Review : JBL Synchros E40BT headphones

Balanced sound, cleaver controls make wearing on-ear headphones enjoyable

MacNN Rating:


Product Manufacturer: JBL

Price: $100

The Good

  • Bluetooth range
  • Control system
  • Sound quality

The Bad

  • Flimsy construction
  • Headband adjustment
  • Uncomfortable after two hours
For all the different configurations of headphones on the market, it's always a tough choice for buyers to get something that is just right. For consumers searching for a strong sound but who don't want to shell out a couple hundred dollars on over-the-ear headphones, on-ear is the next step down. But does that mean the sound quality is a step down as well? The JBL Synchros E40BT headphones aim to convince users otherwise, with its balanced approach to sound and mid-range price. Does that mean that the headphones are good, or something that consumers would be settling for?

The Synchros E40BT headphones feature a plastic construction that incorporates aluminum highlights on the ear cups. Each foldable ear cup is approximately 2.75 inches in diameter, with an inner diameter of about 1.3 inches. The headband has the JBL logo stamped into the crown, as well as etched into the aluminum disks on the ear cups. Maximum band extension from the center of each cup is approximately 18.5 inches, with a minimum band length of about 16 inches. Each of the pads, including the headband pad, contain a soft foam wrapped in leatherette.

Band adjustment was concerning, the first time the headphones were picked up. Without wearing the set, each ear cup can be adjusted very easily, since there's only a small amount of friction to overcome. Users can feel the teeth grabbing, but shouldn't expect the ear cups to hold if they are swinging them around. However, once the headphones are on the head, the cups become harder to move. The outward stretching of the band gives enough pressure to increase the hold.

However, the issues with adjustment also has to do with the choice of construction materials. It isn't that the plastic feels cheap or inflexible. In fact, the E40BTs have a surprising amount of "give" to them. The problem seems that the tolerances aren't as small as they could be. The slider for the band adjustment shows this when looking at the front of the band. If slid all the way up, the part that grabs onto the notches acts as the sole anchor point. Holding the Synchros sideways, almost 0.125 of an inch can be seen between the band and the slider.

It's recommended that users refrain from putting too much pressure on the headband of the E40BTs, as they feel like they might snap if stretched or pulled in too far. Since there doesn't appear to be any metal in the band, breaking them could result in them being unusable without a generous application of duct tape.

If there is something larger to fault with the E40BTs, it's that after a few hours they aren't very comfortable. The padding isn't that thick, only about 0.25 inches, which leaves wearers with mild discomfort after a long listening session. It's hard to fault JBL here, as this is a common problem for on-ear headphones. Either padding is so thick that it deadens the sound, or its just thick enough not to change the sound signature and remain somewhat comfortable. It's a hard balance to meet.

JBL included a control system on the Synchros E40BT that is neat and functional. Making use of four buttons on the left ear cup, users still maintain every level of control they would have at the device level. On the surface, there are only buttons for pause/play, volume up and down and one for phone calls.

While the volume buttons only control sound levels, the other two buttons are multifunction. Pressing either twice moves to the next or previous track. A press followed by a press-then-hold fast forwards or rewinds a track. The call button uses short and long presses to answer, hang up, switch calls or hang up and connect to the next one. The multifunction buttons take a little bit of time to get used to, but once a wearer is comfortable with them, it will be a welcome level of control in as few buttons as possible.

On the topic of phone calls, the Synchros makes the user sound a little distant. The headphones use a microphone on the left ear cup to pick up sounds, which depending on the user, can mean it's a decent distance away from the mouth. It functions fine, and picks up voices well, but it's like the voice is a little hollow or far away.

Battery life for the Synchros E40BT is stated to be 16 hours, but in everyday use it was closer to 12. This was noticed over the course of three days of listening at near-maximum volume. They also took 160 minutes to charge, compared to the 180 minutes JBL states. Either way, it's enough battery life to cover light-to-moderate listening on any given day. For the times the battery dies, JBL has included an auxiliary cable for continued listening. The battery indicator is the same as the Bluetooth pairing light, making use of red and white LEDs to indicate the charge.

Bluetooth range for the headphones was impressive compared to many other wireless headsets. In the testing environment, the signal stretched from one side of the building to the other without an interruption. At a straight shot, the distance was approximately 45 feet. Within the building, the Synchros were the first set of headphones to reach this distance. By comparison, many begin to lose signal between 20 and 30 feet.

Sound quality for the E40BTs is a bright note in their use. JBL uses "PureBass performance," which is intended to add clarity and precise sound. The result is the 40mm drivers pushing out an almost crystal clear sound across any type of song. The odd thing about the Synchros headphones is that they feel like they highlight the sound characteristic of each song without appearing to favor one element over another. Balance for the tested songs felt almost perfect.

When it came to the bass heavy "Hunter," the speaker push could be felt from the ear cup and in the ear, but it was never enough to block out or otherwise hinder the vocals. It was noticed that some of the high end liked to break up, especially during some of the high-pitched vocal notes on "Welcome Home." It wasn't enough to ruin the listening experience, but it was noticed on more than one occasion.

Even with this issue, sound volumes had fairly even drops, with each drop tested. "Hunter" peaked at 96.6 dB at 100 percent volume, while "Notorious" recorded 71.3 dB at 25 percent. From 100 to 25 percent, volume levels dropped between 10 to 13 percent.

Given the great sound quality and the unique-but-easy control system, it's hard to find another set of on-ear Bluetooth headphones as good as the JBL Synchros E40BTs. Yes, there are some comfort and construction issues, but taking a break after a few hours should be able to overcome them. Consumers will also need to be careful not to be too rough or they might be facing a band that's snapped in half. The $100 cost seems like a perfect fit for the Synchros, as it sits in an affordable range, but can compete with some with some of the much pricier designer headphones on the market.