Now , few words about THD spectra shaping ;
Papa taught us during the years several tricks how to imbalance that perfect Symmetry (ironic , isn’t it …… working principle of amp itself is called Supersymmetry/SUSY , while we are trying to spoil it .
Anyway , we want some sugar , and we are getting that with 2nd harmonic above 3rd ; again – Papa’s Lectures – some people prefer that way (Tubelovers?) , while some people prefer dominance of 3rd (Sandworshippers?).
Further – we can divide both of these groups by polarity of dominant harmonic- some prefer negative , some prefer positive.
What can I do regarding that , except to find how (hardly first one knowing that) and then organize easiest way of doing it ……..
If you take a look at LTSpice schematic of amp (third pic from top) , you can see two resistor positions circled in red. These resistors are path to modulation of Aleph CCS-es and their values are directly defining amount of that modulation , thus defining amount of Aleph CCS-es contribution in output signal .
So , simple ; disclaimer – my goal is to invoke 2nd , and control it’s polarity and amount :
-If these two resistors are same in value , there is greatest amount od symmetry , resulting in zilch 2rd ,dominant 3rd.
-If we increase value of said resistor at side of positive output , there is increase of 2nd (and dominance over 3rd) , while our dear 2nd being negative phase,
-If we increase value of said resistor at side of negative output , there is increase of 2nd (and dominance over 3rd) , while our dear 2nd being positive phase.
That’s it .
How it is organized in vivo ?
I had idea to introduce sort of already know device among Greedy Boys , called -ZAP (Zen Amount Pot) , but later decided that would be impractical , and probably leading to constant play with , while forgetting enjoyment in music
…. so I decided to use pin sockets/or whatever their name is , in said resistor positions , thus allowing easy change of resistors in situ , without involving soldering equipment etc.