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Retrofit stock subwoofer in non UHFS

Discussion in 'Model S: Interior & Exterior' started by Noctrin, Dec 3, 2019.

  1. Noctrin

    Noctrin New Member

    Dec 3, 2019

    Wanted to post some quick details on my stock sub enclosure retrofit in my pre-refresh 2015 model S.

    I managed to find the enclosure and stock sub on ebay for 100 US, getting it to canada ended up doubling the cost, but was still way better value than going with something else. I also like how it tucks the speaker in and does not leave it exposed, so it was a clear choice for me.

    I had 3 issues installing it:

    1) the carpet liner will not allow you to install it, i had to cut pieces of it and make some slits to relieve some pressure and allow the sub box to fit, it will be very snug. As long as you take your time and make the cuts correctly, once the sub box is installed, it will not be noticeable. The biggest issue is on the side, not right behind it. There are also 2 bundles of wires that will be somewhat in the way, one near the wheel well which is very thick and not easily moveable (its for the lift gate and parking brake) and another one near the trunk side which is much thinner and held with clips to the body. I took out the clips holding the bundle on the trunk side and moved it out of the way.

    2) the sub box i bought said 2012-2015 but the mounting points on the front did not match, for some odd reasons they are angled on the box i received, while the tabs are in the right place, they do not sit flush with the bar they are supposed to mount into. Because i had the carpeting in the back, i had to apply a lot of force to get it in, so mounting it is unnecessary, i also added some foam behind it so it doesn't rattle the metal it sits in contact with.

    3) I already covered this in #1 but there will be wire bundles that are in the way, different models might be different, but you will most likely have to move them to get it to fit.

    I'm powering it with a 300W amp, i put a 20A fuse on it instead of the 30A it had and have it turned very low given the original sub was only getting 80W, i dont plan on pushing more than 100-120 into it right now. I powered the sub from the liftgate power, that has a 30A fuse. I looked at draw from the amp, and it sits below 10A, i had no issue with the fuse popping while operating the trunk. You can also put a 10-15A fuse on your amp to prevent issues as well and have that fuse fail rather than the one in the front for the circuit.

    In terms of results, the bass is overpowering, i'm pushing maybe 20% into it of what the amp could do to make it sound balanced, but i dont like it rattling my car, i simply wanted to fill the low end. The stock subwoofer is not great and does get muddy on tight firing lows, the ported box might also be an issue, but i suspect with a better drives that issue should go away.

    For anyone thinking of doing it, it's a solid choice, the only issue is you need to destroy the carpet liner on the driver side. You can run power from the front and put a more beefy driver if heavy thump is your thing, or do what i did if you just want to fill in the sound.

    I just need to find some matching carpet and glue it on the box to make it blend in better.

  2. beatle

    beatle Member

    Aug 31, 2019
    Springfield, VA
    What did you use as an input signal?
  3. Nishantsh

    Nishantsh Member

    Apr 20, 2019
    Wonderful - this is something I have been thinking so far for my car. the carpet liner us different for cars with subwoofer/UHFS. Probably getting the carpet (from salvaged tesla to cut the cost) will be helpful. Can you advise me how to get the 12v power from lift gate. I just don’t want to run power from front to trunk.
  4. tccartier

    tccartier Supporting Member

    Oct 27, 2015
    There is a hard plastic carpet covered trim piece that you are missing that hides the entire installation. You may be able to find this from a salvage car. My car has UHFS sound In stock form. It's pretty good enjoy!
  5. Ostrichsak

    Ostrichsak Active Member

    Sep 6, 2018
    Colorado, USA
    I added a sub to one of our non-UHFS cars. Knowing that factory audio systems (even upgraded ones) usually are trash I opted for a Rockford Fosgate P300-10 (300-watts & 10-inch sub) aftermarket subwoofer. I paid about $160ish shipped to my door and it's box, amp, high/low converter, carpet, mounting options and the whole works. Buy an amp kit for another $20-$25 and take an afternoon to install it all and you're done for less than what you invested in an inferior performing system.

    I located it in the rear bottom storage and it's out of they way completely. You just have to run a power wire from the battery to the back (I wouldn't trust tapping the hatch wiring for something like a subwoofer amp) and tap the speaker wires to provide high-level audio input to the unit which then converts to low for the built-in amp.

    IMO this is the best cheapest option for this application. You're not going to shake neighbors walls two blocks away but it sounds much, much better than the entry-level audio system. Some songs even sound better than our other Model S with UHFS at times.

    If you want something more of a stock appearance there's options out there for around $600-$700 (I think) that will put a similar box in the same location on the driver's side and give you a real subwoofer and for much better performance. You didn't say how much you spent on the amp but you could have taken all of the money you invested and put it towards something like this and knocked a fair chunk of the price is my guess.

    Not hating at all because I like that we have different options. I'm just questioning out loud if it's the best option for most. I think that the options I listed above are better for more depending on if you want budget or performance. Your option kind of falls in the middle but with the lesser of both options; more expensive than option 1 and not as good of performance as option 2 (arguable option 1 too really).

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