How much does price usually equate to good tone when it comes to buying brand new vacuum tubes?

[Dolmetscher007]

I have this feeling that mentioning the words: "price", "tone", and "tubes", in an online guitar amp forum is like juggling sacks of gunpowder beside a campfire.

I know the question, "Which tubes are the best?" gets asked a lot, but I'd like to frame it in maybe a more specific way. I am new to building amps, and am thus new to purchasing vacuum tubes. I decided to build a tube-based "boost / tremolo" unit that I saw in a two part video on Uncle Doug's YouTube channel. It's just a little chassis with a voltage doubler power section, and a 12AX7 tube that acts as a preamp boost and a tube-tremelo effect that you can switch on and off as well as affect the speed and depth. I bought all the components online recently, and they've arrived. But ever since I was combing through all the online stores that sell vacuum tubes, trying to decide which 12AX7 to buy, I've been dying to ask some guys who know what they're talking about... How in the hell does one decide which tubes to buy when they range in price from a few dollars to a couple hundred dollars?

I've heard about people spending big cash on "new old stock (NOS)" tubes, where they found some stash of vintage 1940-50's tubes that were actually made way back then, but just never used. Let's exclude NOS from the conversation, please. I would like to focus on tubes that are still being made, today. It is my understanding that there are zero vacuum tubes that are made in the US or in the UK anymore. They are all made in Russia, China, or the Czech Republic. (Please correct this last statement if I am wrong!) I have really noticed that brand names are quite shady in tube circles, with historic brands being thrown around, like Mullard, but are now made in Russia, and have nothing to do with the old UK tube company. Either way, I can certainly see some guys focusing on the country of origin when they consider which tubes to buy.

When it comes to situations like this, where I have to decide which [unit] of some product like this to buy, here is usually how I operate.

1. Read as much as I can about the subject
2. Ask as many people as I can, listening for any good science-based arguments for/or against something
3. Find any [units] that are priced esoterically higher than the rest, and exclude them
4. Then I line them up, from rock-bottom cheapest, to most expensive (not counting any ridiculously "over-priced" [units] see above)
5. Start to narrow my choice down by looking towards the middle of the pack

I also look for any words or phrases that I think are "tells" of bullshit. Words like, "Pro" or "Extra" can sometimes carry a real meaning, but often companies will take their "Model-X" of whatever, and add something almost meaningless to it, and slap the word "Extra", "Plus", or "Anniversary" to the end of "Model-X Plus" just to upcharge. A hypothetical example would be, a Russian Mullard 12AX7 that had 24k gold paint used to silkscreen the logo onto the tube to commemorate the "2021, 70-Year Anniversary of the 1951 model."

So, anyway... that is kind of how I tend to use "Price" as a guide when deciding between loads of different options for something I have no experience with. It's def. not scientific, but... it's what I do. What do you guys do? Can any of you really tell a measurable difference between brands and models of the same tube?

[nosaj]

Not me.. I dont have golden ears nor do i pretend to hear what I cannot. To me it is all subjective BS. I think you can get good tone out of most tubes if you know how to set the governor Which defines how the tube will be driven. I think the majority of people will just plug a tube in an say sounds good sounds bad. Not unlike buying sparkplugs and not gapping them. Yea they will work but not as efficiently as if tuned. Me i usually will stick with JJ's Some people hate them but for myself its fine. The only time I have old vintage tubes is when Ive recycled an organ.
But me I'm a cheapskate why pay more when i don't have to. Now for other peoples amps I put in what they ask for on the precondition they know I don't have golden ears and i don't buy all that. But unlike a preacher I don't try to convince them thats up to them if they want to pay an pay they will sometimes, mostly just so they can brag.

nosaj

[Leo_Gnardo]

Substitute Slovak Republic for Czech and you will be up to date, at least for the general run of tubes commonly used in guitar & bass amps. The countries are side-by-each in central Europe, and I'm not sure I could tell which was which if you asked me to point them out on a map. Czech to the west, Slovak to the east, but I could be wrong.

There was, 10 years ago more or less, an effort to revive 12AX7/ECC83 production at the old Mullard Blackburn plant in UK, but it fell flat on its face shortly after sending out some production samples which got good reviews. I'm sure they would have sold for gold dust money, not attractive to our amp aficionados.

Also there was a rumor of a US made 6L6 by a company called RCH in Carson City Nevada. Those of us who are sorta old techs & engineers will get the joke in "RCH." Presumably they showed samples at some hi fi convention, also around 10 years ago. Haven't heard a peep about it since then. I reckon it was sort of a joke, and who knows where the "samples" came from, AFAIK none were distributed. Price I'm sure would have been out of sight, but so what, it was just another "I saw a unicorn, really!" story.

There's a company in Connecticut who claim they cryo-treat tubes and sell them as "Telefunken" at high prices. Photographs reveal these are JJ, a far cry from Telefunken. Buy JJ's and soak 'em in liquid nitrogen yourself, those that survive can boast of having survived the cold treatment. Claims are the super chill "rearranges the crystal structure of the metal." But nothing is said about what happens when the filament is lit up, and those same parts heat up to 700F more or less. Wouldn't that re-rearrange the metal's crystals? Yes, I expect so. Another bust. Meanwhile other outfits "heat treat" tubes and claim special effects. Same with guitar strings. The beat goes on... buy OURS because they're special, so special, gotta have some of your attention, and lots of $$$$$$$$$$$$$$.

