[clintj]

To clarify one thing, Fender does not typically use linear taper pots for volume. This is a common urban legend on the Internet. Virtually all their amps from the fifties through at least the seventies use audio taper, as well as the clean channel of the Blues Deluxe and Hot Rod series amps. The Hot Rods actually use audio taper, 15% taper (one of the slowest tapers commonly available, and designated with the code A15 on schematics) for the clean channel volume and Drive channel gain. The master volume on these is linear, however. The silverface and earlier amps have less gain overall in both channels so the sound comes up more controllably.

What makes the Hot Rod amps seem so touchy is the preamp as a whole has a large amount of gain available, so small adjustments early on yield drastic changes in room volume. It's also not uncommon for some pots to have a near dead spot in the first few degrees of rotation, which accentuates this jump.