Tech Article Title Author Date
Installation and Review for USA Spec iPod Interface Brad Rawson 2008
Note: This article was written specifically for a 1998 Audi A4 with the factory Bose stereo, but may apply to other Audi models as well.


After about a year of suffering through the poor sound quality of an FM transmitter for my iPod, I finally decided to replace it with something better. I was looking for a solution that would meet a number of requirements. First, it had to work with my factory Bose stereo (no replacement head unit). Second, it had to retain the stock appearance (nothing mounted to the dash). And finally, it had to sound as close as possible to CD quality.

After some research into all the iPod adapters, I selected the USA Spec iPod Interface. I purchased it through and was able to find the appropriate model via their vehicle selection guide. For my 1998 A4, the part number is 581PA11VW6 and the manufacturer’s picture of the kit is shown below.

The website claims it works for my car and shows it for $140 but that’s only part of the story. If you dig into the details a little more, you finally realize that the VW unit requires an additional cable to adapt it to an Audi stereo. That part number is 581CBPAU, and it costs an additional $30. Shipping was free for both items. The adapter cable is shown below.


One of the first things everyone needs to know about the installation of this product is that it replaces the CD changer. This fact makes installation a breeze, but it also means that you have to be willing to give up CDs in the car completely – unless you happen to have a single CD slot in your head unit, unlike mine.

To begin, I pulled the trunk carpet and then removed the screws holding the CD changer mounting box. The box and changer were lifted out of the hole with only one wire left attached. At that point I loosened the changer from the box by taking out the screws. Now I could get to the connector, pull it apart, and set aside the changer.

With the vehicle wire still in the CD changer mounting box, I then took the female end of the adapter cable (the $30 cable separate from the kit) and ran it up through the same hole and plugged the two cables together. In order to keep the car looking stock and to allow for a fallback to CDs if ever desired, I reinstalled the disconnected changer into the mounting box.

Next the cable had to be routed to the mounting location of the control box. The adapter cable was pretty long and the cable to the iPod itself wasn’t, so I knew I’d have to get the control box relatively close to the driver’s seat. Having seen another Audiworld tech article where someone routed cables under the rear seat, I looked there first. All you have to do is pull straight up on the front of the seat bottom to release it from its two latches, slide it forward a few inches, and then take it out through the door. It turned out to be a great location.

Before reinstalling the CD changer mounting box back into the trunk, I routed the long adapter cable up under the carpeted side wall of the trunk and then under the driver side rear seat back, exiting in the space under the rear seat bottom, as shown.

With that completed, the CD changer mounting box was reinstalled and the rest of the trunk was put back together. Then, the parts from the kit itself were finally used. The main wiring harness in the kit (the one with the blue connector) is specific to VWs and gets replaced by the newly installed adapter cable. Next the control box had to be mounted to the body of the car under the rear seat. I selected the location shown in the picture below after making sure that it wouldn’t cause any interference with the seat cushion. I marked and predrilled the holes and attached the box with the screws supplied in the kit.

The cable from the trunk was then plugged into the control box. To keep it from rattling or moving around, I bundled the excess and routed it through the existing wiring looms as much as possible. The iPod docking cable from the kit was plugged into the other side of the control box at this point.

I was hoping to find a way to get that docking cable from the rear seat up to the center console without being seen, but I simply ran out of time. I think I could fish it under the carpet and have it exit next to the front passenger seat, but who knows if I’ll ever have the determination and patience to do it. The easier option was to simply run the cable out from under the seat, along the transmission hump (as seen above), and up next to the passenger seat. Having the cable on that side of the console has allowed me to store the iPod in the little cubby hole under the center arm rest. It would take a sharp eye to notice that I have an iPod in the car at all, which is what I was going for. I don't want to attract thieves. The cable has enough slack that I can pull the iPod out and comfortably control it.

Product Use and Review

To listen to the iPod through the stereo, you simply press the Mode button, just as you would to listen to a CD. Because the USA Spec adapter uses the factory CD wiring harness, the stereo is tricked into thinking the iPod is a CD changer. Happily, I can say that the iPod also behaves like a CD as well. In other words, when you start the car, it powers it on automatically and it resumes playback from where you left off. It also pauses the iPod when you shut off the ignition and eventually powers it down.

The unit allows you to control the iPod in two different modes, direct or hybrid. The choice is controlled by a DIP switch on the control box now under the rear seat. Direct mode requires you control everything from the iPod itself. The only exception is that the Audi head unit buttons will skip forward and back. Hybrid mode allows you to use the iPod as if in direct mode but also allows you to play up to 5 playlists using the numbered CD buttons on the head unit. Buttons 1 through 5 call up specially named playlists which are set up in iTunes, while button 6 is for direct mode use.

I thought hybrid mode would be ideal so I went into iTunes and made a few playlists and followed their specific naming instructions, starting each with VW1_, VW2­_, etc. However, it didn’t take long to find out that the adapter doesn’t have a long term memory. As long as I drove the car frequently, it would start playing where I left off. However, if I went more than a day or so without driving the car, it seemed to pick a random spot within a random playlist. And when manually switching between the 5 special playlists, it didn’t do any better. Sometimes it would start at the beginning of the playlist, other times it would start at a random point, with no discernable pattern in its choice. I gave up on hybrid mode and have been using direct mode ever since.

Direct mode has been nearly flawless. It has always started playback in the right spot, has always powered on and off as expected, and never locked up, skipped, etc. Controlling the iPod is no different than normal so it’s intuitive to use. The only slight flaw is that it will quickly flash back and forth from NO CD to CD 1 TR 01 until the iPod has fully booted, but this only seems to happen after an extended period of non-use. The first few times it happened I thought I had a short in the system.

The best part of all is that the sound is wonderful. All of the static and other FM hassles are gone. Some of the lower bitrate songs are between FM and CD quality, but most of mine have been ripped at high bitrates and sound nearly identical to CD.

I’d recommend this system to anyone wishing for a more permanent iPod solution for their Audi. Installation was straight forward and reasonably quick, with an integrated and clean appearance. As long as you control it in direct mode and ignore the display during bootup, it works as expected and provides a far superior experience to FM transmitters. At a total cost of $170, it’s a more expensive solution, but the sound quality alone is worth the extra money.