33.33% chance it is either Chinese, Slovakian, or Russian. China tubes are Shaguang, Slovakian tubes are JJ's, and Russian tubes are made by New Sensor, which is owned by EHX. However, most " Brand " name tubes, such as Svetlana, Groove Tubes, Fender, Mesa, Sovtek et all, are simply sourced by one of the three major factories and then branded as such. JJ tubes are JJ's, Electro Harmonix tubes are only New Sensor made EHX branded tubes and Shaguang are only Shuguang tubes. If there is any other name on the tube, it is rebranded and sourced from any one of the three factories with the exception of the EHX brands. The EHX brands are Electro Harmonix, Sovtek, Tung Sol, Svetlana, Mullard, and Gold Lion. Those will all be New Sensor made tubes. Groove Tubes are a distributor, so they buy tubes from whomever, give the tube a rating and resell them as they see fit. Mesa does the same thing for the tubes it acquires.
I like JJ's and have had no issues with them. The EHX brands are great as well, again never having a real issue with them. I have had great luck with the China tubes too. A working tube is a good tube. I don't care who makes it.
