[Ian Iveson]

How would you explain to a novice how to design a valve
amplifier?

I see two possible approaches. One way to begin is to
establish the purpose of the machine, divide that purpose
into a series of processes, and develop a block diagram of a
generic amplifier. The other is to examine various circuit
fragments in order to understand how they, and their
components, behave. These two approaches may be termed "top
down" and "bottom up", respectively. Most books on design
cover both aspects, in one order or the other. Both can be
dealt with using the common logic of analysis.

Both are problematic. Whichever aspect the novice encounters
first, he will be bemused for lack of prior understanding of
the other. It's hard to grasp a block diagram without
knowing what might be inside the boxes and why; and it's
hard to grasp a fragment such as a mu-follower without
knowing what it might be used for and why.

Perhaps the novice could be reassured if, in a preface, the
author were to acknowledge these problems, and provide some
logic that the novice might employ to guide him through the
process of learning to design?

This year I have resolved to write such a preface. Ideas are
welcome.

Is the process of design predictable? Can you characterise
the logic of development, from start to finish?

The best structure, by far, I have come across is in the
late J L Hood's "Valve and Transistor Audio Amplifiers".
Typical circuits are introduced and analysed in historical
context, so the reader becomes aware of the issues in just
the same way as history did. However, the reason for using
such a narrative style is not made explicit, and so the
novice may not get the point.

New valve enthusiasts, and especially young people, are
needed or there'll be nothing left when we all die.

Which won't be this year, I hope.

Anyone else made a resolution.

Best wishes,

Ian