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Posted by: drem914 Apr 24 2019, 03:52 PM

I am looking to add an amp for a footwell subwoofer. Where is the easiest and best place to pull power from? I really don't want to run a power lead back to the battery. If I have to do that I probably will scrap the whole idea.
TIA

Posted by: jim_hoyland Apr 24 2019, 04:10 PM

A separate line from the battery is recommended....

Posted by: drem914 Apr 24 2019, 04:37 PM

But I really don't want to drill anything or remove my recently install interior, back pad, seats, etc. You know the drill. Can the fuse panel just not handle the added load? Even for a small amp?

Posted by: bandjoey Apr 24 2019, 05:10 PM

fuse panel has 1/2 always hot and 1/2 switchable hot with empty terminals, but what's the amp load?

Posted by: windforfun Apr 24 2019, 05:20 PM

Don't forget the "Pi" filter. It attaches in series with the power connection. Without it, you'll have a ton of alternator noise

Posted by: Dave_Darling Apr 24 2019, 09:55 PM

If your amp and sub are low-powered, you can probably get away with using fuse #8. If it's anything more than a tiny little thing, you're going to want to run a new fat wire and a relay or two...

--DD

Posted by: Steve Apr 25 2019, 06:28 AM

I ran a thick wire through the center tunnel back to the battery. I did not have to drill any holes or remove anything except for the carpet piece over the tunnel. I did put heat shrink over the power wire for extra insulation in the tunnel.

Posted by: drem914 Apr 25 2019, 10:41 AM

Thanks Steve.

Posted by: drem914 Apr 25 2019, 10:43 AM

Don't know yet because i was holding off until i figured out what i was going to do and to see what is available.

Posted by: VaccaRabite Apr 25 2019, 11:33 AM

Don't go through the fuse panel. Run a wire to the battery to a relay to the noise filter and to the amp.

Keep in mind that if your amp is big enough its going to draw more then your little alternator can provide - it does not take much.

What size amp are you putting in?

Zach

Posted by: porschetub Apr 25 2019, 03:03 PM

Only way is direct to battery,nothing in the fuse board with handle it,I added an extra Hella 4 fuse board direct to battery,it runs my stereo and anything I need to add latter,mounted it under the dash.

Posted by: drem914 Apr 25 2019, 03:07 PM

Concesus understood. Fuse panel and alternator were never desinged to run anything more than a radio.
Likely will use something like this small JBL or the Infinty equivalent.

https://www.crutchfield.com/p_109STAGEA2/JBL-Stage-A6002.html?cc=02&tp=72998

Thanks for the solid advice.

Posted by: windforfun Apr 25 2019, 03:25 PM

Go with the largest power amp you can afford. Old cars aren't quiet - especially with the roof off & a loud exhaust system. Power it directly from the battery with a fuse & noise filter. Put the fuse at the battery & the filter at the amp. Trust me, BTDT. I prefer something along the lines of 100 W rms per channel. Don't waist your time with a little diddly shit power amplifier. If you blow out your loudspeakers, you'll know what to do next.

Posted by: Chris914n6 Apr 25 2019, 04:09 PM

140w RMS@4ohm should be fine for a 8" sub in our tiny car, but it depends if the rating of the speaker is close.
ex: a 280w speaker will be too tight to make much sound with 140w, but a 150w speaker would be in it's sweet spot.

Posted by: drem914 Apr 25 2019, 04:25 PM

currently have this 8" Polk DVC https://www.amazon.com/gp/product/B073JX8NPX/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 ready to go in this enclosure for the front footwell

Posted by: windforfun Apr 25 2019, 05:49 PM

This isn't necessarily true. Loudspeaker efficiency & maximum power handling capacity are very different things.

Posted by: Chris914n6 Apr 26 2019, 04:08 PM

Check that it actually is DVC, 2 pairs of terminals. If so then you will want an amp that can do 1 channel @ 2 ohms as both coils will need to feed from the same signal.

* Not many amps will state they are 2 ohm stable bridged, but my experience has been it works to a point... as in some amps would overload sooner than expected. But then I was minitrucker in a past life so I was pushing harder than an normal person would want to go anyways.

Posted by: VegasVic Jun 1 2020, 06:05 PM

Would you elaborate on your specific routing?

Posted by: bbrock Jun 1 2020, 06:56 PM

I have a couple pics of routing my amp wire on my build thread here:
http://www.914world.com/bbs2/index.php?s=&showtopic=307290&view=findpost&p=2801031

I ran my 8 gauge wire right through the rubber snorkel alongside the factory harness. With the engine out of the car, it was a much easier operation to snake the wire than I expected. Took less than an hour total. I just taped a length of the wire along a stiff #9 wire to push it through and grab from the other side.

BTW, I'm also running an 8" sub so installed a 4-channel by 75W@2ohms (50wx4 @ 4 ohms) to power a pair of Infinity Kappa speakers and the sub with 2 channels bridged. The amp I bought is listed as stable bridged at 2 ohms and not all that expensive either.

Posted by: Steve Jun 1 2020, 07:38 PM

It’s been a while but, I ran the wire through the speedometer grommet and then out the same hole the harness goes through on top of the tunnel. I routed it along side the other wires. I think I followed the harness pass the fuse box and into the front trunk, where, mounted the main amp. I also spliced that same wire for a powered sub woofer in the car.

Posted by: VegasVic Jun 1 2020, 10:01 PM

Great! Thank you!

Posted by: porschetub Jun 2 2020, 06:04 PM

Did the same as Steve mentioned ,I used small positive cable but larger than the stock wiring gauge to the battery.
This thread has been real handy as I know little about subs/amps and learning here.
I have the Hella 4 fuse aux block ,no point in overloading the somewhat minimal stock fusebox afterall.