If the device is designed well, and the tubes used have generally the same operating point, you shouldn’t be able to hear the differences between tubes. Changing tubes will affect ideal operating point of the tube due to variations in tube construction, even amongst tubes made from the same batch on same production line.
These people who hear differences between brands of tubes I think are likely experiencing psychological effect of listening with their eyes, or their equipment is not well tolerant of minor variances in tubes. Adjust the cathode bias resistor and plate voltage to get relatively the same operating point, and I bet in a blind test people don’t hear the differences they claim they do.
@anchorman
That was a meaningless post since all that uses tubes know that basically all manufacturers of tubes, both historic and current have their own design and build-up of how the tube is built. You would be lucky if you find two manufacturers that can produce tubes that sound exactly the same.
They don't sound alike and that's why we are tube rolling and test a lot of tubes to find the best combination.
Have you even tried different tubes in a tube amplifier?
That was a meaningless post since all that uses tubes know that basically all manufacturers of tubes, both historic and current have their own design and build-up of how the tube is built. You would be lucky if you find two manufacturers that can produce tubes that sound exactly the same.
They don't sound alike and that's why we are tube rolling and test a lot of tubes to find the best combination.
Have you even tried different tubes in a tube amplifier?
@anchorman
I will not comment on that suggestion.
Please don't turn this thread to anything else than discussing and commenting of different versions of 12AX7.
I will not comment on that suggestion.
Please don't turn this thread to anything else than discussing and commenting of different versions of 12AX7.
Because it's harder than swapping tubes 🙂
There are small variations between tubes of the same manufacturer and from the same batch (tolerance of 20%). Between batches, there can be more factors, such as tooling, i.e. stamping of the plates, winding jig for the grids, chemistry, i.e. coating of the cathode, and so on. Between manufacturers... anything goes.
My fav.: TFK ECC803S (no, I didn't pay 1K+ a piece), Siemens ECC83, both real and rebranded (Philips? RFT?).
It’s odd to me that you think there can be an objectively better version of this tube, when depending on the circuit it’s used in, one particular tube might be better than another, and in another circuit a different one might be best. I don’t understand how there can be universal agreement of which is best…
I’m curious what properties that we could control for by objective measurements of a particular tube of this type that make it better than others? Is it inter-electrode capacitances? Transconductance as measured at a particular operating point? Plate resistance at a particular operating point? Amount of bias needed in order to achieve cutoff as defined by some number of microamps of plate current? Is it how the curves match the ideal curves published by RCA? Surely given the level of sophisticated measuring technology available we could determine what makes one brand of 12ax7 better than another.
@anchorman
Wrong thread for objective discussions. You can start one if you want.
This thread is only subjective where people share their experience of different 12AX7 tubes.
Wrong thread for objective discussions. You can start one if you want.
This thread is only subjective where people share their experience of different 12AX7 tubes.
That's why this thread will die, too. Like all the others. No foundation for subjectivity.
My experience going back to the early 1990s, and back to the 1980s in guitar amps (which is not relevant to this thread), is that in some circuits one brand or variant of 12AX7 may sound better than another, but in a different circuit I may have preferred the other 12AX7 variant.
Over the years, I've used:
RCA 7025
RCA 12AX7
RCA 12AX7A
Sylvania 7025
Sylvania 12AX7
Sylvania 12AX7A
GE 12AX7A
Tesla E83CC
Smooth plate Telefunken
Ribbed plate Telefunken
Mullard ECC83
Sovtek 12AX7WA (shiny silver plate structure)
Sovtek 12AX7WB (dull gray plate structure)
Chinese 12AX7A
Ei ECC83 (Yugoslavia, 1980s)
I've probably heard others, like ProComm, Realistic, Tung Sol, in various circuits that were re-branded something-or-others, but none ever stuck out as anything special.
At any rate, over the last 25 years or so...
The only consistent differences I ever thought I could hear were between USA-made, European-made, and Russian-made.
I always thought the USA-made 12AX7s sounded a bit 'harder', while European ECC83s had a slightly 'softer' sound, and the Russian (Sovtek) ones have a damped, kind of 'duller' sound. But the differences are so slight, I think they're of the kind where if I had to go to the bathroom and you swapped one 12AX7 type for a different one while I was gone, I'm sure I wouldn't notice when I got back.
I can also say that in a Dyna PAS preamp, which uses its 12AX7s inside negative feedback loops, I could never hear any difference between this or that 12AX7 type (other than fresh ones vs. old ones). In the simple 12AX7 > passive RIAA EQ > 12AX7 > source follower preamp, I could hear very slight differences between 12AX7 types, but really not enough to make me say I thought one type was any better than another.
