Description
More than a classic, this is history. Solid 70’s. How nice those switches and knobs feel! This pre-amp is often praised for its clear and detailed reproduction, with a subtle softening of harsh tones that makes listening more enjoyable.
Tubes and electrolytics measured and are in good condition. No crackles or in potmeters or switches, in short in excellent condition. Small dent in hood repaired. Green on/off light defective. Easy to turn out so no issue, only it is not a standard bulb and not readily available. We haven’t put the time into it here.
The Audio Research SP-3A was designed in the early 1970s as a result of intensive research into tube amplification technology. Lead designer William Zane Johnson wanted to create a preamp that was both musically and technically outstanding. The SP-3A uses high-quality tubes (12AX7 and 12AT7), with a hand-wound, point-to-point construction. The housing is brushed aluminum, and internally only carefully selected components are used for optimal sound.
Audio Research was founded in 1970 in Minneapolis, Minnesota, United States, by William Zane Johnson. The company began developing electronic tube equipment, starting with the SP-1 preamplifier. Over the years, the brand introduced several products, including the D-150 power amplifier in 1974 and the original REF1 in 1995. Audio Research moved its headquarters to Maple Grove, Minnesota, in 2007. In 2020, the company was acquired by AR Tube Audio Corporation, led by former employees. Audio Research manufactures all of its products in the United States and focuses on manual assembly of equipment. Repairs and maintenance can be done in-house. The company uses hand-wired point-to-point wiring combined with printed circuit boards. Documentation and schematics of products since 1970 are available through the company, and parts are kept in its own warehouse.