Loud grumble from subwoofer when head unit is switched "Off" (Video attached)

[dimi_108]

Perhaps one of you audio experts on here could help with my install.
So out of curiousity, i've temporarily installed my mate's old Soundstream dual 6" subwoofer box and four channel amplifier onto my factory head unit. It sounds good, performs well and i'm really happy with it.
I just have one problem though, when I turn "Off" the head unit, the subwoofer will give off a never ending, super LOUD grumble.
It's almost like a stampede getting closer and closer. Like something from Jumanji.

Has anyone else has had or heard of this sort of problem before?
Maybe a grounding issue?

Here's a short video of what's going on:

Photo taken after install. As you can see, it's nothing flash, I just installed it for more richer bass. Yes, i know there
are bits of wire and rubbish on the carpet.

 

[Bennyboy]

how is it wired in Dimi? how is the amp wired to the headunit? It's obviously still getting a feed even after you've turned the power off...

 

[Scottie]

If the amp stays on when the stereo is turned off, then you are getting a groud loop noise. Same thing as if you unplug your speakers on you computer and you get that buzzing noise.

I assume is goes when the key is turned off?

 

[Scottie]

Whichever way, you will need a HU that has an Amp signal on it.

Alternatively, you can splice the 12v+ wire going to the HU and wire it up to the Remote connector on the Amp.

 

[Bennyboy]

i agree, try moving the earth points sounds like a bad contact; if you've wired it to the factory headunit wiring it could be the earth point that's been used under the dash for that, or maybe the feed is running to close to something else in the dash although you'd really get a wine not a stampede. loose wire it in a move it bit by bit trying to get rid of the fault. I know thats not much info but hope it helps...

 

[dimi_108]

Cool. Thanks Ben and Scottie, I appreciate the replies.

Hey Scottie, the loud sound comes on with the key in the ignition or the while the engine is running.
It doesn't come on when the key is out of the ignition (i'm guessing because the subwoofer obviously has no power to it)

Yo Ben, the amp is wired through an RCA converter onto my head unit, as my factory head unit does not have any RCA input/outputs.

Scottie, you reckon I should splice the 12v+ wire going to the head unit and wire that to the "remote" slot in the amp, yeah?

Also, one more thing which might have something to do with it, I can hear a very slight "whining" noise when the system is turned on. It's not very noticeable, but I can hear it increase (when the volume is down) as I accelerate from stop until 30km/h.

Here are some additional photos which might give a better idea of my no-frills install.

 

[Scottie]

What do you have the "Remote" on the amp connected to at the moment?

 

[dimi_108]

Hey Scottie, it's spliced into the speaker wires.

 

[montgomery]

It really shouldn't be spliced into the speaker wires.
If it was, the amp would be turning off and on w/ your speakers beat.

Try connecting your trig wire directly to the +ve and see is that fixes the problem , although then your amp would constantly be on.

 

[dimi_108]

Thanks Chris, let me inspect it later on tonight.
From what I can see, it's spliced into the speaker wires but I could be wrong as I need to pop out the head unit and take a closer look at the arrangement.

I had an actual audio installer wire most of this up for me yesterday.

 

[montgomery]

Let him know , if he's any good he will sort it out.

 

[Scottie]

Yeh, i have never seen it connected to speakers before. If you can get it out easy, hook it up to the 12v+ (Not the battery, the ACC switchable)

 

[RaZZa137]

if you connect remote to positive wire and your amp is constantly on you will drain your battery..... if you can hear a whine coming from the speakers that seems to get louder the higher the revs of the engine...that's engine noise, try running your rca or sound wires on the opposite side of the car to your power wire...if there is no remote wire for amp, just connect it to the power of the head unit so the amp turns off and on with the head unit...that should get rid of the grumble noise.... hope it helps

i have seen engine noise filters to reduce that whine but in my opinion it's a waste of money

 

[pu-11-me]

Give me a call tonight if ya want bro and i'll give you a guide on exactly where to wire it to

 

[happymatch]

dimi, where is your rca conveter? sometimes it picks up engine signals by EMF (electro magnetic field). I had same problem with my old hyundai Grandure. The "Dup" sounds. well, when i pluged my amps directly to rca line on my "Made in China" dvd deck, i had same porblem. I was told by one of my good "audio" friend, that when it is turning off, it does not mutes the speaker first then shuts it down or something. which means some "left over" current of built in amplifer leaking out to all the possible out source.
I connected china deck to sony deck, then to amps. If i play cd's from sony deck, it is ok. However, if i play some dvd from china deck with sony aux input setup, it still "dup"s.

If problem persists, i know i can not be a great help but i will have a look on monday night

might bring my miserable collection of tools monday night.

 

[dimi_108]

Well I spoke to the installer today, and he said I need a larger "capacitor" to solve the problem.
Audio buffs, is he telling me the truth? Or should I put him in an arm-bar for speaking nonsense?

PS: Thanks for all your inputs. I'm starting to have a really good understanding of audio stuff now

 

[Scottie]

No. A Capacitor acts like a reservoir for power. It takes from there instead of giving the battery a bit hit everytime the bass comes on loud.
It is not a massive setup you have there, you really think that many people run capacitors?

It is in the way the amp has been wired to the head unit.

Even if you wire an amp to the ignition switch rather than the remote wire on the headunit, you will usually get a pop from the sub. If you feed any amplifier without a loop, you will get a buzz/hum. Ask people who play electric guitar. The rule for pre-amps (how your headunit is acting because you have the amp connected) is "On first, Off last". The remote wire will actually delay the signal to the amp to ensure itself is on first, not at the same time.

Are you selling the car with or without the sub? If not, prob not worth your while

 

[dimi_108]

I see. Yes, selling the car without the sub.

 

[pu-11-me]

It'll just be wiring bro.... If your only looking at keeping it for another week or so then just rip it out. Not worth re-wiring it all only to take it out again hey!

Next time we meet i'll show you how to do it and why

 

[Smashdy]

Yeh, i have never seen it connected to speakers before. If you can get it out easy, hook it up to the 12v+ (Not the battery, the ACC switchable)

Agree with this for sure