From: pallison49@gmail.com   
      
   Xtrchessreal wrote:   
      
   =======================   
   > > > Section 1 is so called due to lower hum compared to section 2.   
   > > >   
   >   
   > > ** The 2 triodes of a 12AX7 / ECC83 are identical,   
   > > one doe not "hum" more than the other.   
   =====================================================   
   > >   
   > > Internal connection arrangements for grids and heaters vary   
   > > between versions and brands, maybe having a small effect   
   > > on capacitive coupling if high impedances feed he grids.   
   > >   
   > > It is very common to use DC voltage for the heaters to   
   > > eliminate any issues whether grid or cathode related.   
   > >   
   >   
   > Just read the REMARK on the bottom of page one.  https://drtub   
   .com/datasheets/ecc83-philips1970.pdf   
      
      
   ** My post is *about that exact remark* - explaining it.   
      
   An *earthed* internal link from pin 9 travels past grid pin 7 in the scenario   
   described. A link carrying 3.13VAC travels past grid pin 2.   
      
   This might inject up to 1mV into pin 2 if the grid source impedance were   
   *10Mohms*. However, for a MM phono cartridge, the impedance is 1kohm at   
   50/60Hz and for a guitar PU about 10kokms.   
      
   So hum injection falls to under 1 microvolt in the above examples and is   
   buried in tube noise  - so completely inaudible.   
      
   > I don't understand the perpetual misinformation.   
      
   ** There is a great deal more to your not understanding.   
      
   > But hey, thanks for making my point more clear.   
      
   ** You never made any clear point - sunshine.   
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)