Do you know which factory the Brimar came from?
I only have experience with the Brimar CV4034/12au7 and I was surprised at the difference in sound between Brimar tubes made in different years, at different factories. The “regular” 1970 halo getter CV3034 tube has a wonderful warmth to it, like a Mullard 12au7 I’d previously bought, but the Brimar has the highs that I found lacking in the Mullard. I use it in my Pendant, and really like the warm sound.
I also bought a Brimar 1956 CV4034 made in Footscray and that is much more neutral than the other brimar. I use that one in my Nautilus, to give a different “tuning” than the Pendant. I like this tube a little more because the neutrality makes the amp a little more versatile with different headphones.
I’m assuming the CV4033’s built at the same factories at the same time have similar sound.