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