Quote: Originally Posted by quarzo /img/forum/go_quote.gif Yes, absolutely shure. They light but don't shine very much. Just a bit on the bottom and on the top Quote: Originally Posted by quarzo /img/forum/go_quote.gif By the way, I had the power source made so it's not bought from a dealer. I get 46v instead of 48 and I' starting to worry about the amper measure but i have no idea how to use the tester to get that value. I'm a beginner sorry Quote: Originally Posted by UKToecutter /img/forum/go_quote.gif You will only see a slight glow from the heaters. Most of the people here have put LED's underneath their valves, so don't be fooled by how bright they look. Actually most 19J6 give out a considerable amount of light. There are some, though, that have enclosed heaters and those will shine a bit on the bottom and on the top. They work just as well in the circuit. As to the power supply it's ok if it's a couple of volts off. My Cisco supply puts out 47 volts. The current that the supply puts out is a little bit more important; but I'm guessing if your amp turns on (meaning the tubes light up) your supply is quite probably coping with the current demand ok. cheers!