Audio Research LS-3 Preamplifier (1992–1993)

Overview

The Audio Research LS-3 Preamplifier came out in 1992. It is a solid-state line-level preamp from a company known for vacuum tubes. The LS-3 took the brand's sonic approach and built it as a fully balanced, dual-mono transistor design. It was built by hand in Minnesota, and it was aimed at audiophiles who wanted the clarity and control of solid-state without losing the musicality Audio Research was known for.

The input stage is a differential JFET design. It feeds a bipolar transistor voltage amplifier, and that feeds a Class A output stage. This topology is confirmed across multiple sources. The LS-3 is also expandable with optional cards, including a phono stage for MM/MC cartridges and a DAC module with optical, coaxial, and USB inputs. It has four single-ended and two balanced inputs, which was a lot of flexibility for its time and handy for systems with several high-end sources.

Specifications

Manufacturer	Audio Research
Product type	Solid state preamplifier
Gain	20dB balanced output / 20dB single-ended output
Input Impedance	25K ohms (balanced and single-ended)
Inputs	4 X SE Inputs, 2 X Balanced Inputs
Optional expansion cards	Optional Phono Card: MM/MC; Optional DAC Card: Optical, Coax, USB
User Interface	Touchscreen User Interface
Remote Control	Included

Key Features

Fully Balanced, Dual-Mono Solid-State Architecture

The LS-3 is a fully balanced, dual-mono solid-state preamplifier. The left and right channel signal paths are electrically isolated from input to output, which cuts crosstalk and improves channel separation. The balanced design covers both inputs and outputs, so it connects cleanly to other balanced components and rejects noise over long cable runs.

Differential JFET Input Stage with Bipolar Voltage Amplification

The input stage is a differential JFET design, chosen for its high input impedance and low noise. That matters for delicate source signals. After it comes a bipolar transistor voltage amplifier, which provides gain with low distortion. The JFETs handle quiet, high-impedance input buffering, and the bipolar transistors handle linear amplification.

Class A Output Stage

The output stage runs in Class A, so the output devices conduct current continuously. That eliminates the crossover distortion that can show up in Class AB designs. Class A is less efficient and generates more heat, but it is favored in high-end audio for its sound in the midrange and its low-level detail. In the LS-3, this contributes to a smooth, coherent presentation that fits Audio Research's tonal signature, even in solid-state form.

Expandable Functionality via Optional Cards

The modular design is one of the LS-3's most forward-thinking features. Owners could add a phono card that handles both moving magnet (MM) and moving coil (MC) cartridges, which removes the need for a separate phono preamp. Or they could add a DAC card with optical, coaxial, and USB inputs to bring digital sources in directly. Buy both cards with the LS-3 and Audio Research knocked $500 off, which suggests it expected demand for a complete analog-digital front end.

Touchscreen User Interface with Remote Control

A touchscreen user interface was striking for the era. Tactile knobs dominated preamp design, but the LS-3 went with digital control, likely allowing precise channel balancing, input labeling, and card configuration. An included remote control came with it. Traditionalists may have disliked the interface.

Collectibility & Value

The LS-3 has a current market price of $8,450.00, matching its base MSRP. House Of Stereo lists the original price as $9,950.00, though an eBay listing cites an original MSRP of $9,650.00, a minor discrepancy. Optional cards add $1,000 each (or $9,950 for both together), so a fully loaded system came close to ten thousand dollars, a significant investment in the early 1990s. Used units have appeared on Facebook and eBay, which points to some turnover in the collector market. No data on common failures, maintenance needs, or parts availability is documented. It is a rare solid-state offering from Audio Research, though it lacks the cult following of the brand's tube classics.