Back to our subject of direct coupling. Why did we wind up with coupling capacitors in the first place?
We know that many are simply a holdover from when tube circuits dominated the landscape and as soon as solid state came into the forefront designers of those circuits just kept doing what they knew how to do. After all, nearly all solid state designers in those days converted from tubes to the new fangled transistor without having much in the way of focused training on the new devices.
But in the early 70's a new crop of designers came onto the scene and they, like Stan and I, had never designed a tube circuit and knew only about transistors and designing with them. When we came onto the scene we started questioning "the old guard" about their practices and, like many young turks, did things our way because it worked better specifically for what we were doing.
Getting rid of extra components in the signal path was high on our list of ways we could build better sounding products.
The problems that we faced wasn't so much from the circuits themselves - in solid state design it's pretty easy to get rid of the coupling caps at the input and output of preamps and amps - but with other pieces of gear that might lead to trouble. So these coupling caps were needed to guard against products that output DC.
I'll go into more detail about this subject tomorrow.