Amperex was a manufacturer of tubes and semiconductors producing out of Brooklyn starting in the 1920s. Through its development as a company, Amperex relocated several times but one thing remained stable: it continued to produce quality tubes like the 12AX7, 12AU7, and 12AT7 that made it a staple in the hi-fi market. In fact, audiophiles today still clamor for Amperex tubes. Though the company closed, you can still find tons of NOS and vintage tubes from Amperex on Reverb today.