Help!....horrible Whine After Installing Active Sub To A3 Sprtbck

[Gaffer]

Hi guys, think I might need some help with this one.

I have an RNS-E with satnav and the Bose 10spkr option.

Unfortunately, the Bose sub sounds a bit poor so I've added an Alpine SWE-815 to the boot:

I sent the supplied power lead through the grommet under the scuttle above the fuse box as everyone does, then ran it under the side sills to the boot, then into the Alpine sub's amp.
It is grounded to the panel in the bottom right of the boot as you look in (looks like a big plate bolted to the base of the boot). This was ground with the dremmel to expose bare metal on the base, screw and earth lead's "blade". Then tightened up.

Then onto the Bose amp, I disconnected the plug and according to this diagram, wired in the phono input and remote on to the Alpine sub:

Alpine sub turns on and works as required and adds useful bass to the mediocre Bose system.

HOWEVER

There is now an extremely loud, high pitched whine in ALL the speakers when the engine is on (increased with speed).
Whine disappears when engine shut off, but still have new loud clicks and pops as other things in the car turn on and off.
Disconnecting the sub (removing it's power lead and it's fuse) AND disconnecting the earth lead to it (so Alpine sub is now not powered at all) does not improve the problem.
Because this therefore happens whether the new Alpine sub power lead is connected or disconnected makes me think it isn't a problem in how I've routed the power lead.
Because this also still happens whether the new sub earth lead is connected or disconnected makes me think it isn't a poor Alpine ground problem.
Basically, removing the amps power path doesn't "cure" the problem.

This makes me think that it's something to do with either how I've tapped into the Bose harness or maybe how I reseated it?
Cue, reseating the plug and ..........nothing changed.

The phono lead is a cheapo job that you get in any shop (I just wanted to see it worked first so tried with this). I'm thinking that the phonos, as well as sending the line-in info to the new Alpine sub, are maybe also sending interference back to the Bose amp?
I'll try "proper" phonos on Monday bank holiday but wanted to check I'm on the right path first.

Finally, could this be a simple case of a ground loop created by the phono's (which is why disconnecting the Alpine's power and earth don't change anything, as long as the phono's are connected, the stray current is going through them to cause the whine?)
In which case would a ground loop isolator on the phono's going to the Alpine sub fix the problem?


Basically, apart from the new Power, Earth and Harness tap-offs (line outs and remote) I haven't altered anything else.....so sorry for all the Q's, but I can't for the life of me figure out what I've done wrong here (all my previous car installs were done from scratch and replacing the whole system, this is one of the few times I've tried to "piggy back" into an OEM system).


....any help would be appreciated

 

[Gaffer]

Hmmm, no one eh?

Firstly, I switched to high quality double shielded phonos for the sub (each conductor shielded and then the whole lot shielded again) with much thicker conductors........no change.

I then had a look at the Bose amp harness I had tapped into and decided to not use the PreOut Shared -ve on the bundle, but terminated the phono negatives directly to their own ground instead (using a screw in the boot base - so the only thing used in the OEM Bose harness is RemoteON, LR+ve and RR+ve).
This had the effect of transferring the high pitched whine from all the speakers to a low pitched hum on the Alpine sub alone.
From the passenger seat this is MUCH less noticeable but I now have a low grade Alpine sub hum that I would like to resolve.
The hum reduces when I reduce the gain, but I would like it gone forever.

I managed to get a Ground Loop Isolator today for a fiver, but it didn't change anything so I'm now a bit stumped as to what to try next...

 

[Gaffer]

Still no one? Really? So no one here has added a new sub to their Audi?

Wow!

Anyway, at least I can document my thought process so that if ever I do fix it, others can at least benefit from the thread.

My plan of attack

1. Solder the phono input +ves to their respective Pre-Out pins in the harness - may not improve the hum but at least I can optimise the signal going in. Plus, I don't think I'd ever use the leads again so when I eventually sell the car on, I can leave the phono's in place and the new owner can use them themselves.
2. Change the Alpine sub's Earthing point - from the boot base where it is now to the seat bolt which is a more substantial size (more surface area - hopefully a better contact point)
3. Re-check the input plug to the Alpine's digital sub - it's fine but I may use some hotglue to make it a bit more secure (it's a plastic plug connector jobbie which won't ever be as solid a connection as the screw in type on standalone subs):

Currently, it all sounds great with the following settings:
Balance = normal
Fader = +1 (slightly rear, reduces harshness up front and gives a nicer more "inclusive" soundstage)
Treble = +1 (I may put this up a bit to +2)
Bass = -3 or -4 (this turns the Bose sub down more and leaves the Alpine pretty much as-is)

^^^ at normal to high volume the hum is drowned out but at lower volumes or on speech (e.g. Radio 5 Sports) that hum is there and needs to be removed ....

