sub cutting out: insufficient grounding? diagnosis/advice please

[CDN 2.5i]

My sub is cutting out when I'm running it hard, with music with heavy bass. Hits all the notes then cuts out for a bit, sometimes just one note, sometimes several, then back to normal. I've checked all the connections (except for at sub, but I was very careful to make that connection very secure prior to installing it) and nothing is loose - it does this with car stationary as well as moving anyhow, so I don't think it's a loose connection.

My headlights will dim with some of the heavier notes and it would seem to cut out around the same time sometimes... The amp will get hot in this scenario, but I've had it happen when the amp is not hot yet so I doubt it is overheating.

I've got a JL Stealthbox powered by a JL e1200 amp. I've got 4AWG power cable from the battery to a distribution block with 8 gauge from block to amp (short section, couple inches). Amp ground is 8 gauge going from distribution block forward to gas filler assembly floor bolt.

Is this a symptom of poor grounding, at the alternator/battery side or for my amp? My main speaker four channel amp is not cutting out... Have people upgraded the ground on the charging circuit? Thoughts anyone?

http://img.villagephotos.com/p/2006-4/1167542/CIMG0104a.jpg

[ldc2335]

try sanding down the bolt and nut you have it grounded to if its painted...this worked for me on a bolt in the trunk of the sedan

[PGT]

I've got a 500/1 on the same enclosure and don't have issues. I ran 2awg from the battery and grounded with 2awg to the spare tire well.

I'd say a poor ground is your culprit. Electrically speaking, the ground is more important than the positive lead. The above advice is correct - make sure you get clean, bare metal to ground to and you use a heavy duty screw or bolt that's not coated.

I used JL's Master Ground Lug kit:

http://www.abtelectronics.com/images/products/l_91459jl.jpg

[CDN 2.5i]

Alright, I will revisit the amp side ground first and see what that does. I'll clean off the screw (it wasn't painted) and what not and see if that improves it.

PatGT - where in the spare tire well did you ground?

[PGT]

as you face the tire well from the rear of the car, the bottom front corner on the left (towards the front of the car). I copied this location from Manville's install (look closely at his install pics for more detail). The bolt goes through near the rear swaybar.

[BLACKonBLACK Limited]

My System is doing the exact same thing.... it will cut out when the bass hits hard sometimes, then come right back on. If its cutting out i turn it down 1 click and its fine... i guess ill have to sand the ground point (rear seat bolt)

[CDN 2.5i]

I'll clean off the screw (it wasn't painted) and what not and see if that improves it.

Turns out the screw WAS painted. The nut wasn't though... that's what I remembered. Wirebrushed it all with the dremel to freshen it up and looks (sounds) like problem solved. Couldn't get it to cut out and I let it POUND!!! :icon_bigg

Cheers all, thanks for the advice.

[PGT]

:sweet:

[CDN 2.5i]

OK, so my testing was not comprehensive enough... I still have an issue.

I should have indicated that I only tested the system while sitting in my garage with the car NOT running - i.e. just straight off the battery with key in ACC position.

Driving in to work this morning I was able to reproduce the problem. Still a grounding issue at the amp side?

[PGT]

try using a larger piece of cable. If it's still cutting out, you might be tapping the ability of the charging system to deliver current. A capacitor may help in this regard. I'm not up to speed enough on the requirements of your amp to know if this is the case.

FYI - if you need a capacitor, I've got an extra one that I didn't use in my install as I ran out of space. PM me for the 411.

[CDN 2.5i]

I'll see what I have leftover of my 4AWG to use as a ground and revisit that.

But does the fact that it doesn't cut out if I'm running off the battery itself, with engine not running, have any significance?

[PGT]

you're not powering every other electrical part in the car with the battery off, like the ignition, etc

[msmith]

That's weird... The system should be less likely to shut off with the engine running than with the engine off. I'm running about 1000 watts without any voltage issues in my car. I used a 2 AWG main power wire split to two 4 AWG wires near the amps and 4 AWG ground wires for each amp.

What gauge is your main power wire?

[PGT]

I've got 4AWG power cable from the battery to a distribution block with 8 gauge from block to amp (short section, couple inches). Amp ground is 8 gauge going from distribution block forward to gas filler assembly floor bolt.



Maybe 4 isn't sufficient? I would think it is.

[msmith]

It also depends on the 4 AWG wire... there's a lot of undergauged wire being sold (especially since the price of copper has gone through the roof). They just make the insulation thicker and still call it 4 AWG.

I would think that a single real 4 AWG would be sufficient in that system.

[PGT]

wow....someone call the AWG po-lice. That's irresponsible at best and criminal at the worst.

[CDN 2.5i]

I'm running Scosche EFX2 power cable... I don't think the cable itself is the culprit.

I will do more investigation this weekend. It may be that I'm just overloading the amp with the EQ and subwoofer out both turned up... I will try turning down the main amp to further tune the balance between the doors and the sub.

On a side note, just purchased a pair JL VR650-CXi's for the fronts. Looking forward to installing those and hearing the improvements there!!! :icon_bigg

[CDN 2.5i]

Was just thinking about the difference between when the car is running or not - if I am overdriving the amp with everything turned up, would the amp be more likely to have an issue and go into protect mode sooner if it was getting a higher voltage from the charging circuit?

[BLACKonBLACK Limited]

well we had the SUB wired a lil wrong but i think the problem was the ground , I moved it to the seatbelt bolt and sanded it down to the bare metal. Has not cut out yet, car on or off (knock on wood)

[msmith]

What do you mean by "we had the sub wired a lil wrong?"

[mwiener2]

IB gain is turned all the way up