Hoping to pick the brains of people more experienced with 6SN7 tubes than me.
I’ve been trying to go on a bit of a rolling spree to find my favorite 6SN7 tubes, and despite buying some tubes that are among the “best” (according to the “cools” on various forums), I’ve had some really curious results.
I’d love to know if I’m doing it wrong, or if anyone has had similar experiences. Here is what I’ve got right now:
From left to right (top row), we have (1) Sylvania “Bad Boys” (non-JAN) with matched date code, (2) more Sylvania “Bad Boys” (JAN) again with matched date code, (3) very non-exclusive Sylvanias I think from the 60’s, but I don’t actually know, and then (bottom) (4) Sylvania 6SN7W.
Pair (1) sounded very good (excellent clarity and presence), but one of the tubes, despite testing well, was very unstable (I could initially coax it to life with some tapping) and died on me about a week in. I didn’t really get to fully evaluate, but they sounded much better than… Pair (2) despite looking (and supposedly testing) NOS, sound absolutely dull dull dull (poor detail, veiled, poor treble extension) - least favorite pair here. Pair (3) came with my amp, and despite being the “no big deal” tubes have the most clarity, airiness, and detail of the bunch, and are my current favorite. Pair (4), which should theoretically be better than the black-base-yellow-label tubes are not as clean, a bit slower, and have slightly tubby bass.
Most pressing is that I can return pair (2), but am hesitating to do so because they look to be in fantastic condition, (supposedly) tested very well, and are theoretically among the best 6SN7 tubes out there. Could they really be that bad and open up after more burn in? I’ve got about 30 hours on them, and they’re no better so far. I’ve never had a tube get as much better as these would have to for me to be happy with the purchase. Also, one of the these was highly microphonic/static-y to start, but has mostly dropped that behavior (but not entirely).
Anyone else run into this kind of strange experience? Anything I should be trying?
Much thanks for any advice.