that modern opamps often lack. It's not a colored EQ in the Neve or Pultec sense, but it's not neutral either.

Proportional Q: Smart by Design

Most graphic EQs treat each band as a fixed filter, with the same width no matter how much you boost. The 560 doesn't work that way. Thanks to its proportional-Q design, the bandwidth tightens as you increase gain. A 2 dB boost at 1 kHz is broad and musical, gently lifting the presence range. Crank it to 10 dB and the curve narrows, focusing the effect like a spotlight. The same happens on cuts. A -4 dB dip removes a general resonance, but a -10 dB plunge becomes a surgical notch. This mirrors how our ears perceive loudness and frequency: small changes need to be broad to be noticeable, while big changes risk sounding unnatural if they're too wide. API got the psychology of EQ right before most engineers thought about it. Because the Q shifts automatically, you don't have to think about it either.

Stepped Sliders: Precision Over Pretense

The sliders on the 560 aren't faders. They're mechanical switches with 25 detents per band, each click a 1 dB change. That means no guesswork, no "almost there" settings, and perfect recall every time. It also means you can't make micro-adjustments, which frustrates some people. You don't nudge, you decide. The sliders are solidly built and rarely drift or wear out. Vintage units from the '70s still click crisply today. The only downside is that they're not motorized, so automation is out of the question.

Historical Context

The API 560 emerged in 1969, the same era that produced the 550A and the 312 preamp, during a golden age of American console design. British boards like Neve and SSL were chasing lush, musical coloration. API went the opposite direction: fast, clean, and punchy. Their consoles, especially the 2488 and later 1604, were built for tracking rock bands with high headroom and minimal coloration. The 560 was designed as a corrective tool within that ecosystem, a way to fix problem frequencies without smearing the transient response.

Engineers soon found it could shape tone as well as fix problems. Unlike the 550A's musical but limited three bands, the 560 offered surgical control without sacrificing musicality. It found a niche in mastering, where its ability to tame resonances in the low end or add presence in the high mids proved invaluable. It also became a favorite on drums, especially snare and kick, where a little lift at 1 kHz or 4 kHz could make a drum cut through a dense mix. By the 1980s, as API's console business waned, the 560 (like the 550A) lived on in reissues and modular formats. The 500 Series Lunchbox format in the 2000s gave it a second life, making it accessible outside of full API consoles. Today, both vintage and reissue 560s are staples in high-end studios.

Collectibility & Value

A vintage API 560 in good condition is rare, valuable, and potentially fragile. Original console modules from the late '60s and early '70s can fetch $1,800 to $2,500 on the open market, especially if they've been recapped and tested. But these units are over 50 years old. Electrolytic capacitors degrade, opamps fail, and the mechanical sliders, while durable, can develop crackle if not cleaned. A non-working 560 might sell for $800 to $1,200, but factor in $200 to $300 in restoration costs if you're not doing it yourself. The 2520 opamp is still available from API, but older units may have been recapped with inferior parts or modified with modern opamps, which changes the sound. Always ask for a demo or test report before buying.

The reissue models, marketed as the "Special Edition" or "Lunchbox" versions, are far more common and reliable. Priced around $1,499 new, they're faithful recreations of the original circuit, using modern components and tighter tolerances. Many engineers report no audible difference between vintage and reissue, especially when both are properly maintained. Used reissues go for $900 to $1,200, making them a smarter buy for working studios.

If you're hunting for a 560, prioritize condition over provenance. Look for units with clean sliders, no crackle, and a flat frequency response when all bands are centered. Check power supply compatibility if you're using it in a 500 Series rack, since some older modules require ±16V, not the more common ±15V. The 560 doesn't fail as often as tube gear, but always test it with a known source before committing.