Liverpool preamp tube differences

[Ledvedder5150]

Tonight, I thought I'd try rolling some tubes in v1 of my Liverpool. I noticed some very dramatic differences between different tubes. Much more than I've ever noticed in any of my other amps. So, for curiosity sake, I thought I'd take some oscilloscope measurements. I've never done this before, and I found the results very interesting. I ran a 150mv sine wave into the input, all amp knobs at noon, measuring after the 2n2 coupling cap, right before v2b.

RFT - 3.5V
Mullard - 4.5V
EHX - 1.2V
Genalex - 3.2V

I never realized how much different each tube's gain could be. And I've never noticed how dramatically different they can affect the tone in any other amp before this one.

So I'm curious... What is everyone's preference of tubes in a Liverpool? Or an Express?

[dblgun]

I like the Sylvania 12AX7WA in both Express and Liverpools. I also have had good luck with Amperex,Mullard and Tungsram in the Express, I haven’t tried any of the newer made tubes in either.

[bepone]

can we see pictures of all those tubes? are they all 12AX7? EHX has always the highest gain, so probably is almost dead..
expected voltage gain is 50 so, measured voltage must be around 4.50VAC, all what is less indicating worn tube

[Ledvedder5150]

can we see pictures of all those tubes? are they all 12AX7? EHX has always the highest gain, so probably is almost dead..
expected voltage gain is 50 so, measured voltage must be around 4.50VAC, all what is less indicating worn tube

I'll try to get some pictures of them today.

[Ledvedder5150]

Ok, here are the tubes from left to right. RFT, EHX, Genalex, Sylvania, Mullard.

20230208_091714_copy_3625x2955.jpg

[Ledvedder5150]

And here are the readings I'm getting at the spot noted.

RFT

20230208_092000_copy_4000x3000.jpg

EHX

20230208_092047_copy_4000x3000.jpg

Genalex

20230208_092132_copy_4000x3000.jpg

Sylvania

20230208_092215_copy_4000x3000.jpg

Mullard

20230208_092255_copy_4000x3000.jpg

[bepone]

first, EX tube is 12AY7, it is lower gain tube , so it is normal.
other are here somewhere

[Ledvedder5150]

first, EX tube is 12AY7, it is lower gain tube , so it is normal.
other are here somewhere

Oh you're right! Why was I thinking it was a 12ax7?