Im using them with a conrad - johnson Classic 2SE and they are a great combo.
The bias LED just barely illuminates when it is drawing around 40mA . I put a VHT bias tool between both tubes and the amp and Mike recommended 50 mA which is achieved once the LED is bright. So my meter confirmed the LED’ s are pretty good as a "meter". He told me when I first got the amps that if you can look directly over the LED in low ambient light , that when the LED just starts to glow, you are biased conservatively for longer tube life. QS support is top notch, one of the best I have ever encountered.
As far as a tubes decline indicator, I just press the button every once in a while to make sure the bias doesn’t run away. One thing about these amps ,tjey hold their bias rock steady if you use quality matched tubes, you really only need a matched pair but why not get a matched quad for consistency through both units.
Made in USA , sound great, reliable.....
The bias LED just barely illuminates when it is drawing around 40mA . I put a VHT bias tool between both tubes and the amp and Mike recommended 50 mA which is achieved once the LED is bright. So my meter confirmed the LED’ s are pretty good as a "meter". He told me when I first got the amps that if you can look directly over the LED in low ambient light , that when the LED just starts to glow, you are biased conservatively for longer tube life. QS support is top notch, one of the best I have ever encountered.
As far as a tubes decline indicator, I just press the button every once in a while to make sure the bias doesn’t run away. One thing about these amps ,tjey hold their bias rock steady if you use quality matched tubes, you really only need a matched pair but why not get a matched quad for consistency through both units.
Made in USA , sound great, reliable.....