# Need a little help all: Sub Surges when Amp Turns Off



## dstackmasta27 (Mar 14, 2010)

Hi everyone, 

I am pretty new to doing car audio stuff. I installed a sub and amp in my wife's 2010 GTI a couple of months ago, and have experienced a bit of a problem. 

Before I get too much further I'll give the run down of equipment and how it is set up. 

Pioneer part numbers:
Enclosure- UD-SW100D (I stuffed a bit of poly into the box to help maximize the small volume)
Sub - TS-SW2501S4 (Amazon sells the enclosure pre-loaded with a different "lower" quality sub, but ordering this way was marginally more money for an allegedly better set up ymmv).
Amp - GM-D8601 (This guy comes with little RCA jumpers so that you can tap into existing speaker wires from the stock system as a signal in, no converter box needed!)
Amp Wiring Kit - KnuKonceptz KCA Complete 4 Gauge Amp Install Kit (I got the 4 gauge kit, and I'm sure that was a bit overkill...but hey it wasn't too pricey. Getting the power and ground wires to fit in the sockets...was a challenge.)​

For the amp audio signal, since I am using the stock RCD510 head unit, I tapped into the speaker wires behind the radio and wired those into the RCA jumpers that came with the amp. Since the amp will turn on when it gets the audio input signal, I didn't run a remote turn on wire. For my ground I connected the wire directly to the floor pan under the front left seat mounting bolt. 

When ever the car is turned off, at the same time that the amp shuts off the subwoofer will surge a couple of times. This happens at the same exact time that the power light for the amp turns off, so I suspect that it has something to do with that. Regardless of the input volume the surge is always pretty loud, but sometimes it seems a bit more aggressive. Unfortunately I haven't been able to figure out what causes that to be different. 

As a part of trouble shooting I tried reading around on the web, and didn't really come up with much to go off of. It seems like most people have problems with the sub cutting out but not this I guess. 

The best things that I was able to come up with as a possible cause was:



The amp is having a problem with the turn on/off source
The ground has some sort of problem (cable length too long, poor ground to chassis, something like that)
Gain set too high

For the first potential problem I picked up an add a circuit and ran a wire to the remote turn on from a switched power source. That did not solve the problem. For the ground problem, I just checked and made sure that every thing looked secure. I don't really know how to ensure that the ground to chassis is adequate, and I am kind of unsure how long is long enough for the ground wire or how long is too long. I tried adjusting the gain, and even turned all of the way down the problem still occurred. 

Do any of you have an idea of what could be going on? What can I do to keep trouble shooting? 

Any advice or input is greatly appreciated :wave:
-DS


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## lethal6 (Feb 19, 2013)

Sounds like a spike through the RCA outputs. I am guessing that it has to do with tapping into the speaker wires out of the head unit. Might be the way that the unit shuts down and turns off the factory amp and the aftermarket amp not being able to efficiently accomplish this in tandem with the stock stuff. 

You want the ground wire to at least match the size of the power wire and the power wire should be at least be 4 gauge (IMO). The bigger the better. The length should be as short as possible. There is such a thing as too long. I usually run them less than a foot.

Did you run the RCAs on the opposite side of the car from the power wires?


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## dstackmasta27 (Mar 14, 2010)

lethal6 said:


> Sounds like a spike through the RCA outputs. I am guessing that it has to do with tapping into the speaker wires out of the head unit. Might be the way that the unit shuts down and turns off the factory amp and the aftermarket amp not being able to efficiently accomplish this in tandem with the stock stuff.
> 
> You want the ground wire to at least match the size of the power wire and the power wire should be at least be 4 gauge (IMO). The bigger the better. The length should be as short as possible. There is such a thing as too long. I usually run them less than a foot.
> 
> Did you run the RCAs on the opposite side of the car from the power wires?


Yeah the kit I got has 4 gauge wire for both the power and ground (I figured that would be best for future upgrading if needed, and might help the amp work a bit more efficiently), but it is a little hard to get into the hole on the amp because of how meaty it is :laugh:.

