JJ 6L6GCs... WTF?

[Tom Phillips]

...I thought the whole letter was nothing but BS, with this being the most offensive statement of them all: "Tubes are not better or worse now than through out history."...

Well...Right...I agree that quote is BS now that I think about it. I should have said that the comparison of the different manufacturers was interesting.

It's shameful that such a high percentage of bad out of the box tubes can make it to the end buyer. As far as following the standards it's a pet peeve of mine that some manufacturers can't even get the overall dimensions or contact pin sizes within the correct range.

[big_teee]

The first half of the letter from Robert Hull at TubeDepot seemed like pure marketing hype to me and I almost stopped reading. However, I was glad I continued reading to the end because I thought that the second half was interesting information and It didn't seem to contain anything that I'd call total BS.

Thanks for the posting big_teee

Your Welcome!
It is what it is.
I think we have to keep in mind that they are in business, and he didn't have to answer at all.
With only having foreign tubes to buy, I don't see our tube purchasing choices getting any better.
In Roberts Defense, he's always been helpful, and takes time to answer questions of his customers.
I did read between the lines, that he Thinks the JJs are more fragile than the rest.
T

[Steve A.]

There is no place where a vacuum is total because particles spontaneously pop into existence according to quantum theory.

Wow- I never knew that! Is there something like a "Quantum Mechanics for Dummies" book that you would recommend?

Thanks!

Steve Ahola

[Steve A.]

Perhaps ET is buying the JJ tubes that test out the best. And perhaps CE is buying the less expensive ones that didn't test out as well. Just a thought.
With tube dealers charging more for the tubes they tested I am sure that the ones that failed are being sold as regular tubes unless they don't work at all. Perhaps nowadays more people are paying that premium surcharge which means that regular tubes could be considerably worse than average, more so than in the past.

Steve Ahola

[Steve Conner]

"4 cylinder solid-state sedan" LOL...

Robert's assessment of the tone might be OK, but I think the reasoning behind it is wrong. All tubes from all makers should have a super "hard" vacuum. If they didn't, they would fail in a matter of hours.

A soft vacuum means more grid current, and pretty much every guitar amp violates the spec for maximum grid circuit resistance. So a soft tube would probably go into thermal runaway and red-plate straight away.

[km6xz]

I will apologize in advance, for a long post, it will be long because there are many points related to this thread.....

My own personal take on current tubes is that they are not even attempting to set a standard and meet those standards for testing criteria. I know that the only two companies making tubes for which I had inside knowledge of their test and QC programs, neither has the test equipment to even test for the specs they list, and no curve tracer for verifying whether sample tubes meet the graphs they publish.
I can see their marketing department looking at a tube and saying "well it sort of looks like a 6L6 so we will label it as such and copy an old tube manual's graphs".
When I test tubes on my curve tracer, different brands(different manufacturers, not labels, labels mean nothing as to what it is) I am amazed at the range of values seen and shapes of curves. Just one example of easy to measure parameters being ignored: interelectrode capacitance is not hard to measure yet obviously is not being tested before slapping a 6L6 nomenclature on the output of the factory.

The letter was interesting in that he spent a lot of time answering a customer's question and is a positive trait.

But the content seemed to be a collection of internet myths and forum rehashes. When he attributed sonic characteristics to particular brands, we was getting off into BS territory. But when protesting how tubes are just like always, he was either intentionally lying or too ignorant to be called a technician.
That was beyond BS. Tubes were patented and cross manufacturer licensing was the norm as it is today. A developer of an new part or a tube never wanted their new fangled device to be a orphan, where no designer of new gear would specify it unless there was multiple sources for the part. That was so the unit product manufacturer would never be held hostage for pricing or availability of a required part that had only one source. That is not as true as in the past since product production lifespan for many products are expected to be a single run and replaced by a new whizzer product in a couple months.
But in the day, a tv, radio, military gear or test instrument builder, would only spec , say a RCA tube, if they had several companies building the same part, based on RCA's patent. They wanted the specific part characteristics but would only dare use it in new designs if they were not locked into only buying from RCA or XXX. The patent and designation included parameters that if met could be called a "6L6" for example. So both the licensee and licensor had a benchmark to measure whether the part was in compliance. QC departments were major parts of all the companies, meeting the spec was key to viability and the goal was to have a plug-in replacement second source. If I was a two way radio tech or a TV tech, and determined that a 6AU6 needed t be changed, because a stage did not meet published specs, I would pull a new boxed 6AU6 out of inventory and plug it in, and expect it to perform like every other 6AU6, without adjustment or change in performance. In RF circuits, adjust would be needed, but minor touch up. Imagine QC if in effect now as it was in 1959, getting a Fender amp in, finding a bad tube in a group of 4 in an amp, and reaching for a tube, ignoring the box and label and plug it in and be done. Well that is the way it was 40-50 years ago with tubes. It met spec, based on the licensed patent or it did not get sold as that part number. It was crushed if failed QC tests. If more than one failed the production line would be halted and the reason for the problem was sought and corrected.

