revs drop periodically when sub/amp on (even when vol. muted), VIDEO

[euromandeluxe]

So I've found that if I have my sub and amp hooked up to my system when it's on the car's electricals (and idle) go whack, every few seconds the revs drop, lights dim, etc for a second, then go back to normal.

This is even with the volume muted so i don't think its because of large current draws causing a voltage drop.

If I disconnect the amp's remote turn-on wire, or if the system is off, everything's fine.

watch the vid closely (revs dip everytime lights dim):


http://www.youtube.com/watch?v=DwbwDe75UTs&feature=player_embedded


what's going on? the setup was all working fine for 4 months and now this has suddenly happened. grounds are ok, connections clean, new battery, fuses seem to be fine? I don't see any reason for the alternator to be bad, had it tested recently.

ideas? car is totally fine otherwise.

[GaDgeT-CRX]

thats a tricky 1 bro... muting volume wont do anything, the remote on from the HU powers the amp..

Does look like some kinda voltage drop, which can be tested by hookin up a multimeter to the battery, test. Then do the same with the power and earth connections on the amp, to see whether there is any loss between the 2 points.

How many watts is your amp? What gauge wires are you running? Where is your earthing point for the amp (is it too long, is it touching bare metal)?

[euromandeluxe]

thats a tricky 1 bro... muting volume wont do anything, the remote on from the HU powers the amp..

Does look like some kinda voltage drop, which can be tested by hookin up a multimeter to the battery, test. Then do the same with the power and earth connections on the amp, to see whether there is any loss between the 2 points.

How many watts is your amp? What gauge wires are you running? Where is your earthing point for the amp (is it too long, is it touching bare metal)?

thanks for the reply :) I mentioned the mute thing because I didn't want to make it look like the voltage was dropping when the bass hit or anything, volume (and I guess current draw) don't make a difference..

the volts do drop across the battery terminals when the lights dim/revs drop, from 14+ to around 12+, but they climb straight back up again. I should mention the lights dim periodically when the amp's on when the engine is off too.

haven't checked voltage between power and ground while amp is on, but with car off it reads normal (same as battery, 12.6V or something).

ground wire is short and goes to bare metal (sanded off the paint). what baffles me is it was working fine for months prior.. any other ideas?

[GaDgeT-CRX]

Only thing I can think of with the info provided, is that the battery is not pushing enough power to the amp (as indicated by dimming lights).. Either caused by battery on the way out, or not having sufficient current draw via power cables to the amp.. How old is current battery? What gauge wires are you running to the amp (and watts being drawn)?

[arverson]

didnt we go thru this already?

http://www.ozhonda.com/forum/showthread.php?137173-Revs-dip-lights-dim-every-few-seconds-only-when-sound-system-is-on

[euromandeluxe]

You're right, I had that thread posted a few months ago when the issue first began. Back then I didn't realize the problem was localized to the sub amp/sub - thought perhaps it had to do with the headunit, or the splits and their 2ch amp (180W RMS for the 2ch). Ive reposted as I now know the battery and alternator are definitely fine. I also haven't had time to follow it up.

Battery has been replaced since then (around 2 months ago) with a bigger batt with no resolution.

Wires are at least 8Ga if not 4.

Will check power specs later today.

I've never heard of voltage variation like this before.

[ICACHA]

www.bcae1.com

do yourself a favour and do some reading on how everything works.

[arverson]

if everything you've mentioned is fine then that points the finger at the sub & amp. sounds like a faulty amp. hopefully not but see if you can try with another amp in its place. just to eliminate & see if the amp/s are at fault.

what amp/s have you got? what subs? how are the subs connected to the amp?

otherwise take it to a specialist and they'll be able to troubleshoot it quickly for ya.

[ej20i]

Its your power wire. what brand have u got?
if you got cheapies then thats your problem
go for something like kicker or street wires
solved my problem just by using different power wires

[SRVTIR]

You need a capacitor. This will stock the spikes mate..

[euromandeluxe]

Power wire is just the standard stuff from Jaycar.

I thought a capacitor was needed for when you get dimming etc when bass hits hard (and the amps are drawing peak power).

[euromandeluxe]

Thanks for the helpful replies. Looks like a bad amp.

First I tried re-grounding by sanding a spot of paint/self tapping screw. Same problem. Then I swapped over the power and ground wires from the amp with those from my other amp (which has been working fine). The wire gauges and fuses are identical. Same problem again. This points the finger at the amp, yes? The fuses in the amp itself are fine too.

What can I do about this, is it really time for a new amp? This one's barely 18 months old.

[arverson]

if you're 110% sure its nothing to do with the electrical system (for example, bad grounds/connections, shorting out sumwhere, adequate gauge wiring, batt & alt in good condition, batt & alt can actually supply the needed current, and so on & so on) then id say its a faulty amp, like i said before.

what amp? where did you purchase it from? does it still have warranty?

[euromandeluxe]

It's a Pioneer gm-d7400m.

This happens when the amps powered up even when the sub speaker cables are disconnected. The amp's rated for around 360W RMS I think, but would it draw that with no sub connected?

The only other thing I can possibly think of is that the alternator might not be up to the job. Any way I can test it? Battery voltage with engine on is normal (14+V) , and the battery's new..

[GaDgeT-CRX]

Are you running the amp @ 2Ω or 4Ω? that amp is rated for 800W @ 2Ω, and 400W @ 4Ω..

If 800W is being drawn, maybe you need to upgrade to 2GA power and earth, alternator seems to be doing what it should

[euromandeluxe]

It's running at 4ohm, so there shouldn't be a problem there.
It's about 18 months old so the warranty would be done.
Is there any way I can actually test the amp to see if it's faulty?

[DC2-PWR]

Happend to my mate,

One day his car battery died. Day after he bought a new battery. After all fitted the problem was gone.

Probably not the case but give it a shot, check the battery fluids, if abit low top it up - charge it.

Good luck,

[GaDgeT-CRX]

id say, remove the amp, then connect directly to the battery terminals.. will determine whether prob is with the wiring or with the amp.. if you still get voltage drop, time for a new battery

[euromandeluxe]

The battery is around 3 months old, changed that when the issue started to see if it would fix it - it didn't.

I disconnected the amp's wiring and connected it to the wiring for my other amp (same gauges, same inline fuse) and the problem persisted which tells me the problem isn't in the wiring..

[GaDgeT-CRX]

So wiring is good, amp is good, battery is good... the alternator is the last piece of the puzzle that could be causing the prob

Time to bite the bullet and get into an AutoElec.. You need some expert testing your setup to fix this 1