Electro Harmonix is another brand owned by the New Sensor Corporation that are manufactured at their Xpo-Pul factory (also known as Reflektor) in Saratov, Russia. New Sensor is an American corporation and since taking ownership of this factory has been steadily improving the quality of current production vacuum tubes. These Electro Harmonix audio tubes are all new designs and are of excellent quality. Many OEMs are relabeling and using Electro Harmonix vacuum tubes in their amplifiers. If you want great sounding tubes at a very reasonable price the Electro Harmonix vacuum audio tubes should be on your list. Many of the EH preamp tubes are offered with standard or gold pins. The Electro Harmonix power vacuum tubes are great quality as well. They offer all the common audio tube types: 12AX7, 12AT7, EL34, 6L6-GC, 6V6-GT, KT88, and 6550. Electro Harmonix also offers replacement tubes for the difficult to find 7868, 7591, 6BM8/ECL82, and 6973 power tubes. For audiophiles, the 300B and 2A3 Gold Grid output tubes are both fantastic sounding and very affordable. The 6922 preamp tube produced by Electro Harmonix is also outstanding. It sounds good and is as tough as they come. If you have a "tube-eating" preamp requiring 6922 / 6DJ8 vacuum tubes, consider the EH 6922.