All tubes have been tested on a Maxi-Preamp 2 machine under the respective settings for each type. The transconductance (gm), in uA/V or umho units, and gain (u) of each triode is written on each box as well as a brief description.

Pairs are matched such that transconductance and gain are within 5% and brand/construction is the same.

Singles are sold under one listing for each model/construction type. The image is representative of the construction, but tubes sold under this listing may have different markings or appearances than the image, though the functionality is identical.

Type: 12AX7/ECC83

Brand: Mullard

Description: 163 model

gm1: 1535

gm2: 1243

u1: 94.7

u2: 94.5