Sovtek 12AX7s

[Rhodesplyr]

Sovtek 12AX7WA/WB tubes are pretty much the only ones I find that test 20-30%--or less--of nominal value after only a few years use.

[tubeswell]

... reliable workhorses that they tend to be

[Rhodesplyr]

... reliable workhorses that they tend to be

I'm not sure if irony is your intention here, since it's hard to get tone from text, but in the Fender Bassman 70 that came in with four of these Sovteks in it, I found two with extremely low emission/transconductance. I thought I could still use two of them, but one of the two that tested OK turned out to be noisy. (Someone had dropped in a 12AX7 as a phase inverter instead of a 12AT7.)

[MWJB]

Sovtek 12AX7WA have lower amplification factor that most 12AX7 tubes & they are like that from new, this is good for low microphony, but not always so great for tone.

[Tom Phillips]

Sovtek 12AX7WA have lower amplification factor that most 12AX7 tubes & they are like that from new, this is good for low microphony, but not always so great for tone.

+1
I found that the Sovtek 12AX7WA & WB have always shown low transcunductance even when new. I.e. this has been the case since they were first offered for sale.

[ajeffcote]

The 12AX7LPS is a decent tube, but not for combo's. I have a 12"x12" box of Russian tubes sitting in my closet. Some of them are decent, but I can't say that I really like any of them well enough for 1st stage use.

[Chuck H]

I'd love to use the 12ax7LPS for a first stage. Best sounding current production 12ax7 IMHO. Too bad they're all microphonic as hell. I use them for anything but first tube in the preamp. First tube is usually NOS this or that. I still have a couple of RCA gray plates that sound great and aren't microphonic. They were only US $18 when I bought ten of them. Now I see them as high as $70 if they test new and aren't microphonic. I've tried a few production tubes for first stage and liked NONE of them. Probably the least offensive current production 12ax7 for the first stage is the Chinese tubes that Mesa uses. At least to my ears. They do go microphonic with time, but while they last they're quiet, dynamic and actually make the gain they're supposed to. I don't know who makes those though. They're the ones with the little shield around the plates.

[greekie]

I'd love to use the 12ax7LPS for a first stage. Best sounding current production 12ax7 IMHO. Too bad they're all microphonic as hell. I use them for anything but first tube in the preamp. First tube is usually NOS this or that. I still have a couple of RCA gray plates that sound great and aren't microphonic. They were only US $18 when I bought ten of them. Now I see them as high as $70 if they test new and aren't microphonic. I've tried a few production tubes for first stage and liked NONE of them. Probably the least offensive current production 12ax7 for the first stage is the Chinese tubes that Mesa uses. At least to my ears. They do go microphonic with time, but while they last they're quiet, dynamic and actually make the gain they're supposed to. I don't know who makes those though. They're the ones with the little shield around the plates.

I agree about the NOS-tubes. Funny thing is that those that weren't so attractive ten years ago - like the Sylvania 12AX7WA Grey Plates - are now an awesome tube to pop in your first couple of positions.

The MESA-tube is most likely a Shuguang. I think that TAD sells them rebranded as their 7025 High Grade.

[Chuck H]

I think that TAD sells them rebranded as their 7025 High Grade.

Yup. That's them. Too bad their "selected" (12ax7A-C. I assume "selected" means non microphonic) is $22.50. Sheesh. Considering that those tubes only last about half as long as euro 12ax7's (IME) I think that's too much. But they do sound alright while they last. Not sure what I'll do when I run out of RCA's. Maybe find another NOS that I like and performs well. I bought some old National 12ax7's once that were good (rebranded, made in Yugoslovia). Not a well known brand so might be less $$$. GE's are available all over and affordable but sound poor IMHO. I bought twenty of them and promptly re sold them. Remarkably similar to the Sovtek WA and WB 12ax7's in sound and performance.

EDIT: Well, some research shows that most NOS sellers are onto the National rebrand and have taken to IDing the tubes by characteristics and then selling them for prices akin to the original manufacturer. So a "National" 12ax7 made by Amperex sells for about the same price as an Amperex.

[ajeffcote]

Somebody, anybody tried the FullMusic or the Northern Electric 12AX7's? I think I have asked that question too much already, but just once more to make sure. I want to try some but don't want to be the first.