I am trying to learn how to setup my bass. One of the first steps I need to do is check the truss. To do this people say there should be 3/32nds space under the 12th fret for the E and G string, when a capo is on the first fret. But wouldn’t that measurement depend on the action of your strings? This question came up when thinking about this for one of my basses with an action higher than 3/32nds.
Do you have to set the action to a standard height before doing this?
you are using a capo to press down on the first fret, and your hand to press down on a higher fret (i usually press down around the 15th fret). that completely eliminates string action from the equation, all you are doing is making the E string a straight line so you can see the space at around the 7th fret to check for truss rod relief. also no need to check this on both E and G, just the E.
what you are describing with a 3/32 gap under the 12th fret is for string action, not for truss rod - that you do after you adjust the truss rod.
Cruise on over to YouTube and take a look at this video. There are a series of videos put out by elixir strings on how to set up your base. This is the easiest and most intuitive setup I’ve ever seen anyone do. Really made my two bases stand up and play right when I did them.