[schmiffee]

So I am trying to put in a stereo into my GV. I have installed an aftermarket set of front splits and an amplifier to run them. Everything is wired up as it should be.

1. The line-out for the front left and right speakers has been interrupted and this line has been run to the amplifier (I have tried this connection with AND without a GROUND LOOP ISOLATOR)
2. The amplifier draws its power directly from the battery and is earthed back into the engine bay
3. The amplifier then powers to two fronts speakers by running back to the where the original leads were interrupted at the back of the head unit, and from there follows the OEM speaker leads into the doors.

Now here is where the gremlins rear their heads...

When I activate 'accessories' the amplifier turns itself on (as it draws its signal from 12V cig lighter), and I get a buzz through the system. If though I bypass the amplifier and connect the lead running TO the amplifier with the lead running FROM the amplifier (bypass the amplifier), the buzzing going away and sound is as per normal. HENCE THIS MADE ME FEEL THAT THE BUZZING WAS POSSIBLY COMING FROM A DODGY AMPLIFIER.

....however, I then reconnected the speaker output leads to the amplifier which mean that the amplifier was now driving the speakers. I then connected my iPod directly to the amplifier input via a stereo-RCA lead (with all other POWER, GROUND, and REMOTE wires left as per the previous trial). In this setup, the sound was flawless and beautiful....HENCE INDICATING THAT THE AMPLIFIER IS NOT DODGY.

I have subsequently come to the understanding that the 'buzzing' (and when 'ignition' is activated the high-pitch 'whining') is coming from the head-unit itself or its wiring??

....so my questions then I guess is this.

1. Would my assumptions that the head-unit is the problem be an acceptable conclusion?
2. Assuming the answer to #1 is 'yes'....has anyone else had a problem like this/similar to this?
3. Assuming the answer to #2 is also 'yes'...how do you go about fixing the problem.

Now I understand that it might be best just to swap out the stock head-unit for an aftermarket, but I would prefer to keep the original if possible, as the rest of my system is completely hidden. But if these gremlins are there for the life of the head-unit, then I guess this might have to be an option I need to look in to.

I know this is LONG, but I have been working on this for 3-odd days now, and it is seriously doing my head in, so any advice/options/alternative strategies would be great - it might even spark a brain-fart that delivers the needed answers. So any and all suggestions would be welcomed!! PLEASE PLEASE PLEASE???

[jimny_timmy]

Are you running the stock head unit?

If you are, there'll be no Rem. Activation wire out the back of the head unit. If it's an aftermarket unit, the will be a blue or blue/white wire that you should use as the amplifier activation. I reckon this is where your problem may be as I'm not sure whether it's a 12v signal that activates the amp.

However... Other things to check are bad earths for the amp, RCA leads not quite plugged in properly (I recently had this problem), also running the audio leads next to/over/ anywhere near a power lead. All of these things can/will cause the problem you're describing.

[Daves4wd]

Sounds like what ever you've done to turn the amp on and off is picking up the alternator charge. There's a unit you can buy to fix it... But could also be dodgy RCA plugs

[schmiffee]

Quote:

Are you running the stock head unit?

Yes.

Quote:

If you are, there'll be no Rem. Activation wire out the back of the head unit. If it's an aftermarket unit, the will be a blue or blue/white wire that you should use as the amplifier activation. I reckon this is where your problem may be as I'm not sure whether it's a 12v signal that activates the amp.

Yeah, I assumed that there would be no remote activation back there, so I have connected the amps remote wire to the Cigarette lighter...this is working well - turns the amp on whenever 'accessories' or 'ignition' is selected at the key.

Quote:

However... Other things to check are bad earths for the amp, RCA leads not quite plugged in properly (I recently had this problem), also running the audio leads next to/over/ anywhere near a power lead. All of these things can/will cause the problem you're describing.

As far as I can tell, the earth for the amp is not the problem...have even had the same setup powered by a standalone battery (earthed back to the battery) and the same problems keep occurring. I assumed the RCA's were connected properly - but I will make sure I check this every time (forgot to check everytime ). The audio leads running over the power leads was one of the biggest things that came up as an internet search result, so I have made sure of this as much as possible - even running the leads exiting out the front of the headunit, wrapped in aluminium foil, and me holding the leads as far away from the power leads as possible - still happens.

