Paul McGowan / PS Audio

In 2008, authors Karl Johan Åström and Richard M.Murray wrote about feedback: “Simple causal reasoning about a feedback system is difficult because the first system influences the second and second system influences the first, leading to a circular argument. This makes reasoning based upon cause and effect tricky, and it is necessary to analyze the system as a whole.”

Now, that’s about as nerdy as one can get but their point is well taken. One must look at the whole.

Feedback is taking the outcome of a past event and, in the future, comparing it to one’s original expectations.

We have many different forms of feedback: from customers, friends, family, our own internal loops.

In circuits there’s also a great variety: loop, local, forward, negative, positive.

In my experience, the best use of feedback is to have it do as little as possible. In other words, we shouldn’t rely upon feedback to set our course. Rather, feedback should be the finishing touch.

This applies equally to personal and company feedback as well as circuits. We know that if an audio amplifier’s open-loop performance (operation without feedback) is good, then the addition of feedback generally makes things sound better. We also recognize that the opposite is true. Rely upon feedback for an amplifier’s stable operation and the audible results are not worth your time.

Like all things in life, a little dab’ll do ya’.

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