Attention: Tubes ending on "M" are mesh plate tubes.
Note about storage of AVVT tubes: It seems the storage time of those tubes is minimum 10years, and after that period, all they need is a short warm-up and you can store them for another period. (we write this in the year 2010). It seems at this moment you need to pay no special attention to all AVVT branded tubes. Just plug them in, and that's it.
The VAIC-VALVE tubes that are 10...15 old now, may be going to need a (professional) burn-in before first use. (Such a burn-in you can not do yourself). After this burn-in they are ready for another such storage period.
Does that mean older tubes are bad? No! But... you need to take care of the following:
If the tubes were stored longer, like 10 years or more, they might need to woken up in a controlled way. This is normal, and you should not be disappointed if such tubes do not test very strong, right out of the (NOS) box. If they test at 70% or more DC current (the most important test for any tube) you can use the following procedure, to improve them.
If lower than 70% they most probably can be brought back to life by an experienced person, provided the tubes are really NOS, and you have not been fooled with used tubes put back in the original boxes.
If a NOS tube is initially (at a very short test) at or above 70% DC current, here is the way to go:
THIS PROCEDURE IS DONE ON ALL AVVT TUBES WE SELL
All AVVT NOS tubes I had so far, passed he above procedure perfectly. Most VAIC-VALVE also, but some needed a more professional wake-up procedure, and then were very strong again.
The above process is a very good idea for any NOS tube that has been sleeping very long. Then they can be safely stored again for another period. In case a tube was stored longer than 10 years, you may find the transconductance is 30% reduced or more. So you must verify the original old DC test data, if available. If DC test data got lost or never existed, you have to work with transconductance data, but that is not as good as working with DC current data. In case you observe lower DC current, you will also have lower transconductance, but how much lower nobody can tell.
Remember, this is only the case when the tubes were stored from the beginning, and never used ever since. This is nothing unusual, and it is almost normal with NOS tubes, like 6SN7. I bought a NOS pair WE-205D, that was only testing "fair". After re-burn in, they were exactly like on the data sheet again. When the tubes are used every now and then, they will just stay in good condition much longer than NOS tubes. It can all be explained, but that is beyond the scope of this page trying to do this. So here comes my old saying again, that good "used" tubes can be better condition than random NOS tubes that have been stored for 60 years, and never used ever since. I also had NOS 227 tubes from RCA that could not be brought back to above 60%. These had been sleeping for 80 years, and they would have been fine of somebody just switched them on three or four times during that 80 years. However, it was not done, and they were lost. This was such a shame. The first time I opened the boxes, the boxes fell apart in small pieces, so the tubes were really never taken out. The tubes came out looking so nice, but test values were very weak, and I could not repair them.
IF THE PROCEDURE WILL NOT WORK. There are no general rules what to do now. It requires experience with the particular tube type, and understanding of the processes inside the tube, and these are many, and not the easiest to understand. If you have a "transconductance only" type of tester, you can not say very much about the tube condition, unless transconductance is very strong. When this has happens, do not use the tube, or your attempts may make things worse, or damage the tube permanently. Such a tube can be brought back into good condition, when you have the equipment for it. You can send it, and we can do that for you. So far, this seemed only necessary with the Vaic-Valve 52B's from around 1996, but it will probably also be necessary with other tubes when the years pass by, and older NOS tubes are found.
Replacements: EML grew on the old roots of AVVT. There is probably nothing that remained unchanged, and lifetime and quality of EML is definitely at a very much higher level. In any case, we deliver replacements for most AVVT tubes, and when we have time and resources, we can repair AVVT tubes of the type 32B and 300B.
EBAY: If you buy on Ebay, I have never seen AVVT tubes for sale there, used longer than just 200 hours. It is always the same. So generally you should have strong distrust, because where have those tubes all gone, with 2000, 4000, 6000, etc hours on them? Somebody should have those somewhere and try to sell them. But no, why do we see always like new AVVT tubes Ebay? Do you really think all people ever since, bought those only with the clear intention to store them for 20 years, until you look in Ebay? Buy such only if guaranteed to be good on arrival. Otherwise keep your fingers off.