From: detritus@ix.netcom.com   
      
   Alex Pogossov wrote:   
      
   > ."John L Stewart"  wrote   
   >   
   > > In a previous post John Byrnes asked why I used a resister rather than   
   > > an MJE340 for the long tail in a phase splitter. The short answer is   
   > > that it works & very well at that.   
   > >   
   > > The question has gotta be, 'why does it work so well'? For success the   
   > > circuit surrounding the splitter stage needs to satisfy the relation,   
   > > Rk(mu + 1) >> rp + Rl.   
   >   
   > I would rewrite the relationship as (also ignoring "+1" after "mu"):   
   >   
   > Rk >> (1 / Gm) + (Rl / mu)   
   >   
   > It is more convenient as in most cases you start from Gm anyway. Also, for a   
   > pentode you simply ignore the second term of the right side of the formula,   
   > not bothering calculating the exact mu and Rp of the pentode, which are   
   > difficult to derive from the curves. Also for a pentode Gm shall be   
   > Gmplate+Gmg2, but again it is insignificant given that Rk shall be "much   
   > greater".   
   >   
   > > Some folks still like the self-inverting output stage. It is useful as a   
   > > musical instrument accessory for the even order harmonics (2nd, 4th,   
   > > .Etc) it generates. See one at this link-   
   > >   
   > > http://ax84.com/media/ax84_m276.gif   
   > >   
   >   
   > Why do you think it generates even harmonics, as usually a push-pull circuit   
   > tends to cancel the even harmonics out?   
      
   ...   
      
   Because "even harmonics" is a buzzword   
   that guitar-pickers use, in the mistaken   
   belief that even-order harmonics, being   
   "consonant" intervals, produce a more   
   "musical" tone.  Of course, if you want   
   the classic distorted guitar tone, what   
   you want is odd-order harmonics.   
      
   LV   
      
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