Sugden Audio

About this resource

Sugden Audio was founded by James Edward Sugden in 1967 as a division of Research Electronics, which made scientific instruments and test equipment. The official history describes the first A21 amplifier as initially carrying Richard Allan branding before becoming the Sugden A21. Production later moved within West Yorkshire, with the current factory identified in Heckmondwike. ^{[1] [2] [3] [4]}

The A21 Signature is documented as a pure Class A integrated amplifier with a single-ended voltage-rail circuit. It can be supplied with or without an MM/MC phono input; the line-only version is designated A21L. The A21SE is a related but distinct model with a larger power supply and different power specifications. Those distinctions matter for source compatibility, not merely the names or finishes of the amplifiers. ^{[1] [2] [3] [4]}

The site separates A21 and Sapphire families and provides a historical amplifier catalogue and service routes. Its history describes continued handmade production, including engineering, screen-printing and assembly activities. For a first visit, the individual A21 and A21SE pages are more informative than a generic Class A label: they list input arrangements, outputs and published specifications. The documented A21SE provides five line inputs and remote control, while the A21 Signature offers an optional phono input. ^{[1] [2] [3] [4]}