One V2 radio interference

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

I have an iPod powered by a cigarette lighter adaptor connected to my car radio, and it works fine, until I also plug in my TT One's adaptor. Then I get audible interference (sounds like it's from the alternator as the pitch rises with engine speed). As soon as I unplug the TT One adaptor, the noise stops. It doesn't matter if the One is actually connected or not.

A faulty TT adaptor? Are they known to be problematic? My TT is still under warranty, but dealing with TT seems to be a BIG problem, reading posts here :-(

USB car power adaptors are cheap enough so I could try another, but the TT one is, unusually, rated at 2A and I'm having trouble locating a low cost (or really ANY) alternative.

Any ideas/advice/comment?

tonys66 · Posted: Wed Feb 28, 2007 10:21 am Post subject:

Sounds a bit like the cars suppresser you can get 1 from a car shop or maplings all you do is fit it inline ie fit it to the lighter socket power lead
that should solve your problem.
unless someone else has a better idear

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

Maybe one of these?

http://www.m-99.co.uk/Car_Audio/Noise_Suppressor/noise_suppressor.html

mikealder · Posted: Wed Feb 28, 2007 3:59 pm Post subject:

This One is cheaper, although I am not too sure a ground loop isolator will fix this issue. I would be tempted to try another car charger lead for the TomTom as there must be something wrong if its creating interference even when not powering the device - Mike

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

Thanks. I think Maplin charge for delivery, though.

I will try another bit of kit. What's so odd is that the interference sound pitch increases with engine speed - so I don't think it's the TT power plug actually generating the interference (how does IT know aout the speed?), but rather 'enabling' the interference from somewhere else (alternator?)... Hence my theory that it's a ground loop issue...

dpmiller · Posted: Wed Feb 28, 2007 8:43 pm Post subject:

Is the TT power lead close to/ alongside the audio lead from the Ipod?

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

No, it's not. Listening more carefully tonight (with both iPod itself and TT One both disconnected and volume high), I noticed:

- The noise is always there with the engine started (but, actually, acceptable).

- It's louder (and unacceptable) as soon as I plug in the TT power adaptor.

- It also gets louder if I plug something else in instead (another cig. lighter USB power adaptor), but the increase in loudness is less than with the TT adaptor.

So maybe this IS a ground/earth loop problem? I tried half pulling out the 'RCA' plugs that are in the chain (to disconnect their earths, but leave signal connected). Doing so also increased the noise. But I was expecting it to be reduced having isolated one ground connection... (Removing them completely silences the noise). But ground loops have a bit of a life of their own if I recall correctly.

Maybe I just have 'invest' £10 in one of these isolators *in case* it works?

mikealder · Posted: Wed Feb 28, 2007 9:43 pm Post subject:

Do you notice an increase in "noise" if you increase the load on the alternator? - engine running switch on the heated rear screen, mirror heaters (if fitted) full lights (main beam) - does this make any difference to the interference level with and without the TT One power addaptor in the socket - Mike

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

No, surprisingly. maybe it's being picked up from the ignition system ("modern" Y reg fuel injected engine)

wibbly · Frequent Visitor Joined: Dec 20, 2003 Posts: 315

Bought a ground loop isolator for £8.06 delivered.

http://www.revealcable.co.uk/acatalog/Car_Cables_and_Accesories.html#aAA3443

It's bigger than it looks but seems to have instantly and completely solved the whole issue :-)

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