Comes from a Marshall JTM60. The difference between the LPS and LP below, source internet forum musicplayer.com:
"The Sovtek tube comes in two versions; the LP and LPS. The LPS has a spiral heater that is supposed to reduce hum in circuits that use AC heaters. It was noted that in some amps, they did make a difference. It was also noted that in some DC heated amps, they induced a little noise under some circumstances. It would pay to know if your heaters are AC or DC if selecting this tube."