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In Reply to: Re: 6AS7 life posted by acres verde on February 3, 2005 at 13:42:43:
But I have heard of no concensus on 750 hours! A lot depends on how the tubes are treated, but treated properly they will much longer then that!
Follow Ups:
Ralph, please throw me a bone here, treated properly, what does that mean? How can I treat them properly, and if I do treat them properly what can be expected or what is the norm. Twenty+ years using this tube you must have some kind of life expectation. Ralph thanks again for your expertise..........Bob
Hi ! I'm running an OTL since 8 years now with 6080WA from Radiotechnique . These were given to last 10000 hours on continuous prof and mil service . I've still seen on rec.audio.files that soviet reg tubes like 6AS7 and 6C33 were guaranteed for the FIRST 750 hours . All prof systems had mercury wetted counters so that preventive change could regulary made .
On OTL service, the tests i made on non-soviet ones make me think that with 50 mA / anode, life span can reach 20000 hours ! ENJOY GUYS ! Pierre
I've been using dreaded Sylvania 6AS7GA tubes, the straight bottle types, for two years now. I think I've shut the amp down maybe six times during that whole time, and no problems what so ever. I've left the amp running on purpose because I wanted to see if the tubes really are as bad as everybody on various forums say. They seem to be living just fine. To me the Sylvanias are more detailed than the Sovteks. I have a set of Sovteks that I try every now and then because they have the cool looking coke bottle shape, but keep going back to the US made tubes because they sound better.
We seem to get about 10,000 hours if the tubes are treated right. Various things can shorten the life: factory defects, shipping treatment, dust, fingerprints, over-bias, difficult loads with high power, no warmup in Standby, that sort of thing. Of course, these are things that affect all power tubes, not just 6AS7Gs.So anyway, once that is all figured the tubes will do 10,000 hours, which is actually typical of a lot of power triodes (that run moderate heat). In practice we have seen people do better and worse.
Try at least 5x that number, and probably 10x. I have Sovtek 6AS7s in my MA-2s that have been run pretty hard for 6+ years and are still strong. (Note: we're only talking about the Russian 6AS7s here. All bets are off with US brands.)One recommendation from the old ASOG forum for helping the life of 6AS7s is to burn them in for 48 hours with power to the heater elements only (i.e., on standby in an A-S amp). There will be some variability due to manufacturing tolerances, but if they get past 90 days, they seem to run forever.
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