Flashback

Ok, lets start at the beginning: 1. Can the power tube in the UniValve color the sound? 2. If so, does the testing at GTs detect abnormal coloration?

Well yes that should be the case. It just sounds like the GT6V6 has a big notch out of the high end compared to the NOS EL34 and GT6L6. I dont know, Ill clean my ears and try it again this weekend.

The EL34 tube in the UV is closer to 12 watts. Stick with a good 6V6 or an EL84 in the adaptor. When you say a good 6V6 its as if youre saying the 6V6 should have the same high frequency response as the EL34?

Myles, (Univalve) It seems like the GT6V6 power tube is a little limited on high frequency response. The NOS EL34s' frequency response is fine but with a power output around 20 Watts. Im looking for a power tube with the high end response of at least the EL34 but closer to the power output of the 6V6. Is there such a thing?