Phase Linear 1100 (1981)

Five bands of surgical tone shaping, each one a tiny laboratory of frequency, bandwidth, and gain—this is equalization with the precision of a lab instrument and the soul of a studio secret.

Overview

Turn the knob labeled “Q” on the Phase Linear 1100 Series Two, and you’re not just adjusting a filter—you’re tuning a resonance, hunting a room mode, or resurrecting a buried vocal. This isn’t the kind of EQ you slap on for a quick fix; it’s the kind you pull out when you’ve already got everything else dialed in and you still hear that one frequency poking out like a splinter. Each channel gives you five fully parametric bands, meaning you control frequency, gain, and bandwidth (Q) independently—rare in consumer gear, even today. The faceplate is dense, almost intimidating: rows of concentric knobs, status LEDs, and toggle switches that feel like they were borrowed from a broadcast console. But once you get your hands on it, the logic clicks. You’re not just coloring sound—you’re measuring, diagnosing, and correcting. It was built for people who owned Real Time Analyzers, who had microphones on stands, who treated their listening rooms like acoustic laboratories.

And make no mistake—this was serious gear. While many vintage EQs from the early '80s offered fixed-frequency shelving or graphic sliders, the 1100 let you sweep each band continuously across the spectrum, dial in narrow notches to kill feedback or resonance, or broaden them for gentle tonal shaping. It wasn’t designed to make your rock records sound “punchier”—it was made to fix problems. A booming 63 Hz in your room? Find it, narrow the Q, cut it. A harshness at 2.4 kHz from your tweeters? Sweep, isolate, reduce. It’s surgical, deliberate, and unforgiving if misused. But in the right hands, it can transform a system from merely good to eerily accurate. It’s the difference between wearing tinted sunglasses and getting a custom lens prescription.

Despite its complexity, the 1100 wasn’t just for engineers. Audiophiles with the patience (and the test gear) found it invaluable for tailoring high-end systems to their rooms. And because it came from Phase Linear—the same company that gave us the brute-force 700 amplifier—it carried a certain credibility. This wasn’t some boutique add-on; it was built with the same no-nonsense engineering ethos: heavy chassis, robust power supply, and circuitry that prioritized transparency over coloration. It didn’t add “vibe”—it removed problems. That said, it’s not subtle in form. At 15 pounds and nearly 19 inches wide, it demands shelf space and attention. And unlike modern DSP-based room correction, there’s no auto-setup, no memory presets, no digital wizardry. Just knobs, ears, and a microphone.

Specifications

Key Features

Surgical Parametric Control

Five bands per channel isn’t just generous—it’s excessive by consumer standards, which is exactly the point. Most home EQs of the era offered three bands at best, often semi-parametric. The 1100 goes further: each band is fully parametric, meaning you can set the center frequency, the amount of boost or cut (±12 dB), and the bandwidth (Q), which determines how narrow or wide the affected frequency range is. A high Q creates a very narrow notch, ideal for eliminating a single resonant frequency; a low Q affects a broader swath, useful for general tonal balancing. This level of control was typically found in professional studio gear, not living room components. It turns room correction from guesswork into a repeatable process.

Studio-Grade Build and Signal Path

Open the chassis, and you’re greeted with point-to-point wiring, military-grade connectors, and a power supply that wouldn’t look out of place in a Phase Linear amplifier. The circuitry avoids unnecessary coloration—no “warmth” added here. The signal path is direct, with high-quality op-amps and passive components chosen for accuracy. Input and output stages support both balanced (XLR) and unbalanced (RCA) connections, a rarity in consumer gear and a nod to its semi-pro aspirations. The front panel includes tape monitor switching and a hard bypass mode with LED confirmation, so you can A/B your adjustments instantly. Overload indicators on the front warn of input clipping, preventing distortion before it hits your power amp.

Integration with the 1200 Real Time Analyzer

The 1100 wasn’t meant to be used blind. It was designed to work in tandem with the Phase Linear 1200 Real Time Analyzer—a microphone and spectrum display system that let you see the frequency response of your room. Together, they formed a complete room-correction suite years before digital room correction became mainstream. You’d run a test tone, watch the 1200’s display show peaks and dips, then use the 1100 to surgically adjust. It was a manual version of what modern Audyssey or Dirac systems do automatically, but with more precision and no algorithmic assumptions. Collectors often seek the pair together, though the 1200 is even rarer today.

Historical Context

The early 1980s saw a growing awareness among audiophiles that speakers and rooms interacted in complex, often detrimental ways. Magazines like Stereo Review and Audio began publishing room measurement techniques, and high-end systems were increasingly scrutinized not just for power and clarity, but for accuracy. The Phase Linear 1100 arrived in 1981, right as this movement gained momentum. It wasn’t the first parametric EQ for home use, but it was one of the most accessible from a respected high-power audio brand. While companies like Rane and Drawmer dominated the pro audio world, Phase Linear brought that level of control to the serious hobbyist.

It also reflected Bob Carver’s engineering philosophy: solve real problems with over-engineered solutions. Just as the 700 amplifier gave you more power than anyone thought necessary, the 1100 gave you more control than most would ever use. It competed with high-end offerings from companies like Threshold and Hafler, but stood out for its five-band-per-channel layout and direct integration with the 1200 analyzer. By this point, Phase Linear was still under Carver’s influence, though Pioneer would acquire the company shortly after. The 1100 represents one of the last true Carver-era innovations before the brand shifted toward more mainstream consumer products.

Collectibility & Value

Today, the Phase Linear 1100 is a niche but respected piece. It’s not as sought-after as the 700 amplifier, but it has a loyal following among vintage audio tinkerers and measurement enthusiasts. Units in working condition typically sell between $350 and $600, with pristine examples near $600 if they include the original manual or come from a known technician. The $400 asking price seen in recent forums and the $399.95 original retail from classic audio dealers suggest it’s holding value well for a specialized processor.

However, age is the enemy. The unit relies on electrolytic capacitors, many of which are now over 40 years old. While not as failure-prone as the output stages in Phase Linear amps, degraded caps can cause noise, channel imbalance, or loss of low-frequency response. Service records are a big plus—especially if a technician has gone through the power supply and signal path. Owners report that controls can become noisy over time, and the toggle switches, while durable, may need cleaning if the unit has been stored for years.

Before buying, verify that all five bands on both channels respond smoothly, that the bypass switch works cleanly (no dropouts), and that there’s no hum or crackling. Ask if it’s been powered recently and for how long—capacitors that haven’t been “reformed” after long storage can fail when first powered. A unit that’s been sitting since the '90s might need a slow voltage ramp-up. And if you’re serious about using it, try to find one with the 1200 analyzer—though that’s a unicorn in today’s market.

eBay Listings

PHASE LINEAR Model 1100 Series Two Parametric Equalizer w/Ra

$1,265

Phase Linear 4000 Autocorrelation Preamplifier Control Conso

$350

Phase Linear Model 3500 Series 2 Pre-Amplifier - Original -

$800

Phase Linear Model 1100 Series 2 Equalizer Owners / User Man

$44.97

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