Speakers connected - check. Multimeter connected - check. 0.65 VDC - check. The four 6H30's can go into any of their respective sockets. After this setup play some music for 30 minutes. Keep the meter connected. Then check the meter reading and re-adjust to 0.65 VDC. Play some more music again for 30 minutes. Check meter and re-adjust if necessary. Then, for the third time, play some music for 60 minutes, check meter and re-adjust if necessary. I recommend checking the bias again after 24 hours use. Then after seven days to see if it has remained stable.
Re-tubing my Audio Research Ref 110
After taking advice here I've ordered 8 matched KT120 valves and 4 6H30 (getting difficult to get as can't import from Russia now!)
I've read the ARC instructions but want to make sure I've understood correctly - don't want to blow it (or me) up.
I turn it on for 15-20 with the speakers connected but no signal going through (so disconnect the source or mute?)
The I attach the multimeter, one to the yellow and one to the black beside each pair of tubes/valves. Does it matter which wire goes to which?
Then I turn the blue screw (guess the one adjacent to each set of the two tubes is the one?) The manual says I need to adjust to get 0.65V DC on the meter but that's for the original spec 6550 tubes. Is it the same for KT120 tubes?
And do I just stick the other 4 x 6H30 tubes in - do they need anything?