I always find it interesting how over the years my preamps have been "questioned" by some; but via posts and especially in private such as emails and phone calls I am "pumped" for information.
Seems some are very interested. Not surprising when one looks at typical industry tatics.
My uncle, Aaron, designed and built a new type of combine in the late 1950s that used a sickle and auger front end, and spent 60 grand of his own money. After thorough testing, he demonstrated it to the major farm implement companies, who were not interested. They waited out the multiple patents, and then copied Aaron's design. Aaron never received a dime to cover his out of pocket expenses. A similar situation just happened with Caterpillar Inc. It happens in Audio as well. More than once someone has attempted to steal my designs without paying a penny.
I will say that we see equations used all the time in articles, by diyers etc, but more is involved than just a few theoretical equations from a textbook that assumes parts and designs are perfect. Wires do not have zero resistance, capacitors do not have zero ohms reactance, nor zero DA, DF. Inductors have resistance, capacitance as well as inductance, and hysteresis losses as well.
One must deal with multiple disciplines, a lot of R&D, and a large budget.
Cheers
Steve
