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 🙂

Author: Ale Moglia

"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)

6 thoughts on “THD benchmark”

    1. CCS loaded and fixed bias. Both Vak and Vgk optimised to find lowest THD point

      Should give you an idea of valve linearity.

      Etc? Is not enough? Can you type more than three lines? 🙂

  1. Happy to see your site is up.
    I’m curious to understand whether these THD tests were done on one sample for each, or are these results an average of several? Thank you for your works.

    1. Hi Jeffrey
      Thank you. I cannot recall how many samples were taken to produce but varied depending availability on my stash. Needless to say, average is indicative and should taken as such as variance exist from valve to valve.
      Cheers
      Ale

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.