Overview

The Stancor A-8056 is a heavy-duty, high-fidelity audio output transformer engineered by the Standard Transformer Corporation (Stancor). Designed for push-pull vacuum tube power amplifier configurations, the transformer provides impedance matching between high-impedance plate circuits and standard low-impedance loudspeaker loads. The component was widely utilized in vintage high-fidelity monoblock amplifiers, professional public address systems, and classic instrument amplifiers.

Technical Specifications

Physical Description

The A-8056 is built on a heavy laminated iron core housed within a vertical-mount channel frame with drawn metal end bells. The casing is finished in durable black enamel to resist corrosion and provide shielding against electromagnetic hum. Primary and secondary connections exit through insulated grommets on the sides via flexible, color-coded cloth or vinyl wire leads. The base contains slotted corner mounting feet designed for direct chassis-top installation.

History

Stancor introduced the A-8056 as part of its high-fidelity audio transformer line during the peak of the post-war vacuum tube audio era. As audio enthusiasts and commercial builders demanded wider frequency response and lower harmonic distortion, transformer manufacturers developed interleaved winding techniques to maintain flat response across the audible 20 Hz to 20 kHz spectrum.

When originally sold new through electronics distributors during the late 1950s and 1960s, the transformer carried a wholesale/dealer catalog price typically ranging between 12.50 and 16.75 dollars. In modern vintage electronics and instrument restoration markets as of 2026, authentic tested working original units generally trade between 75 and 175 dollars depending on lead wire length and cosmetic preservation, with higher premiums commanded for matched pairs or units certified for classic amplifier restorations.

With its 6,600-ohm center-tapped primary, the A-8056 became a standard component for push-pull beam power tetrodes and pentodes, including 6L6, 6L6GC, 5881, KT66, and EL34 tube pairs. The transformer achieved notable recognition as the factory-installed output iron on early cathode-biased and fixed-bias Ampeg B-15 Portaflex bass amplifiers, as well as several reference audio amplifier circuits published by tube manufacturers like RCA. Due to its rugged build and generous power margin, the A-8056 remains a sought-after component for vintage audio restoration and custom tube amplifier construction.

References

http://www.tubebooks.org/file_downloads/stancor_1952.pdf – 1952 Stancor catalog archive outlining post-war vacuum tube audio transformer product lines and replacement cross-references.Overview

http://www.tubebooks.org/transformer_data.htm – Vintage electronics technical archive index providing historical transformer catalogs, push-pull amplifier schematics, and manufacturer engineering data sheets.

http://www.tubebooks.org/file_downloads/stancor_1959.pdf – 1959 Stancor Chicago Standard Transformer Corporation catalog detailing high-fidelity audio transformers, electrical impedance ratings, and physical mounting footprints.

The Stancor A-8056 is a heavy-duty, high-fidelity audio output transformer engineered by the Standard Transformer Corporation (Stancor). Designed for push-pull vacuum tube power amplifier configurations, the transformer provides impedance matching between high-impedance plate circuits and standard low-impedance loudspeaker loads. The component was widely utilized in vintage high-fidelity monoblock amplifiers, professional public address systems, and classic instrument amplifiers.

Technical Specifications

Physical Description

The A-8056 is built on a heavy laminated iron core housed within a vertical-mount channel frame with drawn metal end bells. The casing is finished in durable black enamel to resist corrosion and provide shielding against electromagnetic hum. Primary and secondary connections exit through insulated grommets on the sides via flexible, color-coded cloth or vinyl wire leads. The base contains slotted corner mounting feet designed for direct chassis-top installation.

History

Stancor introduced the A-8056 as part of its high-fidelity audio transformer line during the peak of the post-war vacuum tube audio era. As audio enthusiasts and commercial builders demanded wider frequency response and lower harmonic distortion, transformer manufacturers developed interleaved winding techniques to maintain flat response across the audible 20 Hz to 20 kHz spectrum.

When originally sold new through electronics distributors during the late 1950s and 1960s, the transformer carried a wholesale/dealer catalog price typically ranging between 12.50 and 16.75 dollars. In modern vintage electronics and instrument restoration markets as of 2026, authentic tested working original units generally trade between 75 and 175 dollars depending on lead wire length and cosmetic preservation, with higher premiums commanded for matched pairs or units certified for classic amplifier restorations.

With its 6,600-ohm center-tapped primary, the A-8056 became a standard component for push-pull beam power tetrodes and pentodes, including 6L6, 6L6GC, 5881, KT66, and EL34 tube pairs. The transformer achieved notable recognition as the factory-installed output iron on early cathode-biased and fixed-bias Ampeg B-15 Portaflex bass amplifiers, as well as several reference audio amplifier circuits published by tube manufacturers like RCA. Due to its rugged build and generous power margin, the A-8056 remains a sought-after component for vintage audio restoration and custom tube amplifier construction.

References

• http://www.tubebooks.org/transformer_data.htm – Vintage electronics technical archive index providing historical transformer catalogs, push-pull amplifier schematics, and manufacturer engineering data sheets.
  • http://www.tubebooks.org/file_downloads/stancor_1959.pdf – 1959 Stancor Chicago Standard Transformer Corporation catalog detailing high-fidelity audio transformers, electrical impedance ratings, and physical mounting footprints.
  • http://www.tubebooks.org/file_downloads/stancor_1952.pdf – 1952 Stancor catalog archive outlining post-war vacuum tube audio transformer product lines and replacement cross-references.