Exec noisy car audio output when powered by car adapter

[derekfoley]

Having previously owned a IIs and having a standard usb cradle in my car run from a usb connectored "cigarette lighter adapter", I'm used to using my devices as a portable "car stereo". I even wired it up to replace my old crap car stereo, using a small "cheap boy-racer style" £30 stereo power amp under the dash. This has been great for the last year. I get in the car, dock the xda IIs into the cradle, plug in the headphone socket which is wired into the amp and hey presto, music - and tom tom prompts through the car speakers.

Recently I've been eyeing up the xda exec(JasJar/Universal) and after getting a second hand colleague to buy my IIis, decided to get the new device. Obviously the shorter battery life is a bit of a shock compared to my old one, but I was pleasantly suprised that
1) The audio output seems a better quality
2) The new device no longer needed a custom USB cradle plinth or gooseneck holder, ... I could place the "open clam" in the recess in my instrument panel, to the right of my speedo. Basically sitting just behind the steering wheel, which also solves the night-time reflection issues of a bright display.

Just one problem, I discovered that the USB sync cable supplied with the new device doesnt seem to enable charging to the exec when I plugged it into the 12Volt to USB adapter that worked with the XDA IIs that I wired into my dashboard. :(

So I decided to buy a new car power adapter for the new Exec, egged on by installing the great "mort player" which has an ideal "large button" interface on a black background which is ideal for use in the car.... and it doesnt forget the playlist like media player 10 seems to do each time you run it...

However, When the car power adapter arrived today, (from expansys)
http://www.expansys.com/product.asp?code=125511

To my dismay it is very noisy! the audio output to my amp sounds great with just the headphone output to my mini under dash amplifier, but only on battery power. But when the adapter is supplying power, the audio output becomes "crackly" Any electonics boffins have any suggestions to remove the "noise" with capacitors, if so what type and where should I put them, on the audio, or inline with the cigarette power adapter dc input somewhere, or should I just send it back and try and source a better quality adapter?

Expansys also do 2 other models -
http://www.expansys.com/product.asp?code=125969
http://www.expansys.com/product.asp?code=125970

Does anyone know if these are as noisy as the other one? Does anyone else have a similar setup?

Thanks in advance

Derek

[interestingfellow]

you have a ground loop. in america, we use negative as the ground, so be carefull with what I'm telling you (posative is ground in some countries).

What you need to do is run the amp and cigarette lighter off the same ground(s) and possibly the same feeds (supply voltage). Make sure you fuse the lines appropriately, or you might fry something.

I would suggest installing a secondary cigarett lighter outlet somewhere convenient (so you don't cross any other circuts in your car, and burn stuff out), and run it off the same points that your amplifier gets it's power. Fuse the new outlet with the appropriate fuse (should be 5 or 10 amps), and give your new setup a whirl. It's a cheap alternative for you to try (should be about $10 or 8 euro?)

Good luck, and remember, NOT MY FAULT WHAT YOU DO> TRY THIS AT YOUR OWN RISK!!!!!!

[jamfitz86]

I agree with him ^

JAmes

[derekfoley]

Strangely - today the noise is gone... hmm... very strange... :)
perhaps it was a solar flare, or another explosion at hemel :)
or more likely - perhaps there was a loose connection somewhere!

Thanks for all the advice guys, I will certainly make sure I avoid any ground loops and ground the audio on the same physical connection as the car earth. I'll check this at the weekend when I have some daylight to work in!. I'll do this when wiring the new adapter in properly - I can't bear it hanging out of the lighter socket with the near the indicator stalk!

I can say the Exec is great device though... Its a far better solution for car audio - and no leaving an expensive hifi in the car to be stolen.

Hopefully someone else is inspired by this post to also use the device in this way. If you want plenty of storage for a full install of the tomtom uk map and loads of music, you'll be interested to hear that you can actually get a 2 gig card now from ebuyer for about £60!

http://www.ebuyer.com/customer/products/index.html?rb=16670852531&action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=103013

Cheers

Derek