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MG MGF Technical - Amplifier for my Tomtom

Here's one for the electronic gurus... :o)

I have a iPaq/HP based TomTom sat nav that I transfer from one car to another - and jolly good it is too. But I find that with the roof down, and the tunes turned up, I frequently find that the old girl reading the istructions is drowned out.

What I'd like to do is to attach the HP's audio out to one or more of the car's speakers. Thing is that I suspect that the output level is likely to be pretty feeble (most likely designed to power head phones than car audio speakers), so I suspect that an amplifier is called for.

So, two questions. Is there a simple, cheap, mono amplifier I can buy that can be rigged up to the speaker behind the driver in the T-bar that will accept an already amplified single from the HP?

Secondly, and rather more complicated, is there a way of altering volume to the speaker according to ambient noise?

I am sure that there is a way to do this - but what's the best, and most cost effective way of doing it?
Rob Bell

Rob - I purchased an amplifier complete with audio jack from Maplin which I use in the MG - the lead was long enough to run to the T bar and I stuck the speaker 'bit' just behind my ear - works well even at Autobahn Speeds (-:
Ted Newman


If you connect an additional circuit to only one speaker, you will knacker the impedance and cause a mismatch, which will affect the balance of the speaker system.

Some vehicles do have automatic speed sensitive volume control (like my MK3 Range Rover) but I doubt that this could easily be added to the F, as it's integrated with the ECU.

Ted's solution sounds like a winner though.


Sam Murray

KISS principle again - thanks chaps. Sam, I should have thought about the altered impedence, although something that an additional resistor would sort out? Thanks for that :o)

Ted, which amp did you get from Maplins? I don't suppose you have a part number handy do you? :o)

Cheers all
Rob Bell

Rob, I've got a similar set up, and problem. I've tried pairing my iPaq with my bluetooth headset, but it doesn't find any usable services. :(

Ralph Gadsby


It was many years ago so no longer have the paper work. BUT it is more a mini speaker (about 2 inches diameter) than a true amplifier and is made for plugging into the headphone socket of any audio device and comes complete with cord and mini jack - I just browsed the shop and found it on a rack on the wall. Whilst I was unsure if it would work when I purchased it, it was so cheap it was worth the gamble AND bingo it worked.

BTW it has been in the Squirrel for at least six years now and still works.
Ted Newman

Rob you can buy a small transmitter for the output of your Tom Tom or any I pod type devices that transmits the signal to a frequency that can be tuned into by your fm radio and thus played through the system.
I have the Tom Tom 910 that with its 20 gig hard drive acts as an MP3 juke box and I connect that to a couple of my cars with a connection to the aux in jack. However I have a modern Mini that does not have an aux in on its radio/cd so I use the little Transmitter to do the job.
Bob (robert) yes Y8 is toast again :)

Thanks Rob - I had thought about one of those FM transmitter devices. So long as it has a mini-phono jack input, it would be fine... except that I then couldn't listen in on a different radio frequency or cassette/CD. Unless of course it interrupted 'programmes' by using the traffic alert feature?

Ted - thanks. I'll have a look in store. I had a quick look on line, and all I could find was a small mono audio amp which would require a case making up, a stablised power supply and a speaker. Not exactly convenient!

Ralph - rather figured that the blue tooth wouldn't be of much use - and besides, my HP iPaq uses a bluetooth connection with the GPS receiver. :o/

Any other cunning suggestions? :o)
Rob Bell

I can't go down the route of the FM transmitter as one of the cars that I use my iPaq sat nav in has no radio! This is why I tried the bluetooth route. Is it not possible to connect an iPaq to more than one bluetooth device at a time? I've certainly done this on my laptop.



They call it a 'pillow speaker' see:- this looks exactly the same as the one I use with my Garmin.

Mind you expensive at 6.99 (-:

Ted Newman

Thanks Ted :o)

BTW found this too:

It has an 'auxillary throughput' - might this enable a TomTom speaker connection? :o)
Rob Bell

This thread was discussed between 07/06/2007 and 25/06/2007

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