We currently know of no way to turn on bass mode of the JBL Clip 3. In fact, it may not even have a bass mode. But if this were possible, it would make the speaker vibrate more. It would also add a surprisingly large bass quality to the content playing. Indeed if they ever added this feature, it might work something like as follows…
How to Turn On JBL Clip 3 Bass Mode: Proposal
We propose that by default, the Clip 3 would have its extra bass mode turned ON. Just like some of the other speakers in the JBL line do. Specifically, this mode would add a bit of extra treble and lots more bass. Kind of like switching on the Loudness control on those vintage 1970s stereo systems.
But if you turned this mode off, then try turning bass mode back on. First, find the Bluetooth button on the speaker right side, and the Volume Down (-) button on the upper left front. See these in the two pictures above.
You could turn bass mode ON by pressing both these buttons for about ten seconds. Hold until the pilot lamp blinks a few times.
Next, to reset bass mode, then again, you would press the Volume Down (-) and Bluetooth buttons. Hold them in until the light on the top flashes a few times. You would then release the buttons.
Finally after a short pause, the status light would go back a solid glow. Then after that, bass mode would be back to as it was once more.