I've been blessed!

[Penthode]

Originally Posted by old_tv_nut

I do have a colorimeter, but I usually balance by eye against natural light coming in the window. I haven't tried measuring the CTC-5 for a long time, but using my DSLR as a rough colorimeter, it measures somewhere around 7700 to 8000 Kelvin as set by eye. I think many/most P4 tubes from the early/mid 50s onward were far too blue as a color set reference. I seem to recall GE boasting how blue their P4 tubes were.

I was using a late 1940's 10BP4 as reference. It is has a lower color temperature as it is much less blue.I agree as I have seen how mid to late 50s monochrome CRTs do have a higher color temperature.