Most basses have saddles that can be moved backwards and forwards to set the intonation. Usually, you access the saddle adjustment screws from the rear of the bridge but sometimes the adjustment is performed from the front. Either way, the extra ‘chunkiness’ of bass hardware, compared to guitar, tends to make the job a bit less fiddly.
First though, let’s recap the prerequisites.
The rest of your setup must be right for you before you start. Intonation is the last thing to set so get your action, relief, nut and pickups sorted out first. You should have fresh strings (of your usual gauge and brand) installed, properly stretched, and tuned up as normal.
Remember, always check intonation and tuning with the bass in the playing position (i.e. not lying on a table or counter but upright as if you were playing it).
The basic theory, as always, is this:
- Pick the open string and verify it’s in tune.
- Fret at the 12th fret and pick this note. Compare it to the open string—is it flat or sharp?
- If the 12th fret note is flat, move the saddle forward a little using a flat or philips screwdriver as appropriate.
- If the 12th fret note is sharp, move the saddle back a little by turning the screw clockwise.
- Retune the open string and go back to 1.
There are basses, like some of Gibson’s EB models that have a bridge not unlike the ‘tailpiece’ or wrap-over bridges on some Gibson guitars. These bridges do not have an adjustable saddle for each string. Instead the bridge is adjustable ‘overall’.
On the bridge, behind where it mounts on each post, is a small ‘grub-screw’. Adusting the screw on either the bass or treble side can change the angle the bridge mounts at.
For instance, if you adjust the bass-side screw clockwise, it pushes against the mounting post and moves that side of the bridge further away. Essentially, the overall angle of the bridge can be changed and this can be used to approximate a good intonation.
Now, bass strings tend to intonate in a (relatively) straight line to each other—unlike the more zig-zag line of a guitar’s saddles. This usually means having a bridge like this isn’t as much of an intonation drawback as it might be on a guitar.
When intonating an overall-adjustable bridge, set the outside strings first. Check the middle strings then and see how they seem. From there, you can tweak things a little to ‘balance up’ the intonation so that no one string is too far out.
The bottom B can be troublesome. If you’ve got a 5-string, you’ll want to pay close attention to the rest of your setup and make sure it’s good for that bottom string. Nuts, in particular, need to be spot on—too narrow a nut slot and the string will pinch (often choking the note or even giving weird overtones) and too wide a slot will allow the string to move, killing off the tone.
Pickups are another thing to be careful of. Too powerful a pickup, or one adjusted too close, can wreak havok on that bottom string in particular. If you’ve any problems picking up an accurate tuning signal, first thing to do is to lower the pickup.
My advice is to go heavy. Don’t be shy about banging a good heavy bottom string on. More string mass means more stability (usually). Go heavy, my friend, even if you’re buying just an individual string for the bottom and using your regular gauge for the rest.
Oh, and electronic tuners… Some older (or cheaper) tuners don’t have the range and get confused by that low string, misreading it or failing to realise it's there at all. Of course, if you have a 5-string and a tuner, there’s a good chance you know this already.