Thanks for your suggestions though, very appreciated - every little bit helps.

[schmiffee]

Daves4wd wrote:

Sounds like what ever you've done to turn the amp on and off is picking up the alternator charge. There's a unit you can buy to fix it... But could also be dodgy RCA plugs

Yeah I have got one of those. When down to autobarn and picked up a Stinger line converter (line-out to RCA) and also a Stinger ground-loop isolator. This somewhat works, but the buzz is still there and ultimately this is just a capacitor that removes/reduces frequencies (especially low) from the sound.

Thanks for the suggestion though, I had already spent 2 days on this problem before I bit the bullet and tried the ground-loop isolator

[schmiffee]

Could it be the headunit?? Mine has chosen not to play CD's, could there be something going on inside that could be causing interference?? Is it a problem that others have come across also??

[royce]

From the top

The buzz is when the amp is on, NOT when the engine is running?
The buzz goes away if you disconnect your input?
Does the buzz go up and down with volume?


You are using speaker outputs from the stick headunit to provide signal to the amp? you are doing this via a high low converter? where in the system is the converter located? near the amp or near the headunit?
does the amp have speaker level inputs?

Shops say all this stuff works but it rarely does and fixing it is harder than jimny wobbles.

Things to try
Does you level converter or loop isolater have an earth point? if so try it
Try the level converter plugged in with no speaker inputs connected
Try the loop isolater with nothing else connected
Try both with nothing else connected
Try the level converter with the speaker input leads connected but not connected to the head unit
Is the amp screwed to metal? unscrew it so the case is isolated

You are looking to see what part of the system introduces the noise here so you can then work to eliminate it

[schmiffee]

Quote:

The buzz is when the amp is on, NOT when the engine is running?

Buzz is when the amp is on, both when the car is on and off. When the car is on I also have a high-pitch whine that I cannot discern does or does not increase with the vehicles revs (alternator).

Quote:

The buzz goes away if you disconnect your input?

The buzz goes away if I disconnect the input, yes! If it then connect my own external signal source (ipod) to the amplifier it works a treat!...If I reconnect the headunit up to its original specs (headunit running speakers) - no discernible buzz.

Quote:

Does the buzz go up and down with volume?

No. Volume does not matter...but I have noticed that on initial activation of 'accessories' it starts relatively softly and increases fro approximately 10 seconds, but then gets no louder (reminds me of a feed-back loop that increases in volume).

Quote:

You are using speaker outputs from the stick headunit to provide signal to the amp?

YES

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you are doing this via a high low converter?

YES

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where in the system is the converter located? near the amp or near the headunit?

Converter is located approximately 30-40cm from the headunit, and just before the amp. Source pathway would be: headunit>30-40cm speaker wire (shrouded in aluminium foil)>high low converter>0.5m RCA lead>amp

Quote:

does the amp have speaker level inputs?

YES. Have tried this option as well and the buzzing still occurs - hence why I feel that it is either coming from the headunit OR the speaker wires from the headunit.

Quote:

Things to try
1. Does you level converter or loop isolater have an earth point? if so try it
2. Try the level converter plugged in with no speaker inputs connected
3. Try the loop isolater with nothing else connected
4. Try both with nothing else connected
5. Try the level converter with the speaker input leads connected but not connected to the head unit
6. Is the amp screwed to metal? unscrew it so the case is isolated

1. Yes. and have both had it connected AND disconnected. The only discernible difference is that when it is connected the signal is stronger...buzzing still there.
2. Yep. Tried this, all sound (buzzing included) stops - hence part of my assumption that the converter is not the problem.
3. Same as suggestion #2
4. Same as #2 and #3
5. Havn't tried this yet as the leads have been connected to the headunit output lines since the start, so this is something that I will try today.
6. No. It was initially mounted to pine timber that was mounted to the underside of the passenger seat but the problem still occurs when the amp is just sitting on the carpet floor.


