Part1) Information about mesh tubes
In Germany, we have an old saying, copying of your products is the highest form of recognition. Only, when I see what the Chinese factories are doing, I am so not sure if this is a form of recognition.
So we speak out a serious warning here, for faked Chines mesh tubes. The word mesh is by definition for things that are woven into each other. With mesh wire, this is what you get with the Emission Labs 300B-mesh. The Chinese are fooling us with so called "mesh tubes", which are not worth that word. Sure they look like mesh tubes, but this is only an optical illusion. These are metal plate tubes, with very fine holes in it. Some sellers call it now semi mesh, which word suggests something comparable, but other than the optical illusion that is not what you get. So in in normal language we would call that false mesh, or fake mesh, to be much clearer to the reader.
A product is made of mesh, or not made of mesh. There is nothing in between. Same as a woman can be pregnant or not pregnant. Indeed there is a thing like "semi pregnant" in nature, which results in very rare cases, from a pathetic whish to be pregnant, but there is no man involved. So beginning signs of pregnancy will develop, but it should be clear, this situation will never result into a baby. We bring this example for the humour of it, but it describes the word semi-mesh really well. The special sound of mesh tubes, can of course not be reached by the optical illusion of it. So it can not be reached by glowing light shining trough holes. It can only be reached by low resonance and the wire structure of mesh. Even so, mesh wire is used in industry as damper element, but I never heard of punched plate materials being used as such. Here are some examples of damper elements with mesh: Pic1 - Pic2
However, the correct designation for such tubes is punched plate, but I see no seller use this clear word. Of course, we are not against punched plate tubes as such, but the objection is against fooling the buyer with an optical illusion. Since "mesh" tubes is simply not what they are. The word semi mesh is misleading also, because that suggests it has something to do with mesh, but the only relation, is the optical illusion.
So to avoid the misleading situation, the seller must clearly say you receive not mesh tubes, but punched metal tubes. Otherwise it gets semi honest.
We do not say these are bad tubes, or anything like that. However we seriously protest against the use of the word MESH for this, because this is simple not what these are. Sorry for telling the truth here, but to speak openly about this is more beneficial to my opinion.
If you were sold mesh tubes, but you were send punched plates instead, you have been fooled.
The below picture is a EML 2A3 mesh. You can clearly see the anode is made of..... METAL WIRE
THIS and only this is MESH
Part2) Important information about carbon plate tubes
We do not recommend the use of CARBON ANODES (CARBON PLATES) at Emission Labs.
At Emission Labs, we are conservative with following ideas about what we call "fun tubes". In China, at the moment, the main tube factory "SHUGUANG" is producing many such "fun tubes" for re-branding sellers. So you see interesting sounding brands come and go at the moment. Today it's a "Golden Dream", tomorrow it's a "Black Dragon" or "Green Beauty", and inside is the same old tube system by the SHUGUANG factory as always. The Chinese just produce what the markets desire, so everybody is happy. There is nothing against creating happiness. The markets want it, the markets get it. However it gets less nice, when the Chinese start "playing" around with anode materials on the cost of reliability, and tube specifications, just to make you semi happy.
Another trend we see is CARBON anodes (plates) for tubes that are not suited for this.
There is one golden rule with tube design, which professionals accept and understand. Please read this text carefully, because it touches the core of the philosophy we have at EML. This rule says, do NOT try to invent something new, without looking back into history first. This is such a common mistake, you can see it everywhere when vintage technology is "improved". We are totally used already to "new" and "better" digital tube testers, but their makers have never even touched, or at least studied the best vintage testers to learn from it. They simply ignore learning experience from 75 years, or three generations of people, while these testers are available everywhere to study them first, and then invent the improvements. Also buyers have requirements like this. With tubes itself, we see exactly the same thing. Though we have to say, a tube is a 100x more complicated product than a tube tester. Tubes production was at it's top from 1930...1960 with HUNDREDS of factories producing tubes and 100.000's experienced and dedicated tube design engineers, trying to improve products and processes. It was THE MAJOR industry for decades, and the winning of the second world war was greatly influenced by who had the best tube technology. After the war, the dominance of complete nations was determined by tube technology as well.
In the environment like described above, It can be observed that after 1940 NOTHING NEW was invented any more on the area of electron tubes. Simply nothing! The last break through was the portable (airplane) RADAR technology with resonance tubes, in 1938 by the British. Reason is not, these 100.000 engineers were not clever enough. Reason is simply, all technologies had been discovered and that was pretty much final. Whatever you try, it was done before by others. Only miniaturization came, and even that was no progress, because it was on the cost of technical performance.
