Power for subwoofer behind seat

[ESPREE]

Hello all,

Just purchased a slim subwoofer to install behind the passenger seat, and I am wondering where is the best place to get power and ground for it.

In another post someone mentioned a power tap in one of the "A" columns, but I am not sure where that is. Also saw a post about a factory hole in the firewall, but again I can't seem to locate it.

Any suggestions? Photos would be ideal.

Thanks,

Kent

[Günter]

if you look under your dashboard (Lotus-position) you will find the feeds attached to the metal columns forming the door mount support. Other way could be to go directly with the main wires to the battery-posts, from the bulkhead plate to the channels on the roof sides and on top of the fuel-tank bay to the rear.. ?!

[ESPREE]

Hi Gunter,

Thanks for the info. I will take a look under the dash.

If I do go with a direct line from the battery (with an in-line fuse of course), I can see how I would get the wires to the ECU area. But once there, are there any existing holes that go into the cabin area, or would I have to drill something (maybe next to the seatbelt unit)? If so, anything in particular I should be careful of when drilling through the firewall?

Kent

[ESPREE]

Hi again,

Nevermind, I found an easy route from the battery. Will post pics later.

Kent

[dbaker]

Hey Kent,

I would love to hear more details on how you accomplished this feat. I'm also in the process of adding a powered subwoofer to my '99 V8 and have found myself at the same juncture - how to best to tap into a suitable power and ground.

Thanks,

Doug

[ESPREE]

Hello Doug (and all),

So I decided it would be best to run the wires directly from the battery. For one I couldn't find any way to access those power taps under the dash (airbag in the way), but also because direct to the battery is the best way to go for the best sound and no drain on other systems.

It sounds perfect! Not overpowering, but a great solid feel and sound that fills in the missing low end. Now the regular speakers can just handle the treble and not work so hard. No license-plate rattling here, just a solid sound that any music lover can appreciate, no matter what genre of music you listen to. And it does not interfere with the passenger seat at all!

Some details...

The slim subwoofer I got was this one for $103:

Pyle PLBASS8

First up was the removal of the pocket - just use a seam puller to remove the stitches that hold it in place. It was a little painful, but I kept telling myself it would be worth it!

Getting the power wires to the side window area (where the ECU is) was not a problem - wide open space in front of the battery. But then I wasn't sure how to get the wires into the cabin without drilling a hole in the firewall or having visible wires. Fortunately, I just recently had my passenger side seatbelt replaced, and I noticed that the casing for it is way oversized. Once in the cabin, there is a wide open channel across the top of the back wall, and then the wires can go under the carpet completely hidden. A perfect route for the wires!

So I ran two #8 gauge power and ground wires up the window area, then drilled a hole in the seatbelt cover (using a piece of flat metal slipped into the seatbelt hole to prevent damage), and snaked the wires through. Once through the seatbelt hole, I took out the sunroof and ran the wires across the lower leather window trim (nice open channel in there), and then snaked the wires behind the carpet to the area where the subwoofer would go. Completely hidden.

Of course for the audio signal and remote turn on I had to get some RCA wires and a #14 wire up to the head unit, as well as the remote level control for the sub volume. But the center column provides a perfect place for those wires. Just push the wires up under the leather, then attach the RCAs to the Front output of the Alpine unit, and splice in the remote turn-on wire to the blue wire with the white stripe. See my iPod input tutorial for details on head unit removal.

I mounted the sub level control up under the driver's side of the dash so that I can adjust it easily:

I mounted the sub horizontally, and it does not interfere with the seat at all! I was worried about that, but instead of mounting it vertically, I went horizontal and lifted it up off the floor by a couple inches so that the lower portion of the seat wouldn't hit it. The sub rests right in the "soft" part of the seat, and the lumbar pump still works fine.

Lastly, I added a custom cover so that you can't see the sub controls from the side. Just a piece of sheet metal with craft-store bought felt that has adhesive on one side. Bend it the way you want, and it looks factory. Slides in and out for easy access to the controls if needed. In the photo the flash makes everything look gray and washed out, but in real life it all looks black and blends very well.

Of course the settings had to be tweaked to make it sound just right, but after a little playing around it sounds great. One note is that if you use the "Front" RCA outputs from the Alpine head unit, you have to press and hold the "Eject" button for 3 seconds to turn the "NFP" to "ON", which allows the subwoofer to get the audio it needs that is unaffected by the fader.

While I was adding this power feed to the battery, I also added a volt meter with switch and custom mounting bracket (same method as above with sheet metal, but with sticky-backed foam). The voltmeter and the sub both feed power off of the Positive post by the fuse box (I added an inline 15A fuse), and the ground is a direct connect to the negative terminal of the battery. Add a Lotus sticker and call it a day.

Hope this is helpful for someone! Let me know if you have any questions.

- Kent

[ESPREE]

By the way, here is a link to the voltmeter on Amazon:

http://www.amazon.com/Stinger-SVMB-Voltage-Gauge-Display/dp/B001HEE8IS/ref=sr_1_7?s=automotive&ie=UTF8&qid=1311217536&sr=1-7

- Kent

[dbaker]

Well done Kent - and thanks for the fantastic tutorial and photos! I've been scratching my head for awhile now on the wire routing issue. I also know exactly what you mean about cutting out the map pocket - it's a bit nerve racking taking a knife to anything on the interior of these cars.

Thanks again for taking the time to document and post this project.

--Doug

[ESPREE]

Hi Doug,

You are very welcome. Keep us posted on how it goes!

Maybe I will re-use the map pocket in the trunk or something.

Kent

[Günter]

so I see you used the suggestion to use feed & ground directly from the battery terminals.. my additional suggestion for others would be -why not try to fabrikate a bracket that sits on top of the plywood plate on the RH side fuel-tank. Just like the ECM-module ...this way you can use the space there for some slightly smaller electronic packages (for example two seperate 2way ampplifiers/IC boxes) -the power supply would be realy short, and you can route the wiring between head-unit & IC still the way you did on this project -but the interiour needs no handbuild covers or pocket 'cuts' (not all have this optional map pocket by the way..) and would also look clean.

The question is the temperature there, as I would guess the ECM does not radiate heat as much as an IC/amplifier does ..

Edited July 22, 2011 by Günter

[ESPREE]

Hi Gunter,

That's a good idea. Certainly if someone has a separate amp and speaker setup the amp could go there and the speaker could go in the cabin. But I agree that I am not sure about heat.

Amps do usually produce a lot of heat, and need airflow to function properly and not fail prematurely. Not sure if the ECM area offers any real circulation. But it is a handy space in general.

On the plus side of putting it behind the seat, my wife may have a heated seat back in the winter.

Thanks again for your help and suggestions!

- Kent