Recommended reading

[FYL]

Rod Elliott has recently added a full section dedicated to tubes - valves in Oz - on his ESP web site.

Iconoclast, thought provoking, with a lot of excellent technical points.
Here's a short extract:

"Power Supply
 
While you could be forgiven for thinking that no major manufacturer could possibly screw up a power supply design, sadly, I'm afraid you'd be wrong. One of the worst is common with Marshall amps, and is caused by the way the negative bias is derived. To blow the internal HT fuse in most Marshall amps, all you have to do is disconnect the power lead (or switch the amp off), wait for about 2 seconds and turn it back on. All output valves conduct hard because they have almost no bias at all. This often blows the high tension fuse and will almost certainly damage the valves to some degree. The bias voltage takes about 3 seconds to reach a safe value, but discharges to an unsafe voltage in as little as one second when power is removed. How stupid is that?"


http://sound.westhost.com/valves/index.html