i have read all and it is really interresting
i would like just to tell me a story between nos and brand new tube
i trust in nos but you must know what you buy or you will be not happy
beguin of the story
i have buy this fender reverb reissue from 93 us model 110 v with the 220 110 v transformateur
the guy give with this spare tube
in it i have a 12at7 rca ,a fender 12ax7 and a 6v6 tad
it sound good but i have a hiss coming from the verb ,when the mix was at 3 and you push the volume on amp a larsen appears ,i swap with the tube in my deluxe and found it is the 12at 7 rca was the trouble
then i go to buy some tube for spare and i find some groove tube (12ax7 and 12at7 )at a musical store and the store work with a tech then i visit him and buy also tube 12ax7 EH and 12at7 syvania (nos) for sure
result the groove tube works don't know for how much time but my trouble is solved i can reput the tube in my deluxe that i have swap to try
the 12at 7 don't work ,i call the guy and (it is an asshole to be short) cause he explain me no refund on tube i could have make lot of thing with ,bla bla then i go to him and tell him that i have swap with other tube and it is his tube that doesn't work (the trouble is no reverb on my unit ,the 12at 7 is the tube for the tank then it is the culprit)
then he give me another 12at7 syvania (same looking ) and you know what ,it doesn't work too ,then i have visit another technicien to make repair my bass amp and ask him to test this tube
answers he have try in his head(he repair and build amp) and the tube don't work too
all of this to say ,if i can i will buy totally new tube cause i think it is rare to have one not working ,for the nos it is really risky cause lot of guys sale old tube ,not tested ,or maybe worst old tube out of life they have find in a box that come from an old technicien and this box was the box where not working tube where stock
don't know for you guys but for me in France there is not lot of good tech who can test tube ,and if you put a dead tube in a good working amp the damage could be grave for the amp ,shortcircuit ect...
i have seen lot of auction for tube but i haven't the knowledge to look at ?
on this 6k6 the sylavania have a label writen on 38- 45 like the RCA ,but the third is Ge but no marking and more over no 6k6 marking on it then i don't know what it is ?
i have swap the 6v6 tad for the sylvania 6k6 to my taste the sound is better ,more hot
i see lot of auction for nos ,full tested ,90 % of life , or result in ma but where do you find chart to knew if the tube is good enought to be use ?
for exemple a 12at7
it is a rare saler who tell the caracteristics
polard = -2,v
anode =250 v
10 mA-10 mA correspond à = 100%
10,8mA - 9,8 mA
10,0mA - 10,0 mA
cause lot said tested and you buy something you don't know if it is nos or uos or worst ready to dead
sorry for the book
also i have an old EL84 Mazda in a old radio can i try it in my little vox ac4 without too much risk ? ,if it work it is ok ,if it is not working will it blow something in the amp?