ooglegroups.com> 317d4d78   
   From: phil_a@tpg.com.au   
      
   "mike s"   
   shawn s wrote:   
   >> need two pairs of tubes for my altec amps   
   >> Sha...@windstream.net   
   >   
   > I'm curious,  do they have to be that type?   
   > In the UK we call the equivalent type EL34.   
   > Used to be made by Mullard and > the like.   
      
   ** The Sylvania 6CA7 is a rather different tube to the EL34 made by Mullard   
   and others - the structure is different and the electrical characteristics   
   quite different.   
      
   I used a fair number of them in the 1980s for guitar amp repairs - but soon   
   found they were not happy in 100 watt Marshall amps. The screens would glow   
   very brightly at full power and the tube soon expired.  What I found was   
   that the screen supply must not exceed 400 volts with them.   
      
   In amps that had a screen supply voltage between 360 and 400 volts, the   
   performance and longevity were both excellent.   
      
   Probably the nearest tubes in current production are the " big bottle" 6CA7   
   by Electro Harmonix and the JJ KT77.   
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)