GoPro Hero Modification for Audio

The GoPro Hero2 camera is a very interesting little piece of equipment that is making waves in the film-making world.  Considered a disposable camera in many cases ($299) it can capture 1080p footage at 30fps across a 170 degree angle.  It can also capture 11mp still images and uses a fixed f/2.8 aperture.  The camera by itself (naked) is very boxy in shape, and it relies on a clear plastic housing for various mounting options.  The housing also offers protection against knocks and dust, and there are waterproof versions of the housing.  So it is pretty normal to use a housing with the camera.

The problem is, if you want to capture sound at the same time…

• Mono, 48 kHz, AAC Compression, Auto Gain Control
• Stereo External Microphone Input (3.5mm)

…the housing does not allow a mic to be plugged in.

Odd.

I guess you would not be using a mic underwater but I can certainly imagine cases where you want to be using a housing to, perhaps, mount the camera to a snowboard or car interior, where protection is required and capturing audio is expected.  I have seen suggestions of using an external audio recorder to capture sound separately, and then bring the content together in the editing suite, perhaps using a product such as PluralEyes for frame/sound sync.  But I feel that if the camera is designed to capture audio as well as images, then it should be usable in that way.

I searched for modified products and other solutions to this problem, but found little of any use.  So I decided to take matters in to my own hands.  It was a very easy process.  Here are the steps I took:

With the GoPro camera inside its housing, use a Sharpie to mark the location of the audio input:

Remove the GoPro camera and you should be left with something like this:

 

The housing is made of plastic which can be a brittle material.  When you start to drill the hole, you need to drill very slowly.  To help guide the drill bit and prevent it slipping, and scratching the housing, I put several layers of masking tape over the spot where I need to drill:

 

And in order to make sure I drilled in exactly the right place, I remarked the spot using the Sharpie:

 

I made an investment in this Dremel tool.  This is the Dremel 3000 which I bought from Home Depot, in the United States, for $69.00 as a kit, complete with the 561 drill bit I needed to work on the plastic GoPro housing.

As I mentioned, you must drill slowly.  I had the drill on its slowest setting and pressed only very lightly on to the plastic material through the masking tape.  I recommend that you wear eye protection because small shards of plastic will fly around.  I also recommend that you keep the drilling spot lubricated.

You are trying to minimize the risk of the plastic case cracking, so you need to not force the drill bit through the material, but let it gently do its job of removing the plastic to create the initial hole.  Lubrication helps keep the drill bit cool (avoids the plastic from melting) and helps the drill bit ease its way through the material.  Candidly, I just used spit.

After a few minutes, you will have created the first hole:

This hole has already been enlarged a little.  Enlarging the hole is achieved by continuing to drill against the sides of the initial hole in an even and circular manner.  SLOW is still very important!  This is what the hole looks like from the inside of the housing.

Notice all the bits of plastic.  You should insert your camera back in to the housing to make sure that the hole is in the right place but be sure to wash out all the bits of plastic before you do so.  You do not want a stray plastic shard scratching the lens or embedding itself in a data port.  Dry the housing before inserting the GoPro camera.

Most 3.5mm cables will not connect properly through the casing which is surprisingly thick (in a good way).  So you need to enlarge the hole to allow the entire 3.5mm connector to slip snugly through the hole to complete the connection.  To do this, you should position your cable through the hole, with the GoPro camera inserted in the housing, and note the shape of the hole required:

You can now continue to drill out the plastic to the required shape of the 3.5mm plug.  The hole will progress in size and it is up to  you how neat you want the hole to be.  This is not quite where I want it to be:

This is the final hole, neatly shaped, and just the right size for the 3.5mm plug.  I used a soft polishing attachment on the Dremel (came with the kit) to smooth off edges and make the hole more perfect:

And, as you can see, the fit is very good:

I decided that if I wanted to seal the hole, it would be easy enough with some clear silicon sealant around the plastic cable housing.  But this would commit that cable to this housing.  I had also looked at using a rubber grommet to help seal the hole with the cable inserted through it, but found that the rubber had the tendency to cause the plug to disconnect, causing crackling audio – not good.

I now have GoPro cameras attached to a variety of shot-gun and other mics using this 3.5mm input and a 3.5mm to XLR cable adapter.  I generally attach the GoPro camera to a K-Tek Norbert frame and use that frame to mount mic, phantom power supply, if required, and even a light if necessary.

The whole project took about one hour at a cost of the Dremel which will be frequently re-used on other projects.