[R.G.]

Think about how selling and advertising works, and the general ethics of people who sell things.

[xtian]

There have been some great preamp tube shootouts recently on youtube, by Pete Thorn, and another by SpectreSoundStudios. They used "reasonably" scientific methods--same guitar loop, same exact setup, just swap tube. You can listen and judge for yourself. (SPOILER: there is VERY little difference. You can make a much larger change by turning the Treble control a few degrees in either direction.)

[Jazz P Bass]

To me, the issue comes down to quality control.
Is every tube that comes off of the production line exactly the same?
I would think the 'bell curve' is rather wide.

Then again, the tube is an amplifying device.
Other than inter electrode capacitance, how can the tube itself have 'tone'?

Then there is the gain of the tube.
I have seen 12AT7 tubes that have more gain than a 12AX7.

[pdf64]

nickb ran some interesting ECC83 / 12AX7 comparison tests https://bmamps.com/v01/home/techie-c...parison-tests/

As the trem/boost pedal only uses 1/2 the tube in the actual signal path, and it can be bypassed anyway, and unless you're going to run a booster into it (in order to overdrive it) it should operate fairly linearly, there doesn't seem any point going overboard. The other half of the valve is used as an oscillator for the trem, it doesn't pass any audio.

The key thing when buying valves is that the vendor at least checks that they're functional, preferably burn them in for a good few hours to weed out the early failures, and provides a warranty. For valves to be used early in the signa path, eg such as a booster pedal, it may be beneficial for the vendor to check them for noise, hum, microphonics and gain, and to warranty that too.
Note that warranties are of limited duration, may only last for a short time, eg 90 days, so don't buy valves until they're needed, or at least until you can check they're ok soon after receipt.

[Pedro Vecino]

Can any of you really tell a measurable difference between brands and models of the same tube?

Yes, but don't expect to find relevant differences by listening to them as a spectator. Playing the instrument is how it is perceived, and of course depending on each function and each amplifier, as well as your level as a guitarist. They are much more related to their contribution to the timbre than to frequencies.
Many of us also couldn't tell a Epiphone LP from a Gibson LP just by listening to it when, for those who play it, just holding it is enough. These things work like this.

[xtian]

for those who play it, just holding it is enough. These things work like this.

So do placebos. (I'm not arguing that some guitars feel better than others, tho!)

[nickb]

For me it come down to reliability, reliability and most important of all, reliability,

As Jazz hinted, the tolerances are are so wide that I think you can pick a good sounding tube (i.e one you personally like) from any of the manufacturer. The other side of that coin is that next time you buy the exact same part number and the same manufacturer, it probably will not sound alike.

[uneumann]

Differences often become more pronounced when a tube is overdriven. Differences are often hard to hear or measure at low signal levels. Unfortunately, a listening or measurement test with low signal levels doesn't predict how the tube will sound at high (overdrive) levels. To make things more complicated, the circuit matters too - so a tube that sounds a bit fuzzy overdriven in one circuit can sound different in another overdriven circuit. All the labels and hype and $$$s tell you little if anything about how an overdriven tube will sound in a particular amp. You just have to try it. I personally find low-med priced tubes very satisfying for guitar amp purposes. I save my money for other things. I keep 4 or 5 different common tubes on hand and I'm likely find one (or more) I'm happy with in a given amp.

[Mick Bailey]

Playing the instrument is how it is perceived, and of course depending on each function and each amplifier, as well as your level as a guitarist. They are much more related to their contribution to the timbre than to frequencies.

That's how I think of tone. My reckoning is that Jeff Beck playing through an amp fitted with what anyone here would consider to be the worst tubes would make that amp sound much better than anyone here playing through the same amp fitted with what they consider to be the best tubes.

[mozz]

Just buy a old tube tape recorder or phono or whatever. Pull the 12ax7's.

[pdf64]

My hypothesis is that much of the tonal difference that might be perceived between 12AX7 of different manufacture etc may be due to their grid conduction / forward g1-k bias characteristics; even with clean sounds that aren't perceived as being overdriven, signal peaks might result in some degree of grid conduction and hence clipping, with the resulting harmonics being perceived as a brighter tone. A sharper transition into grid conduction / differing forward biased characteristics, between one valve and another would generate a different profile of harmonics and hence tone.
The thing with grid conduction / forward g1-k bias mode is that I've not seen it being a controlled / specified characteristic for the valve types we use, so even in the golden age it would seem to be perfectly fine for it vary from one to another, as the valve could still conform to the type bogey.
Any thoughts?

[Helmholtz]

Any thoughts?

Zollner's measurements of grid current characteristics of a large number of ECC83s support you hypothesis.
Variations are huge even with same manufacturer.
Here's alittle teaser:https://www.gitec-forum-eng.de/wp-co...-impedance.pdf
The effect should be especially noticeable with attack response.
Stages mostly affected might be the input triode and DC coupled CFs.