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Sennheiser MM 400-X

On-Ear Wireless Bluetooth Headphones w/ apt-X Technology

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Audiophile, Premium, Best In-Class, Sennheiser

The award winning Sennheiser MM 400-X on-ear Bluetooth headphones offer you the best of both worlds: the freedom of wireless Bluetooth music and the high quality sound that Sennheiser is known for. These premium on-ear headphones don't skimp on the internals. Utilizing the latest aptX technology, an advanced audio circuit to deliver true high-fidelity sound over Bluetooth, the MM 400-X headphones don't disappoint. Sennheiser's patented Duofol™ diaphragms provide you with incredibly detailed, crystal clear sound. To go along with the convenience of Bluetooth and awesome Sennheiser sound, the MM 400-X's were carefully engineered to provide you with the ultimate in comfort during even the longest listening sessions. Premium soft padded headphone cushions and an adjustable headband ensure these headphones allow nearly any user to wear these headphones discomfort-free for hours on end.

Enjoy Bluetooth Freedom with the Sennheiser MM 400-X HeadphonesBluetooth Freedom

No matter how carefully you wrap and store cables, they somehow find a way to get tangled up. Headphone cables are no different, and the MM 400-X headphones were designed with Bluetooth to give you that wireless freedom. Combined with the built-in microphone, these headphones are perfect for getting lost in your music and managing your calls without getting ever tangled up in that mess of wires again.

Integrated Controls for Easy UseOn-Board Controls

When you're in a groove the last thing you want to do is pull out your phone to adjust the volume or skip a track. These headphones have eliminated that inconvenience by integrating volume, track and phone call controls into the right earcup to give you total direct control of your device. You'll never have dig your phone out of your pocket, purse or backpack to control your music or answer a call again.

Collapsible Headphones for Easy PortabilityPortability

Let's face it, as much as we would all like to never take off our headphones, there comes a time where we just have to. While the MM 400-X's are best served being listened to, Sennheiser engineered them with collapsing hinges with those non-use times in mind as well. When collapsed, these headphones are incredibly compact, making them both easy to transport and store.

Do You Want to Make Your Listening Experience Better?

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General Features

  • On-Ear Wireless Bluetooth Headphones
  • Computer optimized magnet systems minimize harmonic and intermodulation distortion
  • Connect wirelessly to any Bluetooth apt-X enabled devices
  • Connect everywhere:to mobiles, laptops, MP3 players, or in-flight entertainment systems with an all-in-one headset solution
  • Easy headset controls in one intuitive cluster
  • Extremely lightweight aluminum voice coils ensure excellent transient response
  • Neodymium ferrous magnet systems ensure optimum sensitivity and an excellent dynamic response
  • Exceptionally natural, spatial and accurate sound
  • Detachable, Kevlar reinforced, OFC copper cable
  • Sennheiser HH 10 Universal Holder (Mount) Available
  • Primary Color Tone: Black
  • Secondary Color Accent(s): Silver, Brushed Aluminum, Blue
  • Manufacturer Part Number: 502888
  • Authorized Sennheiser Internet Retailer
  • 2-year Manufacturer's warranty


  • Cable length: 10 ft. (3 m)
  • Ear coupling: On-ear
  • Frequency response (headphones): 15-22,000 Hz
  • Battery:
    • Talk time: 20 hours
    • Listening time: 10 hours
    • Charging time: 3 hours
  • Sound pressure level (SPL): 107
  • Total harmonic distortion (THD): 0.1 %
  • Transducer principle: Closed, dynamic
  • Weight w/o cable: 9.2 oz. (260 g)

What's in the Box?

Sennheiser MM 400-X What's in the Box
  1. Sennheiser MM 400-X Headphones
  2. Protective Storage Case
  3. USB Wall Charger
  4. Wall Adapters for US, EU, UK and AU
  5. Audio Cable
  6. Airplane Adapter
  7. USB-to-Micro USB Cable
  8. User Guide

Headphone Design

Headphone Type

Headphone type refers to the construction of the headphones.

Around the Ear means that the headphones wrap around the ear to provide a secure fit. This is most often seen in active and sports headphones.

Around the Neck means that the headphones wrap around the neck. This is also seen in active and sports headphones.

