So after reading all of the praise on the BNB kt66 gold lion tubes I decided to get a quad of them to use in my st70. Got them today and gave them a go. They biased alright and I set them all to 430-440 to start with. I left the amp playing for a while and didn't notice any problems. When I turned out the lights to look at them in the dark I noticed some rather strange things.
1-The plates were glowing dull red in some areas This is only noticeable in the dark. The KT88's I have only glow like that if the bias is set to something crazy like 900+ on that one tube.
2-Looking through the plates of the tubes there are some weird blueish purple streaks between the plates or something. At higher bias like 450+ they put out a noticeable amount of light from the tubes. These are NOT like the blue glow from the glass on my sovtek kt88's from electrons hitting the glass in areas.
I promptly turned the bias all the way down to 380-390 per tube and the plates were still glowing dull red in the dark. Tried switching it to triode mode to further reduce the the power to the tubes. Still glowing red.
It actually plays music alright, but at idle with the preamp turned off one channel has a noticeably louder buzz or some kind of noise. With the kt88's back in they're both extremely quite at idle.
Also the power transformer is getting hot ?faster? than with the kt88's. Surely something is wrong here.
1-The plates were glowing dull red in some areas This is only noticeable in the dark. The KT88's I have only glow like that if the bias is set to something crazy like 900+ on that one tube.
2-Looking through the plates of the tubes there are some weird blueish purple streaks between the plates or something. At higher bias like 450+ they put out a noticeable amount of light from the tubes. These are NOT like the blue glow from the glass on my sovtek kt88's from electrons hitting the glass in areas.
I promptly turned the bias all the way down to 380-390 per tube and the plates were still glowing dull red in the dark. Tried switching it to triode mode to further reduce the the power to the tubes. Still glowing red.
It actually plays music alright, but at idle with the preamp turned off one channel has a noticeably louder buzz or some kind of noise. With the kt88's back in they're both extremely quite at idle.
Also the power transformer is getting hot ?faster? than with the kt88's. Surely something is wrong here.