XPost: sci.electronics.design   
   From: xxx.syseng.yyy@gfsys.co.uk   
      
   On 12/28/18 03:11, 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.   
   >   
   >   
      
      
   If you want to see an interesting audio amp, look up the Editors and   
   Engineers Radio Handbook from the mid 60's. There's a design that   
   which uses 6 or 8 6080 double triodes to build a direct coupled   
   amplifier, no output transformer and dual power rails, positive and   
   negative. Never built built it here, but a very original design. Could   
   probably update that to use power mosfets...   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)