The Joys and Sorrows of Hardware Modification

For the last couple of weeks I’ve been butchering my perfectly functional Native Instruments Audio 2 DJ soundcard. The end goal is to place it inside my portable audio rig, which is a combination PC and MIDI controller currently at the Jack Skellington stage – all bones and no skin.

The point of this endeavour is to avoid having any superfluous pieces of hardware scattered around my live set-up. There’s also the added bonus of having less cables to carry and one less thing to forget at the end of the night. And, of course, it’s fun to have a project…

It’ll soon become apparent that I’m no electronics wizard. I have a very low amount of skill when it comes to soldering, and my prime asset is my willingness to break things open and muck around with the innards, which is exactly what I did with the Audio 2 DJ.

The Audio 2 DJ, for those that don’t know, is a fantastic little soundcard, with the emphasis being on the word ‘little’. What you get for your money is a box the size of a cigarette carton with a USB input (which doubles as the power lead), two outputs (main output and cue output), and a dial to control the volume level of each channel. It’s really basic, really simple, and perfect for the kind of mod I’m looking for – essentially a tiny no frills gizmo that’s small enough for me to hide in any gap in my rig case.

The initial idea for the soundcard was to discard the case and reposition the knobs and inputs onto custom drilled holes in my rig case. This idea was stupid, as it assumed that the components inside the soundcard would be wired, rather than soldered directly to the circuit board as turns out to be the case.

The USB port is easy enough to reposition; just grab any old USB extender from the net, such as this one from Adafruit:

Simply pick a spot on your rig case for the new USB socket, drill a couple of holes, attach, and run the cable internally. In my case it was even simpler as my rig is also a custom PC build – I simply ran the USB cable internally to a USB header on the motherboard, using a suitable adapter.

I figured out quite quickly that I wasn’t going to bother with moving the jack inputs (the main and cue outputs). They’re soldered onto the PCB, as is everything else, so I figured I’d just press that end of the card against the rig case, cutting two holes for the jack inputs to poke out of, as with the original soundcard case.

The only difficulty in this process is that you need to secure the soundcard firmly in the case, and it has to be oriented in a certain direction. For me that wasn’t a problem, as I was building the case from scratch, so could plan for the space needed by the soundcard protruding backwards into the case.

In the event that this isn’t possible it should be quite easy to remove the barrel inputs from the PCB using a small pair of clippers. The barrel inputs actually have a thread on the protruding end, so securing them to the case would be a simple task given the correct size of nut. The soundcard can then be positioned anywhere in case, with cable soldered between each pin on the barrel input and the corresponding pin on the PCB.

In terms of securing the card to the inside of the case things are quite straightforward – the card already has three mounting holes where it was connected to the original case. Simply run a couple of M3 bolts through these, preferably using some acrylic washers as spacers to stop the underside of the card pressing against the case.

The final step, and the most troublesome by far, is repositioning the volume controls. The volume dials are 10kΩ linear dual-gang potentiometers, which are pretty standard for stereo outputs like this. As with the barrel connectors, these are soldered to the PCB, and can be easily removed using clippers. It’s worth noting that it helps in the long run to leave as much of each pin as you can still attached to the PCB. These act as pin headers to solder onto later. Once this is done the obvious move is to find more suitable dials for the outside of a case, as below (hello, Maplin!):

These can then be attached to the case, with wiring running between the potentiometers and the corresponding spots on the PCB, right? Well, almost.

Unfortunately, the aforementioned spots on the PCB, with the handy pin-headers left in place, don’t seem to have any logical pattern to them so it’s not as easy as just connecting the dots. I ended up having to test each output from the board (the two channels are laid out completely differently, by the way!) and wire accordingly.

The diagrams below shows the designations I gave each pin on the board and the potentiometer:

For those interested, the potentiometer runs on two channels (stereo), each comprising one row of pins. From left to right the pins read ‘ground, input, output’.

For the soundcard to function correctly the potentiometer must be wired up as follows.

For channel (A):

1 -> A
1->D
2->E
3->B
4->C
5->F

For channel (B):

6->F
7->A
7->D
8->C
9->B
10->E

Note that in each channel the ground is used twice – this is achieved by splitting the single ground output from the card into the two ground pins on the potentiometer.

There you have it! One well-designed, compact soundcard broken down into its constituent parts and re-organised.

Naturally there’s a disclaimer here – while I’m all for people modding, re-purposing and re-imagining hardware, I take no responsibility for any damage done to your hardware or your person.

Take every care while you’re working – be sure not to overheat the board as you’re soldering, be careful you don’t damage the board when you’re removing components, and preferably wear an anti-static wristband when working on PCBs. And for God’s sake, don’t electrocute yourself, burn yourself or cut yourself open – take all necessary precautions, then enjoy yourself. After all, modding is fun!