So let us say it again, because it is so hard to learn, but ever since 1940 NOTHING new was invented any more in terms of "better" tube technology. This makes it so silly, if some tube factories today present one innovation after the other. The use of CARBON Anodes was only done in Tungsten heated tubes. So the bright emitters like 211 or 845, these had CARBON tubes as an improvement. (In the beginning these had METAL anodes). For the bright emitter tubes, the good part is, the anodes can be soaked with getter material, and the great heat will help to keep the vacuum good. Some carbon will evaporate, and come everywhere in the tube, mainly visible as a dark coloring on the glass. However since the almost white glowing filaments are so hot, there will be no carbon residue on the filaments. Though after long use such look very "old", the ultra thin carbon layer, and coloring doesn't seem to do any negative to the tubes at all. These tubes are a concept by itself, and they work great as long as you can accept their high voltages.
Today, the marketing machine, has recently "invented" CARBON anode tubes, using modern (red glowing) BARIUM Cathodes. So not the (white glowing) Tungsten Cathodes. All they do, is take a normal 300B "as is" and use a CARBON Anode. Such tubes are sold as "better sounding". Well strangely, why did they not do so 50 years ago at Western Electric, and at Tung-Sol, at RCA and Telefunken, at TESLA, and everywhere. The Western Electric and TESLA engineers must have been very stupid then, not knowing CARBON Anodes are "better". Specially since carbon is lower cost. But you see, nobody ever used this lower cost technology. Why would that be? So when you say CARBON anodes are better sounding, we don't want to argue, but what you are saying, 100.000 Engineers of the past have been mistaken ever since.
And yes, of course also AVVT (Alesa Vaic Vacuum Technology) has tried carbon anodes. From those experiments at AVVT, which I have seen myself, I can first hand say what the problems with such tubes are, and why this technology is not good.
The CARBON is a powdery material. The anode gets bombarded with electrons, and even so at great surface heat at the place of bombardment. So logically, some particles get loose, perhaps we use the word evaporation, but it is in fact nano particles. They fly around, and get hit by electrons. If so, they get ionized, and the positive ion gets attracted by the Filament, colors it dark, and contaminated the surface. I could see this by opening a defective CARBON 300B. The filament should be bright grey, close to white. Not dark grey, coated with some layer of carbon dirt. Likely, under the heat of the filament, and due to electrolysis effects, the carbon reacts with the Barium, Calcium, Aluminum and Strontium present in the emission material. This dark grey composition creeps also deeper inside the cathode, thus blocking the self-repair function of the filament. With such tubes, I have seen, contamination begins already after 500 hours. The temperature of a BARIUM OXIDE filament is not high enough to remove the carbon residue by evaporation, but even when chemicals like Barium Carbide, or others build, this can not even be removed any more, and the the begins to die slowly. .
The above is the main problem, and it can not be solved. The next problems listed below here (Nr2 and Nr3) are a matter of technology and price.
Technology. There is just no good way to connect a metal wire to solid carbon. That means the tubes must survive shipment. Historical tubes like the 211 and 845 used a shrink connection, which connection by definition has mechanical tension, whereas carbon is brittle. This works only with best and finest process control, like the old USE tube factories in the 1940's sure had. Yet, when you know, the original packaging of those tubes was very large, with soft filling materials. The Chinese just ship their tubes as if this is "no problem". Add to this, because of cost savings, shipment companies today use monkeys to handle the boxes. They do not admit it, but from the box damage, it can be clearly seen this is as I expect. They dropping and kicking of the shipment boxes will cause micro cracks in the carbon. In fact this is one of the reasons why Chinese 845 and 211 tubes can fail too early. The crack is right where the shrink connection is. Due to heat, the crack gets larger while the tube is used, after some 100's of hours developing sparks inside, or crack sound, or total malfunction. The same happened with AVVT Carbon Anode tubes as well. The solution is to used finest carbon, and have extremely skilled workers who are not under time pressure. Which brings us to the next point:
Price. The really PURE and CLEAN carbon is very expensive. To obtain this, you must out glow carbon under vacuum for WEEKS, since it would burn in air. So this is a very expensive process. We all know, in Chinese factories production, three things count most. These are: Cost, cost, and cost. So they can never withstand the temptation to use lower cost materials, and shorter processes. Users of Chinese 211 tubes can compare those with 1940's stock of USA made 211, still around today. I have seen these 1940's USA tubes last extremely much longer than Chinese 211. Like 20x longer or more. So why is that? 1940's 211 (also called VT4C) should last 10.000 hours and can be regenerated successfully several times, as even written on the by pack information sheet by General Electric, inside original tube boxes. Chinese 211 however, I have seen many fail after 500 hours, or best way a thousand hours. This difference is enormous, and to my opinion related to low class carbon materials, not properly cleaned.
Even if above points Nr2 and Nr3 can be overcome, point Nr1 remains. So for this reason you will never see a carbon plate tube with Barium Oxide filaments at Emission Labs.
Continue HERE for the data sheet of the one and only real 300B-MESH