 

[Orange225]

I fitted a sub in mine but had no problems so far. Power down the left of the car, remote down the centre and phono down the right

 

[AK47UK]

I had a whine on my aftermarket headunit but ground loop isolators fixed it right away...

 

[Gaffer]

I fitted a sub in mine but had no problems so far. Power down the left of the car, remote down the centre and phono down the right

Good to know - so it's not an inherent issue with the Bose system not playing well with others ...meaning it's definitely my install gone a bit wrong.
I've put power down the left side and that's it (all other wires (remote on, phono in and control unit) are in the boot, so interference shouldn't be an issue.
This is why I think it may be a ground loop and will change the earth point of the sub to the seat base.
When you fitted your sub, is it an addition to the Bose or a replacement of it?
(i.e. Did you disconnect the Bose sub completely?)

I had a whine on my aftermarket headunit but ground loop isolators fixed it right away...

I thought the same and tried those but they had no effect. Plus, they filter anything below 30-40 Hz so wouldn't have been ideal for a sub as a permanent fix for me. I tried them as I thought they should've at least pinpointed the issue but they have no effect on the hum .

 

[Orange225]

Sorry. Mines none Bose. Pulled out the old factory blaupunkt sub and run everything seperate from the audi system

 

[Orange225]

I did notice that my rear speakers buzzed all the time when they were powered by the factory sub

 

[easy going Si]

Hi yer Gaffer

Did you find the problem of noise in the end, in my 05 a4 cab I tried some novel solutions to get rid off noise if you need any help or advise give me a shout, also the alpine amp looks at bit small as a sub-amp what was the rating off the fuse that connects the amp ??????

As the fuse rating is the true measure of the power output of the amp not the manufactures wattage output figures, for example the amp I'am getting for my sub is an alpine MRV-1507 with an 80amp fuse, equals ( 4 ohms x fuse rating =320 watts ) 1 x 300 watts rms at 4 ohms, equals 1 x 600 watts rms at 1 ohms, 1 x 1200 watts rms at 1 ohms but PMPO equals 2400 watts

Gaffer all manufactures like listing the peak music power output figure but it is useless measure because it contains so much distorsion you are much better using the RMS figure root means square which is a true measure of the output off an amp

hope the above helps

 

[Stickystuff]

Maybe a it late but sometimes wires will pick up interference from the engine, try twisting the signal wires around each other and see if that helps

 

[Gaffer]

@EasyGoingSi, Nope, haven't got to the bottom of the problem yet. In fact, things have just got wierder:
I left the car alone for a week and when I got back in, the alternator whine in the main speakers had returned

So I did 1 (Soldered the phono input +ves to their respective Pre-Out pins in the harness) and 3 (Re-checked the input plug to the Alpine's digital sub and hotglued it in). This had the effect of making the whine intermittent.
So for example, driving home from work today - start of journey no whine. Half way home whine appeared with a vengeance. Got home and as I was parking up, whine dissappeared.....now I'm REALLY stumped

Only thing left to do now is secure the negative Earths into the better seat base bolt and trouble shoot from there.

BTW, the sub amp looks small because it's a digital amp (MXE-M150CKD), meaning it's much more efficient and can crank out the same volume in a much smaller, neater design. Have a look at some digital amps on google and you'll see what I mean.
I'm not sure how the power would "create" or relate to an alternator whine but the sub is ****** loud as it is - easily loud enough to completely drown out the Bose one but I've set it not too loud so that I don't sound chavtastic.
It's also not just about power imho (if you double the power, you won't double the loudness as it isn't a linear relationship) - driver efficiency has the biggest impact on volume....I've heard 15W speakers in a home HiFi setup kick the seven bells out of 400W setups because they used extremely efficient single driver horns....and by loud I mean literally shake the room.
The sub itself is a dual voice coil (2x) 2 Ohm Type G which after calculating ends up being about 106W RMS into 91dB/W@1m.
Again, I've had louder and quieter subs before so I don't think the power of the sub is the issue here.

The alternator whine is due to something else but because it's intermittent, it's driving me insane trying to track it down.

@Stickystuff, the phono inputs for the sub are fairly stiff jacketed things, but I'll definitely try twisting them as you suggest. I'll also have a look at the coupling from phono male input to phono female lead coming out of the sub amp. it could be something there is loose maybe.

