Will Adding an Amp + Subwoofer require any other electrical changes?

[jmarch1122]

I hope I might be able to get a little guidance here with some electrical issues. BIG PROPS to anyone with some knowledge.

I have a JL HD750 amp and JL 10w7 woofer which have been working perfectly for almost a year. A week and a half ago the sub started cutting out. Apparently it goes into safe-mode because it isn't getting enough power? But after the LED flashes red/green so signify that, it turns back to solid green but doesn't put out any sound. It seems to happen when I turn up the volume, or run the stereo with the car in neutral or off, and only starts working again after leaving the car off over night. Unplugging the battery doesn't reset it immediately. I brought it to the dealer that installed my amp and had them look at it. I don't know what they tested, if anything, but they told be I had a torn voice coil and that was the problem.

I happened to have another 10w7 sitting around and I switched them only to have exactly the same problem with the other speaker! I can not for the life of me figure out how a system could work fine for a year, then act up like this unless the amp is broken.

When I called JL to return the amp under warranty for repair, they said it doesn't seem to be the amp, but couldn't tell me much more. They suggested it could be the alternator, the battery, the wiring, or the amp. Way to narrow it down JL!

JL also told me its impossible to tell if its the battery or anything else without a $1000+ electrical tool that measures the current range not just the average like a regular multimeter does. My multimeter shows my amperage at 12.4 and doesn't fluctuate when starting the car or the stereo. I have never had an issue with my HID lights dimming. I did notice the backlight of my AWE boost gauge dim a little under max gain though.

JL said I should replace the "Big 3"-the OEM battery ground, engine ground, and alternator to battery cables with 0-guage wire. I don't want do work that isn't necessary, and I feel like I should be able to run a 750w amp on the factory alternator and power wires. I also researched the alternator before I bought this system and I think ours has a 150amp output, which would seem to be more than enough.

Any tips on how to identify the real problem here? Im getting really frustrated and Im sick of the dealer who installed it just dicking me around.

[bman005]

Do a voltage drop check on your + cable for your amp/sub. See what the voltage is up at the battery and then back at the amp.

[jmarch1122]

Do a voltage drop check on your + cable for your amp/sub. See what the voltage is up at the battery and then back at the amp.


DC voltage is 12.39 at the battery and 12.30 at the amplifier. Thats sounds about as good as it gets to me. grrr...

[bman005]

Yeah, thats not much of a drop. Maybe your amp is just getting weak?

[jmarch1122]

I guess so, I just don't wanna pay to mail it to JL if it turns out not to be a problem. I just told see why this is so difficult to isolate and explain.

[bman005]

Do you have a friend who has an amp you could swap in quick and check? At least then you could verify

[Operator]

Man, I wish I had seen this before I left for work. I won't be back to my car until Weds afternoon. But for some reason your voltage seems low. I'm just going off vague memory, but I think mine is normally in the 13 range. And I'm running a JL 1000/1 and a 450/4. Are you still on the OEM battery?

[jjcannon]

I'm not an Audi guy yet, but you will want to consider a deep cycle battery (optima brand.)

[jmarch1122]

Do you have a friend who has an amp you could swap in quick and check? At least then you could verify

Unfortunately I can't get ahold of a different amp right now to test that.


Man, I wish I had seen this before I left for work. I won't be back to my car until Weds afternoon. But for some reason your voltage seems low. I'm just going off vague memory, but I think mine is normally in the 13 range. And I'm running a JL 1000/1 and a 450/4. Are you still on the OEM battery?

No I don't have an OEM battery. Its only 6 moths old but it is a braille compact one. Maybe this is the issue. Braile assured me this battery would me completely fine to power this amp. They could have lied.

I just tested about everything that I could and I realized that while the car is running, the battery voltage is 13.8-14.1 with no accessories running, while the amp remains at 12.2. As I turn on the lights, fogs, heating/seats, and volume the voltage at the amp dropped to as low as 10.4, but I couldn't turn the volume up all the way. During these measurements the JL amp was off, solid green LED, but off. I can definitely see the voltage dropping below 10 at higher volume and kicking it into safe mode though.

Does this specifically indicate the battery as the problem, or is it the alternator not being able to re-power the system?

[bman005]

I wasn't thinking that was your voltage with the car running, I figured it was just keyed on. Thats too low for sure.

[doublezero30]

if your amp has fuses on it, check the fuses.

