Wednesday, April 10, 2013

Tweaking Harman Kardon Bluetooth Headphones

The HarKar-BT is by far the best sounding headphones among my collections including Sennheiser HD-580 and RS160, wireless or wired, significantly better than these Sennheiser's. Its battery life, 12 (>18 in real life) hours, is the longest as a Bluetooth device and it is the thinest as an over-the-ear type.

However, it is not comfortable enough, even after I stretched its band span from 5" to 6.5". After some exam in a mirror, I found the problem. The joints have very little freedom; so the ear pads never settle down evenly around my ears. This video explains it well:


The fix is also shown in the video.

For those who want to open the cases to see what's inside: there are five screws under the seal, use a small magnet to locate them. The speakers are not closed type, there are large holes on the back. This may explain why this BT cannot isolate noise as well as other true closed type cans such as the RS160. Furthermore, there are large holes on the front panel, allowing even more noise in. This is also the main reason for its exceptional good sound, especially as a "closed" type, because it is more like open type, and, with phase-reverse holes like home speakers!


A small square foam was at the wrong location, it did not seat the joint, I moved it to the right place -  bottom center of the circuit board. Without this soft seat in place, the joint makes click noise with the plastic case. The wire to the leather strip was too short, I removed the yellow hot glue and pulled more wire out of the case. The antenna, the small white bar on the top, is very short, I might solder a 30mm wire to it to extend the range even further, but I found that the bottleneck is my other devices (Samsung Note 2 and Sony TX/RX).


The battery is on the right side, quite large indeed, no wonder it can last for more than 18 hours per charge. With such long play time - more than a whole day, lacking of audio during charging is not a big deal. I just need to remember to plug it every night before I sleep and my music won't stop for the next full day. To less the pain further: full charge takes less than 2 hours, not the usual 3.5. When battery is low, sound becomes obviously worse. For the best sound, you really should charge it after about 12 hours, even though it can play much longer than that.


Anyone can explain why these yellow hot glue on the back of the speakers? Seems they block some holes and leave only three (or one, on the metal cover) of them open. The audio engineer seems know what he's doing, the mechanical and electronic engineers don't. I guess you can open or block more holes to tweak the sound style to your like.

I could not find its manual online; so I scanned it for you: HarKar-BT manual, in English and Chinese. The most interesting info is how to know whether it's in APT-X, AAC or A2DP mode based on the flashing pattern of the LED. There is also a flyer on the specs and features, here.

Abstract in Chinese

海尔曼-卡尔丹的蓝牙耳机声音杰出的好、电池长、盒子薄,但是压到脸上的时候不均匀,最好根据自己的情况把钢带的角度调节一下。中英文说明书

17 comments:

  1. Thanks for scanning the manual. I was going crazy trying to find it online.

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  2. Your mods are great, thank you for posting them. Have you tried opening/blocking holes for sound modification?

    Is there any way to stop the headphones from auto-muting when charging?

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    Replies
    1. I did not try to block the holes, because I was already satisfied with the sound. I tried, but could not find a mod about the muting. I sold the HK after I got the Samsung HS3000.

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  3. Can't find how to disassemble them. Can you help?

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  4. is the battery eventually stop working on a lot of models ?

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    1. This comment has been removed by the author.

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  5. I charge my head phone but it doesn't turn on is there a way to fix that problem?

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    Replies
    1. My HK BT (battery) have stopped to work, complete blackout. I figured out that it's battery failswitch problem. I've opened left casing (one without controls) and plugged into battery contacts (red:+ and black:GND) directly from USB power accordingly (without unplugging anything from board) just for a few seconds, and overall BT functionality was restored.

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  6. I love my HK BT headset, however less than a year after I purchased it, the joint connecting the earbud to the band has unglued itself. Have tried gluing it back but it never stays long. Any suggestions on how to fix this?

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    Replies
    1. You need the right glue: J-B Weld, it worked for mine.

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  7. Hi can anybody help,
    the battery in my harman bt only lasts for about 1-2 hours. I have taken them apart and located the battery but can't find a supplier of them. The info on it is

    BAK 602254P
    DENO279
    3.7V 580MAH
    2.15WH 2F07
    PETER

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    Replies
    1. You can replace it with any battery that fits in. An old cell phone battery is a good option, so is a cheap MP3 player etc.

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  8. Hey do you think this battery would be good as a replacement? http://www.ebay.com.au/itm/580mAh-3-7V-Li-ion-Replacement-Battery-for-Apple-iPod-Video-30GB-/262570720240?hash=item3d226f3bf0:g:yNAAAOSwyLlXpZ8y

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    Replies
    1. The pins of the tip might be difficult to solder.

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  9. Hi,
    My headphones lose audio in one ear after a few minutes randomly.
    I found that when that happens, one of the wires going into the speaker doesn't have continuity with anything else on the speaker or the board. It randomly comes back at times.
    Any help is appreciated!
    Rohit

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  10. Nice product post! For more you can also check out for the Best Bluetooth Headphones ! Thank you for sharing!

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