My power tubes glow orange when the amp is on standby but when i hit the on switch they develop a blue hue aswell as the orange. The blue increases in brightness the longer I play. The amp is 5 years old and has stock mesa 6l6s. Are they due a change?
T'would appear so. You can pick up some 75 watt lightbulbs almost anywhere. Put them in and they'll boost the output of your amp, and give you a really (wait for it) bright tone.
Blue hue is nothing to worry about. If the tubes are 5 years old change them out.
Blue is nothing. If you are worried about them being too old just plug in your spares and see if you notice a dramatic improvement in tone. If not put the old ones back in and keep your spares for when you do need them. Don't have spares? Well it's about time you bought some.