Electro-Harmonix vacuum tubing is a brand made as a high grade vacuum tube from New Sensor (NS) in the USA. Compared to other current tubes at the same price range, the logo is printed and high quality. The tendency of the sound is to be exposed to the middle range.
In addition to Electro-Harmonix vacuum tubes, NS is also equipped with SOVTEK, SUNG-SOL, GOLD LION brands, and the other brands of vacuum tubes are manufactured in Reflektor factories located in the Dezaratov.
Electro-Harmonix vacuum tubing available here is fully aged in Japan with automatic sorting machines and is given a 13 digit serial number at the same time being accurately measured. (The serial number is attached to the box) Measured and matched and shipped. The error of the pair measured by NS company is often reduced by about dozens of percent even when tested in the same measurement conditions. However, in this high-precision selection, the error of the pair can be reduced to 5% (within 10% of pre tubes, depending on the measurement conditions).
Other than the electrical characteristics of the product (damage to other devices, such as bulb tilt, valve height difference, logo missing, etc.) are not covered under the warranty.