LS-3b

About the LS-3b

The Audio Research LS-3b is a line stage preamplifier featuring an all-new circuit design that emphasizes a shortest-signal-path layout with minimal point-to-point wiring and DC-coupled inputs. It has a tightly regulated power supply and includes the patented Decoupled Electrolytic Capacitor circuit found in more expensive Audio Research products. The LS-3b offers balanced outputs (500 ohms output impedance) and a main output impedance of 250 ohms, designed for high-purity input sources with a direct gain path that bypasses all controls except gain. It delivers less than 0.01% total harmonic distortion at 2 V rms output from 2 Hz to 100 kHz, with a gain of 18 dB and a frequency response of 2 Hz to 100 kHz ±0.5 dB. The preamplifier is built with a pure Class A circuit design, using a differential input stage with I-FETs, a J-FET follower, and a MOS-FET common gate stage, all designed for high sound quality and low noise. It is highly regarded for its clarity, neutrality, dynamic soundstage, and ability to reveal musical detail and realism, especially in the lower midrange. The LS-3b was originally released in the early 1990s and remains a sought-after audiophile component.