bluesboy Posted April 23, 2006 Share Posted April 23, 2006 I just got my first tube amp. It's a Fisher X-100 that I got off a guy on Audiogon. I hooked it up to my homemade K-Horns and the sound is great. However, I started looking at the 12ax7 preamp tubes and noticed that one was a Russian tube another was Chinese and the other three were unmarked. So I decided to buy a set of EI Yugoslavian tubes from a guy on ebay. When I plugged these in three of them didn't light up. So I took the two EI's that worked and plugged them into the sockets where the other EI's didn't work. They didn't work there either. Why do the old tubes work in those three sockets and the new EI's don't? Don Quote Link to comment Share on other sites More sharing options...
intotubes Posted April 23, 2006 Share Posted April 23, 2006 Maybe you got burned? Do the "new" tubes work in any of the 12AX7 sockets? Quote Link to comment Share on other sites More sharing options...
bluesboy Posted April 23, 2006 Author Share Posted April 23, 2006 Yes the the new tubes work in two of the five sockets but not in the other three sockets. But the old tubes work in those three sockets. Quote Link to comment Share on other sites More sharing options...
rockbobmel Posted April 23, 2006 Share Posted April 23, 2006 Some older tube pins are larger in diamater than the newer tubes, so try to compress the little tube pin receptors with a small jewelers screwdriver or knife tip. Then insert and remove the new tubes two or three times to scrape off oxides in the sockets. There is some tube pin cleaner out there, but this should remedy the prob. Quote Link to comment Share on other sites More sharing options...
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