 

[easy going Si]

Hi yer Gaffer
Intermittent problems are the worst to find, sorry I didn't get back to you I'am in the midst of rewiring two houses (yes I'am not a car stereo guy but a sparky) so I can look out of the box and find some novel solutions to problems but gaffer (you sound as if you know about hifi) in my opinion digital amps will never sound as good as older analogue ones hence my choice of the alpine MRV-1507 but hey we all make choices, I tried to work out the whine problem I had on my Audi a4, but from my experience lets go back to basics

1st look at every connection you have made if you have used the Audi wiring this is shielded cable, have you tried a suppressor on the alternator ????? have a look at Durite they do one that bolts on to the alternator I fitted the durite suppressor on a brand new alternator I fitted to my A4 the alternator is supposed to be suppressed but I didn't take a chance , also power cable to the amps try ferrite beads or ferrite coils there the little clamps with magnets in (RS do them look for TDK ones) clip these around the power cables that will suppress the cable it doesn't stop cable picking up noise but stops a cable next to it irradiating noise remember a phono cable voltage is lower than 12 volt power cable voltage and may be picking up induced EMF you may have to clamp both ends of the cable because you don't know which is the noisy end but try the amp end first

Also perhaps another option is a line driver this raises the output phono voltage this is one way of cancelling noise at very low voltage but there is off coarse the extra work involved in fitting the line driver but also you need to turn down the volume on the sub as the line driver ups the volume try and check the input voltages of the controller

Also check all the earths at the back of the stereo also if you have a multimeter check the earth return on the aerial, you could also put a new power wire in to the back of the stereo and wire direct from the battery do both negative and positive if you mix and match wiring you can in theory present the car stereo with two different voltages you ignition voltage can vary as much as 0-5 volts to over a volt from the battery voltage

Your ignition voltage will normally be higher than your battery voltage. there is also power filters that you can fit inline with the power wiring but I would suggest this as a last resort as the ones I use come from the USA and their only 10 amps each normal load so my sub amp I'am going to fit 8 to filter the incoming power

Gaffer it took me nearly 6 months of trail and error to get the stereo system noise free and replacing the rubbish Audi system I hope what I've typed above helps in some way have a look for another member called dual mono he is very good for audio but keep in touch and we will sort this out

Regards Simon

 

[Gaffer]

Hi Simon.
No probs
You have my sympathy. Just had a double storey extension done myself and got a sparky to:

• replace the old fuse box with a brand new one
• new fuse box for the extension
• new wiring throughout the new extension
• Plumb in all the new sockets for the new rooms
• rewire the garage.

Took him ****** aaaaaaaages....


Anyhoo - you're right in that it's really hard to track down.

Something even weirder has happened now.....so I poked around roughly where the phono connections to the sub were (couldn't see them as they're under the boot floor lining and I was in the staff car park at the time so couldn't empty the boot). Subsequently:
Drive home = NO interference
Driving to work this am = NO interference
Driving home from work today = NO interference

.....which makes me think the phono couplers are to blame.

Basically, the Sub amp has an input plug coming out, the phono line-in of which are a pair of female phono plugs. You just plug the phono input into these:

I think maybe they were loose or something around there (+ve, Earth or RemoteOn connection) were loose, because now it appears to be OK.
On the weekend, I plan to deconstruct the boot again and try and isolate the exact cause (will hopefully be easier now that I think I'm in the right ballpark).

BTW, Thank you VERY very much for helping me out on this, it's very helpful and with a defective stereo I find my drives to work unbearable so need it fixed

 

[Gaffer]

Hmmmm...can't seem to edit my posts so I'll have to add a new one.

So I took everything out of the boot today (baring in mind that the whine seems to have gone), expecting to find a bare negative shield or something that was allowing interference on the wiring like something loose.

However, all wires appeared to be fine from when I first installed it .

The bundle coming out of the Sub amp that I poked (see above) had:

• the Power wire going off to the left, no breaks in the jacket and not pinched anywhere
• -ve, Remote ON and Phono Input leads all going to the right:
  • ALL of which had no breaks in their shielding/jackets
  • The phonos of which were properly connected and even had the rubber surround still snugly covering the -ve outer metal of the male-female connection ......so everything was connected tightly and normally
  • None of which were pinched or squashed in any way and there was no contact between any metal wire and the metal of the boot

^^^^ So everything appeared to be absolutely fine. Yes, the whine has gone but I cannot for the life of me figure out what caused it now .

Hopefully it will never return .

