david chau Posted March 5, 2014 Posted March 5, 2014 Hello All, I just recently purchased a set of 4 Black Sable SED KT88 tubes. I went to switch the four tubes with my old ones and I noticed one tube after a while (i.e. 1 minute) was glowing blue and then the plate was glowing red down the middle. I have tried to switch it around different plug ports and when going to rebias my tubes to 0.3V, I cannot seem to rebias that one tube, my meter reading just keeps on increasing past 0.3V until it just reaches max. Does anyone know what is wrong with my tube - is it faulty? I have currently replaced it with one of my old tubes in its place for the time being. My amp is an Audio Space AS3.8i. Thank you. David
ehtcom Posted March 5, 2014 Posted March 5, 2014 Hi David. Yes, the tube is faulty. Most likely an internal short, or pin 5 (grid) has come loose internally. Happy to test it for you. I'm located near Rye on the Mornington Peninsula. Regards, Earle. 1
Sierra Posted March 5, 2014 Posted March 5, 2014 (edited) As Earle said ... it will be a faulty valve. Bummer as it sounds like it's an expensive set of tubes you have. Did the tube set come with any length of warranty? Edited March 5, 2014 by Sierra
david chau Posted March 5, 2014 Author Posted March 5, 2014 That's a shame. I was looking forward to a new set of tubes... I will give the guy a call and see what he can do. I take it the tube cannot be fixed internally?
Sierra Posted March 5, 2014 Posted March 5, 2014 Nope ... a faulty tube is a throw away unfortunately.
david chau Posted March 6, 2014 Author Posted March 6, 2014 Anyone got a set of 4 tubes in Adelaide for sale...?
Owen Y Posted March 10, 2014 Posted March 10, 2014 A bit late comment sorry but... It's a good idea to reduce the bias current before plugging in new tubes - in case the new ones start running a lot hotter, then you can wind them up one by one. Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/
david chau Posted March 20, 2014 Author Posted March 20, 2014 thanks for your reply owen! i ended up getting the broken one replaced and i got some spares. biased and good to go now, one happy champ.
LogicprObe Posted March 20, 2014 Posted March 20, 2014 So...........how do they sound over the others?
Owen Y Posted March 20, 2014 Posted March 20, 2014 Good work Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/
Recommended Posts