Alternator Noise From New Speaker Setup

waynerp

waynerp

Dedicated Member
British Zeds
Joined
Jun 8, 2015
Points
44
Location
Kent
Model of Z
2.8
Hi All.
Over the past few weeks I have been tackling a leak issue and have completly removed the interior to dry out the waterlogged carpets and sound proofing.
While the interior was out i have always wanted to upgrade the sound system, so no better time to do it.

I have replaced the front footwell speakers with the Hertz DSK 130.3, and fitted the tweeters to the front of the dash.
The rear speakers i have used the Hertz DCX component 130.3.

Initially i was going to use the head unit for power to the speakers bvut this would have been pointless so reluctently i got an Amplifier ( the cheapest that was suitable for my setup ) which is a Auna AMP CH06 6 channel AMP

My intensions was to fit the Hertz HX300D Subwoofer into the middle copartment between the seats, but the sub is HUGE so i downgraded to a Slimline Pioneer sub.

Now Initially after reading many forums and actually reading the manual for the AMP i ran the RCA cables from the head unit to the amp down the left hand side of the car and the power cable from head unit to amp down the other side. I didnt really take any notice of the speaker cables and if i rember some were on both sides.
The negative cable from the amp is fitted to bare metal in the boot, and set up according the amp instructions.
yet i was getting huge alternator squeel coming from the speakers.

I took the car to an audio specialist today and they said that as long as the RCA cables are well shielded, (which they are) then all the cables should run down one side of the car, as otherwise it causes a loop, which is what creates the interfearance.

So i came home took the bloody car apart again and put all the cables down the drivers side, and now if anything it is worse!!!

Anyone got any ideas what can be causing this ?????
 
Sounds possibly an earth issue to me, but I'm no expert on Audio faults, @zedonist is your man.

Tony.
 
First thing I would do is float the round of the head unit, that is remove all ground wires from it and let it ground through the RCA's going to the amp.
If it works you had a "Ground loop".
 
You could always fit a 'ground loop isolator' between the head unit and the rca leads. I had quite bad interference and one of these took the problem away. Cheap on eBay or they can be picked up in Maplins.
 
That works too but I would rather have a solid signal path because those adapters in effect lift the ground on the signal side.
6 1/2 of one and 3 dozen of the other perhaps, but this old dog prefers to do ground path breaks on the power side of the equation.
This leaves the signal path intact :)
 
How long is your earth lead to the amp, it needs to be as short as possible, suggest the same for the head unit, I would say no more than 12 inches, if it still does it after this then It is the amplifier, so you can buy a better one or fit a ground loop isolator (not my preferred option).

For reference I ran all cables down the centre of the car on mine.
 
So I spoke to another audio specialist today, and he advised that I have either broken something in the head unit, as i earthed the amp last when setting up.
So he advised trying another head unit, which i did and the noise is till there.
He also said that the ground loop isolators are not the best route to go.
He also said that it could be the AMP as its not the best available. Although i agree with that surely a brand new AMP shouldnt do this?? How can they sell them if they are going to make this much noise from the alternator ??
Not if this helps at all when the ignition is turned one turn the sound is not there, its only when the car is started that it makes the awful noise.
The ground on the amp is less than 30 cms. I have attached it to the bare metal inside the boot.
As someone previously mentioned i have cut the ground wire on the head unit loom. Not sure if this is correct or not but the noise is there with it cut and not cut
 
Many moons ago, back when I were a lad we had to fit suppressors to the alternator / dynamo and to ignition coils to get rid of interference from running engines.

These days I understand that our cars have "built in" suppressors but they can go wrong can't they?

Auto electrics is not my field of expertise, in fact it comes after rocket science, quantum physics and women on the never ending list of things that I know **** all about =))
 
If you've removed the possibility of a ground loop it's could be RF pickup from the alternator. That could be because of a faulty component in the amp or on the inputs from the head or even a poor connection somewhere. A case now of isolating the cause.
 
As i see it, with audio equipment you get what you pay for, cheap components are made with cheap components, its why they are cheap, sound like a bird cheap..cheap...cheap, but there it is. I also understand that my hearing at the age of 45 after years of industrial abuse is never going to appreciate top level audiophile. So my recommendation is always to but middle of the road. You will get well made equipment with built in noise suppression and nice tone to the signal and end notes. Cheap amps are not shielded and the output is always distorted, may be great if you want it loud when stationary, but not good if you like listening to music.

I would also advise this, if you have a slim active sub you do not need an amplifier it is built in. I am sure that with an after market HU with 25 watts rms per channel you do not need an amp with the hertz speakers either.

On my set up I use an Alpine HU with an Alpine in line amp which gives 75 watts rms, I have run all new speaker cable, all cables including components go down the centre tunnel. For the sub I am using a kicker 6.5" slim sub speaker in a custom enclosure where the OEM sub would sit, this is coupled to a FLi 300 watt amp )agian not the best, but middle of the road). the earth to the amp is 6 inches long. it does not suffer from ground loop interference. The sound is awesome.
 
Just a thought that sprung to mind, I had to change sparks and leads on one of my Jeeps many moons ago.

Radio Frequency Interference (RFI) or electrical "noise" is caused by ignition systems, alternators, wiper motors, etc., but the ignition system causes the strongest "noises" and they include a wide range of frequencies. This noise can cause interference with the operation of radios, electronic components, fuel injection systems, depth finders, and other sensitive electronic equipment. Resistor plugs, wires and spark plug caps are used as a RFI suppression system to reduce this noise.

 
Sorted.
Taking on @zedonist advice, i had one final try and put all the cables down the middle of the car and presto no more whine!
Absolutley cristal clear no hiss nothing. Very happy, very loud compared to previously
Many thanks for all your advice
 
When you able to buy a good amp(s) I suggest you do.

I also went the cheap amp route but when that died I searched for ages on Ebay and picked up an Alpine sub amp and one of the Alpine inline ones like zedonist suggested.
With my Hertz components and the JL 6,5 inch sub in the custom enclosure in the OEM space the sound is just amazing.
It's hard to explain the difference a good amp makes vs a cheap one, even on the sub where I thought it wouldn't matter so much.
 
Last edited:
Excellent advice and guidance Zedonist! :thumbsup:
 
zedonist said:
Fantastic news, how do you like those hertz speakers?
Click to expand...

Awesome. Still got to setup the sub. I could happily say its just as good as the 'Premium' Meridian system in our R.Rover.

Also i bought my Hertz speakers direct from a company in Germany. Saved about £15 if i remember correctly. Fast delivery too
http://www.extremeaudio.de/gb/
 
You must log in or register to reply here.
Back
Top