MYTFASTSS

iTrader: (5)

I recently installed a new HU (Kenwood Excelon KDC-x692) w/ 2 JL Audio Amps. I have a dilemma that is bugging me. Every time I turn off the car, and either open the door or turn off HU, I get this loud thump from all the speakers (including sub amp) about 10-12 seconds later. I have checked all my grounds at the amps, with no avail.
The RCA’s are on the opposite side of the car. I don’t get engine whine, just the loud turn off thump. I do hear a slight pop noise when the HU turns on, but nothing drastic.
Another thing has popped up. If I pull the key from the ignition after driving somewhere, if I don’t get the turn off thump, I can’t lock the doors until I put the key back in the ignition. I get the common triple ding sound, (as if I left the key in the ignition/left lights on) when I press the door lock button.
Back to the turn off thump, sometimes it’s mild to a bone jarring loud “thump”!
Has anyone else experienced this sort of thing, and if so, how did you fix it?

bmnicolosi

iTrader: (2)

What are you using as an amp turn on?

MYTFASTSS

iTrader: (5)

The remote turn on lead (blue). Unsure exactly where it goes.

05vette

i use to have this same problem in one of my old cars which i wired up myself...and never did find out why it was doing it...never hurt anything that i knew of though..and have wired a bunch since then and never had the problem

BRD-PREY

iTrader: (5)

Just a guess but to me it sounds like your getting inductance into your wires going from the head unit to the amp. When a circuit is shut off the magnetic field produced by that circuit collapses. It has the potential of causing signal in nearby wires. This pop could also be produced from the Head unit being defective or poorly designed and as power is removed from the circuit a capacitor is discharging through your pre-amp out. This is the most likely source as you said it happens when you shut the head unit off. The door being opened removes the power from the head unit right through the rap or remote accessory power. If you sit in the car for 10 minutes and the rap power shuts down automatically do you still get it? Try removing one output at a time to isolate the circuit. If you identify the circuit (ie. left front, sub-out) call kenwood with the info and get to a good technician they should replace it or tell you what to do.
Ed
Ed

dorifto83

iTrader: (7)

Blue cable is power antenna, the cable you should connect to is blue/white, that's the correct turn on lead. Blue will work, but some radios can thump when powering on or off, or sometimes when you go to cd if it's programmed to turn off antenna will make your amp shut off as well thump.

MYTFASTSS

iTrader: (5)

Thanks for all the advise & information. I pulled the HU and discovered that the remote wire lead (from the amps) is wired to the "yellow ignition wire" (or a yellow wire as it may).

I do believe this is not the right way, am i correct?

As it appears, I have 2 blue wires from the the stock harness. Both are blue, w/o a white strip. The FAQ section does not state any blue wires.

I had the monsoon CD radio system w/ CD changer.

Al 96 Ram Air T/A

iTrader: (1)

Let's back up a second...

You're looking at the blue/white wire coming out of the Kenwood H/U, right? You don't care about the stock harness. Intercept the wire directly out of the Kenwood and run a wire to the amp off of this.

On my pioneer, it's also blue/white, and is labeled "remote lead".

MYTFASTSS

iTrader: (5)

Yes, the blue/white wire in connected to the stock harness via the Kenwood harness. The "actual" remote lead wire is currently pig tailed to the yellow ignition wire (i didn't does this {{had my JL audio sub amp installed seperately when i had the Stock monsoon deck. They needed to use the speaker line out for the amp to work. This is how the amp was wire for the remote turn on. It did not have this turn off thump/pop prior to this install.}} .

I will disconnect the current setup, and run a new wire from the blue/white wire to the amp's. Hopefully, this will either minimize the sound or eliminate it all together. I will keep you up to date.

dragonrage

Which amp models? JL has a few different lines. Some amps just do this. I wonder if maybe you have one of JL's cheaper amps and perhaps they do this. Or maybe you could have a faulty amp.

I find it highly unlikely that the remote wire has anything to do with this because any decent amp deals with it internally either way.

MYTFASTSS

iTrader: (5)

One is a slash sub amp, the 250watt (had this for a few years)

The new one is the G series 4500 4 channel 80watt.

they both do it! If it was just one, then maybe, i would think was normal

This still doesn't explain why I can't lock the doors without the Pop/thump.

whatever is causing this, I believe it's from the deck. I will try grounding the deck to the chasis and try grounding the RCA's if necessary (audio ground).

MYTFASTSS

iTrader: (5)

Quote::If you sit in the car for 10 minutes and the rap power shuts down automatically do you still get it? ................Yes!!

I,ve tried changing the remote turn on lead to the proper wire (blue/white wire for the Kenwood deck), nothing changed.

I grounded the RCA's to HU, thump still there. Undone did this, because it didn't work.

Thoughts....I do run the remote turn on lead down the same side of the car as the hot 4 gauge power lead. Can this cause a problem???

Should I ground the HU deck to the chassis?

any thoughts on nailing this coffin shut and burying this problem..

shoemike

iTrader: (25)

I get a pop when first turning on the amp, it's normal.
Some amps have a soft turn on.

MYTFASTSS

iTrader: (5)

No it is not normal. If it is a cheap amp, more then likely, you will get some sort of noise, but not for the majority of newer amp's on the market. If you do get a Pop/Bump/thump/ in any order, then something is not right and needs to be investigated.

I have cured my problem!!! I don't know what is was, but a little fooling around back at the amp's (switches, unplugging RCA's, moving the amp's away from the body of the car) added to what i had done with the remote turn on lead, the turn off thump is gone (for now). This is a preliminary result and further testing will be needed to completely put this bugger to sleep. I have read about this issue via Google ("turn off thump") and some have fixed it, just to have it reappear later on.

for those looking too fix this on others cars, I did not have engine noise/whine. If you have this, with the turn on/off thump, then i believe you have a grounding issue. In my case, i just had the turn off thump. Fiddle with things, don't give up.

Al 96 Ram Air T/A

iTrader: (1)

Just to further, I did some digging on the internet for you.

It is possible your ground is insufficient due to one of two things. 1) the gauge of the ground wire is too small. This can be diagnosed by feeling the wire at the amp connection. If it's warm or hot, there is a bottleneck of energy causing the wire to heat up. 2) the grounding point is a poor conductor. This too will cause issues, as the current will not properly flow into and out of the amp.

Not sure if this was the issue, but if the amp's chassis was acting as a ground, when you moved it, perhaps this alleviated the problem...somewhat. I doubt the remote lead is picking up any energy from the power lead. You're RCA wires could be if you bought into the hype of using CAT 5 cable for RCA. I'm using fully shielded RCA cables from Monoprice. While designed for home use, they are much better for automotive purposes. The new "craze" is to use RCA made from CAT 5. These stink, as you can research for yourself on the net.

If I think of anything else, I'll let you know.

For now...good to hear the problem has subsided.

MYTFASTSS

iTrader: (5)

Thanks dude. I hope who ever else experiences this problem, will get some knowledge from this thread. Again, his is still preliminary, but i hope I have nailed it.