We currently know of no way to adjust the low frequency mode on the JBL Clip 2. But if this were possible, it would makes the speaker vibrate a lot more. It would add a hefty extreme bass quality to the content playing. But if they ever add this feature, it might work something like as follows…
How to Switch JBL Clip 2 Low Frequency Mode OFF and ON
By default, the Clip 2 would have its low frequency mode turned ON, as some other JBL speakers do. Indeed, this mode would add a bit of extra treble and lots more low frequency bass. It would be like switching on the Loudness control on older stereo systems.
How to Turn JBL Clip 2 Low Frequency Mode OFF, and then ON Again, Proposal
Find the Bluetooth button on the speaker right side, and the Volume Down button on the lower left side.
You could turn this low frequency mode OFF by pressing and holding in the Volume Down (-) and Bluetooth buttons. Hold for about ten seconds, until the pilot lamp on the top blinks a few times.
To turn low frequency mode back on, again, you would press and hold the Volume Down and Bluetooth buttons in. Hold until the light on the top flashes a few times. You would release the buttons when that happens.
Then, after a short pause, when the status light would go back a solid glow. And extra bass mode would be ON once more.