I think there are some decent tubes out today, but they certainly are not plug in replacements for other brands and the part to part variance in all parameters makes it very difficult to get truly matched set. Sure, at 200 volts, and a 5k load resistor, and cathode bias, a close plate current is seen between "matched" tubes but try a dynamic signal, at real world loads and anode potentials and driven screens instead of testing in triode mode and all bets are off. If someone was really interested they could pull two random tubes and manually draw family curves, it only takes a meter and power supply to plot grid versus plate at many test points and a lot of time. The manufacturers don't do it, the tech in the letter surely does not do it.
Tubes are marketing items now, not engineering items so the ratio of tech savvy to marketing savvy people in any of the brands is very lopsided towards sales. In fact none of the rebranders I know have a clue about the tech issues. They are salesmen. Nothing wrong with sales people, but they have a different set of goals and a different set of criteria for success. In this context, a salesman has his own metric for how good a tube is, sales totals. A lot of technical damage can be inflicted on a product if sales rules and criteria are alone applied to engineering.

Another note about the technical veracity of the letter writer. He commented that transistors were better at the time tubes and transistors were first confronting each other. HUH???? Tubes got a life extension BECAUSE early transistors were anything but precision devices, with beta's varying over a very wide range until well into the late 60s.
Solid state test instruments needed more adjustments and trimmers than tube circuits which had a narrower range of unit to unit variation. Transistors did not get into the realm of tube precision until the early 70s. Tubes were closer in tolerance than solid state for about 20 years of their overlap period. Tubes were more rugged also.
Remember the first 5 years of transistors were point contact, which were as precise as Galena crystals in early crystal set radios, meaning not at all precise or consistent and even less rugged. The early junction transistors were an improvement but still far from the reliable repeatable devices of the 1970s. Looking at them sideways was enough for the junction to fail, but they were 20 times more rugged than point contact transistors. Remember the Raytheon ads promoting the experimentation with their wonder device, the alloy junction CK722 for only $10 each(which in the 50s was about the same as a prime rib dinner for a family of 4 in the best restaurant in town, or about $150 now) that came with instructions 4 pages long on how not to kill it, just trying to test it. Later, a yields improved and volume increased, the prices dropped to a couple dollars.
They died if the junction reached 85 degrees C, they recommended transistor sockets and not soldering, they recommended shock mounting so vibration did not kill them, etc. And they were the second generation ruggedized class of Germanium transistors. Silicon transistors did not replace Germanium until the late 60s. My first transistor was a CK722 which I saved 6 months of allowances to buy in 1958. My second transistor was a surface barrier type from Philco, a 2n128 that I actually got to oscillate up to 21 Mhz which was pretty cool at the time. Considering you could buy the parts to build a 75 watt ham transmitter and talk all over the world for what it cost to buy one little transistor, it was a big deal.

The only piece of equipment that a consumer had which needed a bias pot was the car radio that used tubes for all but the power output, class A single ended 1.5-3 watt doorknob transistor. The tube portion of RFamp/osc/mixer combination, IF amp, Detector and AVC and first AF circuits were all plug and play tubes(although they needed alignment adjustments for tuned circuits like all radios)

So, my review of the letter is that it might have been sincere in trying to help but only resulted in codifying marketing BS and internet rumor. If sent to many people, it would be used as a foundation document as proof for generations of clueless believers in tone fairydust.

Regarding tube reliability, I have learned it is not worth the risk to install JJ power tubes in a unit that has a repair shop warranty on parts and labor. I have more faith in EH now for 6550 and EL34 than in the past. I find some very good Chinese tubes but they tend to work best in circuits that do not have too high anode potentials. The very quietest 12AX7s I buy are from China. My EH buys of bulk 12AX7s have been disastrous. I have never seen as many initial failures from any brand. From a technical and financial security point of view, I use primarily 12AX7s from China in preamps and especially V1, and a mix of Chinese, EH and when I can get them, СЕД which are the most rugged of tubes. I also like old surplus Soviet era 6П14 in place of EL84s and 6П3с-е in place of 5881 and mid gain 6L6 applications. They outlast everything else and handle a lot of abuse. They are also cheap, about $3 for the 6П3с-е and $2 for 6П14.
The circuits that are wired for 6.3volt heaters can use another Soviet era surplus dual triode that is very close to the RCA 12AX7 but it has only two heater pins, for 6.3 and no possible configuration for 12v series heaters. I got 100 of those surplus for $90 and every one tested so far has been spot on, quiet, low microphonic and long lasting in combos that shake apart lesser tubes. The Soviets did build the best economies but sure knew how to make tubes. By the way, I saw a price list for a couple tubes dating 1974 and a 6П3с was 9 kopeks. A Kopek is 1/100 of a Ruble and a Ruble is approximately $0.03. But the Ruble was pegged at the dollar back then it was worth 33 times as much. A car or TV was pretty expensive however.

