With this variant, the input signal S1 is fed directly to the non linear network in {HEAD ~ front} of {TAIL ~ the amplifier} 4 
of
With this variant , the input signal S1 is fed directly to the non linear network in { HEAD ~ front } of { TAIL ~ the amplifier } 4
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH