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Posts by gibosi

 I would agree that "8526" sure seems to indicate 1985. Interesting... I would never have guessed that this tube was still being manufactured at that time. But Cetron did purchase some part of Tung-Sol in the 1970's. And it is my understanding that power regulator tubes were among the last vacuum tubes to be replaced by suitable solid state devices. So it would seem that Cetron kept this part of the business going as long as there was adequate demand. Regarding the two...
I am very skeptical about the claim that WE421A were being manufactured as late as 1985. Halo getters began to appear around 1960. And therefore, based on the getter shape alone, that tube could have been manufactured as early as the mid-1960's. I would like to see what markings and/or other construction details folks are using to conclude that it was manufactured in 1985....   Switching to music, which I assume is the reason most of us have a Glenn amp, is anyone else...
 You can... but why would you? Normally, we want to treat both channels as equal as possible. To use a pair of 6080 on one side and a pair of 421A on the other would be like using two different amplifiers, one for each channel. Seems way too strange to me...... But installing one 6080 and one 421A in each channel, would be perfectly acceptable. :)
Yes, in your Glenn OTL, you can run four, or two per-channel, of each of the following: 6080, 6AS7, 5998, WE421A, 7236, 6H13, 6N5P or 6520.
My favorite combo at the moment... if you ask me next week, it will likely be different lol :)   A quad of 3-mica Sylvania 6BX7, GEC U18/20 and Lorenz C3g (1960's embossed flat-black cans). With the same rectifier and output tubes and a pair of Siemens C3g the presentation was just a bit too bright for my ears. Swapped in the slightly more laid-back Lorenz and the magic is back.  
 First, clean the pins very, very good. I use fine-grit sandpaper. And then, give them some time.... They may well quiet down after 20 hours or so.... Umm... I am pretty sure that British GEC did not manufacture the 6BL7. I assume you have three American GE?
And just so folks know they exist, these are from the late 1940's with two small cup getters on opposite sides and black bases.   Edit: It might be more useful to refer to these as "cup" getters to distinguish them from the "flying saucer" getters found on the Russian product.    
 Unfortunately, the Glenn OTL requires a rectifier that can provide at least 250 ma. As the CV31/U20/FW4-800 puts out only 125 ma, I can't even consider it. I believe that there are a number of other 4-volt/B4 base rectifiers out there as well, but again, they are too wimpy for the Glenn....  :(
And finally, for folks who want to know a bit more about these rectifiers:   http://www.head-fi.org/t/600110/2359glenn-studio/13095#post_12526829
  From the left, all with B4 bases.... Mullard FW4/500, which is a 4-volt Mullard 5U4G Cossor 45-IU, which is a 4-volt Cossor 53KU And GEC/MOV U18/20, which is a 4-volt GEC/MOV U52 Edit: More pics: Detail of the FW4/500 above the top mica:    Detail of the U18/20 above the top mica: 
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