I make no recommendations on "tone", just reliability, parameter matching and other characteristics which really are in the realm of performance which is determined by tubes. Tubes are given way too much blame and credit for tone. I discount any further statements, even about the weather as soon as a fairydust believer claims a sonic characteristic of a tube brand. It is proof positive he is clueless and dangerous and should be kept away from small children and sharp objects. A SYSTEM of tubes are a part is what generates the transfer function that is related to tone. There is nothing in a tube that contains tone.
If they say, " I like the sound I get at xxx level, with my xxx guitar fitted with xxx pu's, in my modified or aged Fender xxx, which happens to have xxx brand tubes in it right now", I listen to them and might even want to listen to their playing. For more knowledgable people, do not let people get away with making clearly false statements about tubes and inherent sound traits without calling them on it, that is how the whole mythology started about tubes. Making such claims is akin to a car hobbyist claiming that "xxx brand pistons should be used because they are sound fatter".

[Steve Conner]

Word. I wish more people would realise this, tone is a holistic thing that comes from the whole system, it doesn't reside in any single part. You can't make a Marshall sound like a Fender by swapping the EL34 tubes for 6L6s or whatever.

Heck, if you know what you're doing you can make a perfectly good sounding amp with transistors. On a related note, when the first hybrids came out, they used a solid-state preamp and tube power amp, for the reasons Stan gives. Transistors weren't as rugged as tubes to start with, it was well into the 70s before devices were made that could stand the abuse of a guitar amp output stage.

Now the situation is reversed, we have crappy new-production tubes stacking up against power transistors that will go on for ever without wearing out. They probably don't have quite the same distortion harmonics as tubes, but if you agree that tone is a holistic thing, you can compensate this elsewhere in your design.

[Leo_Gnardo]

Wow- I never knew that!

Look up Casimir Effect. Where there should be nothing, there's something, and lots of it. If you believe in a Creator, you'll find that Creator has a sense of humor. And if you don't, you'll still be amazed at another facet of our bizarre universe.

Yes if anyone has a Quantum for Dummies I'd like to know too!

[Jazz P Bass]

The idea (or concept) of a virtual particle can be attributed to John Wheeler, in the 1960's.
He called it 'Quantum Foam'.
There is no such thing as emptiness. There is only quantum foam.

This article is not "Quantum for Dummies".
But it is close.
Quantum Foam, Virtual Particles and Other Curiosities « NOVA's Physics Blog: The Nature of Reality

[big_teee]

I forgot how forums nitpick everything.
My apology for the Copy Paste, I Promise not to do it again!
T

[Tom Phillips]

I forgot how forums nitpick everything.
My apology for the Copy Paste, I Promise not to do it again!
T

I think it was good you asked the vendor, good he replied, good you posted the reply and good that we got to see the comments it generated. Overall, this discussion is more worthwhile than the type that ask "what brand (marked on the box) will give me the best mids in my **** amp."

[Chuck H]

Excellent post. A very good distillation of the circumstances plaguing modern tube manufacturing. It actually backs my observation that the making of tubes has become less like the manufacture of an electronic component and more like the manufacture of something like cloths pins. But hearing it from someone with such a high level of direct contact and experience is very solidifying.

I will take one contention though...

You've said, reiterated, explained and otherwise tried to concrete the notion that tubes aren't responsible for tone and get too much consideration. And to this statements end the implication is that tubes, when used in an electronically equalized environment, are neutral in their contribution. I'm by no means the tech or expert on the subject that you are but, for me, some glaring common sense is being ignored. You've talked in this very thread about interelectrode capacitance, hard vs. soft vacuum, differences in operation NOT tested for in common matching practices and other parameters that may or may not alter a tubes performance in a variable way with operation. A bottom line observation is that the great majority of builders, techs and players that have been through many sets of tubes DO in fact recognize sonic differences. Now, you never said there weren't sonic differences. But you do often imply that they are insignificant. I'll humbly request that any disagreements are handled with the consideration that I am NOT an engineer or vacuum tube designer. But that doesn't mean I'm not smart enough to see relevance where it exists.

