Thank you both for the responses. Much appreciated. Question about the matched voltage of the tubes. The amp manufacturer says to bias the tubes to 40 mA and the tubes I received were a matched set with 30 written on them. What should I bias them to (I biased them to 40 on my meter)
Bad Tube?
Hello,
I am new to tubes so forgive this question if it seems silly. Last month I picked up a pre-owned Muzishare x7 integrated tube amp. I enjoy the sound very much, and it is functioning fine, but I read that upgrading the stock tubes could improve the amp even more. I purchased a matched quad of Shuguang kt88_Z black treasures power tubes as well as a pair of electro-harmonix 12ux7's and a Gold Lion 12ax7 (I haven't touched the rectifier tube). I dropped my bias to zero on all the power tubes, replaced the tubes, and re-biased the power tubes. They sound much better than the originals immediately. Still detailed but weightier, if that makes sense. My problem is, after 1/2 hr, I noticed audible static from my right channel. Checking the V4 bias meter showed that the voltage was not settling at 40 (needle is fluctuating between 30 and 60). I zeroed out the bias on all the tubes again and after letting everything cool off for a bit, swapped my V4 tube into the V1 position (left channel). Starting the tube up and biasing them all again, I now hear static in the left channel and the V1 bias meter is not stable. I have only 1/2 hr on the tubes. Is that tube bad? or will it settle in? Or did I do something wrong?
Thanks so much for helping a new tube enthusiast out!
Ed
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- 14 posts total
- 14 posts total