Windows Phone Thoughts: Bluetake's i-PHONO mini Bluetooth Headphone Kit Reviewed

If you wish to use the i-PHONO mini headphones with a media device lacking Bluetooth, then the accompanying i-PHONO mini stereo transmitter works wonders. The transmitter, by default, fits into the connector of select models of the iPod range. The audio/remote plug on the transmitter is adjustable, since different iPods have different connector layouts. If, however, you wish to use the transmitter with a media device other than an iPod, you can connect the universal 3.5mm audio adapter to the transmitter, and then connect the transmitter to any device. The transmitter enables both A2DP and AVRCP support on the iPod, but when used with the adapter, only A2DP is supported.

Here is a rundown of the transmitter's specifications:

• Dimensions: 55 x 36.5 x 16 mm (2.17 x 1.44 x 0.63 in.)
  
• Weight: 36 g (0.92 oz.) (Battery Included)
  
• Stereo Plug: 3.5 mm (1/8 in.)
  
• Frequency Response: 20 Hz - 20 KHz
  
• Sample Rate: 48 KHz, 16 Bit
  
• Bluetooth Specification: Bluetooth v1.2 compliant
  
• Bluetooth Profiles Supported: A2DP (Advanced Audio Distribution Profile), AVRCP (Audio Video Remote Control Profile)
  
• Power Consumption: 190 mW
  
• Power Input: 5 V / 200 mA
  
• Built-in Battery: 3.7 V / 300 mAh / Li-Polymer / Rechargeable

We'll Need Some Juice First!
The headphones and transmitter are powered by rechargeable lithium batteries. They aren't charged immediately out-of-the-box, so you will need to set aside a couple of hours of charging time in order to use the accessories. Because my BT450Rx-L and BT450Tx combo pack lacked an AC power adapter, I had to use the supplied USB cables for charging. They're great for travelling, but they have a downside in that they do not allow for simultaneous charging off a single cable (via the Y-splitter power cable) as most computers do not supply enough power to the USB ports.


Figure 6: Charging the headphones and transmitter with the supplied USB cables.

Both first-time charging and subsequent charging cycles take approximately two hours. The indicator light on the transmitter indicates the progress of the charging cycle. It's red while charging, and blue when fully charged. The aforementioned applies to the headphones as well. It differs in two areas though - first, the charging indicator light is on the Y-splitter cable itself and not on the headphones; second, it uses red and green as its indicator colours.

Pairing and Establishing Connections
In this section of the review, I focus on connecting the headphones to two Bluetooth-enabled devices, the Dell Axim X50v and E-TEN M600, as well as a standard CD player via the Bluetooth stereo transmitter.

A lot of today's Windows Mobile 5.0-based devices now use the Microsoft Bluetooth stack, as opposed to the Broadcom Bluetooth stack that was commonly employed in earlier versions of Windows Mobile. Prior to this review, my Axim X50v was running Windows Mobile 5.0 and it had not yet been updated with the Adaptation Kit Update 2.0 (AKU), which adds A2DP support to the Microsoft stack. As a result, I had to downgrade my device to Windows Mobile 2003 Second Edition in order to sample stereo audio through the Broadcom stack.


Figure 7: The Broadcom Bluetooth Manager searching for a device. And no, I'm not Bluetooth-enabled. My M600 (bearing the same name as me) is. ;)

But, even in the current version of the Broadcom stack for the Axim X50 series, A2DP support is not present. However, HP's iPAQ Bluetooth Stereo Headphones driver, while not officially supporting the Axim, does actually work on it. When installed, it adds a new entry to the Bluetooth Manager titled "High Quality Audio Setup". This is markedly different to the other entry titled "Hands-free/Headset Setup" which only offers mono audio through HSP/HFP.


Figure 8: The Broadcom Bluetooth Manager requesting a passkey.