Home > Reviews > The JBL Synchros E40BT: A Bluetooth on-ear headphone set well worthy of consideration


If you’re in the market for a Bluetooth headphone set, you owe it to yourself to consider the JBL Synchros E40BT. It’s an on-ear set that boasts excellent sound, is designed very well, is easy on the eye, and can be relied upon to last quite long on just a single charge.
The world, it seems, has gone crazy for Bluetooth, and for good reason. The increasing quality and battery efficiency of Bluetooth connections mean that going wireless doesn’t automatically mean you have to put up with poor sound and bad battery life. The sound quality of Bluetooth sets is in many cases not exactly as good as that of wired sets, it’s true, but it’s not all that far off any longer.

Leave it to JBL to design on-ear Bluetooth headphones for music-lovers who want the convenience of a wireless headset, but yearn for good sound in this price and size class.
What’s in the box
There’s nothing to write home about the contents of the E40BT box. Aside from the unit itself and the requisite manuals, warranty and documentation, users also get a USB cable that plugs into the headphone jack to charge the unit, and another cable to help use the unit even while the battery’s charging.
Styling, features and initial impressions
As far as Bluetooth on-ear sets go, the E40BT is relatively compact and lightweight. Heft and bulk are always prime concerns when it comes to these kinds of headphones, and we're happy to say that JBL seems to have designed these quite efficiently. Although sets like these could always be smaller, it seems, these don't feel unnecessarily bulky.


The E40BT's noteworthy industrial design and excellent fit and finish contribute greatly to this impression. This is a stylish piece that makes good use of high-quality plastics, metals and leatherette (for the ear cushions). It's quite the looker, too - our red test unit turned more than a few heads while we were putting it through its paces in public. The color isn't too garish a red, mind you, but is just bright enough to call a little attention to itself. If even a muted red isn't your thing, no problem - a black version is also available.
In this world of throwaway electronics, it's also gratifying to see that the E40BT appears to have been put together with care. Our tester had no panel gaps or misaligned parts to mar the user experience.

Now a few words about the E40BT’s feature set. It isn’t one of the range-topping Bluetooth headsets, but is a midrange set, so don’t expect all the bells and whistles. It boasts 40mm drivers, putting it a little below its elder sibling the Synchros E50BT (which has 50mm drivers).
It also comes with a cool feature - ShareMe - intended for those who like to enjoy music or other forms of media with friends. In a nutshell, ShareMe lets users share audio from paired devices with other compatible JBL headsets. This can be a cool option if you have friends and/or family with whom you'd like to share your music (and who also have headsets from JBL).
User experience
By and large, the E40BT is neither just a looker, nor is it only a nice piece of equipment; it both impresses and satisfies when it’s put through its paces.
Sound quality. We tested these headphones with a wide range of music (from classical to heavy metal) and watched quite a few movies and TV shows with it on as well. The sound the E40BT pumps out is impressive - clean and balanced, if a bit on the bass-heavy side. Whatever we listened to, it was lively and dynamic, even when we turned the volume up. Everyone but fans of extremely heavy bass will probably be impressed by the quality of sound this unit generates.
Comfort. We found the E40BT quite comfortable to use in situations that aren’t too warm. The unit’s light weight, relatively slim profile and generous but not excessive padding make them comfortable to have on for hours on end. The unit’s easy to tweak to ensure a good fit, thanks to an adjustable headband and earcups that pivot inwards. (By the way, this also makes them easy to store.) When it’s a little hot, the leatherette can get a little uncomfortable because it traps some heat, but then again that’s par for the course when it comes to on-ear headsets.

Switchgear. The switchgear for this headset is relatively comprehensive. The buttons are on the outside of the left earcup and allow users to click up or down to adjust the volume; left to access a multifunction button for skipping tracks and taking calls; and right to trigger the ShareMe function. Finally, there’s a button on the underside of the left earcup that switches Bluetooth connectivity on and off.

While button tactility is decent, we think the switches could still use a little work - they’re not all that easy to use with the headset on. It’s a little hard to tell, for example, if you’re about to lower the volume or activate ShareMe. We think raised or embossed symbols would make it much easier for a user to know what s/he is about to do. As it stands, a little familiarity with relative button positions is required before any user can actuate button functions with confidence.
We’ve also inadvertently turned our tester off a few times by pressing the Bluetooth button by mistake. (The button’s located in the path of the left thumb when the left hand is raised to the head, making it very easy to trigger accidentally.) It might be best for this button to be moved elsewhere if and when the unit is redesigned.
Battery life. JBL claims an admirable 16 hours of battery life and up to 24 hours of talk time on one charge. These figures seem adequate. The unit will also shut itself off if idle after just a couple of minutes, to preserve battery life. To charge the E40BT, users will just need to plug the provided USB-to-headphone jack cable into the headphone port. Topping its battery up should take about three hours; thanks to the included cables, the unit can still be used even when it’s charging.
Final words
So there you have it - the JBL Synchros E40BT turns in an impressive performance thanks to its great sound and good design.
We look forward to seeing how the E40BT will influence its market segment and help raise the level of midrange Bluetooth on-ear headsets.