You can adjust the bass response of the JBL Flip 4, by turning on and off its Extra Bass mode. Thus when ON, this mode makes the passive bass radiators vibrate a lot more. Further, Extra Bass mode adds a hefty extra bass quality to the content playing.
JBL Flip 4 Extra Bass Mode: Explained
First, by default, the Flip 4 has this mode ON. This adds a bit of extra treble and lots of extra bass to the audio. It’s like switching on the Loudness control on vintage stereo systems. Not to mention that it can draw significantly more power from the battery. So it can indeed shorten battery life per charge.
JBL Flip 4 Extra Bass Mode: How to Turn OFF and ON
You can turn this mode OFF by pressing the Volume Down (-) and Bluetooth buttons. Then, you hold these in until the Power and Connect+ buttons light up white. This can take up to 12 seconds.
Also, to turn extra bass mode back on, again, press the Volume Down and Bluetooth buttons. Then hold them in until the Power and Connect+ buttons light up again. Finally, release the buttons when you see that.
Then, when the buttons return to their prior states, this mode is ON once again. If you had paired with a source device, the Power button turns steady blue again. And, if you did not connect this speaker via Connect Plus, the Connect+ button then goes dark too.