Reposted here from my original post here .
I use my GPS unit as a hands-free for my phone. My Nokia N97 Mini isn't fully supported by either my nüvi 760 or my Navigator IV but it's enough to make and take calls. In the car, I have a Garmin accessory mic. into the input in the GPS mount and I usually run a pair of these Philips speakers connected to the 3.5mm stereo jack on the side of the nüvi. This setup works well and enables me to hear calls and for me to be heard by someone on the other end of the phone.
Unfortunately, the Zumo doesn't work so well in this respect. Both input and output volume are too low. It's clearly not a problem with the rating of the amplifier in the Zumo as it's loud enough to drive the stereo speakers when giving voice directions in routing mode and powerful enough to distort its own internal speaker when not connected to the external ones. I suspect it needs a software update to fix the Bluetooth volume.
So, can we please have a Bluetooth upgrade to increase the output volume and to increase the gain on the microphone input?
A bit of further surfing suggests that the problem is twofold:
A) When connected in Bluetooth mode, the internal mic. in the Zumo doesn't switch off so that my external mic isn't being used to pick up my voice and relaying it to my phone.
B) The output volume of the Zumo isn't great enough when it's in Bluetooth mode.
The real problem arises with my BMW Navigator IV when used in the motorcycle mount on my bike. The Nav IV mount obscures the 3.5mm output jack on the GPS unit so it's not possible to use it in hard-wired mode like the Zumo 660. This effectively renders the unit useless as a means of transmitting sound from a phone or mp3 player to Bluetooth helmet headset.
There has been no response from Garmin techs here on the forum. I don't know whether this means that they're unwilling to publicly recognise that there is a problem or that they're reluctant to say if they're working on a fix. In either case, the unit's performance is currently not good enough for a high-end motorcycle specific GPS unit.
I'd be grateful for an indication of when Garmin will address these bluetooth performance issues on the Zumo 660.
TIA
