Change how much rumble you get on the JBL Boombox, by turning on and off its extra bass mode. When ON, this mode makes the passive bass radiators vibrate much more. Plus it adds a low rumble quality to the playing program, that carries pretty far from the speaker.
JBL Boombox Extra Bass Mode: How to Turn OFF
By default, the JBL Boombox has this mode ON after a factory reset. This adds a bit of treble and lots of extra bass to the sound. Indeed it makes the Boombox sound much bigger than it actually is.
You can turn this extra bass mode off by pressing the Volume Down (-) and Bluetooth buttons. Then hold them in for about ten seconds.
Hold until the Power and Connect buttons light up together. Find all these buttons on the top of the speaker.
JBL Boombox Extra Bass Mode: How to Turn ON
To turn extra bass mode back on, then again, press the Volume Down and Bluetooth buttons. Hold them in until the Power and Connect buttons light up. Then release them. When the buttons inside the oval island light up, the Extra Bass mode resumes once more. You should be able to hear the change in the sound, which is generally quite obvious.
Warning
The drivers really rock when you activate this mode. So use caution in how loudly you play this speaker when EBM is active. Doing so avoids damage to the speaker drivers inside. So if the bass is crackling, tapping, or otherwise distorting, turn it down ! Also, keeping the bass down saves battery power. So this can be particularly important if you’re playing music at an outdoor party. But there’s no access to AC power for the charger. So, keep the bass down to avoid the speaker running dead before the party is over.