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Getz sub wiring

09 Sep

While we have the panels off doing the dynamat, let’s take the opportunity to lay some wiring as well.

Firstly, I have to say that the amp I’m using for this can be a 2, 3 or 4 channel amp. Firstly, a “channel” is one speaker, or splits because splits are really one speaker split into tweeter and woofer. This is an over simplified definition but it works for the moment. So, 2 channel means that the amp runs two speakers (usually the front two), 3 channel is 3 speakers (usually the fronts and a sub) and 4 channel is two sets of speakers – front and rears for example. In this set up, I’m using the 3 channel option.

Now, for this to work, I need to get the output from the headunit to go to the right place. For this project, I’m going to use the front speaker wire to send output to the front (duh) and the rear speakers to send output to the subwoofer. The trick here is knowing when to pass the high frequencies to the front and the sub-range or low frequencies to the sub. Luckily the amp has a switch which indicates low pass or high pass.

So all of that is a bit technical, but I wanted to explain why I’m going to steal the wires from the rear speakers to run to the sub.

Firstly, we need to steal the rear speaker wire. We can assume that the headunit sends it’s output to the rear speakers directly through wires. We want the headunit to send that signal to the amp and the amp to then pass that signal to the sub. Therefore, we want to send the wires from the headunit not to the rear speakers, but to the amp.

Conveniently, the rear speakers have the rear speaker wire attached to them. If we take those wires and plug them into the amp, that’s the rear inputs. To do this, we need to remove the wire from the rear speaker and then connect that with a wire to the amp.

Step one: Remove the plug connected to the rear speaker.

Step 2: Work out where the wire will go from the rear speaker to the amp so we can lay it under the carpet, out of sight. (In the photo below, I’ve laid the black speaker cable on top of the carpet to work out where it will go.)

Step 3: Prepare. Get all the stuff you’re going to need to join wires together. I have an old camping mat piece of foam thing that I lay near the car door to kneel on. I’ve lined up all that I’ll need so I don’t have to get up when I’m half way through something.

In the above picture, on the right hand side is the soldering iron, plugged in and hot, ready to use. On the left from top to bottom, I have: Speaker wire, heat shrink, a sharpie, a roll of red electrical tape and wire strippers. At the bottom, that’s my foot. I’ll probably need that, maybe even two of them.

Step 4: Be fastidious. By taking a couple of extra seconds to do stuff properly, things are a lot easier in the long run. Take the speaker wire, strip the ends. Then write on a piece of electrical tape which wire it’s connecting to and that it’s for the rear speakers. Every wire in your set up should have a label on it. If something goes wrong in future, this is the easiest way to know which wire does what. Then cut some heat shrink and slip it over the end ready for once it’s soldered.

Now, do the same with the wire that was connected to the speaker. Cut the connector off, join the wires, solder them to help the connection and then heat the heat shrink over the top. I haven’t shown this step here, but earlier in the tutorial, I went into a fair bit of detail….

Step 5: Run the wire under the carpet in the same way it was laid on top. Use strips of dynamat to hold the wire down if you have some left over. Stick the wire out near the amp (there’s a convenient hole where the wire to the seat goes) and label those ends too. You’ll need to know that stuff when it comes to connecting them to the amp.

In the photo above, you’ll see that I’ve done both rear speaker wires and labelled them with IN. Then I’ve also run the sub wire while I was there and had the trims off. I just ran a decent length of it to the boot following the other wiring paths. I’ve labelled it as well.

So now that’s all done, we can start to put things back together. All you need to do is pretty much everything but in reverse.

Two things I wanted to point out though. Firstly, as you’re putting the rear quarter panel on, think about how we’re going to get the wiring to the sub. I found a nice little cover inside the shelf area that I thought would be a nice neat way to run the wiring. I drilled two holes in it, stuck the wiring through and then replaced the cover. These wires will then be connected to the sub. I’ll show more about that later when we actually hook it up. For now at least the wires are there. (Note the below photo shows them, but prior to me labelling them).

Secondly, as you’re replacing the trims, but before you put the spare tyre back in, why not fix up the dynamat in the place where it needs it the most? The area where the spare tyre goes is usually pretty flimsy and resonant. Ideally, you would throw 4 or 5 sheets at this area to stop it vibrating, but if you can’t (or don’t want to) afford that, cut some strips and go for it. I used about three quarters of a sheet in the picture below…

This should be enough to go a long way to stopping vibrations coming out of there.

So, now everything is back together, we only have two things left to do. 1) Pull out the head unit and run the wiring to the amp, and 2) POWER!!!!!

The next post will be all about getting power!

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