Audio breakout cable for ipod/iphone

(update) I inadvertently said I got the 4 conductor plug at Jameco – it was Mouser, and is listed correctly, with the part number in the blog.

Have you ever wanted to plug in a professional studio mic to your iPod touch/iPhone? There may be a commercial solution, but I couldn’t find one. Even if there is one, I figured I could build one cheaper than a ready-made one. You could also use this for a line-in (my original reason for the project), but the source really needs to be taken down to mic level from line level for good sound quality.

The hardest part was finding the 3.5 mm 4 conductor plug (found it at Mouser, #171-7435-EX). The soldering to the plug was a bit tricky too. I needed a cable with at least 4 conductors inside, and I wanted to build this for next-to-nothing, so I used some CAT5 ethernet cable I had. CAT5 has 8 conductors, so if you know of any other common cable with at least 4, you can use that.

I’ve included a rough wiring diagram below.
***UPDATE: Thanks to PTM for pointing out the iPod/iPhone’s audio input is meant for an electret mic. Therefore, there is 2.7 v across the input. However, there is only a tiny bit of current. If this concerns you and you want to get in the habit of doing it the right way, you should put a 1 – 10 uF cap like this one in-line to block the dc. If you don’t know how or want to do this, the current probably won’t do any damage, but be warned.***

The sound quality with a Shure SM58 plugged into the iPod touch was way better than a very good pair of Shure earbuds/mic. When you look at the files in Sound Forge etc., the noise floor was about -60dB with the SM58 and about -50dB with the earbuds. The SM58 had way more dynamic range and obviously less background noise too. Not that surprising, since it’s a professional mic, but more proves that for serious recording, this is well worth doing.

The earbuds/mic aren’t terrible. It’s more a question of “how good” do you need to get? On a pair of normal home computer speakers, there may not be as much of a difference, but I’m listening through a $1400 pair of Event studio monitors.

Here are the sound files to compare. They were recorded with the free Griffin iTalk app at 44.1k and file transferred directly via wifi :

69 thoughts on “Audio breakout cable for ipod/iphone

  1. Question: any ideas why this adapter is producing a distorted, lower bass, low-level headphone output and very low-leve mic in?

    The relevant symptoms are with both TRS and TRRS (iPhone headset w/mic) headphones, with or without a TRRS mic plugged in, in both an iPhone 5 and an original iPad.

    I haven't had a chance to continuity-test the wiring yet, but the voltage for the electret mic in iPhone headsets shouldn't be causing a problem for headphones going through this adapter, right?


  2. First, thanks for publishing this; it took me quite a while to formulate my Google query properly so that it led me here.

    All I want to do is make an mike extension for my iPod4s. Your blog makes it easy by including the plug item number from Mouser.

    FYI the female inline jack for the other end of the wire (to mate with the mike I already have) item number is 161-6435-EX. I expect that connecting the appropriate terminals with a two-conductor wire will give me exactly what I need. Thanks so much for this blog entry!


  3. So, regardless of whether I can make or buy a cable that works, are you guys saying that there is no way you can monitor while recording?? That is what I want to achieve the most. I want to be able to buy FourTrack, lay down guitar tracks with AmpKit+, import a drum loop or something, then SING over it. I can bounce that stuff down all day long. But if I can't monitor the tracks I've already laid down while recording, what is the point??

    The bottom line is… is it possible to record vocals, guitar, whatever, while hearing what has already been recorded, via headphones. Essentially, basic multi-track recording like on a real fourtrack, with a 3G iPod running OS 4.1.

    I noticed that GuitarJack was on sale for $150, but it doesn't work with the iphone 4 or iPad! It's always something isn't it!! LOL!

  4. I'd like to use this as a DIY project to go hands-free in my car using my Samsung Galaxy S phone. I'm farily sure the phone uses a 4-pole 1/8 phono for audio out/mic in. Does anyone know of a good mic to use that would be sufficient to pick up my voice in a car? And should i go so far as to amplify th mic signal?

  5. Hi,

    Many thanks for your tutorial. I was wondering if you know how to mod an iPhone 4-pole headphone w/mic to be compatible with Nokia 4-pole headphone w/mic.

    One more question, if I remove the last black isolating ring from the iphone 3.5mm jack plug, will it become a normal 3-pole jack plug?

    Any advice will be highly appreciated!

  6. I've just finished building a similar cable to work like an iRig for connecting a guitar to my iPhone 4. To get it to work properly you have to place a 1uF capacitor in series on the microphone signal (to remove the DC voltage), and a 1K resistor between the iphone side of the mic wire and ground. The resistor is necessary to make the iPhone 4 detect that an external microphone has been connected. I'll create a wiring diagram and post a link here soon.

  7. Question. I essentially built the same cable using 1/4 stereo phone jacks, as noted here: . Everything works perfectly EXCEPT one thing.

    When I plug in a cheapo microphone (with 3.5mm connector (via 3.5mm to TRS adaptor) its works perfectly. But I plug in a mic with a mono TRS cable, it only work if I pull the plug out a bit -ie no tip connection. I assume this is because tip and ring and jumpered. Will the breakout cable still work wihout the jumper?? I assume its there for a reason.

  8. Thank you so much, I was looking for this for a while and since I already had a cable from a camera will start tinkering soon. May I suggest you update the(why rough? it's great!) schematic with the potential location for the 10uF cap?
    Like is it in series with the input's center (hot) connection, right after the plug?
    That would be killer dude 😉

  9. The mic is a Behringer XM2000S cardiod. Just your average SM57 wannabe shaped like a black 58.

  10. @cele_82 My how time flies!!
    I made the XLR end of the cable and thought I'd get around to doing the headphone end soon. I didn't realise it would take me 6 months!!

    I posted pics here:

    Audio test is here: (aiff converted to 192KBps mp3)

    I started with a 4 conductor mini jack to 3 x phone cable. I think it was meant for a video camera. The three wires were hooked up like this:

    RED (XLR)
    red wire (+) to #2
    ground (-) to #3
    jumper from #1 to #3 (that's the blue cable in the photo)

    WHITE (headphone jack)
    white wire (+) to tip (left hand connection)
    ground to sleeve

    YELLOW (also headphone jack)
    red wire (+) to ring (right hand connection)
    ground to sleeve

    I had to use a multitester to determine which was the ring and the tip in the 1/8" jack.

    Now to go find something to record!

  11. Nice one! Any idea what's the frequency response of the iPhone? Does it do any kind of pre-filtering to the input? since it's mainly used for voice I would think that it would do some kind of bandpass filtering to separate speech, and then use a low sample-rate for all kinds of processing (recording etc.). Which kind of defeats the purpose of using a professional microphone… Just wondering though, I don't have an iphone but I'm thinking of getting one – on the other hand I'm sure it could capable of recording at 44.1kHz full bandwidth…

  12. okay. so I bought that cable. I plugged it in.. tried to record directly to my iPhone with it. It works and doesn't.
    I have the TASCAM.. so, if I use the TASCAM as a mic and record it on the iPhone.. that works. BUT, and this is weird to me, if I play some audio from the TASCAM to the iPhone, the iPhone won't record it. Also, if I run a plug from my Laptop headphone jack to the mic in (on the split cable) and that into the iPhone to record. nothing. nada. zilcho.. except, it still wants to record with the iPhone mic.. not through the cable. help.