Stereo Amplifier STA12

The Radford STA12 is a vintage stereo valve amplifier, introduced in the early 1960s as part of Radford's pioneering efforts in high-fidelity audio equipment. Below is a summary of its key features and historical significance:

Technical Specifications

• The STA12 was designed to produce distortion below 0.1% at powers up to 12 watts, meeting and surpassing this requirement during testing.
• It utilised EL34 valves running at lower plate voltages than typical for the era, which contributed to its detailed and refined sound quality.
• The amplifier's design was based on the Mullard 5/20 circuit but optimised with Radford's proprietary high-quality output transformers to address common issues such as phase shifts and frequency response imperfections.

Performance and Sound Quality

• The STA12 gained recognition for its "sweet" and detailed sound reproduction. Many enthusiasts consider it one of the most musically engaging amplifiers Radford produced, especially when paired with Mullard valves and Quad ESL57 speakers.
• Despite its relatively modest power rating, the STA12 was highly regarded for its ability to deliver audiophile-grade performance, setting a benchmark for valve amplifiers.

Historical Context

• The STA12 was reviewed positively in Hi-Fi News in March 1961, marking it as a highly recommended product.
• Radford continued to refine its designs, introducing Mk2 versions with improved transformers and circuit configurations that further reduced distortion and expanded frequency response capabilities.
• The STA12 is considered rare today, often overshadowed by later models like the STA15 or STA25. However, it remains a cherished piece of hi-fi history among enthusiasts.

Legacy
Radford amplifiers, including the STA12, are celebrated for their craftsmanship and contribution to valve amplifier technology. Arthur Radford's dedication to quality and innovation ensured these amplifiers retained their reputation well into the modern era.

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Elenco delle radio e altri apparecchi della Radford Electronics Ltd.; Bristol