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Tube reviews seeming pointless and futile

Discussion in 'Glowing Bottle Tube Amp Forum' started by CV Jee Beez, May 4, 2017.

  1. CV Jee Beez

    CV Jee Beez Tele-Holic

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    I just received a TAD 6V6 tube and put it in my Supro 16T single ended 5 watt amp.

    To my ears, a great tube. Plenty mids, nice highs, and big bottom.

    Compared to the Tung Sol and the JJ that were in their previously, not worlds apart.

    For me the Tung Sol was a let down considering how man great reviews it got. Pedestrian. Less powerful, than both the JJ and TAD.

    The TAD to me seems a bit more musical than the JJ.

    So here's the punchline.

    When talking about tubes, essentially your talking about what you hear.

    When you talk about your hear, it's part perception, part feeling and mostly made up of adjectives.

    So it seems like a crapshoot to read a tube review, get that tube, and be like, oh yeah, that guy on the forum was absolutely right.

    Even the descriptions made by the vendors are dubious. Seems like you just have to get a tube and see if you like it or see if it works with your particular amp.
     
  2. Piotr

    Piotr Tele-Afflicted Silver Supporter

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    Sure it is subjective and amp dependent. Still - I chose tubes for my AC30 based on tube reviews for that specific amp. It turned out that the reviews were spot on.
     
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  3. Jupiter

    Jupiter Telefied Ad Free Member

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    It hasn't yet been demonstrated to me that tube brand makes a very significant difference. I'm not disputing it, but I have never sat through a live demo, and YT vids haven't convinced me yet.
     
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  4. MuddyDitch

    MuddyDitch Tele-Holic

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    Sweet mother of dog, the gateway to the TONE GLASS debate has been breached.
     
  5. Andy B

    Andy B Friend of Leo's Silver Supporter

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    I base tube purchases based upon reliability drawing from the last decade of working in repair shops.
     
  6. Count

    Count Friend of Leo's

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    This could be the start of something BIG. :):):):)
    To be honest, and i'm not ashamed to admit it, my ears are not good enough to pick up subtle diferences in diferent brands of tube consequently I don't bother to read tube reviews other than for how reliable they are.
     
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  7. Norris Vulcan

    Norris Vulcan Tele-Afflicted

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  8. perttime

    perttime Tele-Afflicted

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    An amp builder posted elsewhere that there are big differences in tubes within brands.

    He tests tubes, and groups them into batches of similar ones. Then he charges more for the measured ones because they are more of a known quantity. Not sure about the electrical details of what exactly he measures.
     
  9. koko1

    koko1 TDPRI Member

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    Some tubes are louder than others. Some are noisier. Physically there cannot be a difference in what is called "tone". Most of the tonal difference comes from different biasing. That means more or less overdrive, if a tube is changed with an other without changing the bias.
     
  10. robrob

    robrob Poster Extraordinaire Ad Free Member

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    There's also variation between individual tubes of the same model and manufacturer. Couple that with variations in amp circuits, music taste, hearing ability, mood, etc. and a tube shootout can be worthless.
     
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  11. chemobrain

    chemobrain Friend of Leo's

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    is it true that tube are not made to a spec that makes one of brad x's tubes sound exactly the same in every circuit. I think maybe when all the + &- variations, even with in the amps specs, cause amps, circuitry sound different
    One old deluxe may not sound as good as the next one or the one after that. some things magically line up and out comes the juju.
     
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  12. perttime

    perttime Tele-Afflicted

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    https://en.wikipedia.org/wiki/Tube_tester

    "A tube tester is an electronic instrument designed to test certain characteristics of vacuum tubes (thermionic valves). Tube testers evolved along with the vacuum tube to satisfy the demands of the time, and their evolution ended with the tube era."
     
  13. SamClemons

    SamClemons Poster Extraordinaire

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    Add to that I think the preamp tubes affect the sound more than the power tubes. The differences are subtle. There is no magic tube that is just all of the sudden going to make you go "Wow". Maybe if you have a really bad tube in your amp to start with.
     
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  14. mad dog

    mad dog Friend of Leo's

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    Reviews are only useful as general guidelines. The variability in how each different amp reacts to a given tube makes prediction impossible. So the only way to know what works is to get some tubes and start trying.

    As to Koko1's statement:

    "Physically there cannot be a difference in what is called "tone". Most of the tonal difference comes from different biasing. That means more or less overdrive, if a tube is changed with an other without changing the bias."

