Quote Originally Posted by Simon Barden View Post
Glad you're happy with the changes. It can be a real let-down when you splash out on some reportedly extra special valves only to find you liked the old one's better. Done it myself several times!

Pre-amp valves last for ages so you won't need to buy any more for the Marshall for many years (except for an early failure). It's the power valves that need replacing, but even they can last for many, many years if the amp isn't used that much and is always driving into the correct load impedance.

Yep, that's because the preamp valves usually only have anything up to a milliamp of current flowing through them, on the other hand, the power valves tend to conduct the most current while the Amplifier is operational, hence the reason why most valve guitar amps have a standby switch which does two things, firstly it enables the valves to properly warm up before the + HT is applied, secondly it prolongs the life of the power valves while the amp is powered up and not actually being used, there's been stories of used preamp valves being still good after 40 years of use.

When I am powering-up my Marshall amp, the first thing I do is make sure the standby switch is set to "Standby", then I set the mains power switch to "On" and then I give the amp time to warm up, then I switch the Standby switch to on so that the + HT gets connected and the amp is fully operational.

When I power down my Marshall amp, I simply set the mains power switch to "Off", leaving the Standby switch on so that the filter caps in the amp's power supply can drain.