One of the most important parts in setting up a bass is adjusting the action (the length of the fingerboard strings) on the instrument. This process should be done when the instrument is new. Additionally, exposure to changes in temperature, humidity, and changes in string thickness can affect the setup of your bass in such a way that adjusting the action is required.
Part 1 of 4: Tune the Bass
Step 1. Tune the bass while playing as usual
Use an electronic tuner for better tuning. By doing this, you will ensure that the strings are in the proper tension when adjusting the action.
Part 2 of 4: Check the Bass Neck
Step 1. After you've made any significant changes in string tension, wait at least 30 minutes before checking or adjusting your bass neck
- It will take time for the bass neck to settle into its final position after significant changes have been made to the forces generated.
- Waiting longer will increase the precision of your settings.
Step 2. Set the looseness or tilt on the mast
- The neck of the bass should be slightly angled to play the bass properly. If the neck is straight, the fret will hum mostly in the notes of the first 5 frets.
- If you have a nut, place it on the 1st fret; otherwise, press the E string (or B string on a 5-string bass) with your left index finger on the 1st fret. Press the string at the 12th fret with your right thumb or right elbow. Use a set of gauges to determine the widest gap between the string and the edges of fret 4 through fret 8. If the string touches either fret, the neck needs less pressure. If the space between the string and any of the frets is greater than 0.5 millimeters, the neck will need more pressure.
- You can also place a capo on the first fret and press the G string at the first fret with your left index finger and the G string at the end of the neck with your elbow. Use a set of gauges to measure the space between the end of the string and the top of the 8th fret. If the space exceeds 0.3 millimeters, the neck will require more pressure. If there is no space, the neck will need less pressure.
- You will need to adjust the truss rod if, when examining the neck, you notice that it needs less or more pressure.
Part 3 of 4: Adjust the Soul
Step 1. Remove the web cover that is on the blade, next to the nut
Depending on the model of your bass, you will need a small Phillips screwdriver to remove the screws that secure the core cover or a small flat blade screwdriver to lift or detach the core cover
Step 2. Use an allen wrench of the appropriate size to tighten the web
- If the neck requires more pressure, secure the truss by turning the truss nut clockwise.
- If the neck requires less pressure, turn the truss nut counterclockwise.
Step 3. Adjust the web by doing a 1/8 turn in a row
After the twist, tune the strings again and measure the string length again.
Step 4. Make more web adjustments with no more than 1/8 twists at a time
After each adjustment, re-tune and measure.
Step 5. Test the fit of the web by playing each bass string at each fret
- If any of the 5 frets hum, the neck is too straight and the truss rod will need to be loosened.
- If the frets only buzz past the 12th fret, there is very little pressure on the neck, therefore the truss rod needs to be more secure.
- If the frets hum evenly across the neck, the truss rod has been positioned properly and the bridge will need to be raised to adjust the action.
Part 4 of 4: Adjust the action
Step 1. Raise or lower the bridge or the string saddles on the bridge
- If your bass does not have screws to adjust the length of the individual saddles, you will need to adjust the action when raising or lowering the entire bridge. There are many bridge designs, each with specific fit characteristics. Choose the right tool for your bass setting. In general, those that secure (rotate clockwise) the length of the bridge, manage to increase the action; those that loosen the bridge adjustments (rotate counterclockwise) lower the action.
- If your bass has screws to adjust the length of the individual saddles, raise or lower the entire bridge to make general adjustments to the action. Then change the length of the individual string saddles as part of the final adjustments. Typically, single rope saddle adjustments are made with allen keys.
Step 2. Play bass on each fret to test the action settings
If you hear buzzing, it's because you've turned the action down a lot.