First, pls understand that I am NOT a golden-eared audiofile…sometimes more of a tin-eared audiofool. I do hear some differences fairly quickly, but usually it takes me days or weeks to begin to be able to characterize differences. Hence, the tone of this note.
Friday, since the '300s have at least 500 hours on them and all seven sets of tubes have at least three to five days on them, I listened to each set, using the same short movement and using cold or at least cool tubes, twice around. My conclusions are that they all sound the same but for two sets which MIGHT sound SLIGHTLY harsher than the others. This ‘difference’ is possibly nonexistent so I’m not saying which tubes they are.
The seven tubes are, left to right, (A) original Genelexes, (1) and (2) both British 6DJ8/ECC88s–Amperex A-frames and Mullard ring-getters, (3) Tungsram PCC88 from Upscale, (4) Matsushita 6DJ8s labeled ‘National’ (note), (5) Vokshod 6H23ps (in the picture, these are in the amp and NOT on the carpet), (6) Britsh Mullard (Mitchum) E 188 CCs (AKA 7308s) labeled RTC from thetubestore.com.
Meanwhile I’m off to spend an hour or two listening to them again.
Note–these are from Vintage Tube Services and are also labeled ‘157 0125 00’, all in bright red ink.