Up for sale is a matched quad (4 PCS) of vintage NOS Hytron 5814A dual triode vacuum tubes, packaged in clean white boxes. Manufactured in the USA to ruggedized military-grade specifications, the 5814A is a premium, low-microphonic upgrade replacement for 12AU7 and ECC82 tube types. These feature dark black plates and square getters, prized by audiophiles for their warm sound stage, precise imaging, ultra-low noise floor, and excellent musicality in high-end Hi-Fi preamplifiers, line stages, and driver circuits.

As shown, all four tubes have been thoroughly tested on an advanced Amplitrex AT1000 tube testing system in full fixed-bias mode, yielding a tightly matched set across all sections. Plate current (Ip) and mutual conductance (Gm) measurements alongside percentage performance ratings relative to nominal factory specs are detailed in the table below.