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Cary SLM-100 Bias in Triod Mode

Does anyone own a pair of these amps? The manual states a bias of 175ma but I believe this is for the default UL mode. Which, I think, would explain by I keep blowing the tube fuse despite my tubes testing as "good." Wish I could bias each tube individually. Also, another symptom, related or not I don't know, is that sometimes the bias doesn't stabilize for about 10 minutes. It just keeps creeping up. Does anyone know what might cause this?
pawlowski6132
listener57
730 posts
 
In addition to getting your info here, you can call Cary Audio for their analysis, and advice. One of the manufacturers that provides best customer service even when you are not the original owner.
sns
3,657 posts
 
Pawlowski, I used to own the SLM 100's. I recall biasing them at 150 per Cary's instructions. I think this is especially important if you're using EL34's. The rising bias could be due to a bad bias circuit resistor. I had that problem with one of my monoblocks when it kept on blowing ouput fuses. In my case I also ruined some output tubes. If your tubes have glowed cherry red prior to fuse blowing you may have some iffy tubes.
pawlowski6132's avatar
pawlowski6132 OP
592 posts
 
SNS, thanx. In fact, one set of tubes ddid get all excited (really bright) before the fuse blew. I changed all eight power tubes and was OK for a few days. Since then, with the different (not NEW) tubes experienced blown fuse twice. I didn't notice them getting bright, although they may have and I didn't notice, but did notice the creeping bias. Thanx for the thoughts.
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