My Fisher X100B has been serving daily duty for a little over a year and has sounded awesome (after all it is a former @rufleruf unit, it already received a recap and a replacement OPT as noted here: https://audiokarma.org/forums/index.php?threads/x100b-receives-400-output-transformer-swap.768263/).
It's started distorting on the left channel via either the 8 or 4 ohm taps at any volume. For a little history ... over the last year, I had been using it with appropriate, efficient speakers (Cornwall, Altec A7, JBL L200B) until recently. But recently I've been using it to power harder to drive speakers, starting with Magnepan MG-IIA via the 4 ohm tap. They sounded good though.
Then, a few days ago, I picked up a pair of Thiel CS1.2 to see what the big deal is (glad I did, they are awesome), but noticed that the left woofer was distorting badly playing Radiohead Amnesiac. I noticed some glue on the rubber surround had come undone, so I thought that was it. After re-gluing it, the left speaker was still distorting badly. So I hooked the Thiels up to my MC7300 and they sounded fine (OMG they sound GREAT).
Putting the Magnepans back on the Fisher, the left channel distortion is still there. So I think it's pretty conclusive that there's a problem with the left channel.
... now what? I'm new to diagnosing tube gear. I've read that bad output transformers can cause distortion, and that the output transformers in X100B / KX100 go bad commonly (and, one already did go bad in this unit). Should I first measure the output transformer? Or do bad tubes also cause this kind of distortion (I imagine they do) - should I first swap the tubes around?
Thanks in advance for any guidance.
It's started distorting on the left channel via either the 8 or 4 ohm taps at any volume. For a little history ... over the last year, I had been using it with appropriate, efficient speakers (Cornwall, Altec A7, JBL L200B) until recently. But recently I've been using it to power harder to drive speakers, starting with Magnepan MG-IIA via the 4 ohm tap. They sounded good though.
Then, a few days ago, I picked up a pair of Thiel CS1.2 to see what the big deal is (glad I did, they are awesome), but noticed that the left woofer was distorting badly playing Radiohead Amnesiac. I noticed some glue on the rubber surround had come undone, so I thought that was it. After re-gluing it, the left speaker was still distorting badly. So I hooked the Thiels up to my MC7300 and they sounded fine (OMG they sound GREAT).
Putting the Magnepans back on the Fisher, the left channel distortion is still there. So I think it's pretty conclusive that there's a problem with the left channel.
... now what? I'm new to diagnosing tube gear. I've read that bad output transformers can cause distortion, and that the output transformers in X100B / KX100 go bad commonly (and, one already did go bad in this unit). Should I first measure the output transformer? Or do bad tubes also cause this kind of distortion (I imagine they do) - should I first swap the tubes around?
Thanks in advance for any guidance.
