This new production tube 12AX7/ ECC83 is the New Sensor reissue of the famous Mullard 12AX7.
In our opinion: "Microphony is not a problem despite the larger average structure of this plate. The transconductance on my sample was the same as the two NOS samples I measured. Not really a high gain, but a very good background noise and a nice softness a sound that does not encourage ear fatigue as some preamps can be.
The name and brand Mullard were acquired by the New Sensor Corporation. This new Mullard 12AX7 production tube is manufactured at their Xpo-Pul plant (also known as Reflektor) in Saratov, Russia. New Sensor is an American company and since it became the owner of this factory, the quality of the current production tubes has continued to improve.
Another remark about the construction of these tubes is that they have filaments that are almost completely embedded in the plate structure. Often they do not "light up" when they work properly. This is not a problem, it is normal for the Mullard 12AX7/ ECC83 reissue.