So there you go, my subjective experience with numerous brands/countries of origin of 12AX7 types, for whatever it's worth, do with it what you like.
--
PS - I should buy a couple of Sovtek 12AX7LPS to try them out. The problem is that I don't have anything that uses 12AX7s since I gave my 12AX7-based phono preamp to a relative. I'm thinking of making a push-pull power amp using a 12AX7 as its input stage, so maybe that would be a good test. But I have a large stash of perfectly good 12AX7s and ECC83s, so why would I spend more money?
Over the years, I've used:
RCA 7025
RCA 12AX7
RCA 12AX7A
Sylvania 7025
Sylvania 12AX7
Sylvania 12AX7A
GE 12AX7A
Tesla E83CC
Smooth plate Telefunken
Ribbed plate Telefunken
Mullard ECC83
Sovtek 12AX7WA (shiny silver plate structure)
Sovtek 12AX7WB (dull gray plate structure)
Chinese 12AX7A
Ei ECC83 (Yugoslavia, 1980s)
I've probably heard others, like ProComm, Realistic, Tung Sol, in various circuits that were re-branded something-or-others, but none ever stuck out as anything special.
At any rate, over the last 25 years or so...
The only consistent differences I ever thought I could hear were between USA-made, European-made, and Russian-made.
I always thought the USA-made 12AX7s sounded a bit 'harder', while European ECC83s had a slightly 'softer' sound, and the Russian (Sovtek) ones have a damped, kind of 'duller' sound. But the differences are so slight, I think they're of the kind where if I had to go to the bathroom and you swapped one 12AX7 type for a different one while I was gone, I'm sure I wouldn't notice when I got back.
I can also say that in a Dyna PAS preamp, which uses its 12AX7s inside negative feedback loops, I could never hear any difference between this or that 12AX7 type (other than fresh ones vs. old ones). In the simple 12AX7 > passive RIAA EQ > 12AX7 > source follower preamp, I could hear very slight differences between 12AX7 types, but really not enough to make me say I thought one type was any better than another.
So there you go, my subjective experience with numerous brands/countries of origin of 12AX7 types, for whatever it's worth, do with it what you like.
--
PS - I should buy a couple of Sovtek 12AX7LPS to try them out. The problem is that I don't have anything that uses 12AX7s since I gave my 12AX7-based phono preamp to a relative. I'm thinking of making a push-pull power amp using a 12AX7 as its input stage, so maybe that would be a good test. But I have a large stash of perfectly good 12AX7s and ECC83s, so why would I spend more money?
This thread will be short one, but it still will be there in the archives for those that want to hear other peoples opinions about 12AX7.
If interested you read the thread in your search for other peoples experiences.
Yes, the circuit and operating points make a big difference in sound.
Of course, the PAS is a terrible design: not enough loop gain in the phono section, and way too much in the line section, not enough current, etc... But the difference between tubes are clearly audible, even after I tweaked the circuitry extensively.
Regarding guitar amps, my approach is much more restrained: I bought a Pignose 60W combo about 20 years ago, and started collecting exotic tubes for a tube rolling journey... that never even started. After I fitted the Cannabis Rex speaker and did some minor tweaks, I realized I could get all the tone I want just by using the tone stack! So the tube line up in this amp is 12AX7, 6L6GC, all Chinese. And the frontend is a Gibson SG and a Heritage 535.
Interestingly, I heard non negligeable differences in my PAS-3x, which served as a platform for my "tube tasting" for a while.
Of course, the PAS is a terrible design: not enough loop gain in the phono section, and way too much in the line section, not enough current, etc... But the difference between tubes are clearly audible, even after I tweaked the circuitry extensively.
Regarding guitar amps, my approach is much more restrained: I bought a Pignose 60W combo about 20 years ago, and started collecting exotic tubes for a tube rolling journey... that never even started. After I fitted the Cannabis Rex speaker and did some minor tweaks, I realized I could get all the tone I want just by using the tone stack! So the tube line up in this amp is 12AX7, 6L6GC, all Chinese. And the frontend is a Gibson SG and a Heritage 535.
There are best sounding 12AX7 tubes. That is why tube rolling exists. A mediocre tube amp cannot fully hear a 12AX7 tube characteristics and many own less that great amps.
Guys, guys, I thought we established long ago the best is the one we spent the most money on?
Where/how are you using these high gain tubes? That's a crucial missing piece of info. Someone else commented that 12ax7 is good in guitar and phonostages. I agree.
Maybe if you have high power PP amp with high feedback and need to power tower speakers? IMO In a system with horn speakers such tubes have no use other than phonostages. My approach is to use only as much gain as I need and no feedback.
I thought it was the one that went in the last 2 seconds of an auction listing for 50p more than your max bid.