|
|
Post by MetalHeart on Sept 11, 2010 14:41:18 GMT -5
I bias my SuperComp at 51 ma, and blew a tube 3 days later. Think I should call Scott?
|
|
|
|
Post by DonaldDemon on Sept 13, 2010 9:47:43 GMT -5
I bias my SuperComp at 51 ma, and blew a tube 3 days later. Think I should call Scott? You have 4 KT88's in your Supercomp? I need to call Scott myself because I am having some issues. Maybe my bias is to high. This sh!t is confusing.  |
|
|
|
Post by MetalHeart on Sept 13, 2010 16:36:29 GMT -5
I bias my SuperComp at 51 ma, and blew a tube 3 days later. Think I should call Scott? You have 4 KT88's in your Supercomp? I need to call Scott myself because I am having some issues. Maybe my bias is to high. This sh!t is confusing. Nope just two for right now. Got two more coming plus the replacement tube. The old Gold Lions were known to handle high voltage. I hope I just got a bad one. 51 ma for KT88s is not high at all,if you do the math. Thats around 60%,right?  |
|
|
|
Post by DonaldDemon on Sept 14, 2010 15:43:49 GMT -5
You have 4 KT88's in your Supercomp? I need to call Scott myself because I am having some issues. Maybe my bias is to high. This sh!t is confusing. Nope just two for right now. Got two more coming plus the replacement tube. The old Gold Lions were known to handle high voltage. I hope I just got a bad one. 51 ma for KT88s is not high at all,if you do the math. Thats around 60%,right? For a quad it came out to 51 ma for me but with just two tubes it should be different maybe? |
|
|
|
Post by MetalHeart on Sept 14, 2010 17:40:09 GMT -5
I bias the pair in 50 watt mode,when I get all 4 I will bias in full power 100 watts. Still should be 50 to 52 ma at 60% |
|
|
|
Post by DonaldDemon on Oct 17, 2010 18:10:01 GMT -5
My amp has been making a lot of noise (squealing and feedback) so I decided to recheck the bias after a month or so. It turns out the bias is at 58ma and I can't get any lower out of it with the bias screw. So either I deal with the super high bias or buy yet another set set of PT's rated at a lower wattage...or I guess change the bias resistor. I think I might just deal with the noise unfortunately. I can't afford more tubes and I don't want to have to start changing components in the amp when all I need is lower rated tubes. When bias drifts over time does it usually drift down or up? I hope running the tubes that hot won't hurt it. |
|
|
|
Post by MetalHeart on Oct 17, 2010 18:22:42 GMT -5
That sucks Dennis. Josh at Splawn said not to bias above 50ma. But I bias mine by ear and 52ma I think is where I bias mine this last time. That or 51 Fook it , its sounds the best there. |
|
|
|
Post by DonaldDemon on Oct 17, 2010 19:34:27 GMT -5
That sucks Dennis. Josh at Splawn said not to bias above 50ma. But I bias mine by ear and 52ma I think is where I bias mine this last time. That or 51 Fook it , its sounds the best there. That's what someone else on here (phlim?) said too. It's hard to get a definite answer. Some people say KT88's have a max dissipation of 42 watts and some say 35 watts. That makes a big difference in the calculation. I was planning on just going down to 50 because the amp sounds a little muddy but it looks like I am stuck where I am at until I can buy tubes again. Which KT88's you using again? |
|
|
|
Post by MetalHeart on Oct 18, 2010 16:14:57 GMT -5
Right now,Gold Lions. I have a pair of Cryo treated SEDs but like the GLs a little better.
|
|
|
|
Post by DonaldDemon on Oct 18, 2010 21:05:55 GMT -5
Right now,Gold Lions. I have a pair of Cryo treated SEDs but like the GLs a little better. Cool. I have the Penta Labs which are similar I think |
|
