Meaning it's an engineering prototype? What a unique find if that is the case. I've never heard the t-plate Raytheons, but the ladder plate military tubes are quite good. Sort of boring I must confess, at least in my opinion, but at a technical level they perform very well. I have a GTB Raytheon, at least I'm pretty sure it's Raytheon (it's branded Traveler), with an unusual getter that is attached to the side of one of the plates. I didn't think much of it at first listen, but when I took the time to really play some music through it I was blown away at how good it sounds in terms of speed, detail, and control. The bass is amazingly taut and it has what may be the best dynamics of any 6SN7 I've heard. Definitely the opposite of romantic, and I didn't find the tone quite to my liking but it still wasn't bad. Proof positive that there are some good finds amongst the GTB tubes that go overlooked.
