The Audio Research LS-3 is a fully solid-state line-stage preamplifier that brings Audio Research into a different circuit architecture while retaining the company's familiar chassis design and user interface. It was inspired by the original LS3 line stage introduced in 1992, but the current LS-3 uses a completely modern solid-state design centered around JFETs and bipolar transistors.
 
The signal path is fully balanced and dual-mono, with separate power transformers for the left and right channels. The input stage uses differential JFETs, followed by a bipolar transistor voltage amplifier and Class-A output stages. A zero-gain-cascaded voltage reference and linear power supplies are used throughout the design to maintain low noise and stable operation.
 
Fully Balanced Dual-Mono Design
The LS-3 uses a fully balanced differential architecture from its JFET input stage through its output circuitry. Each channel has its own power transformer, creating a true dual-mono layout with substantial separation between the left and right channels.
 
The JFET input stage provides a high level of linearity and low noise, while the bipolar transistor voltage amplifier supplies the current needed to drive the Class-A output stage. Both balanced XLR and single-ended RCA connections are provided.
 
Class-A Output Stage
The LS-3's output stage operates in Class A, maintaining continuous conduction through the output devices. Audio Research designed the stage for a low 10-ohm balanced output impedance, allowing the preamplifier to drive a wide range of power amplifiers without requiring a high input impedance from the connected amplifier. The single-ended outputs have a 25-ohm output impedance.
 
Modern Touchscreen Interface
The LS-3 shares the same machined-aluminum chassis as the LS-2. Its full-color touchscreen provides input selection, input naming, display intensity and color adjustment, along with additional system controls.
 
The display uses the typeface associated with Audio Research's Reference GhostMeters, giving the LS-3 a visual connection to the company's Reference components.
 
Optional DAC and Phono Modules
The LS-3 can be fitted with optional plug-in DAC and phono modules. The DAC module adds USB, coaxial and optical digital inputs, while the optional phono module provides an integrated analog front end for vinyl playback.
 
Both modules are user-installable, allowing the LS-3 to be configured as a more complete control center without requiring additional external components.
 
Key Features
• Fully solid-state line-stage preamplifier
• Fully balanced differential JFET input stage
• Bipolar transistor voltage amplifier
• Class-A output stages
• Fully dual-mono signal path
• Separate power transformers for each channel
• Zero-gain-cascaded voltage reference
• Linear power supplies
• Balanced XLR and single-ended RCA connections
• 20dB gain
• 25kΩ input impedance
• 10Ω balanced output impedance
• 25Ω single-ended output impedance
• Full-color touchscreen display
• Input naming and display customization
• Machined-metal remote control
• Optional DAC module with USB, coaxial and optical inputs
• Optional user-installable MM/MC phono module
• Machined aluminum chassis
• Hand-built in Minnesota