Part1) Important 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.
This is serious warning for faked 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. It should be clear, that the special sound of mesh tubes, is not reached with solid pate tubes. It should be clear that the mesh sound is not achieved by glow light shining trough the holes, but by low resonance of the wire structure. 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 the text being "not so nice" but I see no reason to protect people that fool others. To speak openly about this is more beneficial to my opinion. So this is what we do here.
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 Beauty", and inside is the same old tube system by the SHUGUANG factory. The Chinese just produce what the markets desire, so everybody is happy. There is nothing against creating happyness. 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. This rule says, do NOT try to invent something new, without looking back into history first. Tubes production was at it's top from 1930...1960 with HUNDREDS of factories producing tubes and 100.000 experienced and qualified design engineers trying to improve products and processes. it was THE MAJOR industry for decades, and world dominance of complete nations were determined by tube technology. In this environment, 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 RADAR magnetron tube, 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.
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. You must ask yourself this question, since CARBON is even cheaper to manufacture. But you see, nobody ever used this lower cost technology. Why would that be? So when you say CARBON anodes are better sounding, it means 100.000 Engineers of the past were wrong.
From the experiments at AVVT, 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 evaporation gets attracted by the Filament, and colors it dark. I could see this by opening a defective CARBON 300B. The filament should be cleaner than clean for good lifetime! Not dark coated with some layer of "whatever". I say whatever, because likely the carbon even reacts with the Barium, or some of the other chemicals deeper inside the cathode. Specially when so hot, chemical reactions can take place, and electrolytic effect does the rest. Overall, with this contamination on the filament, by some Carbon composition, or whatever I have to call it, such tubes have lower lifetime. We have seen, contamination starts to begin already after 500 hours. The temperature of a BARIUM OXIDE filament is not high enough to remove this by evaporation. This 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 NO good way to connect an electrical 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. The monkeys here are the shipment companies. They drop and kick the shipment boxes like old potatoes, and this can 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: The price, the price and the price. So they can never withstand the temptation to try cheaper 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 lower class materials of new production.
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