tube bias

WOW that is high for a single KT88, that a pair? at 110 MAX
and 90 for 8417, The KT88 again at 80ma, that has to be a pair.. I think I'm right.. Tell me if I'm not... :-).

28-45 ma covers almost ALL power valves.. I use.. 6V6, 6L6, EL34, KT, 66, 77, 88, 90. and 6550s. You go higher than that.. Tube life goes WAY down..  You should be able to get 2 years at 20 hours a week...2080 rule.. 40 hour work week...1 year...

Turn on cycles play a part after 20 hours a week.. 10, 5 so on. 4 years pull, inspect and check... Time to be a little more aware..

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noromance5,041 posts01-17-2021 11:26amEmail them. I’ve biased amps for years using the red-plate method. Dim the lights. Power up. Adjust so that the tube anodes (plates) just start to glow red. Now back off a little so the glow fades away.

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I thought I knew something.. Petty clever. I use a dark room to see problems in my valve amps.. Sure shows any little problems..

I use to do the same on Equipment, chasing a LVDC ground issue, or direct short to ground.. Breaker popper in certain positions.. The dark is your friend..

Regards

@harley52
Deleted prior post linking to the Q&A section the QS site. Update: Found more updated manual information on the newer Silver 88 monos, which coincides more closely to your Silver 70s with KT88 tubes. The Silver88 manual shows 40ma per KT88 tube on Silver 88s amps. Another reference when you email mike at QS. 

http://quicksilveraudio.com/wp-content/uploads/2017/11/Silver-88-instr-for-web-.pdf

Thanks guys will email Mike.