VINTAGE TECHNOLOGY ARCHIVE / AUDIO / PHASE LINEAR / MODEL 2000

Phase Linear Model 2000 Preamplifier

A $299 control center that hid genuine high-end engineering behind a panel full of buttons — and one odd little "ambience" circuit that still divides listeners.

Overview

At first glance the Phase Linear Model 2000 looks like it wandered out of a control-room catalog rather than a hi-fi shop. The front panel bristles with controls — a selector switch, master volume, balance, separate bass and treble for each channel, a row of push buttons along the bottom — yet underneath all that furniture it is, as Audio (September 1976, p.58) put it, really quite a basic control center with few frills. The aesthetic works, though: the layout is symmetric and deliberate, with the selector at the upper left, the volume at the upper right, balance and ambience tucked into the lower corners, and the smaller per-channel tone trims clustered at center. A tiny power indicator sits just below the model number. It is a handsome, businesslike face.

The numbers behind that face are the interesting part. Phase Linear rated the Model 2000 for a 2.0-volt output with a 10-volt maximum into a 5 kOhm load — headroom that matters when you're feeding a power amp that wants a stiff signal. Phono sensitivity is 3.2 mV with 56 dB of gain at 1 kHz, and the phono input presents 47 kOhm in parallel with 290 pF, close to the textbook load most moving-magnet cartridges expect. High-level inputs sit at 40 kOhm and 350 mV sensitivity. Phono overload is a claimed 80 mV, which is comfortable for a moving-magnet front end. Hum and noise are quoted at 74 dB below a 10 mV phono input and 88 dB below 2 volts out on the high-level side — quiet enough that the preamp shouldn't be the noisy link in a sane system.

The tone controls are more flexible than the button count suggests. There are two turnover points, and the range is genuinely wide: with the 50 Hz turnover engaged the bass control swings ±11 dB, and with the 2 kHz turnover it reaches ±14 dB. A tone-defeat switch bypasses the whole tone circuit when you want the signal path clean, and a low-frequency EQ button adds a fixed bass boost below 50 Hz that operates independently of the tone and volume settings. For vinyl hounds chasing thin early pressings, that fixed low-end shelf is a useful tool that doesn't disturb the rest of the curve.

Audio (September 1976, p.58) put the Model 2000 through the lab and came away impressed by the distortion figures. At the rated 2.0-volt output, THD measured an almost unmeasurable 0.009% at 1 kHz, rising to 0.02% at 5 volts and 0.022% at the full 10-volt maximum. Waveform clipping didn't set in until 11.0 volts. At 20 Hz and 10 kHz the numbers were 0.04% and 0.027% respectively at rated output — the kind of performance that makes you wonder why the preamp ever got a reputation as the weak link in a chain. RIAA accuracy was similarly tight: the same review noted the phono response held within ±0.5 dB, and a separate High Fidelity (April 1976, p.60) lab report measured the largest deviation across 20 Hz to 20 kHz at a mere 1/2 dB, with the RIAA curve down 3 dB at 20 Hz. That's not perfect-flat, but it's honest, and it's well inside what most listeners will ever hear.

The rear panel is as generously stocked as the front. All outputs cluster at one end — main and "rear" outputs plus two sets of tape-out jacks — and five sets of inputs cover two tape loops, tuner, AUX, and phono. There's a chassis ground terminal, a switched and an unswitched AC receptacle for auxiliary gear, and a line fuseholder. Only one phono position is provided, which is the one place the Model 2000 shows its "basic" side; anyone juggling two turntables will need an outboard switch.

Internally, the parts count is almost shockingly small. The entire solid-state complement is three ICs, a single bi-polar transistor, a bridge rectifier, a Zener regulating diode, and the LED indicator. One IC handles preamp-equalization, a pair of type 4136 ICs cover tone control and voltage amplification, and a type 4739 IC working with that lone bi-polar transistor handles the mixing and phase inversion for the "ambience" or rear outputs. That ambience circuit is the Model 2000's party trick: it feeds left and right inputs in a way that combines difference information (R-L or L-R) with the primary channel signal, and the ambience control sets how much of that difference content reaches the rear outputs. Run those rear outs into a second stereo amp and a pair of back speakers and you get a synthesized hall effect. Audio's reviewers found it pleasant enough on genuinely live recordings — the random out-of-phase content fed to the back channels can sound quite nice, they conceded — while warning that the effect depends heavily on the recording. On multi-track studio mixdowns it does less. The extra circuitry probably cost Phase Linear very little, and the magazine didn't fault the company for straying from the purist path.

That purist objection is worth sitting with, because it's the honest knock on this preamp. The Model 2000 is not a minimalist line stage. It has tone controls, a fixed low-frequency EQ, an ambience matrix, and a front panel that invites fiddling. If you want a straight wire with gain, this isn't it. What it is, instead, is a remarkably well-measured control center for the money. At a suggested $299, with 0.009% THD at 1 kHz and RIAA tracking within half a dB, it undercut plenty of competitors on paper while offering features they didn't. The 19-inch width and 5½-inch height mean it drops into a standard rack or a wide shelf without drama, and at 9 lbs (4.1 kg) less the optional wood cabinet, it's easy to move and easy to service — a sparse board with socketed ICs is a technician's friend.

Collectors should go in with clear eyes. The Model 2000 turns up regularly and doesn't command collector premiums the way Phase Linear's big power amps do; it's a working preamp, not a trophy. The push-button switches and the ICs are the usual wear points on any unit this age, and the ambience circuit is a love-it-or-leave-it feature rather than a reason to buy. But the fundamentals — the low distortion, the healthy output headroom, the sensible phono loading, the genuinely useful dual-turnover tone stack — are all there. For someone building a period system around a Phase Linear power amp, or anyone who wants a flexible vinyl front end with lab numbers to back it up, the Model 2000 remains an honest, unglamorous bargain.

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VINTAGE TECHNOLOGY ARCHIVE / 11-05-2026 / FEEDBACK