Audio Research D-51

A tube amplifier using push-pull 6550 output tubes, noted in user setups with Quad electronics and speakers.

Overview

The Audio Research D-51 is a tube amplifier manufactured by Audio Research. It employs a push-pull configuration with 6550 output tubes, a design choice shared across several high-fidelity amplifiers of its era. While specific production years and technical performance metrics are not documented in the available sources, the D-51 was used in high-end audio systems, including pairings with Quad preamplifiers and Quad ESL-57 electrostatic speakers, suggesting a role in quality-focused listening environments.

Specifications

Output tubesUses push-pull 6550s

Design

The amplifier uses a push-pull circuit topology with 6550 tubes,

Context

Owners have paired the D-51 with Quad preamplifiers and either Quad ESL-57 speakers or a tuner, reflecting its integration into respected British high-fidelity systems of the period.

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