Anyone up on their Termination Insensitive Amps? R3,4 and 6 set the input impedance to Q1 at 50R. What is the actual equation used to derive that? I have tried following the Wes Hayward rabbit hole of PDF's all over the internet that quote missing information from other PDF's and cannot make sense of what information i have found. Anyone know the formula or if there is an online calculator, I want to change the input impedance to 200R, so i can forgo winding a transformer.