Phase Linear 1100 (1981)
Five bands of tone shaping, each with its own frequency, bandwidth and gain controls. It's equalization with the precision of a lab instrument.
Overview
The Phase Linear 1100 Series Two weighs 15 pounds and is nearly 19 inches wide. It is a dual-channel parametric equalizer for people who measure their rooms, map response curves, and treat resonance like a disease. Released in 1981, it arrived when high-end audio was starting to face a hard fact: no matter how expensive the amplifier or speakers, room acoustics could ruin everything. The 1100 wasn't designed to hype bass or brighten treble. It was made to fix problems. Each channel offers five fully parametric bands, so users control center frequency, gain (±12 dB), and bandwidth (Q) independently. That was almost unheard of in consumer gear at the time. It demands a microphone, a test tone generator, and patience.
Despite its complexity, the 1100 wasn't a boutique import or a one-off experiment. It came from Phase Linear, the same company behind the legendary 700 amplifier, and carried the brand's no-nonsense engineering. The build is industrial: point-to-point wiring, military-grade connectors, and a power supply beefy enough to support serious signal integrity. Input and output stages accept both balanced (XLR) and unbalanced (RCA) connections, a rare feature in domestic equipment that points to its semi-professional aspirations. The front panel is dense with concentric knobs, toggle switches, and status LEDs, including overload indicators per channel and a hard bypass switch with LED confirmation for instant A/B comparisons. There's no automation, no presets, no digital anything. It's all analog control.
Unlike graphic EQs with fixed bands, or semi-parametric units that lock Q to frequency, the 1100 lets you narrow the filter to eliminate a single resonant peak, say a 63 Hz boom from room modes, or broaden it for gentle tonal balancing. The signal path uses high-quality op-amps and passive components selected for accuracy, not coloration. It doesn't add "warmth" or "punch." It removes anomalies. It's not for everyone. Misuse can do more harm than good, and the learning curve is steep. But in the hands of someone with a Real Time Analyzer, especially the Phase Linear 1200, with which it was designed to work, it becomes a system-transforming tool. This was manual room correction years before Audyssey or Dirac existed.
Key Features
Five Fully Parametric Bands Per Channel
Five bands per channel was excessive by 1980s consumer standards. Most home EQs offered three bands, often with limited Q control. On the 1100, each of the five bands per channel allows independent adjustment of center frequency, gain (±12 dB), and Q (bandwidth). A high Q creates a narrow notch, good for removing feedback or room resonances. A low Q affects a broader range, useful for general tonal shaping. This level of control was typically reserved for professional studio gear, not living-room components. It turns room correction from guesswork into a repeatable, measurable process, assuming you have the tools and patience.
Studio-Grade Build and Balanced Connectivity
Open the chassis, and the 1100 reveals its true nature: point-to-point wiring, heavy-duty transformers, and connectors that feel like they belong in a broadcast facility. The power supply is overbuilt, typical of Phase Linear’s design philosophy under Bob Carver. Input and output stages support both balanced (XLR) and unbalanced (RCA) connections, a rarity in consumer audio and a clear signal that this unit straddled the pro-hobbyist line. The signal path avoids unnecessary coloration, relying on high-quality op-amps and precision resistors to maintain transparency. Overload indicators on the front panel warn of input clipping, preventing distortion from propagating to downstream amplification. It’s not flashy, but every element suggests durability and purpose.
Integration with the Phase Linear 1200 Real Time Analyzer
The 1100 wasn't meant to be used by ear alone. It was designed to work with the Phase Linear 1200 Real Time Analyzer, a microphone and spectrum display system that showed room response. Together they formed a complete acoustic correction suite years before digital room correction became mainstream. The process was methodical: play a sweep tone, watch for peaks and dips on the 1200's display, then use the 1100 to apply corrective EQ. It was a manual version of what modern DSP systems do automatically, but with finer control 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 harmful ways. Magazines began publishing room measurement techniques, and high-end systems were increasingly judged not just by power or clarity, but by 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. Companies like Rane and Drawmer dominated the pro audio world, while 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. The 700 amplifier gave you more power than anyone thought necessary, and 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. Phase Linear was still under Carver's influence at this point, though Pioneer would acquire the company shortly after. The 1100 is 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.
Age is the problem. The unit relies on electrolytic capacitors, many of which are now over 40 years old. They're not as failure-prone as the output stages in Phase Linear amps, but 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. If you're serious about using it, try to find one with the 1200 analyzer, though that's a unicorn in today's market.
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Related Models
Audio (December 1981, p.54) confirmed the Phase Linear 1100 Series Two delivers a frequency response of 20 Hz to 20 kHz, +0, -1 dB, with THD+N at 0.02 percent and a signal-to-noise ratio of 100 dB.