Got a ground wire run from sewer vent pipe in attic to outlet. Secured the ground wire by putting it under a hose clamp and tightening the clamp down on it. Replaced the outlet also. Now all tubes except one are silent, as far as I have been able to tell so far.
The Raytheon tube still has a funny hiss, not the hum I was hearing from the other tubes.
So, $25 spent at Home Depot, and a little sweat, and I have a silent Ember. Now I can get down to listening, and I'm a happy guy
Dang - the clear top does get some static, but only when the volume is turned up, and it worsens as volume is turned up more. I'll have to check the other tubes to see if they do the same thing with increased volume.
Feel like I am taking little baby steps, but have figured a few things out.
I *think* my ground is fine now. Discovered today that the static I am getting is caused by the laptop I am using as my source. As soon as I close the lid on the laptop, the static goes away. Open it up, static comes back.
I can't see how to add a photo to a reply, but a fellow head-fi'er sent me a copper foil covered cardboard (tp) tube to try as a cage. It had no affect whatsoever.
However, I did take one more baby step. When looking through my cables, I came across another power cord for the laptop. Gave it a try, and the interference was reduced. With the old power cord, I would begin hearing static at about the 9 O'clock point on the volume. With the new cord, I have to turn it past the 12 O'clock point before any static can be heard, and with some tubes, even farther than that. I almost never turn the volume past 3 O'clock, and when I do it is only a very little bit.
I tried setting up a server PC at my listening station, but it interfered more than the laptop! I was very disappointed at that. The laptop is very old, but so far has been stable, but I would have liked to have gotten the server set up.
*If* the copper cover is to act like some sort of Faraday cage, then it would need to be grounded also, correct?
It seems strange to me that I am having so many issues. I have a hard time imagining many users going through all of this just to get an amp to function well.
I just ran my ground from the back thumb screw by the line out to the screw on my outlet plate and that did the trick for me.
Ad far as tubes go, I've used some 6BQ7A tubes that were pretty level sounding and didn't add any bass. They're pretty cheap on eBay. Mostly because I don't think they're anything special, but that's me.
The brightest tube I've used is a 12BZ7. They may add some bass too though. I wouldn't pay more than $20 on eBay for one.