Subaru: Sound system upgrade

This entry is part 7 of 19 in the series Subaru Legacy
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The OEM speakers and such in my Legacy were not up to much. I took a look at them in the doors and found they were shot: the paper cones had rotted away and the terminals were rusty. Plus, I’ve read, the OEM sound systems have room for improvement anyway. Anyway – everything sounded flat and distorted and the volume was paltry.

Actually, when I first started my job the first example I was given of pressure-equalised cavity design was car doors.  Basically, the inside volume of the door is external air and it’s wet. Water comes down the window goes through the gasket into the door, and drains away in holes at the bottom. From what I’ve seen they normally glue/ weld some thick plastic sheets to the inside face of the door internal framing to form the system air seal, but everything outside of that is wet. And the back of the speaker is this zone: the back of the paper cone and the electrics. This is a bad place to be, particularly if you are paper or bit of steel acting as an anode (the negative terminal on the speaker). Wet, warm, and grime and salts from the rain and road (which never get washed away by the car wash or rain) abound in this zone, particularly in New Zealand. The sad conclusion (for paper speakers with steel terminals) is and mould, rot and corrosion.

That aside, I had two options:

  1. Pull out the whole system and put in a new head unit, amp and speakers, or;
  2. Leave the system stereo as-is but stick an amp with speaker levels inputs in there (which takes speaker level outputs) and replace the speakers.

I did not really want to spend a ton of money, nor did I what to start screwing around trying to shoe-horn a new headset into the I-am-made-for-here combined air-con and audio system in my car, so I went for the second option and went down to Hyperdrive . I had a good chat with the guy in there and walked out with new speakers, an amp and an active sub.

What I bought


Sony XMS400D amp. 4 x 45W RMS Class D compact amp.

A Sony XMS400D compact class D 4-channel amplifier. Incidentally, the guy who sold it to me said it was ‘digital’. It’s not really, and the ‘D’ does not stand for digital either: it’s Class D as being different from classes A, B, AB and onwards.Class D amps use switching transistors to convert the analogue signal into pulses, which is then amplified and turned back into an analogue (sound signal). Their advantage seems to be they are more efficient and more compact.

The amp is about the size of a laptop power block thing. I just taped into in behind the stereo, out of sight and out of mind.


Pioneer TS-A1676R for the back

Pioneer TS-G1605C for the front

Two sets of 6.5″ Pioneer speakers:

  • Two-way with separate tweeters for the front (Pioneer TS-G1605C)
  • Three-way combined for the back (Pioneer TS-A1676R)

Both are rated 50W RMS. installing was a bit of a hassle, but I used the shroud of the stock speakers which made things a little neater

New speakers fitted reasonably neatly into the plastic shroud of the stock speaker, having ripped all the stock cone and gubbins out and hacked it up a bit with my Dremel.


Fusion CP-AS1080 Active Slim Profile Sub

A Fusion CP-AS1080 sub. It sits under the passenger seat. Pretty neat. Again, like the amp its active Class D and takes speaker level input. I just spliced it into the speaker lines for the front speakers upstream on the Sony amp. Fusion, incidentally, is a New Zealand company – they don’t make car stereo stuff anymore so these units will become rarer. You can chain them together so maybe I’ll get another and put it under the driver’s seat.


It took a weekend to put in. Pretty happy. The only bits that needed some thought were getting power from the battery through the fire wall and into the amp and sub, and the wiring/ harness from the back of the stock stereo.


The amps both draw some current so you kind of have to do this rather than piggy backing on the stereo power or the cigarette lighter. I screwed around trying to find a hole through the firewall – lots of false leads on the internet. I eventually found that there are two handy gasketed holes through – I choose the largest. Both amps have a ‘remote’ function that turns on the amps when ‘high’, and the stock radio has a pinout for this (which I found they had wired the band expander into as well). This pin is a handy thing to know about for any other electronics you might want to run (and not drain the battery).



Finishing touch

My old car – RIP

My old Subaru had these cool little stock tweeters perched up on the C-posts at the back. Was never sure if they worked, but I liked the idea of them: very cinematic. So I reproduced them.

I went to Pick-a-Part. You pay 2 bucks and go into a car scrap-heap to hunt out what you need or just have a poke around. IT IS GREAT! Better than MOTAT or the Science Museum. All the cars are old and shit, so don’t expect to find a new seat warmer switch for your Mercedes (you might have to pay the 500 bucks to replace that)  but if your car is +10years-old and Japanese (and weirdly, no Toyotas) and you need a ‘new’ whatever, get your spanner out and off you go down there.

Pick-a-Part: I had to check this sorry sight was not my old car. It was identical…which was good as I had the bits I wanted.

Scientific scaling of the hole I needed to cut for the speaker covers…screwdriver for scale.

I found exactly what I was looking for: the speaker covers for the little C-post tweeters, and in a car that could have been our old car’s twin.  I installed them, with the help of a Dremel, and mounted the OEM tweeters from the front doors (that had been replaced as part of the whole upgrade) into the C-posts. I wired these, in parallel, into the wires for the rear speakers at the B-posts where the wires bundle route into the door. The tweeters have their own little cross-over capacitors which take out the lower frequencies.

The tweeters work… and a bit of nostalgia when I see them when I turn round to reverse.

The old tweeters I pulled out of the doors (replaced with Pioneer ones). I moved these to the C posts

Tweeter installed (using a bit of scrap wood) into the C-post

Cover replaced with new speaker cover (scavenged from Pick-a-Part)



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