iPod + car charger = BZZZZZZ???

December 5, 2007 12:43 PM

How can I listen to and recharge my iPod at the same time in my car without the audio quality sucking?

I have a 2nd generation iPod and a car with an aux input for the stereo. I can plug my iPod into this input and listen to it though the car speakers and it works great! The problem comes when I want to recharge it while listening.

First I bought a DC to AC inverter at Radio Shack, and then plugged the iPod's AC adapter into it. The iPod was able to recharge, but when I listened to music while charging a loud and annoying HUMMMMMMMMMMMMMM sound came through the car's speakers.

I thought maybe the problem had something to do with the ridiculously overcomplicated DC/AC/DC conversion, so I went for the direct route: I bought this car firewire charger. This worked a little better, but instead of a loud hum, I get a BUZZZZZZZZZ sound which seems to go up and down in frequency in sync with the engine revolutions!

So where am I going wrong? Has anybody done this without causing audible interference?

posted by steveminutillo to technology (18 comments total)

I just bought a ground loop noise filter for this problem, but haven't actually tried it yet. I am told that it is the fix for this problem.
posted by Lyn Never at 12:47 PM on December 5, 2007

You can get an FM transmitter that plugs into the cigarette lighter. I have a Belkin and it works great -- no interference due to charging. I have more problems in cities, where it's harder to find an FM station that doesn't have a clear signal, but other than that I don't have any problems.
posted by mudpuppie at 12:48 PM on December 5, 2007

I've tried those FM transmitters and always had absolutely terrible audio, way worse than the problem I'm having now.
posted by steveminutillo at 12:51 PM on December 5, 2007

This adapter from ipd works great for me, but it's wired directly into the CD player behind the dash so it may be more than what you're looking for. On the other hand, I went with this approach after trying all the others, so... Look around for after-market built-in solutions for your specific make and model (ipd is just volvos). It took me about 2 hours to install mine (ka-ching - $500 I didn't have to pay the dealer).
posted by cocoagirl at 12:56 PM on December 5, 2007

I tried the Belkin FM transmitter and it sucked ass. I decided to try the Monster one (the unit with a full modular plug, not jsut a minijack) despite Monster's reputation of a jacker-upper of prices on its wires. So far, it's worked great (1 month) - it's a strong enough signal to block out regular radio stations.
posted by notsnot at 12:56 PM on December 5, 2007

I've been using a DICE setup since I got my car, and I love it. It allows you to play through the radio (sounds awesome, no crappiness) and charge at the same time (if you've radio controls on your steering wheel as I have you can use that as well). You can find used ones on eBay fairly cheap I, it's how I got mine.

You will however have to dismantle your dashboard to plug it into the back of your radio, so this may or may not work for you.
posted by sephira at 12:57 PM on December 5, 2007

Unfortunately that DICE thing will not work with a 2nd gen iPod. I don't have a docking port, just a headphone jack.
posted by steveminutillo at 1:01 PM on December 5, 2007

I use a different Griffin car adapter for my 4th gen ipod, and I don't get any noticable line noise when I use my aux connection.

Maybe the noise is from the firewire cable you're using. Could you try using a shorter one? Or possibly one that's shielded? I had tons of problems with a set of speakers that used long, unshielded cables.
posted by burnmp3s at 1:08 PM on December 5, 2007

Would this help?
posted by null terminated at 1:11 PM on December 5, 2007

Bah. I was thinking you had a 2G Nano.

Well, you can always try the Altoids tin charger route instead of charging from the car.
posted by sephira at 1:11 PM on December 5, 2007

My DLO fm transmitter is incredible. I thought the Belkin was pretty crummy also.
posted by docpops at 1:14 PM on December 5, 2007

this is it
posted by docpops at 1:15 PM on December 5, 2007

if it's a 2nd gen, it'd have a firewire port on the top and no dock connector on the bottom, so most of the FM transmitters that people've been suggesting won't work. the humming is probably coming from the inverter, so try using something like this instead.
posted by mrg at 1:16 PM on December 5, 2007

The ground loop filter is the solution. I got one at Radio Shack for about $12.
posted by kdern at 1:20 PM on December 5, 2007

I'm going to try the ground loop filter route and will report back. Thanks!
posted by steveminutillo at 1:28 PM on December 5, 2007

Nthing ground loop filter. The one from Radio Shack doesn't have 1/8" headphone jacks, though, so if you want to use one without any adapters this one is good.
posted by zsazsa at 1:29 PM on December 5, 2007

My Belkin car charger has a jack you can plug your aux cable into - so you're running your audio out of what is essentially aportable iPod dock, versus the headphone jack. It sounds good thru my car stereo. Especially if you can find one on sale, one of these seems like it's worth the cost versus running thru an inverter.
posted by altcountryman at 10:16 AM on December 6, 2007

Yes! That Crutchfield ground loop retroencabulator arrived today and it works PERFECTLY! We even got free shipping! (with secret coupon code PA145)
posted by steveminutillo at 4:09 PM on December 7, 2007