Buildlog: 3.5mm interconnect

Amui

Canada10567 Posts

February 19 2014 08:01 GMT

Since my family got a new car, and it features a 3.5mm input, I decided that while I could buy a 3.5mm to 3.5mm cable fairly easily, that's no fun. So here we go.

Parts: Total cost is ~$50, but I bought enough to make about 10m of cabling. You could probably drop it down to about $30 or so, but almost half of that is going to be in shipping costs at that point.
Mogami 2893 wire - Bought from redco.
Amphenol 3.5mm jack. Also got these guys from redco, but there's a ton of different brands out there that you can get. Neutrik is good as well, but this looks slightly better I wanted the silver with gold plated, but that was out of stock

2mm sleeving. I got these from axon modding, although there's plenty of other places you could get it from, as well as different sizing. I got blue and white, although other colors can be fine.

To begin,

This cable is absolutely unusable for an interconnect at first glance, as it's nearly 5mm in diameter. But we want what's inside. Getting to it isn't easy though, there's the outside insulation, then the EMF insulating copper strands, and finally the paper and string wrapper/filler. Trick is it use a knife to run down the length of the insulation to score the insulation. Then just slowly pull it apart and remove the inner core. Unwrap the copper/paper layer, and separate the string from the wires and now you have 4 wires that are much, much smaller than the outside layer.

This is one of them, there are 3 more like it, blue, clear, and black.

Next step is to sleeve the cables. Since this is an interconnect, it's not necessary to have separate grounds for left and right, and because I'm lazy, only one of the cable sets are braided and then sleeved. The other is simply one wire running straight through. Not very difficult, but exceedingly tedious. Heatshrink the ends so they look nice and stuff. I don't actually own a heatgun, but a hairdryer+lighter does pretty well.

From here on out it gets a bit tricky. You need to heatshrink one end together and prep the wires to go into the jacks for soldering. Haven't done the soldering yet, but hopefully I'll get around to doing it tomorrow.

And a look at the cable as a whole.

Was busy yesterday so I didn't have time to do the soldering, but spent the time today to finish it up and test. Works great, sound out of both ends, can bend the cable without sound cutting out.

Pretty ugly solder job, IMO I did a much better job on the other end, but I guess that's to be expected because I'm soldering outside(ventilation) in the cold and my hands are starting to freeze =(. One thing of note is that 99% of the time you'll need to trim off solder with some crosscut's after you're done in order to let the covering go on smoothly. It's important not to force it to fit. Also had to do some finagling with a lighter and pliers to mold the heatshrinked area into a more circular shape so that it fit(was kinda rectangular before)

The finished cable

Lastly, the cable in it's final environment.

Birdie

New Zealand4438 Posts

February 19 2014 08:44 GMT

Soldering the end is something it's worth spending time on to make sure that even if the cable twists, there won't be any contact between the wire ends/solder. You basically have to redo the solder job if you get it in there and find out that any movement makes your left channel cut out, for example.

Amui

Canada10567 Posts

February 19 2014 08:51 GMT

On February 19 2014 17:44 Birdie wrote:
Soldering the end is something it's worth spending time on to make sure that even if the cable twists, there won't be any contact between the wire ends/solder. You basically have to redo the solder job if you get it in there and find out that any movement makes your left channel cut out, for example.

Yeah, I've been through that before. Definitely the most delicate part of this process, although now that I'm using an actual temperature controlled station as opposed to a wattage controlled soldering is a lot easier.

seiferoth10

3362 Posts

February 19 2014 10:17 GMT

I tried this once, and it was a pain in the butt. Setting up the wires to each of the three miniscule prongs of a 3.5mm plug is a test of sanity. I used the standard Neutrik plugs, which have one of the smallest barrels possible.

If I had to do it again I'd go with a bigger barrel, or even 1/4 in.

wei2coolman

United States60033 Posts

February 19 2014 19:01 GMT

Jeez, so much work for a simple cable.
but looks sweet. Gj man.

Amui

Canada10567 Posts

February 21 2014 04:57 GMT

Finished up the build, Not bad, although I probably could've done better in a few places.

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