How to have one RSS feed URL

I have disabled unwanted feeds but I now want only one URL. Ideally I would like to redirect or rewrite the URL of the category-specific,tag-specific,post-specific feeds. Basically I dont want /post-name/feed to resolve I want all requests for my active feeds to go to the URL /feed or /feed/rss. Must be possible but I can’t figure it out?
Any suggestions would be appreciated – thanks