 

[easy going Si]

Hi yer Gaffer
What I would do in your case is go back to the start as I did, as I said it may not be a problem with any cable or connector it may be a higher voltage is inducing EMF noise on to a lower voltage cable when I was looking at my car stereo I had alternator whine ( you would know this because it would become louder the faster the alternator spins I also had a loud clicking sound when turning on the lighting switch and a hum that I could not get rid off from the rear speakers

After rewiring the car twice I thought to myself to do some research about induced noise in cars I searched the internet for weeks pulling my hair out and remember I have a fair amount of knowledge from my city guilds part one in electrical installation I could also go on you tube and pick out the video's which actually meant some thing rather just looking at American idiots talking loads of rubbish and there is so much youtube video's that are just rubbish so don't believe everything you see

1st problem in any car install is the power source its a crap 12 volt supply and remember a car is not a ideal environment to listen to high quality music, through my research I discovered that any car amp pulls in 12 volt but raises the voltage to 48 volts before it amplifies music which means the hardest part of the amp to design is the pre-amp stage where the power goes in, it also means that any dash in car unit is limited to about 18 watts rms at 4 ohms x 4 speakers, because unlike the amp the in dash unit has not got the ability to raise the voltage to 48 volts but has to work with 12 volts, also a true measure of an amps output is measured in RMS ( root means square ) this is a measure of power output without distortion most amp manufactures normally put PMPO ( peak music power output ) have a look at (www.bcae1.com) very good car stereo website although very American in its wording its still a good read and when you buy the amp which looks better on the cover i.e. sub amp 1 x1000 watts at 1 ohm (pmpo) or 1 x125 watts at 4 ohm's (rms) but the rms figure is the true output figure but neither is wrong

2nd you have described a whining sound if it increased with engine revs its alternator whine, remember an alternator produce's AC not DC which your battery uses, the alternator uses full wave rectification to make a clean DC waveform basically it chops out the alternating part of the output voltage but even a new alternator will produce a tiny amount of ripple on top of the DC current ( this is the noise which you here) the alternator will be fitted with a suppressor by the manufacture but this normally is a small value so if you can find a local car electrical shop that does durite they do a suppressor that bolts on to the alternator and is far better than the internal one supplied, also remember that the alternator is a mechanical device and will not last for ever, the suppressor will take a out that slight ripple Gaffer this is where I would start, I replaced my alternator which was 120 amp Bosch but found the 140 amp Bosch would fit my car with the durite already suppressor fitted to the alternator

3rd Check all the terminals around the battery especially the black negative lead (on the A4 the black battery lead goes underneath the battery to the earth stud for the car I replaced that lead with a brand new one and cleaned the earth stud to give a good clean earth ) you may be surprised to know if you took an earth lead from the battery to the stereo and another one from the earth stud to a car amp the 2 wires would present the stereo with 2 different voltages so you could induce noise from the difference in voltage although it would be a tiny difference

Sorry for the long winded replay but just trying to share my thoughts with you about the problem's I had, if we go through each stage in a methodical way we will find the solution to your problem where are you based I'am in Somerset but also have to travel to Slough so if your close to either perhaps meet and have a coffee lol

Regards Simon

 

[Gaffer]

Hi simon, thanks for the reply

I had the same symptoms as you, not only did the whine increase with alternator rpm, but I'd also got added whine when pressing the brake as well as clicks when the indicator was on.

I seem to remember about rectifiers from A-Level Physics days but I wasn't sure about the alternator purely because the whine wasn't there when I had the car initially. In fact, I had the car some time before I installed the sub, and during that time I had no problems at all with whine.
It only appeared after I installed the sub which makes me think it's an issue with the sub install (as I haven't fiddled with the OEM wiring otherwise).
Unless of course, you mean that the sub is pulling more power which introduces more noise from the alternator? In which case thanks, I'll look into adding the better quality suppressor to it.

Oh, I already have that bcae site in my bookmarks, I think it's great . I especially like the fact that they got RMS right. It really annoys me when I see various UK and US sites claiming that RMS is simply the PMPO halved - it isn't, it's PMPO divided by "the square root of 2" (hence the name Root Mean Square). I'm amazed how many people on the 'net get this wrong.....


Anyway, an interesting thing happened today (noise had gone from when I soldered the phono inputs into the line in to the Bose OEM amp).
I go over a bump - noise appears in the rear speakers only but then slowly decays over the next 5 sec or so before disappearing entirely again.

This makes me think it's probably related to a loose connection.
However, I have soldered and tightened all connections securely - nothing is now loose.......apart from that crappy plastic connector going into the Alpine D Amp (see piccie in my 3rd post above).
I think maybe it's loose enough to move around a bit? I'll have to look into securing it differently as my hotglue fix appears to not have worked.

Interesting point you made about the wiring too. Could it be that the power lead (routed to the bonnet under the carpet, into the passenger well, out through a grommet in the passenger side scuttle and into the fuse and then battery terminal) is causing interference in a nearby audio wiring loom?
The only thing that counts against this is that wouldn't I therefore only get interference in the Left hand channels and wouldn't it be there all the time, not intermittently?
That power lead was a ****** to get routed so I'm hoping I won't have to do it again .

