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In Reply to: RE: Who makes that tube? posted by dave slagle on July 08, 2020 at 05:32:19
made in China, of course, in which the top mica does not touch the glass to secure the inards of the tube.
Good sounding tubes but microphonic as all get out.
Later, Full Music/TJ claims to have fixed this with a larger mica that held the workings in place and claimed less microphonics than the first version.
I find it hard to believe that firmly fixing the structure to the top of the envelope as well as the bottom helps isolate it from outside vibration. If anything, I would expect it to push the resonant frequency of the vibrating bits up which i would expect to be much more objectionable.
My gut feel is that the top support showed up in conjunction with the ST tube to make assembly easy and repeatable... nobody wants a tube with a plate leaning to one side or the other... all of the electrons will most certainly fall out.
Well, the ST build fixes the top to the glass with some mica. The design of this mica varied a fair bit, usually little nubs, the Tung-Sol mouse ears, and the 5881/6098-style additional pads...
The folks I talked to all said this was assembly for assembly alignment. As with all the internal features that often seem taken as hallmarks of THe Right Tube, I do have my doubts as to their intentional addition for anything else other than improving and shortening the ramp up to full specification production when it came time to execute a type run.
There have been plenty of leaner tubes through my hands, though this has mostly been base to glass. Sift a big pile of 6SN7's and see...:)
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
My thoughts exactly!
Whatever they did, and maybe they did other things as well, they claim to have fixed the microphonics in later TJ/Full Music globe tubes. I never tried them so I have to take their word for it.
Have a pair of early KR 300B (ST with very thin glass) that are also mircrophonic. Later KR had thicker glass and were supposed to be less microphonic.
Who knows. Best 300B I've had in my system is the Charlie's Kansas made WE300B which I've had for about 15 years? No getter left but they still play.
Doubt I'll live to see another WE300B from Charlie. :-(
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