A brief history of 12ax7 tubes

A brief history of 12ax7 tubes

The 12ax7 tube is arguably the most popular audio vacuum tube that has ever been created. It’s popularity is driven by use in many Hi-Fi tube amplifiers and especially guitar amplifiers, where it’s pushed really hard and burns out fairly quickly. Introduced in May of 1947, the tube gained almost immediate popularity due to its very high gain – mu: 100, so it amplifies voltage 100x! Although I’ve seen JJ and Sovtek 12ax7 tubes go as high as 115, but that’s not up to spec.

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