XPost: sci.electronics.design   
   From: lcargill99@comcast.com   
      
   tubeguy@myshop.com wrote:   
   > I found a schematic of a stereo amplifier containing TWELVE 6L6 audio   
   > output tubes. But aside from sharing the power supply, it's two   
   > mono-blocks with each having SIX 6L6 output tubes. Unfortunately, I was   
   > not able to get any real detailed information on this.   
   >   
   > I compared it to several guitar amp schematics which use FOUR 6L6 tubes   
   > in push-pull parallel, and this is very similar. It just has 3 tubes on   
   > each side of the phase, rather than two. The plates are all wired   
   > together and cathode / grid components are duplicates to each tube.   
   >   
   > They did use as bias adjust potentiometer on each tube, which I have not   
   > seen on the guitar amps.   
   >   
   > Obviously the purpose is to increase wattage output.   
   >   
   > 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.   
   >   
   > Another question that comes to mind is the impedience of the primary on   
   > the audio output transformer. Assuming I could find a transformer that   
   > would handle the wattage, would the impedence be the same as those used   
   > with FOUR 6L6 tubes, or would that change since there are two more tube   
   > plates connected in series.   
   >   
   > Anyhow, looking at this schematic makes me think that any PPP amp with   
   > FOUR tubes could have more output tubes added, as long as power supply   
   > current is available and a suitable audio output transformer is   
   > obtainable.   
   >   
   >   
      
   The largest production tube MI amp I am aware of is the   
   Mesa Boogie 400+. It uses ( I believe ) 12 power tubes,   
   essentially 6 push-pull pairs ).   
      
   SFAIK, it exists only to compete with the Ampeg SVT.   
      
      
   I wouldn't want to lift it.   
      
   --   
   Les Cargill   
      
   --- SoupGate-Win32 v1.05   
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