Single Ended puzzle

[vibratoking]

IME, single ended amps sound best when idle dissipation is 100% and maybe more. Mostly base on 5E3 experience. A single ended output section has more dissipation at idle than any other time. Don't be afraid to run it up to 100%.

You might find this interesting:
http://valvewizard1.webs.com/se.html

[sepulchre]

I was taught that SE amps run at about 90%, perhaps by an over cautious mentor. But the KT88 was biased pretty low. Don't know if that had anything to do with its demise though.

Well the good news is I've learned not to work on this stuff when I'm so short on sleep. Came in with fresh mind this morning and checked out all the components in the area - they were all okay as far as I can tell. I reflowed all the joints, checking the wiring as I went. Out of curiosity I did check the KT88 outside and found the dead short across the screen and cathode. The control grid was not a casualty, fortunately. I didn't try metering the socket but I did retension it; it was a bit sloppy.

Then, with very little hope, I gave the power switch one last try - the PT came on just fine. I checked the voltages in the pertinent places - all good. So the tubes went back in with a 6550 replacing the 88. Check voltages wit the tubes in - good - biased the 6550 to 100mA with 359V on the plate and plugged in a guitar. Sounds just as good as ever!

I will keep it on the bench and play it, watching for possible problems but so far it seems that the 88 went down without taking anything with it. Man, I Love tube amps! SS stuff would have all fried immediately.

Thank you all for your help. Once again I learn from this place. I hope that I can give something back somehow. But being not much more than a noob I have little to offer. But I do learn and eventually . . .

Thanks again, guys!

@vibratoking: I've got all of Merlin's books - wonderful stuff. Got bookmarks all in them - great references. Thanks!

[sepulchre]

Btw, went it first went out my wife said, "It's probably a tube."

I won't be living that one down anytime soon - maybe never.

[JazzGuitarGimp]

Happy endings always seem to cap my favorite stories.... Good job!

[vibratoking]

Glad you got her going. It shows how easy it is to say, "Did you check the tubes?" Kinda from the department of redundancy department.

[sepulchre]

. . . from the department of redundancy department.

ROTFL Gotta remember that one.