Jafro

I bought a 40GB iPod for my girlfriend for christmas. She drives a metallic pink BarbieŽ car, with big Barbie@ wheels, and big unproportionally large BarbieŽ subwoofers and amplifier. She has a really expensive Alpine CD head unit that she really doesn't want to get rid of.

I've been over all the FM broadcasting products, and quite frankly, I think that whole idea sucks. Radio frequencies are in kilohertz... that's 2 decimal places... that means its dynamic range of frequency cuts off by this equation...

FM khz frequency x 100 = maximum audible and broadcastable frequency

example...
99.7 x 100 = 9,970 hz

Humans are supposed to be able to hear 20 - 20,000 hz because the distance between their ears isn't wide enough to hear any frequencies that are lower than that, and their fluid-dampened eardrums are too heavy to vibrate any faster than 20,000 times a second. Ha! Stupid humans.

With that in mind, using an FM frequency to broadcast MP3's cuts out half of the music's dynamic range... in addition, the FCC limits those things to .005 watts of broadcasting power, so there are lots of signal strength and interference problems. Especially in any place with a lot of humans.

What is the best option for getting line level input into this CD deck (that drives everything but the bass)? This deck doesn't have an auxillary jack, but can control a disc changer. Someone's got to make some kind of line converter that takes audio input from that...

Anyone know of any other devices that will let me use the line-out jack of this iPod to hard-wire it in and use this deck's built-in power and line-out signal?

Dr. Isotope

If that Alpine head is mondo expensive, it must be hella old, because high $$$ HUs have been featuring Aux jacks for a good while now...

Anyhow, you should be able to build an adapter, you just need to know the order of the pins in the changer cable.

Lastly, the FM modulation thing has good much, much better in recent years-- I just installed a Sirius kit in my mother-in-law's truck, a fancy Ford Ranger with high dollar Pioneer 2500 or thereabouts, and it stunned my by sounding really, really good.

You needn't worry about loss of fidelity through FM modulation-- you are talking about mp3s, and any system that's well set up will show every flaw of every one of those low-bitrate suckers. Mp3s are great because they're free-- but convert something with real range, like Sarah McLachlan or Portishead: Live and listen to the tinkling of digital encoding... its almost like LPs for the car, only without the skipping and the warm tonal variations. But hey, that's the trade for 40gb of music, right?

Dr. Isotope

Curiosity piqued, I dug around for info on FM transmitters and receivers--- the 10khz or so limit was breached in the 1940s. Most modern smaller transmitters can keep distortion below 0.5db distortion at 15khz, and the bigger (broadcast) units can manage the same distortion level up through 20khz. And another nerdy-tech note, most humans cannot differentiate between tonal variations above 12,000-14,000hz-- they can hear the sounds, but they all just sound alike. We may be able to walk upright, but we have a really narrow hearing range.

SumAccordGuy94

IF its a newer alpine unit (please specify the model so we can give acurate info) there is an adapter available for $15 that plugs into the changer input and provides left and right RCA inputs. You then need to go into the menu on the deck and enable the AUX input option.

Jafro

LOL! I know. I was being a goof-ball. I'm glad someone else found that mildly amusing. I'm one of the weird ones that can differentiate the higher frequencies. I was tested up to 16,500 (which was as high as the test went) and I passed, but that was in a soundproof booth. In a car with road noise and vibration it would be impossible to do that.

I just wanted to point out that the dynamic range of frequencies and signal strength would be cut down in the broadcast. I read reviews on the Griffin iTrip, and it suffers from some of the things I was describing. So did most of the low-end units. I wanted to find a way to hard-wire it because FM transmission isn't really all that necessary. It's convenient, but I'd sacrifice that for sound quality.

Another problem with the Griffin iTrip specifically, is that it automatically cuts off after 60 seconds of silence, so long interludes or pauses in a recording could cause you to be blasted by X db of white noise while you're driving if you've got your system cranked, and this condition happens in the recording. That could hurt.

As for MP3 quality... I have over 900 CDs, and I encoded them all at 44,100hz and 256kbps. It comes out to 53GB of music. Enough to play for 43.72 days without repeats. And at that bit rate, just like with higher frequencies, any losses from the compression are completely imperceptible. It's the bitrate encodings at 128kbps and lower where you can begin to hear the compression. At least I do.

Jafro

Sweet! I'll get the model number today. Like I said it's hers, and like most girls, she's not the gadgetphile that memorizes her system's model numbers. I don't often get in her pink car because I'm afraid I might grow boobs and start spending all day in bathrooms, or start having difficulty making snap decisions, etc... But maybe I'll grab a few tool catalogs and my handy football jersey for protection from this estrogen sled, and go out there to find out what it is.

rcurley55

All you need is an AiNet compatible headunit....

And if you can't hear losses in a 256kbps MP3 - you need a new system!!!

MP3's, while convenient, sound like crap...then again, most music today is mixed horribly anyway...but that's another disucssion all together

Falkon

Ahhh! It's Jafro and his majical CX, possibly still with wonder bees.

Well, Alpine has something I believe is called the Ai Net something or other. It plugs into the changer jack and becomes two RCA jacks. If you only have an earphone output for the ipod buy one of those cables that plugs into a stereo earphone jack and outputs as right and left RCAs.

Jafro

Heh, yeah... the bees are still my best mod to date. I'm having great luck with the car since the swap.

I got the model of the deck. It's a CDM7861. Not really that awesome of a deck after all, but she's stuck on it.

We went to the Apple Store today and got all kinds of info about adapters. I found the AI NET adapter for $24.95. Not bad! Other PIE adapters were in the $70-$100 range, but they were mostly for factory stereo systems. Here's the one for Alpine.

http://www.logjamelectronics.com/piealpairca.html

The Apple Store said they get a shload of returns from dissatisfied people on the FM transmitters. There are some that get returned less than others, but the ones that dont get returned, you have to change batteries in every 8 hours. The iTrip doesn't have a good track record from the post-christmas crowd. I'd rather not have something that drains the iPod battery anyway. Especially when using the AI NET adapter costs less than the transmitters do and sounds better.

Alpine is coming out with a deck that actually controls an iPod and charges it. This feature will be available in specific future models. I hope it doesn't cost a spleen and a lung when it comes out.

Thanks for all the info, guys.

rcurley55

IIRC, the CDM lineup doesn't have the AiNet bus, but rather the Mbus for signal transfer...