As I mentioned in the ThumbTack review the lack of a splitter drags down the usefulness of the mic. The obvious solution to that problem is of course to make one, so I did.

I wasn’t really planning on doing this mod because I’m getting an iPhone and won’t need it. However, I saw (in Google Analytics) that a lot of people had found their way to my ThumbTack review by googling for a splitter, so to help out these people I decided to do the mod.

First off, it’s important to understand a few things about how the microphone works. Unlike normal 3.5mm headphone plugs, it has 4 connectors instead of 3. That means that you CAN NOT USE A NORMAL SPLITTER. The microphone has two wires, each going to one of the two pins closest to the plastic part of the mic. Those two connectors on a normal 3.5mm jack, which all known splitters use, equals the ground pin and is one single connector instead of two. Therefore, if you plug the microphone into a normal splitter, you short circuit the microphone part.

To illustrate, imagine you have two different liquids that you need to carry from point A to point B in a single container, without mixing them. That would naturally require a container with two seperate rooms. If not, the liquids would mix. That is the same thing that happens when you use a normal splitter on the mic, it mixes because it lacks the seperate “rooms”.

It is theoretically possible to make a splitter from a plug and a female jack with 4 connector pins, but getting the 4 pin jacks is hard – especially the female one. Therefore I suggest to drop the splitter idea and instead add a headphone port directly to the microphone – which is relatively easy.

Disassembling the ThumbTack

First off you need to disassemble the ThumbTack to get to the inner connections. Do this by using a plier to force open the plastic at the root of the mic, not at the top end where the microphone is located. Be careful not to ruin anything, but it shouldn’t be too hard to force it open.

Parts needed

To do the mod you need a female 3.5mm (1/8″) jack with 3 pins (aka a normal one which you can buy anywhere). You also need three short wires and something to cover it up with. I used hot glue this time because the awesome Fimo model clay I normally use requires 30 min in an oven at 100°C and I’m not sure the microphone would handle that.

Adding the headphone jack

First off, solder the three short wires to the female headphone jack. Pay attention to which wire represents what channel. On a headphone plug, the area of the connector closest to the root of the plug is the ground channel, the middle one is the right channel, and the tip is the left channel. You need to trace this to the soldering points on the female jack, and it’s not always as straight forward as it might seem. Take my connector here; logic would dictate that since the tip of the headphone plug is the left channel, that part would stick farthest into the female jack and so the connector farthest away from the “entrance” is left. Unfortunately the plug has some metal parts going here and there inside the plug, so left and right has switched position. Meaning that the soldering point farthest away from the “entrance” is actually right. THIS DOES NOT APPLY TO ALL JACKS. I’m saying this because depending on what female jack you have, it might or might not be like this. Bottom line: check.

When you’ve attached the wires, you need to solder them to the ThumbTack plug. The correct pinout is shown in the picture below. Obviously you have to solder the right channel from the female jack to the right channel on the plug, left to left and ground to ground – don’t solder anything on the mic pin. If you confuse the mic and the ground pins and solder the ground on the mic pin, you’ll end up with a setup that works but has very low volume and that will sound very weird when you use the headphones, because the headphones won’t be connected to ground and the mic part will be half way short circuited.

All that’s left to do then is to test it (!) and then (if it works) encase it somehow. As I said before, I used hot glue because it’s fast and easy, but you might have something better.

To prove it works, here’s a video: