DT25 Tube Bias in DT50 / DT25 Posted December 15, 2016 Hey everyone, This is my first time swapping out tubes. I ordered a matched set of EL34's with 24-hour burn in. I put the new tubes in, let it sit in standby for a few minutes, took it off of standby. I measured the bias on V2 and adjusted to 25 mV, I then measured V3 and was reading 35mV. I adjusted it to 25mV and then measured V2 again and it was 15mV. So basically I have a 10mV difference between the 2. I assume this is not normal. Any way to adjust them independently? As far as I know there is no way to adjust them independently. I did the same thing you did when I had an issue with sound fading off after 15 minutes of play which culminated into no sound all together. All the fuses checked good so I ordered an ultra matched set of EH's and after making the bias setting had 4mV difference and I thought that was abnormal. I was thinking the tubes should read the same but I suppose they don't most of the time. I'm not sure what the bias was new since I wasn't equipped to check it. I had another problem anyway which Line 6 fixed.