Thanks for your help and suggestions. Any more

[schmiffee]

It might help if I describe the symptoms a little clearer.

1. 'accessories' selected
- headunit OFF - buzzing
- headunit ON - no buzzing, sound produces nicely throughout the volume range

2. 'ignition' selected
- headunit OFF - high pitched whine, with low buzz sound in the background
- headunit ON - same as above with music. Buzz and whine does not increase/decrease with volume. Buzzing/whine remains constant

3. Car running (obviously with 'ignition' selected)
- headunit OFF - high pitched whine that seems to go up and down slightly - not noticeably though when the car is revved
- headunit ON - same as above with music. Buzz and whine does not increase/decrease with volume. Buzzing/whine remains constant


Hope this helps/clears up misconceptions.

[jimny_timmy]

My money is on a dodgy RCA lead... Got anot set you can try?

[royce]

depending on the outcome of 5, will say whether you are picking up noise in the speaker leads or not, then I would look at running them another way to the amp and also getting the converters away from anything electrical that it can pick up noise from.

Where does your power lead run, near any electrical stuff?

Also try a temp feed from the amp power to the trigger terminal so you can turn the amp on without the key to see if it buzzes

[schmiffee]

jimny_timmy wrote:

My money is on a dodgy RCA lead... Got anot set you can try?

This is the second RCA that I've bought. The first was a 5mt Fusion RCA that was way too long so I just had it coiled up. So I then went and purchased a 0.5mt chunky RCA from Jaycar and it happens with this RCA as well.

[schmiffee]

Quote:

depending on the outcome of 5, will say whether you are picking up noise in the speaker leads or not,

Well, with the speaker leads disconnected from the rear of the headunit, the buzzing disappears, and then reappears when connected back up again.

Quote:

then I would look at running them another way to the amp and also getting the converters away from anything electrical that it can pick up noise from.

With the amp going to be mounted under the passenger seat, there is really only one way for them to be routed, but I did hold them in the air (not crossing or coming near ANY leads conducting 12V, and the buzz was still there.

Quote:

Where does your power lead run, near any electrical stuff?

Which power lead is this? the amplifier power? If so, it is routed around the battery, through the firewall (passenger side), has a loop or two inside the passenger right-hand-side kick panel along the passenger door sill and across to under the passenger seat.

Quote:

Also try a temp feed from the amp power to the trigger terminal so you can turn the amp on without the key to see if it buzzes

Just tried this also, and amplifier powers on and NO buzzing...so I would assume the buzzing is caused by the cars electrical system somewhere??

[pezz]

For the high pitched whine, try pulling the fuse for the fuel pump,
That would be about the only thing that would induce that sound in a non fualty system with the engine off..

If you can drop in an alt sound feed at the head unit end it will let you know weather its the head unit or the system downstream from it

[royce]

schmiffee wrote:

Quote:

depending on the outcome of 5, will say whether you are picking up noise in the speaker leads or not,

Well, with the speaker leads disconnected from the rear of the headunit, the buzzing disappears, and then reappears when connected back up again.

Quote:

Also try a temp feed from the amp power to the trigger terminal so you can turn the amp on without the key to see if it buzzes

Just tried this also, and amplifier powers on and NO buzzing...so I would assume the buzzing is caused by the cars electrical system somewhere??

Now with the amp on from the temp trigger, turn the key to acc but radio off and see if it buzzes, if none then turn the headunit on and I assume then it will buzz.

If so I think you've isolated enough stuff and its coming from the headunit, i would of replaced it days ago

[schmiffee]

Both great ideas. Thanks!! Will try them tomorrow and report back on findings. THIS FORUM IS GREAT!!

[schmiffee]

Quote:

Now with the amp on from the temp trigger, turn the key to acc but radio off and see if it buzzes, if none then turn the headunit on and I assume then it will buzz.

Ok so just did this and....with the temp trigger connected, headunit connected (but not on) and key no-where is sight = it buzzes. Insert the key and turn to ACC = still buzzes. Key turned to ACC and turn the headunit on = NO buzz.

