1 Built4speed 3 years ago I'm looking around for some NOS tubes to drop into my tweed princeton clone, and I'm a total newbie to NOS. I know RCA black plate tubes have a good reputation and are scarce as a result, but I see grey plate more readily available. Are they not as good as the black plates? Would a grey plate 12ax7 be a good match for a tweed amp, or not so much? Or am I overthinking it?