XPost: sci.electronics.design   
   From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 12/28/18 3:45 AM, upsidedown@downunder.com wrote:   
   > On Thu, 27 Dec 2018 21:11:35 -0600, tubeguy@myshop.com wrote:   
   >   
   >> I'm not intending on building this, but it's interesting and makes me   
   >> wonder if someone could use EIGHT 6L6 tubes, or TEN?   
   >> (Of course adding more tubes mean bigger audio output transformers and   
   >> heftier power supplies.   
   >   
   > Tubes may age at different rates, so the characteristics might be   
   > quite different after a long time. It might not make sense to replace   
   > a single (failed) tube and you may have to replace the whole set of   
   > tubes with new tubes preferably from the same manufacturing batch.   
   > This can be quite expensive :-)   
   >   
   >   
      
   Unless the tubes are arranged truly symmetrically, e.g. in a circle with   
   vertical air flow, they won't all run at the same envelope temperature,   
   which means they won't have the same cathode temperature either.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
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