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Plantronics Discovery 640 Bluetooth Headset

By Adam Z. Lein February 1, 2006, 12:00 am



For years, Bluetooth headset manufacturers have been innovating by trying different ear mounting systems, getting better sound, making them smaller/lighter, or adding other features like caller ID. You can't see an LCD display when it's hanging on your ear! Anyway, the Plantronics Discovery 640 actually takes a different approach to innovation and makes their high-end headset easier to use, easier to recharge, and easier to carry while retaining the other important things like size, comfort, etc. Read on to see exactly how they did this.



The Discovery 640 has a lot of exciting features. The charging cradle can be modified to fit your existing phone's charging, thus reducing the number of AC adapters you need to car. It can also take a AAA battery for charging.


One of the biggest problems with using a Bluetooth headset, is where do you put it when you're not using it? Other manufacturers often provide a lanyard that you can use to hang it around your neck, but that's not very good for when you want to put it in your ear. Others have belt holsters or just assume you'll keep it in your pocket where it might bang against your keys or whatnot. Ideally, the headset would slide out of your phone so that you could keep the two together when not in use as outlined in my 2003 PDA wishlist. Well, the Discovery 640 comes closest to that type of functionality with it's pen-like carrying case that can clip into any pocket.

Another problem with Bluetooth headsets is that you usually have to have it in your ear to tell if the phone's ringing when you're phone is stored away in your bag or something. When the Discovery 640 is in it's charging cradle, the whole thing vibrates when a call is coming in. And unlike some other headsets, when the Discovery 640 is in your ear (i.e. not in the cradle) it does not vibrate. Furthermore, and this is a great feature I'm happy to finally see implemented, when you take the headset out of the cradle, it automatically answers the call. That's right, no longer do you have to press a button to answer manually! Then with the headset's non-obtrusive gel earpieces, you just stick it in your ear as if it were an ear-bud headset. No difficult ear loop mounting systems to figure out! It's even easier than Nextlink's ear mounting system!

Bluetooth Headset

Talk Time | Standby (hours)

Weight (grams | ounces)

St Price (as of 2/1/06)
Plantronics Discovery 640

15 | 300*

9.00 | 0.32 $80
Movon MF200 5 | 150 15.0 | 0.53 $115
Logitech Mobile Traveller 7 | 300 14.2 | 0.50 $80
Southwing SH305 6 | 300 11.0 | 0.38 $55
Gennum nXZEN Plus 7 | 100 17.0 | 0.54 $150
Bluetake BT400 G55 | 250 20.0 | 0.71 $60
Nextlink Bluespoon 5G2 | 100 5.85 | 0.21 $250
Nextlink Bluespoon AX2 8 | 1000 10.0 | 0.35 $80
Nextlink Bluespoon AX 4 | 200 12.0 | 0.42 $60

*with use of AAA battery option. Click on any headset title above to see our review.



One of the most unique features of the Plantronics Discovery 640 is its modular cradle/charging design. The cradle that holds the headset has a propietary connector on the bottom where you can attach a variety of different charging adapters designed to fit the existing charging cables for most popular phone manufacturers. See the diagram below for what's included with the Discovery 640.


First off, you have to make sure the headset is charged up, and the Discovery 640 has many options for that. The Headset Status Indicator glows red during charging and turns off when fully charged. Then you can turn it on by pressing and holding the call button for about 3 seconds. The status light should glow blue when it's on and will blink blue every 6 seconds. Holding the call button down for about 6 seconds will turn it off (indicated by the red status light). While powered on the status indicator will also indicate battery level between blue flashes. Here's how:

Greater than 2/3 battery charge = 3 red flashes.

1/3 to 2/3 battery charge = 2 red flashes.

Less than 1/3 battery charge = 1 red flash.

Then you've got to pair the headset with your phone over Bluetooth so that you can use it. I used my imate K-JAM Pocket PC Phone. First shut the headset off, and then turn it back on by holding the call button down. Once it turns on, keep holding the button down until the status indicator light starts flashing red and blue. This means that it will be in pairing mode for about 30 seconds. Now you can go to your Pocket PC Phone (or other Bluetooth phone) and search for Bluetooth devices within range. When the "640 Plantronics" shows up in the list, you can initiate a pairing with it. The PIN number to enter when requested is "0000". After a successful pairing, your headset will be functional as a Handsfree or Headset device depending on which Bluetooth profiles your phone supports. Now any calls I make from the imate K-JAM will be automatically sent to the Discovery 640.



The Discovery 640 has a simple 3 button interface. The larger call control button is placed at an angle near at the upper end of the headset. The angle helps keep the headset from mashing against your ear when pressing the button. The other two buttons handle volume up and down. Pressing both volume buttons until you hear a beep toggles the mute function.