[UBZ]

Sounds to me like you are powering the amp and the head unit from 2 different power sources , causing a ground loop or earth impedance mismatch.

The Head unit will have a factory filtered power source to eliminate RFI interference from electrical sources like the alternator etc .
The Cigarette outlet is most likely not wired through this filter due to its potential current draw.

I would try powering the head unit from the same source as the Amplifier. better yet wire both Head unit and Amplifier directly to the battery (both Positive and Earth) though a 30A noise filter.

If the problem still persists , it may be an impedance mismatch between the factory head unit and the down convertor
ie if the factory speakers are 6ohm and down convertor is expecting 4ohm.

[schmiffee]

Quote:

The Head unit will have a factory filtered power source to eliminate RFI interference from electrical sources like the alternator etc .
The Cigarette outlet is most likely not wired through this filter due to its potential current draw.

This is making a lot of sense to me. Just to note - the cigarette outlet is only running the REMOTE connection so that it turns the amplifier off when ACC or IGN isn't selected with the key?? Will this matter? Will I need a noise filter on this line as well.

Quote:

I would try powering the head unit from the same source as the Amplifier. better yet wire both Head unit and Amplifier directly to the battery (both Positive and Earth) though a 30A noise filter.

So two parts to this query:
1. I have run my local Autobarn, and they only have 5AMP, 20AMP, and 40AMP noise filters in stock. Can I use one of these, or would 30AMP better suit my application?
2. Could anyone tell me at the back of the headunit which wires are the power source? I have a light bulb tester, and have found that there are two wires that provide power to the headunit (i.e. two live wires even when the key is not in the ignition)? Also, there are three black wires at the rear (assuming they are the negatives) - would the be the ground/s? and would they ALL be grounds? If, so would I need to ground ALL of them to the battery??

Ultimately, a diagram of the headunit plug would be easiest, but the workshop manual that I have does not seem to feature that? Anyone got a link to that section??

[schmiffee]

UBZNZ wrote:

Sounds to me like you are powering the amp and the head unit from 2 different power sources , causing a ground loop or earth impedance mismatch.

Why would the whole system work/sound perfect when I bypass the headunit altogether and simply plug in my external sound source (iPod)? Even when I turn on ACC, ignition (both with and without the vehicle running) the sound is beautiful with no noise whatsoever (no buzz, no whining, no alternator noise)!! Wouldn't the amplifier pickup any interference when it is connected directly to the battery and earthed in the engine bay with NO noise filter in line??

[UBZ]

Size of Filter really depends on what you are powering . 20A should be fine , but I would probably use the 40A (would allow radios extra amps etc in the future)

Cant help with the Head Unit Wiring sorry.
Most probably Positives are Battery / Memory / ACC .
Easy way to find earths is with a Multimeter with a Tone setting , just look for the wires common with the Body of the car. Normally only 1 or 2 wires


When you plug direct to the amplifier you are only using 1 source of power not 2 . If it doesn't buzz then you may not need a filter with the direct battery connections for Amp and Headunit . A filter / direct battery wiring is just best practice . also allows for Fuses close to the battery .

Just temp power it all up from the same source and see if it sorts the problem.

[schmiffee]

So where would you suggest that I place the headunit power? Should it be spliced into the amp power line (I think it is larger than my needs so this would be fine?)? But then wouldn't it be active 24/7? Or should I splice it in with the amplifier 'remote' wire (which is piggy-backing the 12V CIG socket)?

I went and got the 40AMP Noise filter....attach straight to battery with the amp wire then plugging straight to that? Also, should I wire the amp ground directly to the battery as well (I have never done this, I just assumed that it was NOT the best way)?

[royce]

In 6 odd years of professionally fitting stereos ive never seen a noise filter do anything, you amp and headunit are already doing a good job of filtering the power simply by way of how they work (neither will use the 12v coming in, it will be changed)

Likewise the power source, its all coming from the same battery.

level converters are terrible for inducing noise, another brand might work, might not, but there is enough evidence to show the source of the buzz

[schmiffee]

Quote:

...but there is enough evidence to show the source of the buzz

Headunit??