I have the power and ground run on the opposite sides of the driver foot well because I mounted the amp under the driver's seat. When I hooked up the ground I didn't really cut off any length from the ground wire. So if length can be a problem maybe some energy is getting stored up there and when the system is turned off it discharges (making the sub surge)? The power is run in on the left side (near the rubber grommet that people typically run stuff through to the engine compartment) and the input source is run down the right side from the area behind the head unit. It didn't occur to me until after I tried the add a circuit for the remote turn on, that I didn't try to power cycle the system without the RCA plugged in. I think that trying that should at least help me figure out if it is the taps into the speakers for the source, or if it is the power/ground situation. 

So here is my plan for the next test (once it isn't raining :facepalm:

- Hook up the remote power with the add a circuit
- Unhook RCAs
- Power cycle the system a few times

If the sub still surges, than the problem is coming from the power/ground side. If it does not than it is from the RCA/tapped speaker side. If it seems to be from the power/ground side I'll try shortening the ground wire and I'll clear the paint off a little more for safe measure. If it isn't on that side, and it seems to be coming from the sound source side, what should I do to fix that? Get a source converter box thingy? Would that even make sense? 

Thanks for the help


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## dstackmasta27 (Mar 14, 2010)

Any other ideas bump :wave:


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## Dubtuner98284 (Feb 20, 2014)

Hate to say it, but sounds like the amp has a problem with soft turn on and off. Its an internal issue. Pioneer is not known for making good amps. If you can, I would try a different amp in the car to make sure that there is no wiring issues. If the issue still appears, I would re ground the amp. 

I really do believe it is an internal issue with the amp, though.


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## dstackmasta27 (Mar 14, 2010)

Dubtuner98284 said:


> Hate to say it, but sounds like the amp has a problem with soft turn on and off. Its an internal issue. Pioneer is not known for making good amps. If you can, I would try a different amp in the car to make sure that there is no wiring issues. If the issue still appears, I would re ground the amp.
> 
> I really do believe it is an internal issue with the amp, though.


That isn't ideal 

Is there anything that can be done to remedy the issue? It seems like a pretty bad design flaw if that is in fact what is going on :thumbdown:


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## Dubtuner98284 (Feb 20, 2014)

I was just thinking that you could try tapping your fuse panel for an open accessory slot. I did this and I have no problems with soft turn off or turn on. Just remember to wire in a inline fuse holder. I use a 5 amp fuse, which may be a little to big. I don't remember off the top of my head how many amps the remote lead needs. I think it somewhere around 2.5A because its only looking for a signal. I can look it up at a later time. It may be that your built in LOC is not that great. Any how. I would try that first. Its the cheapest and the easiest way to check the functionality of the auto turn on system.


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## dstackmasta27 (Mar 14, 2010)

Dubtuner98284 said:


> I was just thinking that you could try tapping your fuse panel for an open accessory slot. I did this and I have no problems with soft turn off or turn on. Just remember to wire in a inline fuse holder. I use a 5 amp fuse, which may be a little to big. I don't remember off the top of my head how many amps the remote lead needs. I think it somewhere around 2.5A because its only looking for a signal. I can look it up at a later time. It may be that your built in LOC is not that great. Any how. I would try that first. Its the cheapest and the easiest way to check the functionality of the auto turn on system.


Thanks for the help buddy. I tried a variety of things to get this sorted out. I re-sanded the ground location to make doubly sure that the surface was good enough for current to pass through. When that didn't work, I used an add-a-circuit tap to see if the direct switched power would improve/eliminate the problem--but that didn't do it either. :banghead:

After reading around at various sound problems online I was pretty stumped, and was starting to think that the amp was probably bad. :facepalm:


Somehow in looking at new amps, I came across an article on Crutchfield that gave a rundown on the various sounds that can cause problems with a sound system, and how to resolve them. It looked like a ground loop filter would possibly solve the problem I was having. So I ordered a Scosche in line noise suppressor from Amazon (for less than $10 shipped--although now the price is a little over $13, lame) and plugged it in yesterday. 

BOOM! No more horrible pulse when the system turned off. Adding that into the line did interrupt the built-in turn on from audio signal, so I added in the remote turn on through the add-a-circuit I had bought previously, and everything works excellently. :thumbup::thumbup:

I just wanted to make sure I followed up on how this all worked out so that people can find a possible solution through searching. Good luck everyone :wave:


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