I received a Delphi removable XM radio for Christmas. Problem is that the standard car adapter kit works through one of those stupid cassette adapters (forget that!). The only other option was to buy either a FM modulator, or a radio with XM built in. My question is will there be a significant difference in the sound quality between a radio that has XM built in and one that connects to the radio through the FM modulator?
Well, I have no direct experience with removable XM radios, but I do work in radio and I am an engineer. It is my humble opinion that you would get a more faithful reproduction of the sound by the signal picked up by the tape head in your cassette deck than you would by FM broadcasting it from the XM receiver to your car radio. It’s supposed to sound better and cleaner than FM, without interference and fading, right? The FM modulator method sounds like it would sort of defeat the purpose.
Your tape head, OTOH, has full frequency response with no added hiss or other artifacts. The audio output from the XM radio would be sending an audio current to the head inside the cassette adapter, which would press up against the tape deck head when engaged. This is the cleanest way to transfer the signal from where it is to where it’s going. If there were a provision for auxiliary input on your radio, the method would be nearly identical, just leave out the magnetic head scenario. It’s as close to direct injection as you are going to get without getting a radio with XM built in.
It depends on how good your ear is. There will be some signal distortion just due to the nature of FM modulation. It’s going to cut into the bandwidth of the signal a bit and will limit the dynamic range to something not much better than the cassette interface. If your speakers and amp (and possibly your ears also) don’t have that great of a dynamic range or frequency response, then you won’t notice the difference. If you’re a real audiophile though, then you will be able to hear the distortion.
I should add that the Modulator would not be “broadcasting” the signal, but would be installed in between the radio and antenna, completely supplanting any other radio frequencies.
http://www.xm-radio-satellite.com/product.asp?3=14
I have hooked up the cassette adapter and, just as it has with other products, it sounds terrible. The signal is very weak, so that I have to turn the volume all the way up to hear anything, and there is a constant “hiss” over all of the sound. This is not acceptable.
Hmmph. I didn’t expect the cassette thing to sound great, but I did expect it to work better than that.
Anyway, the FM modulator will definately not sound that bad. It’s going to have about the same sound quality as a broadcast FM station that is coming in clearly (unless they did a bad job of designing the modulator).
I suppose another option (though not a cheap one) would be to get an amp with an aux input. Then you could switch between the aux input from your XM and the speaker output from your existing radio.
What kind of FM modulator is it?
Does it get plugged inline to the antenna cable, or does it actually transmit over the air?
I have a CD player that uses an FM modulator that works pretty well - not as good as a direct connection, but in a car you have to listen very carefully to notice. But it required a lot of work to install, opening up the dashboard and removing the raido. I’d suggest professional installation if you don’t feel comfortable spending an afternoon finding out in great detail what hides behind your dashboard’s plastic shell. I, on the other hand, love doing that stuff.
I also have a little transmitter for my iPod that actually transmits the audio over the airwaves. It works pretty well, assuming you can find a frequency somewhere on the dial that doesn’t have a commercial transmitter broadcasting on it. Any intereference and the quality goes down drastically.
Both are considerably better than cassette adapters. Those things are incredibly bad. A clever hack, I’ll give them that, but unless you like your $10 month satellite radio sounding like it’s being played over one of those old-timey hand crank phonographs, they’re best avoided.
For our new iPod and a 6000 mile road trip, I purchased an FM modulator. It sucked the big one. I bought a cassette adapter on the road, and it sounded really, really, really good, and didn’t use batteries to boot.
YMMV, but it’s some good anecdotal evidence.