Phase Linear

Explore 2 Phase Linear vintage audio models — specs, production history, reviews, and market values in the VTA archive.

If you want to understand the raw, unapologetic American muscle car era of hi-fi, you have to talk about Phase Linear. Founded by the brilliant and eccentric Bob Carver, this brand didn't just make amplifiers; it made a statement. In the early 70s, when 50 watts was considered brawny, Phase Linear dropped the 400, a true 200-watt per channel monster. It was the amplifier that brought legitimate, reliable high power to the upper-middle-class audiophile, fundamentally shifting expectations and letting the massive speakers of the era truly sing.

The legendary Phase Linear 400 and its bigger brother, the 700, are the heart of the legacy. They were famously overbuilt, with massive heat sinks and that iconic blue power meter that would swing with the music. Their sound was powerful, clean, and commanding. But collectors, be warned: that legendary power came from a circuit that ran hot. The original DC protection circuitry wasn't infallible, and a failure could send raw DC to your speakers—the infamous "Phase Linear flame-out." Finding a unit that's been meticulously serviced, with updated protection modules, is absolutely critical. Don't just plug a 50-year-old one in and hope for the best.

Owning a properly restored Phase Linear is like owning a classic supercar. It's not the most refined or detailed sound by today's standards, but the visceral thrill of that immense, controlled power is something special. It represents a pivotal moment when hi-fi broke free from the living room and started to really rock the house.

Amplifiers

• 400 (1972) — The Phase Linear 400 delivers 200WPC with LED wattage displays, defining 1972 high-power solid-state audio with distinctive brushed aluminum styling.
• 700 II — Phase Linear 700 II dual-channel power amp — 200V rail, PL36 driver board, and a documented service history of op-amp and output-stage revisions.
• Dual 500 (1978) — Phase Linear Dual 500 (1978): 505 W/ch into 8 ohms, 36 output devices, 32-segment LED display. Phase Linear's Series Two flagship power amp.

Car Audio

• PLAX60 — Phase Linear PLAX 60 — an obscure 2-channel car amplifier rated at 60W RMS, with adjustable low-pass filter and subsonic filter. Little else is documented.

Power Amplifiers

• 700-B (1974–1976) — Phase Linear 700-B (1974–1976): 350W/ch into 8 ohms, quasi-complementary output, $799 in 1974 — a high-strung powerhouse that rewards careful owners.

Preamplifiers

• Model 2000 — Phase Linear Model 2000 preamp: $299, 0.009% THD, dual-turnover tone controls, and a quirky ambience circuit. An honest vintage bargain.

Tuners

• Model 5000 — SAE Model 5000 impulse noise reduction system — the click-and-pop black box that stripped vinyl transients without touching the music.

Turntables

• PLT-150 — Phase Linear PLT-150, a late-1980s car audio amplifier in the PLT Turbo line: 90W RMS/180W peak bridged, low distortion per High Fidelity.

Unknown

• 700-AS — Phase Linear 700-AS professional power amplifier (1973), 500W per channel into 4 ohms, liquid-cooled with toroidal transformer and twenty 2SC2565 output transistors per channel.

Other Models

• 1100 — The Phase Linear 1100 Series Two is a vintage parametric equalizer from 1981 with five fully adjustable bands per channel.
• MODEL-1100 — Phase Linear MODEL-1100 — unverified model number; archive finds no Phase Linear documentation, only unrelated Aphex and Ampex 1100-inch gear. Identity unresolved.
• MODEL-400 — Phase Linear Model 400 power amp — measured 270 W/ch into 8 ohms by HiFi/Stereo Review in 1972. High-headroom American solid-state with a messy output-transistor history.
• MODEL-700 — Phase Linear Model 700 — 345W/channel RMS into 8 ohms, patented protection circuit, 1000:1 damping factor. The legendary powerhouse amp that outran the speakers of its era.