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DIY: AUX input for OEM NA Type 1 head unit.

12K views 12 replies 8 participants last post by  –Mars– 
#1 ·
Say you're me, and you actually like the look of the OEM radio, but want an AUX input. I've been using a cassette adapter for a while, but the audio quality is just horrible so I began looking for other ways to incorporate an external audio source. I began digging through some old threads and found that a few of them linked to an image/wiring diagram for an AUX input using the 13-pin CD connector in the back of the OEM Type 1 radio that most NAs came with.


The image was hosted by a site long gone, but I was able to scrap it back up with the help of archive.org. The guy who came up with this diagram, Jeff Anderson is still around, and even replied to a few emails when I was figuring out how to do what. Diagram below.





Basically, you are emulating the OEM CD player that some cars came with. If yours didn't, it came with a blanking plug that has the top 4 pins still there. You remove that plug, no audio. Replace it with the above, and you can control the audio source on the other end.

I will include some actual photos at some point, but all of the parts required for this can be had from eBay or Amazon, wires are regular audio wires. I skipped the "Tie all wire shields together/ground" bit, and it works fine. I now have a switch hidden in the center console that lets me switch audio source from radio to RCA/AUX.
 
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#5 ·
What type of switch did you use? On (off) on? or On-On?

How exactly does it work; If you hit the switch it, the radio cuts off tape/fm/am and plays only the RCA input?

Do you have a link for the 13 pin cable you used with schematic? I just did a search and found two different schematics for the 13 pin, so it'd be nice to start off with a known color code.
 
#6 ·
It's a On-Off-On switch, no position is momentary, at least on mine. You may be able to use a DTDT On-(Off)-On switch, which would mean the Off position is momentary, but I don't know if those exist or if they would work.

You flip the switch one way, audio comes from the radio. Flip it the other way, and it comes from the other input. In OEM radios, this was the CD player. In this case, it's whatever you have going into the RCA plugs. No audio in the middle position.

When you say schematics, what do you mean? This cable should work:
https://www.ebay.com/itm/232039202079

You'll have to take the actual plug apart to find out which wires go to the bottom four pins. They are an easy disassembly.
 
#9 ·
Say you're me, and you actually like the look of the OEM radio, but want an AUX input. I've been using a cassette adapter for a while, but the audio quality is just horrible so I began looking for other ways to incorporate an external audio source. I began digging through some old threads and found that a few of them linked to an image/wiring diagram for an AUX input using the 13-pin CD connector in the back of the OEM Type 1 radio that most NAs came with.


The image was hosted by a site long gone, but I was able to scrap it back up with the help of archive.org. The guy who came up with this diagram, Jeff Anderson is still around, and even replied to a few emails when I was figuring out how to do what. Diagram below.





Basically, you are emulating the OEM CD player that some cars came with. If yours didn't, it came with a blanking plug that has the top 4 pins still there. You remove that plug, no audio. Replace it with the above, and you can control the audio source on the other end.

I will include some actual photos at some point, but all of the parts required for this can be had from eBay or Amazon, wires are regular audio wires. I skipped the "Tie all wire shields together/ground" bit, and it works fine. I now have a switch hidden in the center console that lets me switch audio source from radio to RCA/AUX.
Tried this and it did sorta work. It successfully switched between the two inputs but when it was switched to the aux input it was really quiet, and if I wasn’t actively playing music it would play radio quietly in the background. Any ideas?
 
#12 ·
I gave up. Ordered this bad boy and will be hooking it up directly into my power amp. Hopefully this will work:
keep me updated on your brother's progress
 
#13 ·
Just a bit of a chime in from someone with definitely no know how to talk:

the faint radio playing in the background sounds very much like a crosstalk/shielding issue, if the wires are shielded properly I guess it must be within the switch?

Honestly, what surprises me the most is the cassette adapter's quality being terrible.
I mean, a cassette adapter cannot suffer from the two most common causes of bad audio quality, tape hiss and inconsistent/incorrect speed (as shown below)... what is the bad quality you're suffering from about, could it be your tape head needs some cleaning?
 
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