There's one final thing that's top of my suspect list.
In order to piggy back off the Rear R+L Line In that goes from the HU to the OEM Bose Sub/Processor, I have stripped back the "sub phono"s shielding about 1 inch from the +ve wires in order to solder them to those OEM inputs.
The shielding from both was then twisted into single wire (i.e. to make a single shared -ve ground) and that is connected to the bolt in the boot base as the -ve return for those phonos.
Could it be that the 1 inch of "bare" (unshielded) wiring going into (and therefore close to) the OEM Bose Sub/Processor is picking up interference?
In which case how would I fix this? Would wrapping that inch in tin foil (to create an attempt at a shield) work?
The reason I think this may be a possible culprit is that I tapped into the OEM Rear R+L "Line In" only and it just happened to be only these channels that the intermittent whine appeared in this time round (previously it had appeared in all channels).

Apart from that, the intermittent nature is what's got me foxed, because as far is positioning is concerned, everything I have connected is either bolted, taped or soldered down

I think this weekend I'm going to start her up and poke around at everything in the boot until I can reproduce the whine, in which case I'll have the suspect wiring at least and can take it from there....

Gaffer




(Slough's not that far btw, I'm based in Gatwick so it's probably 45min drive or so).

 

[easy going Si]

Hi simon, thanks for the reply

I had the same symptoms as you, not only did the whine increase with alternator rpm, but I'd also got added whine when pressing the brake as well as clicks when the indicator was on.

I seem to remember about rectifiers from A-Level Physics days but I wasn't sure about the alternator purely because the whine wasn't there when I had the car initially. In fact, I had the car some time before I installed the sub, and during that time I had no problems at all with whine.
It only appeared after I installed the sub which makes me think it's an issue with the sub install (as I haven't fiddled with the OEM wiring otherwise).
Unless of course, you mean that the sub is pulling more power which introduces more noise from the alternator? In which case thanks, I'll look into adding the better quality suppressor to it.

Oh, I already have that bcae site in my bookmarks, I think it's great . I especially like the fact that they got RMS right. It really annoys me when I see various UK and US sites claiming that RMS is simply the PMPO halved - it isn't, it's PMPO divided by "the square root of 2" (hence the name Root Mean Square). I'm amazed how many people on the 'net get this wrong.....


Anyway, an interesting thing happened today (noise had gone from when I soldered the phono inputs into the line in to the Bose OEM amp).
I go over a bump - noise appears in the rear speakers only but then slowly decays over the next 5 sec or so before disappearing entirely again.

This makes me think it's probably related to a loose connection.
However, I have soldered and tightened all connections securely - nothing is now loose.......apart from that crappy plastic connector going into the Alpine D Amp (see piccie in my 3rd post above).
I think maybe it's loose enough to move around a bit? I'll have to look into securing it differently as my hotglue fix appears to not have worked.

Interesting point you made about the wiring too. Could it be that the power lead (routed to the bonnet under the carpet, into the passenger well, out through a grommet in the passenger side scuttle and into the fuse and then battery terminal) is causing interference in a nearby audio wiring loom?
The only thing that counts against this is that wouldn't I therefore only get interference in the Left hand channels and wouldn't it be there all the time, not intermittently?
That power lead was a ****** to get routed so I'm hoping I won't have to do it again .

There's one final thing that's top of my suspect list.
In order to piggy back off the Rear R+L Line In that goes from the HU to the OEM Bose Sub/Processor, I have stripped back the "sub phono"s shielding about 1 inch from the +ve wires in order to solder them to those OEM inputs.
The shielding from both was then twisted into single wire (i.e. to make a single shared -ve ground) and that is connected to the bolt in the boot base as the -ve return for those phonos.
Could it be that the 1 inch of "bare" (unshielded) wiring going into (and therefore close to) the OEM Bose Sub/Processor is picking up interference?
In which case how would I fix this? Would wrapping that inch in tin foil (to create an attempt at a shield) work?
The reason I think this may be a possible culprit is that I tapped into the OEM Rear R+L "Line In" only and it just happened to be only these channels that the intermittent whine appeared in this time round (previously it had appeared in all channels).

Apart from that, the intermittent nature is what's got me foxed, because as far is positioning is concerned, everything I have connected is either bolted, taped or soldered down

I think this weekend I'm going to start her up and poke around at everything in the boot until I can reproduce the whine, in which case I'll have the suspect wiring at least and can take it from there....

Gaffer




(Slough's not that far btw, I'm based in Gatwick so it's probably 45min drive or so).

