Bass is one of the most instrument when it comes to the overall presence of the sound of any music, so it is paramount for a bass guitar to be set up right for it to sound right. The objective is plain and simple, a well set up bass sounds well and feels comfortable.
It's is very important to keep a note of the gauge of the strings that you are using. Different gauges apply different tension on the neck when tuned, and hence the neck's reaction will be different.
Now tune your bass accurately to your preferred tuning. Now put a capo on the first fret and press the string at 15th fret. Now try to slip two visiting cards joined together between the string and the top of the fret at the 8th or 9th fret. If the string lifts a little then the neck is too straight, and if the card is moving freely then it must have more curve than it should.
To adjust the truss rod there can be two scenarios for most cases, first being that the truss rod adjustment nut is located in the top of the neck and is visible or covered. Second being the adjustment nut is located at the bottom of the neck and is inaccessible. In the first case, to adjust the neck relief, you need to check if the neck is too flat or too curved. In case of too flat, you need to loosen the truss rod with appropriate tool. It's very important not to choose wrong tools with truss rods as if the screw head gets ruined, there's no turning back. If the neck is too curved, you need to tighten the truss rod.
To start with:
Now this was simple enough, but if you have a bolt on neck bass guitar whose truss screw is not visible, then the task is often too tedious to be done at home and you should take it to a professional as the screw is present at the heel of the guitar. Still in case you want to give it a try (not recommended for beginners) you need to first check if the neck is too flat or too curved like the first scenario and then remove all strings and remove the neck from the body to expose the adjustment screw. Now the same drill goes as discussed before, with a slight change that you need to re-attach the neck each time and retune the bass to check the problem is solved or not, and then try again if it didn't work out.
The objective of setting up the saddle is fairly simple, that being to keep the strings at the perfect height from the fret board so that they have enough space to vibrate when stuck and so that they are not too far to cause difficulty while playing. The process is also as simple as the objective:
Naturally, string action has to be adjusted for an individual’s playing style. If you have a light touch and play very technically, you can get away with slightly lower action. However, you’ll want a somewhat higher action if you love to dig into the strings and produce big, clear, sustaining tones. By experimenting, you’ll eventually determine the ideal action for your music—and that’s the beauty of learning how to do a setup yourself.
For a factory set up action, you should set the bass side of a 4-string (the E string in standard tuning) to 7/64", and then set the treble side (G string) to 5/64". Then increase the heights as you go across the fretboard, making it 6+/64" on the A string and 6-/64" on the D string.
The goal is to achieve the similar curve in the saddle as that in the neck.
Intonation is the overall tuning of the Bass. A well intonated bass will have exact right notes coming out of all the frets across the scale. If the intonation isn’t set up properly, the bass won’t stay and play in tune. A good practice is to check intonation every time strings are replaced so that the bass always stays at it’s best.
To intonate your bass, you’ll need an accurate tuner, and tune all the strings to pitch. Now play a note while holding the string at 12th fret. Essentially it should give an octave high pitch but if it’s flat or sharp, intonation setup needs to be done. To do so, take a screwdriver that fits the screws on the saddle. Now go to the end of the bridge and screw the saddle towards or away from the headstock.
Same quarter turn rule applies here. If it goes worse, start twisting in opposite direction. Finding the sweet spot may take some time and a few tries but the results will amaze you.
So that's it for now! If you need more help with your Bass Guitar setup feel free to leave your questions in the comment section below!