Julia
Well-known member
As I said elsewhere.... holy glass, batman!!! :shock: These things are huge. These are Ruby 6550C that arrived today from Doug's Tubes.
I let them warm up for about 15 minutes with all the vols and gains at zero. Then did the biasing. I was going for 39.5 or 60%, but they kept drifting a little higher. So I relented and found where they wanted to go. I got them to stabilize from left to right:
V1 = 40.4 mV
V2 = 41.4 mV
V3 = 40.8 mV
V4 = 40.8 mV
They held it for about an hour before I shut it down. Wish me luck with this set.
I don't know how you guys get KT-88s in these amps.
I let them warm up for about 15 minutes with all the vols and gains at zero. Then did the biasing. I was going for 39.5 or 60%, but they kept drifting a little higher. So I relented and found where they wanted to go. I got them to stabilize from left to right:
V1 = 40.4 mV
V2 = 41.4 mV
V3 = 40.8 mV
V4 = 40.8 mV
They held it for about an hour before I shut it down. Wish me luck with this set.
I don't know how you guys get KT-88s in these amps.