Further, the operating conditions for tubes are often far outside any reasonable test parameters for comparison. As with the intentional hard clipping of output tubes that is common with guitar amplifiers. Anyone whose used different tube brands in the same amp can tell you that they have different clipping characteristics and frequency anomalies. As it relates to guitar amp tone that isn't insignificant. And guitar amplifiers is certainly the realm where most of the lore and hype come from. With a nod to the hi fi, golden ear ilk.

At this time I should concede that actually creating an equivalent operating environment for different tubes has never been done as far as I know. I suppose it would require not just a change in bias, but also a change in plate voltage, OT primary impedance, etc., etc... But at the very least it's accurate to say that different tubes brands of the same type do sound and perform different in any given amplifier. I agree that doesn't mean that a particular tube that performs well in any one amp is the superior tube. Because it may NOT be the best sounding/performing in another amp. And that is a very good point I have taken from your posts. So, fine. But different speakers of equal purpose are never compensated for either. We have no problems with the idea that they sound different.

I didn't miss your point that tone, as the word is used in this genre, is entirely personally empirical, and therefor doesn't have a definition. I just think it's counter productive to imply that tubes don't sound different. When they do.

[Steve Conner]

Sure, different tubes sound different. But I doubt it's in the manufacturer or retailer's interest to be honest about what they actually sound like.

For instance, imagine the Sovtek 6550 and the reissue Tung-Sol one shared exactly the same innards. (I don't have any proof of this particular case, but I bet there are many.) It would logically follow that they must sound the same. However, marketing would require the Tung-Sol part to sound better in order to justify its higher price. I imagine all claims of tube sound are probably caked in layers of bullshit and forum Chinese whispers like this. (Edit: To be fair to my friends here at MEF, I mean mostly in the hi-fi world )

Since the sonic differences between tubes are quite subtle, it would be very easy, with the forum BS planting thoughts in your head, to be led up the garden path by the experimenter-expectancy effect. I expect about 90% of the forum discussions are perpetuated by this effect. People hear what they've been primed to hear by the marketing blurb, and repeat it in their own personal "reviews", and round it goes.

I have my own subjective thoughts on the matter but I know better than to discuss them.

I've also been involved in a few blind tests over the years with mixed results.

[Chuck H]

I'm also not interested in starting a debate on the matter. It's too easy to find people to back opinion and also too easy to demonstrate paper facts that don't tell the whole story. The whole thing has crap on it to begin with.

I was intrigued by the Rivera EL34 comparison where THEY ALL SOUNDED THE SAME! You could honestly put those tracks on a loop and not be able to tell the difference. So... Too much compression gumming up the video? Maybe that amp, which is obviously a distortion channel switcher, wasn't clipping the power tubes on those tracks?

I just reviewed five completely different pairs of EL34's in a recent build. Each pair was biased to the same idle current. I was testing tones a bit more telling than those on the Rivera video. The difference was VERY obvious but I want to reiterate my concession. Had all the tubes been traced for every pertinent measure and the circuit adjusted (Vp, Vg2, PriZ, etc.) perhaps they would have sounded remarkably similar. I can't say because I would never take it that far. But as noted, speakers can also be equal replacement parts that sound different because of minor design differences and materials. Yes, speakers are mechanical transducers and tubes are more purely electronic but many similar principals still apply. I think. But Stan mentioned long ago that current tube manufacturers are making a lot of tubes that need to be traced to be understood because they actually spec significantly different from the designations they carry. Good on him. A lot more pro active than my mo of just trying a different set of tubes. My point is that right now it seems like tubes selection can be much like speaker selection. One brand may sound good in your amp and another may not. Even though they both carry the same part number. And that's part of why people give so much credit to tubes as it relates to their tone. Unfortunately it's not a 'one size fits all' part any more than a particular speaker is. So trying to choose a "best EL34" just doesn't make sense. The BEST el34 is one you know the specs on and can build around without surprises. That seems to be a rare quality anymore.

[Joe L]

Wow- I never knew that! Is there something like a "Quantum Mechanics for Dummies" book that you would recommend?

Thanks!

Steve Ahola

Just google "alice in quantumland pdf".

Quantum Physics is more weird than you can even imagine. For instance, "Quantum Leap" refers to the jump between energy levels of an electron. As an atom is heated up, the electrons jump to higher "orbits". Supposedly the higher orbits are a farther distance from the nucleus. The mental problem is, an electron does not move across the gap to the higher energy level. It disappears from the lower level and appears in the higher level. This happens instantly.

Also, electrons do not really exist until you attempt to observe them. They are present in all possible locations.

Pass the bong please.