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Post by infernalservice on Jul 14, 2010 1:10:17 GMT -5
Hey everybody,
Does anyone know what Scott recommends for the bias on a KT88 loaded Nitro? I run mine right around 49ma and just went through a pair of Sinos in about 5 months (I only run at half power). The Sinos started causing a really loud hum and one was way hotter than the other.Before that I had a pair of JJ's that only lasted about 6 months.
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ksefan
Junior Member
Posts: 69
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Post by ksefan on Jul 14, 2010 13:47:50 GMT -5
Having you said that... lower then 49 then hahaha
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Post by sasquatch on Jul 14, 2010 17:23:49 GMT -5
The general rule is (watts ÷ plate voltage) x .7. Most recommend using 35 watts for KT88's. I'm pretty sure my QR's plate voltage was coming in at around 480-485 when I installed a new quad of Sino's and biased the amp. That being said, your formula should be...
(35 ÷ 480) x .7, or .729 x .7 = .51 or 51mA.
I think with the KT88's you should have been ok at 48-49mA. Check with Scott on the Nitro's plate voltage and verify this formula is ok to use with a Splawn. Most recommend using 25 watts for EL34 tubes which is what I put in my QR. Using this formula I came up with 36mA, but Scott recommended 30-32mA so I set it to 32. Again, since you were at 49, I think you should have been ok.
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Post by infernalservice on Jul 14, 2010 19:53:06 GMT -5
I have heard that Splawns sound better ran a little colder. I can't remember for sure but I think my plate voltage was right around 497-500. I think the JJ's might of had a little help dying an early death because it happened shortly after I moved. The tubes were out of the amp during the move, but I still have a feeling it helped them die young. The Sino's probably went just because of how much I played the amp after I loaded them in. They are my favorite KT88's right now.
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