Hey guys...I was running a few errands today and noticed something extremely strange when I turned off the car.....my powered sub was staying on and producing just a flat tone.....

I have an Alpine PLT-5 hooked up to the factory system. I had it professionally installed at a local shop and they used the speaker level inputs (No LOC) and tapped the system after the rear bose amp. I am not sure where or if its necessary to tap into a remote turn on wire(never used speaker level inputs before). The PLT-5 is grounded to the metal on the rear deck. The setup has been installed for about 2 weeks with no problems before. The remote bass control is run up to one of the dummy switches up front. While the bass is going (car off, keys out of ignition) I can use the wired remote to lower and raise the loudness of that tone....its a pretty deep constant bass note.

One really strange thing, is that the tone seems to lessen if I open my drivers door and if I leave it open for a few seconds it goes away completely. When I shut the door again, the tone comes back. When I ran into a few stores and came back out, the tone was gone.....same scenario occured again after driving and turning the car off. I think it's possessed.

Does anyone have a clue what this may be? I am planning to take the car to the install shop early this week, but they're closed on the weekends so I couldn't stop by and show them the issue today. Any help would be greatly appreciated. If you have any questions or need more info to diagnose please ask away. I'll check this thread often for the next few days. Thanks all.

My main concern is that something is wired incorrectly and I may short the PLT-5 or the factory headunit.

 

Sounds like a dirty ground. A charge is building up on it and then when you stop the noise has nowhere to go so it dissipates through the speaker.

 

How harmful can that be for the system? I appears to me that the metal they grounded to was factory painted. Where do most people ground their amps in the trunk?

 

^^^Craziest thing I have ever heard!^^^

If you turn your volume all the way down for a minute or so, does it take a couple of seconds for your amp to come back on?

It sounds like they are using signal sense to turn on the amp. If so, it usually takes a few seconds for the amp to shut off. If the sub moves at all in a sealed car it could make the rear speakers move, causing a slight signal to the amp, keeping it on, sub moves more, speakers move more, sub gets louder, speakers move more................................you get the idea. Open the door or trunk, subs don't move the speakers, amp shuts off, all good.

Check to see if there is a switch on the amp for signal sense. If so, switch it off and see if your amp still works. If it does, they hooked up the remote turn on & you are golden. If not, they need to.

 

It seems that the powered subwoofer comes on simultaneously with the factory head unit. If I power it off, it seems that the bass from the sub is going as soon as I power the head unit back on.

After the car is off and the keys are out of the igniton, if I do open the door while the sub is still going off it does slowly fade away, but will return if I shut the door soon after.

I do not see a switch on the amp for signal sense. There is a switch to select whether you are using speaker level inputs or RCA cables, as well as a phase **** for 0 or 180 options. There are also a few various other ***** for gain, bass boost, crossover level, etc.

Any more ideas anyone? Thanks.

 

http://www.crutchfield.com/App/Produ...=detailed_info

that has the connections and pictures of the system but NOT of the power connectors for some reason. maybe that is where the switch is.

could you take a look at your install where the power and ground are connected and see if there is a wire plugged into the "rem" connector? and also if you see a switch for signal sense or remote line somewhere in there...

 

Okay....just went out to the car and removed the end cover to see all of the connections. There is a remote turn-on wire (usual blue) connected to the amp near the power and ground connections.

There is no switch on the amp except for the the phase (0 or 180). Everything else are the ***** you can see in the pictures on Crutchfield. I am absolutely stumped.......

Is there possibility that they connected the remote turn on to a line that has constant power and is not just active when the ignition is on? I still dont know what would be causing the sound signal though...

 

Sounds like it to me. See middle paragraph in post #4 for explanation. Can be the same principle if the amp is not turning off.

 

see if you can track down that blue wire.. find out where it goes.. if it goes anywhere else than the rear cig lighter thats probably what is going on. just connect the wire to the + side of the rear cig lighter... thats the best place to use as a remote.. and it's EASY to hook up.. do a search if you need to see some pictures..

might also try to voltmeter that wire with the car on and off and see if it switches with the car.. if it turns off - then your remote line is good and doing what it is supposed to..

 

Hey guys....I just got a call back from the shop. They're testing has revealed the noise to be coming from using the speaker level inputs on the PLT-5. They are going to install a simple LOC and use the RCAs on the PLT-5 for input. They think this corrects the issue and is a cheap fix. I'll let you know if I have any further complications.

Thanks for the input.

 

EDIT: starting a thread for this....


you know its strange you had this issue... here is my setup
David Navone NE-7V LOC(tapped PRE-Bose amp) into kicker zx series amp, into audio control line driver, 12" kappa perfect sub


occasionally when i start the car on hot days, IF the stereo volume is already up, the first deep note sends my sub into a long static "punch".... as in, it hits and doesnt stop, like a long drawn out buzz... and it sounds like static, not music.. it eventually fades out after i mute or turn off the stereo

also, i have noticed that occasionally my sub will "punch" with this same static when i hit rough spots of road or bumps. this is an instentaneous punch, not lasting.

i had previous issues similar to this and i found the cause to be a bad fuse... i have checked ALL my connections, but not yet the fuse again.

if its NOT the fuse this time, what could it be?
if it IS the fuse again... why would i have fuses that are having this problem?
(what are the odds of getting two fuses in a row from different places/manufacturers with the same issue.....apparently the solder points where the fuse is soldered to the caps?)

 

Sounds like BS to me. It still doesn't change the fact that the amp should be powered down when the car is off. Get ready for a dead battery.