Post by mossback on Jul 5, 2008 8:53:14 GMT 7
James,
If the sound is good at 1.56VDC just use that value, done. Check the bias now and then and watch the plates for red spots.
I do not know why the JJ KT77 liked the higher bias but they did work well at that operating point.
That 6550 is an heavy duty tube and can take a beating from what I have read. I had a quad of GE 6550 that I tested in my Citation II and the HF60. I liked the KT77 or KT88 better. Others have said that tube is outstanding in Heathkit gear. Mike loves them in Heathkit.
If the sound is good at 1.56VDC just use that value, done. Check the bias now and then and watch the plates for red spots.
I do not know why the JJ KT77 liked the higher bias but they did work well at that operating point.
That 6550 is an heavy duty tube and can take a beating from what I have read. I had a quad of GE 6550 that I tested in my Citation II and the HF60. I liked the KT77 or KT88 better. Others have said that tube is outstanding in Heathkit gear. Mike loves them in Heathkit.