GE 5965 / 12AT7 MATCHED PAIR TUBES/1960's, MaxiPreamp II Tested, SM1370
Tested on a Hi End Maxi-Preamp II tester for Gain (Mu), Transconductance (Gm), and Noise (dB). It most likely is because it has a lower gain compared to the 12AT7. Gain (Expected Value=40 mu). This is very important!