Earbuds means that the right and left sides of the headphones are separated and will fit securely into the ear. These are small, compact, and user friendly.

Over the Head headphones mean that the right and left speakers are connected with a support that goes over the head and rests on top. This is the typical headphone type.

Over the Head
Earpiece Design

This is the design of the earpieces on the headphones. Some headphones go inside the ear, while others rest on the outside of the ear. This helps you know exactly what type of headphones you will be receiving.

In-Ear: The ear buds go into the ear. Most often, the right and left ear buds are two separate pieces.

Enclosed-Ear: Usually are found on the larger headphones. They rest on top of the ear and have padding for comfort, as well as enclosing the ear to the speaker. This type of headphone helps to filter out surrounding noise.

On-Ear: This type of headphone involves the speaker sitting gently on the ear without going in the ear or sealing it off.

Specifically For
Some headphones can use an IR Transmitter in your vehicle, while some can be plugged into your media device and be used on the go or at home.

This is the lifestyle that the headphones are designed for. Each style has unique features that make it perfect for particular people.

Designed for those that are active. These headphones are made to stay in the ear during workouts. Whether you frequent the gym a lot or go running outside in the fresh air, these active style headphones will be your best friend.

For those that need the best in music quality. These audiophile headphones are engineered to produce high fidelity and accurate audio replication.

Disc Jockeys (DJs) require a special type of headphone that can meet their professional needs. These headphones are durable, loud, and will often allow for one ear listening.

Fashion Enthusiast:
For those that want to make a fashion statement with their headphones. Not only are these headphones designed with great sound quality in mind, but also great looks!

This lifestyle speaks for itself! If you love video games and want a pair of headphones that will deliver explosive sound and allow you to communicate with others, this is where you need to shop!

Music Lover:
These headphones are made to sound great. They are designed to produce rich, brilliant sounds that will play your music in a manner that the artists would appreciate. These headphones are for those that love music.

Musical Production / Recording Artists:
You're a music creator. Whether you're producing and mixing it down or in the studio recording yourself, you need a pair of headphones that will reproduce the music perfectly without any coloration. Look here for reference quality studio monitoring headphones.

Headphones need to be affordable and durable to keep up with the student lifestyle. A variety of styles can be considered a pair of student headphones.

Those that often find themselves on planes or on the road a lot. These headphones are compact, lightweight, and have a portable design. Some of the headphones in this lifestyle will feature noise cancellation technology that will help shut out outside noise.

Music Lover

General Features

Noise Reduction technology removes unwanted noise from a signal. Background or ambient noise can be removed to produce clearer speech and enhanced hearing. Typically these Active Noise Canceling (ANC) headphones are powered and use batteries to activate the noise canceling technology. Also referred to as Noise Reduction or Noise Cancellation.
Headphone Connection
This is how the headphones connect to the audio source.

Corded means that the headphones use a cord to transfer the audio signal.

Wireless means that the audio signal is transmitted wirelessly to the headphones.

1/4" Stereo Jack Adapter
Some headphones will come with a 1/4" stereo jack adapter to connect the usual 3.5mm jack to a 1/4" stereo plug.

1/4" Stereo jack is a larger audio jack that select electronics have.

Volume Adjustment
Volume Adjustment means that the headphone (independent of the source) can adjust the playback volume. Many headphones and ear buds have in-line volume control, which allows adjusting the audible volume from a switch on the headphones cord. Other headphones have a volume knob on the headphone can.
Built-In Microphone
This means that the headphones or earbuds have a built-in microphone. This can be a microphone on the cord, built into the headphone, or even a boom microphone. These mics can be used for music devices like iPods, for Smartphones to make and receive calls, or for gaming purposes.
Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
15 - 22000 Hz
Primary Color
This is the main color of the item.
Secondary Color
A color that compliments the main color of the product.

Warranty and Return Policy

Parts Warranty Duration
2 years
Labor Warranty Duration
2 years
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

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Average Attribution Rating

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Jeffrey B on Nov 20, 2014

Product Summary


Model Number

MM 400-X





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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Sennheiser MM 400-X

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  • Sennheiser MM 400-X Bluetooth Headphones