Groove Tubes GT-6201-M

GT-6201-M description:

Groove Tubes GT-6201-M - A very quiet selected version of a 12AT7. These were used for critical applications such as microphones which use the 12AT7, studio gear, and vacuum tube preamplifiers that use a 12AT7.

This is a US made NOS JAN spec tube (Joint Army/Navy Spec) made in the late 70's.

They are long lasting, really heavy duty dual triodes, which is great because the are usually used in the driver stage of an amp, aka: Phase inverter, and they take a beating driving the power tube changes (usually were recommend changing the driver stage tube everytime you change power tubes.