Saturday, September 14, 2013

DIY Guitar to GarageBand (gPort)

Devices like the iRig offer a nice way to feed your guitar signal to GarageBand to play with a plethora of amps and pedals.  There are also much more expensive alternatives, i.e. Apogee Jam or iRig HD, which communicate with GarageBand digitally, and consequently produce a higher quality recording.

I decided to look at the lower-end analog version and create my own device to connect to GarageBand....I'll call it gPort for now.


First I found how audio jacks on Apple devices work. A quick search got me to TRRS Standards. Using the info, here's a sketch summarizing the findings.


The wiring for gPort is simple enough.  The device will require 3 components: a guitar jack, a headphone jack, and a 3.5 mm male audio-connector w/ mic.

I went with the following components from DigiKey:

Guitar Jack - SC1316-ND
Headphone Jack - CP1-3524NG-ND
3.5 mm audio connector cable - 839-1030-ND

Total for all 3 components came out to $8.11 at the time I purchased them.  The total could be brought down even lower if I did some extra work with the audio connector.

DIY Build

I trimmed the audio connector cable down from 6 feet to about a foot. Using the data sheet for each component, I soldered the connections and the gPort looked as shown below.

All I needed was a case.  What to do?...what to do?....handy dandy card board?...nah.  I've got a better idea.

I designed a case for gPort and sent the 3D model to Shapeways (

Pictures of the final gPort device:


Including parts shipping (~ $9 =(2 w/ digikey, 7 with shapeways) the total cost for making a single gPort is about $25.

Some slight miscalculations with the 3D print caused some assembly problems, but I got it to fit regardless.  The case is not for sale, unless there's some interest.

So was as it worth it? ....yep.