[Phlogiston]

I Was just looking at THE BOOK (RCA Tube Manual 11/66). It says that the normal fil V. is 1.4V, which is interesting. I did try lowering the fil voltage, it just made thing worse - which is what I would expect on a weak/old tube.

The 1R5 just seems to be worse for this than the 1L6. A brand new, hot 1R5 might run at higher freq than a well used 1L6. If I get time I will investigate.

I will post a blog - mostly on quick electrolytic cap re-stuffing, but I might get into this aspect.

P.S. for anybody interested: The Captain's tubes turned out to not be 1L6s. My request to FAT as yet to be answered.