Tag: EF184

RL12P35 SE Amp – part I

I have plenty of these German WWII pentodes. I’ve been saving them for a few projects. Quite likely for a push-pull amp given the OB speaker project I’m cooking. Either way, I have a nice set of CFB SE as well as PP OPTs from Toroidy custom made. They are very good transformers.

So, if you want a simple SE amplifier that can do 8W, here is a good contraption to go after:

Continue reading “RL12P35 SE Amp – part I”

THD benchmark

I’m still in the process of testing valves, here is how the ranking is coming up so far. This is a mix of driver and output valves. All tested at Vo=+22.22dBu:

THD analysis of different valves

Looking at the chart above a couple of interesting points to highlight:

  • 4P1L is the most linear valve I’ve found so far.
  • 6e5P and 6C45 are expected to be on the top five anyway.
  • 12P17L despite of having similar characteristics as 4P1L is not that linear
  • 6N6P and 6N6P-I disappointed me. I thought the would be more linear..
  • 46 and 47 in triode mode are superb drivers

Have so many other ones to test, but limited time….

Expect this chart to be updated in the future, so stay tuned 🙂