GGG Big Muff with filtered LED. What's a filtered LED?

[skiraly017]

I feel kind of stupid asking this. GGG has two Big Muff layouts, one with a regular LED and one with a filtered LED. What's the difference? I can see that parts differences in the layouts but I don't understand the whole "filtered" thing. Thanks.

[mountainking]

No reason to feel stupid, asking questions is on of the best ways to learn. Check this out: http://www.muzique.com/lab/led.htm