 

[easy going Si]

Hi yer Gaffer
I would not use hot glue bit to permanent for my liking I would cut short strips of Velcro and use a super glue to fix a bit of Velcro to the body lay the cable on to the strip that's glued to the body put a longer piece over the cable and 2 small drops of glue at the edge of the strip so you don't glue the cable there could be a reaction between the iso-cyanate and the outer sheath of the cable keeps it tight but also if you need to move just cut the top piece of Velcro with a Stanley knife and he presto and you can remove the cable

you have more knowledge of electronics than me lol when I did mine the interference around the front light switch was only cured by using speaker cable made by Lapp cable 110 cy olflex a twin core 1.5mm fully continuous screened cooper cable made for industrial machines the shielding is braided cooper and then I earthed at each end either the body or the amps negative ground I used 2.5 twin core for the door speakers and 4mm for the rear speakers cables and sub, 2 x 15 meters of 1.5,2.5 and 4mm cost me 150 pounds not cheap but it did solve a lot of the noise) but also used ferrite beads for the phono cables and after much trail and error I found that stinger 8000 leads were the best but again not the cheapest on the market I have some 1.5 and 2.5 olflex left over if you want

but all the noises you describe are intermittent wear mine where constant it made it easier to narrow done I don't think that 1inch of exposed wire is your problem I would check all the cabling around the battery but also the cleanness of all the earth connections it could be a loose wire that's causing the problem I still think that one of the pieces of your car hifi is being presented with 2 different voltages (I've seen chats about multiple earth point's also being a problem ????) have you got the sub amp/box earthed with cable less than 12 inches from the box if not the amp could be hunting for negative but I've also heard that tin foil also makes for excellent shielding but it has to be continuous to be effected and preferable be soldered to earth at the end of each

I would agree with you that the problem was the sub install purely because the noise wasn't there before, if it is alternator whine then there is only one thing that produces that which is the alternator and its removing that ac ripple on the power feed side is the only way of curing this, the way I wired the 2 10amp car stereo positive feeds to the car stereo was via 2 dietz half farad caps ebay no 111 311 787 123 then into a 12 volt noise filter's ebay no 310 686 852 991 ( ordered from the states ) there used in cb radio but remember the American in car hifi market is 10 times the size of ours and when you want something a bit out of the ordinary
no one here want's to do anything specialist 2 negatives direct from the battery then on to a alpine DVA 9965 ( the Alpine does have a separate power supply) lol lovely cd player

hope this helps gaffer yes Slough to Gatwick not that far around the M-25 lol my mobile is 07787 586 388
if you fancy a chat

regards Simon

 

[Gaffer]

Hi Simon, thanks for the reply. I haven't been around recently due to shift work (nights on call, 13 hours at a time .... ugh) but going to and from work has certainly allowed me more exposure time with the problem.

Hi yer Gaffer
I would not use hot glue bit to permanent for my liking I would cut short strips of Velcro and use a super glue to fix a bit of Velcro to the body lay the cable on to the strip that's glued to the body put a longer piece over the cable and 2 small drops of glue at the edge of the strip so you don't glue the cable there could be a reaction between the iso-cyanate and the outer sheath of the cable keeps it tight but also if you need to move just cut the top piece of Velcro with a Stanley knife and he presto and you can remove the cable

Unfortunately, I read this too late and have already hotglued the wires in place (doh). Anyhow, I did this with a DRL install in a previous car and found it fairly straight forward to remove when I had to replace one of the LEDs so I'm hoping it is fairly reversible. On a side note, it hasn't appeared to change the problem as I still have the problem

you have more knowledge of electronics than me lol when I did mine the interference around the front light switch was only cured by using speaker cable made by Lapp cable 110 cy olflex a twin core 1.5mm fully continuous screened cooper cable made for industrial machines the shielding is braided cooper and then I earthed at each end either the body or the amps negative ground I used 2.5 twin core for the door speakers and 4mm for the rear speakers cables and sub, 2 x 15 meters of 1.5,2.5 and 4mm cost me 150 pounds not cheap but it did solve a lot of the noise) but also used ferrite beads for the phono cables and after much trail and error I found that stinger 8000 leads were the best but again not the cheapest on the market I have some 1.5 and 2.5 olflex left over if you want

No way, I only keep up as it's required of me (it's even in my ****** medical postgrad exams and I'm always astounded gutted at how many questions I get wrong - I swear the b******s deliberately try to mislead you in them).

but all the noises you describe are intermittent wear mine where constant it made it easier to narrow done I don't think that 1inch of exposed wire is your problem I would check all the cabling around the battery but also the cleanness of all the earth connections it could be a loose wire that's causing the problem I still think that one of the pieces of your car hifi is being presented with 2 different voltages (I've seen chats about multiple earth point's also being a problem ????) have you got the sub amp/box earthed with cable less than 12 inches from the box if not the amp could be hunting for negative but I've also heard that tin foil also makes for excellent shielding but it has to be continuous to be effected and preferable be soldered to earth at the end of each

So for shielding would the outer braid of, say, an aerial coax lead do? I have plenty of that lying around so would be easy to hook up.
The negative return for the phono's is quite long (about a foot) so maybe that's picking up interference somewhere.

