excursions are limited by power supply capacitors and the load presented by the amplifier itself. When the fuse blows, these constraints disappear, unloading the secondary. Furthermore, unlike capacitors, inductive elements are dangerous when disconnected while in use. A capacitor stores its electrical charge in between its plates. So when a charged capacitor is removed from an active circuit, it safely holds its charge as long as the plates are not shorted, through your body for example. The inductor hold its charge in its field. So when a stressed inductor is removed from an active circuit, its field collapses and output voltage climbs until its charge arcs through the air or your body if you are unlucky. Thus placing a fuse after choke and capacitor is the safer approach, as this arrangement allows the reservoir capacitor shunt the voltage spike.

    One danger a fuse presents is that is a portal to the lethal voltages within the amplifier. Think about it: the amplifier stops amplifying; you suspect a blown fuse; you turn off the amplifier; you reach over pull out a non-blown fuse (the first tube's filament had opened) and connect your hand to the 450 volt power supply inside the amplifier as you touch the fuse's end cap. Let's say the fuse had blown; now as you push a good fuse into place, you connect your hand to the 250 volt residual charge that the reservoir capacitor still held. The safe choice here is to replace the fuse holder with one that does not allow external access to the power supply voltage.
    Bipolar power supplies present new unsafe scenarios. Here is a paradox. Solid-state amplifiers often blow just one power supply rail fuse and the speakers are not harmed.