To answer a call, you can either press any button or remove the headset from it's charging cradle. Pressing the call control button once will end the call. You can invoke the redial function by pressing the call control button twice (you'll hear a high pitched tone for each press.) A long press of the call control button (until you hear a lower pitch tone) will activate voice dialing, or in the case of my K-JAM, Microsoft Voice Command. Shutting off the voice dialing audio gateway requires another press-and-hold of the call control button.

In addition to the battery level features of the status indicator mentioned earlier, there are a few other unique features. When the phone is ringing, the status indicator light will rapidly blink blue and red. If you missed a call the indicator light will periodically blink blue and red. Now that's another great feature!

The Discovery 640 also supports the Bluetooth 1.2 standard for faster reconnecting times. The battery life should give you about 5 hours of talk time, but if you use the AAA charger cradle to store the headset when not in use, you can get about 15 hours talk time (but not all at once!)

Even with all the usability features, the Plantronics also features an acceptably small form-factor.

It's still not as small as the Nextlink Bluespoon 5G, but comes pretty close to the Bluespoon AX. At 9 grams, it's actually a bit lighter than the 10g Bluespoon AX.

When attached to its charging cradle and AAA powered charger, the Discovery 640 looks like the memory erasing device from "Men in Black." This configuration is about the size of a highlighter marker. There's a pen-like clip on the other side that lets you easily store this in a shirt pocket. And as mentioned before, this whole set-up will vibrate when a call comes in.

The carrying case has form-fitted areas for each of the Plantronics Discovery 640's parts (except for the AC adapter). The whole package will easily fit in a jacket pocket. It looks like some sort of futuristic weapon! Pretty cool.

There's also a mirror on the back of the case so you can check yourself out when mounting the headset.

We tested the Discovery 640 at the Chinese New Year celebration in Chinatown New York City. Due to the soft ear-gel and loud internal speaker I was able to easily hear other callers who were lost and swallowed up into the crowd. However, the 640's microphone did not fair too well in such a noisy environment. I didn't really expect it to, since it doesn't have any kind of noise reduction. On the plus side, those ear-gels are very comfortable. Even though the 640 weighs about 9 grams, it felt like I was wearing the Bluespoon 5G. If it's not sturdy enough for your ear, there's an optional ear stabilizer attachment as well.



Plantronics has some really great support options on their

website. You can search their knowledge base, submit a question via the web, or chat live with a support technician. There's even an Instant Live Talk option where a support representative will call you for free after you send them your phone number! There's also an easy form to fill out for warranty repair and headset replacement.



You need a Bluetooth enabled phone, PDA, or Computer with the Headset or Handsfree profiles in order to use the Plantronics Discovery 640. It will work with any Bluetooth version including Bluetooth 1.1, 1.2, and 2.0.



The worst part of the Discovery 640 headset is that the microphone occasionally performs very poorly. It's sometimes quite random as well. I could be on the phone with one caller who could barely hear me through the headset one day. Then another day with the same caller, he would be able to hear me just fine. Then of course there's the inability of callers to hear me talking at the Chinatown New Years activities, but this headset doesn't claim to have any noise reduction capabilities.

The Discovery 640 is supposed to be able to play your phone's ringtone through the headset when an incoming call is ringing. This unfortunately didn't work with my i-mate K-JAM, and thusly wouldn't work with Microsoft Voice Command's verbal caller ID announcements. This is probably more a problem with Windows Mobile 5.0 than Plantronics' implementation.

I really like the gel-ear-bud type mounting system. However, even though it comes with 3 different sizes, it may still not fit your ear perfectly. I'd like to see a more malleable and ergonomic ear-bud attachment in future versions. It should just pop-in and stay attached. This type of mounting system would also feel more secure if the headset lost some weight. I'm sure future versions of the Discovery headset will address this. Hopefully they'll be able to get the charging cradle down to the size of a ball point pen cap as well.

What would be really nice is if they could make this about 50% smaller, and have the docking sleeve built into a Windows Mobile Phone or Pocket PC Phone. That way you could keep both in the same pocket, use the same charger, and just slide out the headset to answer a call.



Modular charging cradle system9 gramsVibrating cradleVery easy to use and comfortable mounting systemBattery level indicatorMissed call indicator



Outgoing audio can be poor at timesNo noise reductionMini-USB adapter sold separatelyCharging cradle is not built into a Windows Mobile phone

What do these ratings mean?



I was very excited when I learned about all the great features this headset has. The vibrating pen-clip holder/charger/cradle feature alone may be worth upgrading to this headset. The variety of adapters designed to fit other phone manufacturer's proprietary AC adapters is a beautiful idea as well. Perhaps my random microphone issues are an isolated result of a defective unit. Regardless, this headset is so chock full of well-implemented, innovative, and beautiful engineering. It's sure to influence the other Bluetooth headset manufacturers in the future.


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