Electrolytic capacitors, or caps, make a huge difference in the sound of your amp that you may not be aware of. Thusly, there’s a pretty big divide between those who get all excited about original caps and those who’d rather switch them out for quality control.
Like beautiful, unique snowflakes.
If you’re a musician, and you don’t know about these guys, you oughta. While obsessive behavior about any single component may drive you (or your uninterested friends) mad, being aware of what you’re working with will make you a higher functioning shredding machine. This is going to be a fairly elementary overview, so if you’re bored, please skip ahead and look at some pretty things.
In your power supply, the caps function as filters. Electrolytic caps stabilize voltage by sourcing or sinking current as it’s demanded by a load, preventing a sudden change in potential. You see, you need science to rock.
Despite semi-popular belief, caps only really last about 6-10 years. Given, that’s a big range, but its all dependent on how and how much they’re used. Even idleness can deplete their quality (through corrosion). They need periodic charging to maintain the oxide layer and stay formed. After a time, they start to leak either chemical or current and can fail to filter at all, which will cause humming (or joyful motorboating) in your amplifier. The leaking of current can also cause a strain on other components and possibly lead to blowing a fuse.
So why keep ‘em if it may compromise the sound? Because, much like your Star Wars figurines that gather dust in their plastic cases, vintage amps are more valuable when completely intact and original. Hardcore collectors and dealers want the amp to look like it did the day it was born, even though time and (albeit limited) use may have taken their toll. But there’s something to be said for a vintage commitment and rebellious streak– those crazy sounds you’re getting could make you intensely happy.
You can fully swing either way or define your swaying needs on a Kinsey scale of audio affiliation. Your parents probably won’t flip when you come out as cap jobber (or not), so choose your own adventure and rock on.
Sources:
Tube Amp Talk for the Guitarist and Tech. Gerald Weber, 1997.
http://www.nmr.mgh.harvard.edu/~reese/electrolytics/