Hi all!

I just bought my first tube amp not too long ago (a Peavey Classic 30), and I think one of my tubes just blew up. It looks like it's an EL84 and it doesn't light up when I turn the power on.

Does not having 1 of the 4 EL84 significantly affect the sound quality? Would I need to replace this tube immediately?

There is also this weird clanky sound coming from the amp when I play my low E string. It is only noticeable when I turn my Postgain up relatively high... Does this have anything to do with one of the blown tubes??

Thanks guys!
If one of the power tubes was blown the amp wouldn't work. They may just be an old set. If you replace the power tubes, you need to replace all four with a matched quad.
A clanking sound could be fatigued tubes or something loose in the amp. I'd just replace the tubes right away, it's usually a good idea anyway.
Yup, it was bought used.
If I replace the old tubes with the same type, I wouldn't need to re adjust the amp or anything like that right? So there is no need to take it to a shop?
Thanks for your help!
Right, the C30 is cathode bias so you can just plug and play with any 4 matched EL84s from any company. You might want to replace the preamp tubes too.