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Yes, it's just a 12AU7. I foolishly bought the gold plated version of the ECC-82 from AES thinking that it would be more reliable and have better controlled characteristics if I had to replace it in the future.
JJ doesn't list this version on their web site anymore, which is interesting. AES still carries it.
I'm pretty sure the light bulb effect was because of a heater-cathode short. I looked at the schematic of the Precision 10-12 and when you set it up for a particular tube the first state that it will be in is with the filament return selected and all other pins connected to filament supply. With a cathode-heater short, say in the middle of the filament, then it's like applying 6.3VAC to a 3VAC filament. The cathode that is connected to pin 3 is shorted to the heater, but there's no way I could prove that it didn't happen after the burn-out.
I'm going to check the ECC-82 that I have in the vertical section with a leakage checker first.
Thanks for the offer of the 12AU7s. I just bought four "Baldwin Sylvania" 12AU7s on ebay for less than I paid for a gold ECC-82.
John
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