greg928gts Posted February 6, 2004 Share Posted February 6, 2004 I just got my 8417's back from being tested by Mike Sanders at Quicksilver Audio. He's a really nice guy. They were very well equipped to thoroughly test my 18 8417's that I had been accumulating. I got several from the guy I bought my QS's from and a bunch more off ebay. Out of the 18, 1 was marked bad, 1 was marked arc-over, 1 was not marked at all, 4 were marked weak, and the remaining 11 were put in boxes and a number corresponding to the strength of the tube was put on each box. Here's what I have: quantity - strength number 1 - 30 1 - 47 2 - 51 1 - 57 1 - 60 1 - 67 1 - 70 1 - 77 2 - 78 It's obvious that I'll put the two 78's in one of my monoblocs, but what pair should I put in the other monobloc? Should it be the 1 - 70 and the 1 - 77, or should it be the pair of 51's. Life is funny sometimes, idn'it? Greg Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 6, 2004 Share Posted February 6, 2004 The 2-51's pair, Dude. I am assuming that you are talking a matched pair here. If not, nevermind... The rating is not referring the output capability of the tube(s). It refers to the electical parameters (biasing) required for proper operation of the tube(s). In this case, the pair with the closest numbers is the correct choice. Therefore, you should expect to adjust the biasing "less" to balance the matched pair of tubes and experience a better "match" output between the tubes, that is, each tube shares the load equally so that one isn't doing more than the other, etc. Biasing the tubes is supposedly easier when closely matched parameters are used. I hope I put that together in a sensible manner, it is a complex subject. DM Quote Link to comment Share on other sites More sharing options...
greg928gts Posted February 6, 2004 Author Share Posted February 6, 2004 Yes it is a complex subject, and believe me when I tell you, when it comes to electronics, it doesn't take much for you guys to be talking over my head. I only have one bias control on each amp, so I'm assuming I do not have control over the tubes individually. My gut tells me to put the closest matching pair in the other amp, not necessarily the strongest ones. But I don't really know how relative the difference between the 70 and 77 is. It might be so insignificant that it won't matter, in which case I should use these stronger tested ones. If it's the type of thing where in a month, the matching 78's are likely to be 68 and 75 due to wear, then that would help me make up my mind too. Might as well go with the strongest ones. I just don't know. Greg Quote Link to comment Share on other sites More sharing options...
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