Bias adjustment
I got this cheap Woods multimeter at Lowes a few years back for my Cary SLI-80...now use it on my SLI-80HS. Very simple and about $20. https://mobileimages.lowes.com/product/converted/032886/032886958441.jpg?size=xl |
@richfrank Just to confirm what I think you said, the Cary tech insisted your bias reading was incorrect even though they didn’t have the amp in their possession to dispute your reading? Weird. Yes, the manual says 75mA but honestly 80mA shouldn’t be an issue. How old was your amp? Were they offering to perform warranty work and that’s why they said to ship it to them? If in fact "bias neglect" wasn’t the cause of your power tubes burning out why wouldn’t you want them to look at it and figure out what the REAL problem is? When I bought my SLI-80HS from them last fall it arrived with a buzz that seemed to be related to a wonky triode/UL toggle that I suspect was damaged during shipping. They paid for shipment both ways and fixed the issue 100% at no cost to me. The amp is a sweet little unit that I now run with KT-120s and some 60s NOS 6922 Mullards. I feel like they handled my situation just fine and would recommend them. Just another data point for what it’s worth. |
So it appears that the Cary tech was correct. Your readings were wrong. I have to say, due to poor communication with the manufacturer you end up proclaiming that you'd never buy a Cary product again if your life depended on it despite the issue was user error as Cary correctly pointed out. Ugh. I didn't even think that anyone would consider setting bias with music playing. Yes, you want your speakers connected when you check bias but DO NOT play music while measuring. The whole point is that you're checking the bias while the amp is at idle, and running a signal through the amp is not idle. Depending on how you had the volume knob set you could have easily been running the amp 50mA or more ABOVE idle when you were measuring and hence frying your power tubes. |