    Makes no sense to me. If by "physical" you mean tube components, construction, there certainly are differences brand to brand, tube to tube. And new vs older tubes. The tones I hear in tube swapping are sometimes subtly different tube to tube (talking power tubes here), sometimes not at all subtly different, sometimes no change.

    Biasing does have tonal effect, but can hardly be claimed as the only difference tube set to tube set. First of all, you should check bias in a fixed bias circuit when changing tubes. More a safety issue than tonal. Then each different set of tubes will have it's own bias sweet spot, where it's safe to operate and sounds best.

    Bottom line: my experience tells me there are indeed tonal difference tube to tube, and that no single factor can explain it.
    MD
     
  15. fjrabon

    fjrabon Tele-Afflicted

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    Yeah unfortunately tube chasing is probably the most complex thing we do in search of tone as guitarists. And the one that's the most like a "black box"

    The biggest factor, as others have mentioned, is that there's significant difference between tubes within a model. So much so that the differences between tubes within a model are larger than the differences between different models.

    For example, regular Tung Sol 12ax7s are known as bright tubes and JJ 12ax7s as warm tubes. But the brightest JJ will be brighter than the darkest Tung Sol by a noticeable amount. So you might happen to get a bright JJ and a dark Tung Sol and be totally flummoxed.

    The second confusing thing is that brands don't matter when it comes to tubes. It's about the factory and the model. None of these tube brands really make their own tubes, they purchase them from factories in Russia and China and then slap their brand on them. Different factories are often branding the same tube to be as many as 7 different brands. It's not always easy to figure out which tube model and brand lines up with which factory and model. There are tendencies between different factories and models, not brands. Tung Sol is simply a brand name and has little or nothing to do with the tube in any real sense. When EHX recently bought Tung Sol they didn't buy factories or equipment. They simply bought a brand name. I've seen tube reviewers go on about the differences between two different tubes that I knew for certain came off the same line. And the thing is the reviewer may have been correct about the differences he was hearing, but just not for the reason he thought (different brand) but because of factor 1. The two tubes he was hearing *did* sound different, but it wasn't because one was brand x and another was brand y, it was because of intramodel variation.

    The third issue, as has been noted is that tubes behave in complex ways, which is maybe the main reason we like them. It also means that there really is no such thing as a "tube's tone." A tube's tone can't exist in isolation, but rather only in part of a system. A tube that is generally warm might be unusably harsh when fed a different signal and/or feeding to a different output stage and/or speakers. There are tendencies, but that's all they are. One tube can tend to be brighter, but in a different chain it might actually invert things.

    So, yes, the only way to really sort any of this out is to just swap the dang things in and out and see what you like best. Or just don't worry about it. It's less of a difference than changing picks or strings or selecting a different pickup.
     
  16. MilwMark

    MilwMark Doctor of Teleocity Ad Free Member

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    I'm glad to see a couple amp repair types gently dispelling tube mojo.

    My tech has always said - there are good tubes and bad tubes. I.e., tubes built well within spec and tubes not built well and not in spec. Based on experience, he gravitates to tubes built well and within spec. And then biases the amp (if fixed) appropriately for those well-built, in spec tubes).

    I have brands where I've run into microphonics and rattle a couple times. It's a small sample, admittedly, but twice-bitten, once shy. I just move on. So for me it comes down to do they fail. If I find a brand that hasn't failed me yet, I tend to stick with it.
     
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  17. Dismalhead

    Dismalhead Poster Extraordinaire

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    With all of those you're talking decent tubes. I swapped out the cheap Chinese tubes that came with my AC15C1 and it made a WORLD of difference. And yes, I put Tung Sols in the preamp.
     
  18. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    There is a concept in statistics called the intra class correlation, I have to deal with it constantly. If you have a measurement you think can be used to distinguish groups, this value needs to be high. If it is low then there isn't much distinction between the groups.

    Screenshot_20170504-092022.jpg

    I have not noticed a compelling difference between the 12ax7 or 6v6 of various tube brands
     
    Last edited: May 4, 2017
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  19. LKB3rd

    LKB3rd Friend of Leo's

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    I think you are right in that when other people try to translate sound into words, it doesn't necessarily mean anything to you or me.
    You have to check things out for yourself a lot of times.
     
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  20. koko1

    koko1 TDPRI Member

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    Tell me, which component of a tube to change and how, to have e.g. more singing mids?? There is a flow of electrons, that is more or less saturated by voltages on grids and plates. Take the right voltages (given by the manufacturer) for a clean sound for every comparable 12ax7 tube and you will get different levels of amplification, but not in tone. It sounds different in your ears, because frequencies sound different at different volumes.
     
    Last edited: May 4, 2017
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