I would agree with you that the problem was the sub install purely because the noise wasn't there before, if it is alternator whine then there is only one thing that produces that which is the alternator and its removing that ac ripple on the power feed side is the only way of curing this, the way I wired the 2 10amp car stereo positive feeds to the car stereo was via 2 dietz half farad caps ebay no 111 311 787 123 then into a 12 volt noise filter's ebay no 310 686 852 991 ( ordered from the states ) there used in cb radio but remember the American in car hifi market is 10 times the size of ours and when you want something a bit out of the ordinary
no one here want's to do anything specialist 2 negatives direct from the battery then on to a alpine DVA 9965 ( the Alpine does have a separate power supply) lol lovely cd player

hope this helps gaffer yes Slough to Gatwick not that far around the M-25 lol my mobile is 07787 586 388
if you fancy a chat

regards Simon

Well, I was thinking that maybe it's the power lead to the Alpine digital sub. It's routed up to the front passenger bulkhead, goes through a grommet and into the engine bay. I'm thinking maybe it's picking up interference as it's closer to the alternator? Although I wouldn't know how else to route it...it's the best route I could find.

I also have an update for the hum. It's actually mostly disappeared......well for 90% of the time anyway.

Then for the 10% when it does magically appear:

• It only does so for a minute or so, then disappears again
• It only now buzzes on the rear speakers - which is much less annoying
• Tends to appear with either hard acceleration or going over a bump
• Tends to disappear when going over another bump or sometimes spontaneously
• Once or twice, it did appear in all speakers again, but then disappeared quite quickly as before

So it appears to be related to sharp motion.....again making me think it's a connection issue......on the other hand theere's enough randomness thrown in that I'm still stumped.

The other day, it was still there when I parked up at work, so I left everything running and lowered the back seat before poking around the sub harness and wires. Buzz stayed.
Disgusted, I put the seat back up and returned to the driver's seat - only to find out the buzz had gone again.
Random.

Anyway, I'm going to try something in the next day or so and get back to you.


Cheers

Gaffer

 

[easy going Si]

Hi yer Gaffer

you probably found the fault or noise but didn't realise it, poking around the Sub harness we know the noise wasn't there prior to you installing the sub so it could be the power lead or the phono cable or the speaker lead

Co-ax is aerial cable has not got a full screen around it, it is only partly screened which is useless if you go to some where like Maplins get them to cut you a meter of CT100 satellite cable, use a knife and slice it open this has normally got a continuous braid and foil to screen for shielding interference you will see that co-ax is rubbish even in Aerial installs I have used CT100 instead of co-ax

I would also try this disconnect one of the wires (phono or speaker or power) run the car around for a few days and then reconnect that wire and take one others off perhaps isolating the noise that way, also you said you put the rear seat back is any of the cables tangled up i.e. has the insulation got damaged also try and split the wires up into separate looms so there is less chance of a wire picking up noise

Also going over a bump and there noise appears that tell me there is a loose connection some where check any areas where you have jointed cable, crimps and soldered joints are good but if the cabling is hanging around loose or moving say in an area or void behind the seat area where you tucked cable it could be flexing

Power cable should be straight onto the positive battery post a fuse very close to the battery and then routed around the car avoiding phono cable if possible, the alternator will be at the front of the engine I doubt very much that's the problem the noise would be constant and increase with engine speed, also make sure the negative lead is ideally less than 12 inches from the amp and a good clean negative connection on bare metal (seat belt mounting bolt could be a option (get a 12 volt test screwdriver from Halfords and see if you can find a decent negative) seal it after woods with silicone sealant if not the noise could be your amp hunting for negative

Hope this helps Gaffer if no success here is my mobile 07787 586 388 text an update

regards Simon

 

[easy going Si]

Gaffer don't use the phono cable negative cable as a switch on wire I see so many people do this make sure that it has a good earth at each end to drain any noise away

 

[Gaffer]

Right, Sorry for the delay in updating this (I've been busy with a wedding to prepare for) but I have FINALLY fixed the problem


So the phono -ve return is attached to the sub -ve return into a single Earth ground spade/connector.
I couldn't quite reach to the seat base and the whine had returned.
After taking everything out again, I noticed the bolt I had it connected to had gone "dusky" if that makes sense. Not like it's corroded but more like it had oxidised.