[djp2]

and I feel like I should be able to run a 750w amp on the factory alternator and power wires.



Right there where you say you are running this amp on the factory wiring, that's deff a bad thing, for this amp with that wattage you should be running from the battery a min of
4Gauge wiring. Because it being a HD amp, it will run the same output wether it being 14V or 12V.

Best way to here if you have a blown VC, push the cone up and down with your hand and if it scratches, it's blown.

When i get to work tomorrow i will check about the flashing and give you a more deff answer on that. hope this helps so far.

[jmarch1122]

Thanks for the input guys. I had auto zone load test my battery and it failed there test. It still runs my car but Ill have to replace it. It should be covered under warranty, but I will try to ebay the new replacement and yet a yellow top.

When I said factory wiring I mean the battery to ground, engine to ground, and alternator to battery cables. Those are all still stock for me (they are 8 awg I think). My amp's power and ground wires are 4 gauge OFC.

[djp2]

I would recomend you getting a Red Top, Save the money and get that one. Trust me you dont need a yellow top. and unlike the yellow top, with the red top, if its dead it will still start the car.

[jsandor91]

have you checked your amp grounds? on my old car i didn't have a good ground and my amp kept doing the same thing.

[Operator]

While not a must have, digital fuse/distro blocks help with keeping tabs on your audio system power. Example of mine: http://www.audizine.com/forum/showthread.php/386051-Finished-my-Audio-install

[QuattroTi]

Upgrade alternator/battery power and ground wires to 1/0 AWG

[djp2]

Upgrade alternator/battery power and ground wires to 1/0 AWG

That's not needed for what he has, its only 1 amp with one sub, would be different if he was running a full audio setup.

[QuattroTi]

it definitely helps, ive never installed a system in my cars without doing this mod. Its a very simple concept, better current flow not only for your audio but for the whole electrical system. especially running a w7 series subwoofer

[jmarch1122]

Update-

Had my battery tested at autozone and it came up as bad. I talked to Braille about replacing the battery under warranty and try said to try charging it first. I went to a different autozone yesterday, took my battery into the store, and before they would charge it thy checked the capacity again and it came back at 100%.

WTF?!?!?

What do I do next? No one can tell me what the problem is it seems. I still can't get over how it worked fine for so long, then this.

[canadianA4B7]

R u running a cap in line with your amp? Im electrical apprentice an have a minor in auto electrical. If u r dimming lights an loosing voltage/amps to the amp a 1/2 farad cap may fix it. Or did u say u were running an inline cap w/ the amp? Look into it phenix gold may have some answers 4 u, or google 1/2 farad capacitor.

[djp2]

Have you been able to replace the battery yet?

I do recomend you getting a Cap, that will help trumendusly here is a link for you to buy one Click For CAP (http://www.ebay.com/itm/Power-Acoustik-1-5-FARAD-Digital-Car-Capacitor-Cap-With-Red-Dsplay-/350554974326?pt=LH_DefaultDomain_0&hash=item519eb46876&vxp=mtr)

I would replace the battery and buy a cap, do this first, if problem persist, you do have the right to return the amp and exchange it, make sure where they grounded the amp they sanded it to bare metal, I see this mistake a lot. If you where closer I would help you but ima try my best over this.

Ive been doing car audio for to long and have seen what you are talking about with many diff amps, first time for a JL.

[Silveravant]

A fully charged battery should put out 12.6 volts. When batteries start getting bad strange things happen. With my MK4 Jetta the car would actually stall momentarily when I put on the turn signal or brake lights on the freeway. Scary! Would still start and run fine.

[djp2]

A fully charged battery should put out 12.6 volts. When batteries start getting bad strange things happen. With my MK4 Jetta the car would actually stall momentarily when I put on the turn signal or brake lights on the freeway. Scary! Would still start and run fine.

That and check to see does it still have at most 90% of its amperage, ex: it should say like 800 CA and like 1000 CCA, check to see what those are.

[iamshayan]

I have a optima Redtop and I just installed a RE SXX 10 and am powering it with a memphis ST1000D at 1ohm and 1100Watts, I'm noticing significant drive-ability issues and crazy dimming on my cluster. What am I doing wrong. I never had this problem with my JL1000/ and 13W7.
I've had my optima for about 3 years now do you think its going bad?

Sorry to bump an old thread but i really hate starting my own.