I've had very mixed results with 7n7s but some folks love them. There isn't much variety, they were all produced (well, essentially all of them anyway) by Sylvania.
That last two that sold on Ebay last night when for $198. That's about double what I saw two weeks ago. At those prices you might as well just but 6SN7s and not worry about the adapter.
Tyll,
Any way to get the intermediate frequency lines to show up lighter? Kind of hard to read that graph for me otherwise and your old graphs used to do a lovely job of this.
Great looking build!
I agree that more ventilation would be a good thing. In the mean time buy a infrared thermometer and check the temps from time to time.
1. Damping factor absolutely matters with headphones. I say so from personal experience. I tried it, you happy now?
2. Ahhh, the less is always more answer.
How about you try a damping factor of 1 week and see how it responds for you?