A metronome for bass practice
Bass is less about playing the right note than about putting it in the right place. The click is the only ruler that measures that place.
Locking with the kick
In a band the bass occupies the same space as the kick drum. When the two disagree the low end goes cloudy no matter how good the line is. So bass practice with a metronome is less "play on the beat" than "land exactly where the kick lands".
In 4/4, mute beats 2 and 4 and leave clicks on 1 and 3 — the skeleton of a basic kick pattern. Play roots over it and hunt for the point where your note swallows the click. If the click becomes clearly audible again, you are early or late.
Playing behind the beat on purpose
Some styles want the bass fractionally behind the click for weight. That is a player who can hit the centre choosing to sit back from it, which is a different thing from arriving late.
Build the centre first. Once you can land dead on the click at will, push slightly behind it deliberately. Groove starts at the point where you can produce the difference rather than suffer it.
Note length is the groove
What gets overlooked on bass is not when a note starts but when it stops. The same pitch in the same place reads as heavy when held until just before the next beat, and as bouncy when clipped to an eighth. Without control of that length, lines turn to mush.
Turn on eighth-note subdivisions and practise stopping the note exactly before the next click. Then clip it a full eighth shorter. The same figure takes on an entirely different character.
Whether you stop with the left hand or the right also changes the sound. Alternating the two with the click running makes the difference obvious.
Speed after evenness
For two-finger technique the rule does not change: three clean passes earns 5 BPM, a failure costs 5 and the passes must be earned again.
The specific bass problem is that the two fingers rarely produce the same volume. When the index and middle differ, a fast line sounds like it is limping even when the timing is correct. Confirm evenness slowly before pushing the number.
Near the ceiling the left hand usually tightens before the right does. Dropping 20 BPM and releasing that grip often takes you straight past the old limit on the way back up.
Frequently asked questions
The bass drowns out the click.
Use the digital beep or the mechanical click. Both sit in the upper mids, well clear of your fundamental, so they cut through. The wood block disappears into an amp far too easily.
Should I put the click on 2 and 4 like a drummer?
Both setups teach something. Clicks on 1 and 3 rehearse sitting with the kick; clicks on 2 and 4 make you find your place against the snare. Playing the same line under both is the useful exercise.