Since I’ll be doing a good deal of driving in the near future, I decided to iPod my 2003 Subaru Legacy wagon. Little did I know, this is a task easier said than done. As follows are the trials I went through and the final results.
Dissection
I needed to find out exactly what I was working with, so I figured the best way was to actually remove the stereo head unit itself and see what ports are available in the back. In the best case, there is an auxiliary input port. In the worst case, there is no extra port at all. I expected there to be at least an external CD changer port.
I found a great guide for the removal of stereo head units for my car. Actually, it’s a guide for a Subaru Outback 2001, but the dash setup is exactly the same for the 2003 Legacy [wagon]. With the excellent directions and illustrations on said guide, I was able to dismantle the necessary parts and extract the head unit within a half hour, having had zero experience in the area.
Research
Once I had the head unit in my hands, I was able to take a look at what was in the back of it, and see what my options for an iPod hookup were.
Needless to say, there was no auxiliary input jack. As expected, however, there was an external CD changer port on there. After having done some research online, I found that this was absolutely useless to me. The 16-pin port I found is proprietary and has not been reverse engineered as far as I can tell. There are no after-market auxiliary input adaptors for this type of port available at time of writing.
Back to the drawing board. I had to find out what other options I had. I knew all about the wireless FM transmitters on the market, and had read a good number of reviews on various makes and models. There was no way I wanted to deal with any sort of interference or quality loss, especially expecting to be in the Boston metropolitan area as much as I do.
It looked like my only options for wiring in directly to the audio system in the Subaru was to either replace the head unit with one that has an auxiliary input jack, or use a wired FM modulator. I settled on the FM modulator.
How It Works
The small device I ordered online for $25 does the same thing as wireless FM transmitters — that is, converts an input audio signal (say, from an iPod) into an FM radio signal that any radio tuner can tune in to — except that this one sits in between the aerial antenna and the head unit, so that the signal is not broadcast via air but rather wired directly into the antenna port of the head unit.
The idea here is that, since the wired FM modulator sits in between the antenna and the head unit, it is able to directly inject the modulated FM signal into the head unit’s antenna feed, rather than adding to the already existing signals in the air. An on/off switch connected to the modulator allows for selection between the antenna and the modulated signal.
Installation
In order to get it all working, three essential connections had to be made. (1) Power was drawn via a direct connection to the rear plugs on the car’s stock 12V electrical outlet. The (2) Antenna lead was removed from the back of the head unit and plugged into the FM modulator. The (3) Head Unit connected directly to the FM modulator via the head unit’s antenna port.
Lastly, the Power Switch and Audio Leads were routed through the front dash area via a small space underneath the ashtray. With everything nicely in place, I was able to stow the modulator box itself right next to the shift lever — Subaru nicely left a couple of inches on all sides of the shift lever housing. There was no need to cut any holes!
No visible changes were made to the car, excepting an audio lead hanging out from underneath the ashtray, which can be neatly stowed away out of sight when not in use. The on/off switch for the modulator fit nicely underneath the ash tray, completely invisible to passengers and driver alike. Since the whole setup is transparent, not only does the car look as great as it ever did, but it’s also not any more subject to theft.
Results
The sound quality of the setup isn’t quite CD quality by any means, but it’s good enough for the average Joe not to notice any drastic difference. Since the rest of the audio equipment in my car is stock, I can’t really justify putting any additional money into a higher-quality setup for auxiliary input.
In order to reach some level of satisfaction (I’m a picky customer), I had to play with the gain adjustment on the FM modulator. With higher gain comes higher volume but also some distortion. Lower gain yields lower volume but less (or no audible) distortion. I found that once I turned off the ‘Sound Check’ (volume normalization) feature on the iPod, I was able to lower the gain substantially without killing off the volume. Now at a medium-high volume output on the iPod, the FM signal from the modulator is the same volume as an average radio station.
There is one quirk with the setup. Whenever I turn the FM modulator on, and tune it to the station that I set it to modulate on — 88.7 — it takes a few seconds for the modulation to start up. More interestingly, when it does start up, I get a strange shwaap out of the speakers before the silence (or audio from the input signal) kicks in. I’ve grown to kind-of like the satisfying sound, as it helps me recognize when the modulator has just been turned on.
Verdict
All in all, I’m happy to say that I’m a very satisfied customer, and would recommend this setup to anyone willing to rip apart their dash in order to do the installation. Since it’s wired, it shouldn’t be possible to really inject any noise or interference in the line, assuming that all connections are properly insulated. As such, I haven’t experienced any troubling interference on the line (there is a slight hiss if you broadcast silence and turn the head unit’s volume all the way up).
In my opinion, this is a success story.
great article. Would you mind telling me which modulator you bought?