Anyway, I found a new grounding point:
Open the boot and pull the plastic lip/trim directly in front of you. Underneath there are 2 plates (left and right) bolted onto the shell.
Take the Right one out.
Dremel sand the washer on the chassis it attaches to.
Dremel sand both sides of the plate.
Dremel sand the inferior surface of the bolt as well.
Now that everything is sanded to metal, put a bit of tin foil between the plate and chassis, and also a bit between the bolt, spade connector and plate.
So whereas before it was: Bolt -> Painted Plate -> Washer attached (glued) to chassis
It was now: Bolt (underside sanded) -> Earth connector -> Tin foil -> Sanded plate upper and lower surfaces -> Sanded washer/chassis

It's now been over a week and not a problem

So it's ended up being an Earth point issue alone. Where it currently is, is not under the boot lining and therefore less likely to get damp or stay damp. It's up and out of the way so hopefully that's it.....all fixed

 

[easy going Si]

Hi yer Gaffer

had to be something silly like a bit of oxidation or a bad connection, but you must seal the bolt and nut most of the car nuts I've dealt with cover the bolt and screw with silicone sealant but a friend of mine who does body repair said to seal the bolt with silk o flex or that's what he called it lol both products will seal and stop any oxidation and rust but silk o flex is a much more professional product

Gaffer I bet you have put everything back in your car, but remember when the car is cold i.e. in the winter you can get damp in the car/boot because of the temperature difference between the inside and outside air

 

[Gaffer]

Sorry to update this ongoing thread , but the problem returned with a vengeance!

I now knew the grounding wire wasn't at fault so I poked the wiring loom going into the Bose Amp gently. The whine disappeared. I poked again, it appeared. Again - disappeared, again - appeared etc etc.

Thinking it was therefore where I had tapped into the line-inputs for the sub, I undressed everything and tried to remedy it:

• routed the "amp on" signal away fromt the loom as this is a 12V wire that goes live with ignition so may be adding noise into the audio circuits
• checked the soldering on the input wires - everything fine, so re-wrapped with insulating tape
• wrapped metal foil tape around the input wires to act as a shield against further interference.

Guess what? Whine still present.

So this time I poked the connector itself. Noise disappeared. Poked again. Noise appeared. Poking the loom was simply moving the connector - the fault is with the connector itself.

This thing:

The connector is just slightly loose enough to move a bit, and on certain positions/moves a whine starts coming through the speakers which sounds like a ground loop (alternator whine, brake applied whine, indicator applied whine etc etc). This also explains why when I go over a bump, the whine can disappear - the connector is jolted ever so slightly* into a different position (*by slightly I mean less than a millimeter).

So even though I now definitively know what the issue is, I have no idea how to permanently fix it short of getting a new wiring loom connector and wiring the loom into it (which I don't relish doing).
I'm going to try pushing it into one position with some cardboard...

 

[easy going Si]

hi yer Gaffer

So its the connector going into the Audi amp ?????? ( is there a part number ) first thing I would do is unlock the amps connector block spray the amp connector and the mating connector on the amp with electronics contact cleaner ( maplins actually sell a good one and if its oxidation of the pins this will go a long way to solve the problem it will remove anything that could be causing a partial connection ) or it could be thermal expansion which is causing the problem this is where the plastic connector slightly expands check with the mating connector for any browning of the plastic this will hopefully show if I.E. a wire has been taped of further up the line and perhaps used for something else and is pulling in to much current so then would heat the pin up

this would also indicate any wire that is either pulling to much current or you could have general problems with the connector block its self be careful if you have taped any low current wire and normally in car amps there will be a rail inside where the phono ground, negative ground and the 48 volt rail ground are all connected to one point so it gives you 0 volt but remember if anyone has taped this ground point electrons can flow both ways so something further up the circuit could be using this ground and drawing current through this and heating up the pins

Can you pop me a few photo's (simon_uk22) to my email so you can send me photos of the connector (at msn.com) I was in Slough for 2 months but I have come back to Somerset for a month or 2 for a short break but have to go back to Slough to finish my house so if we don't resolve this via here we can get together and sort this whine issue out I am sure the solution is there sitting in front of us

Also just another quick one check how good the earth lead is on the back of your stereo if need be run a new earth cable from the back of the stereo and use a bolt to the case of the stereo not the connector block because it could be one of these pins are making a poor connection and perhaps is the issue ????? the connect the earth lead from the stereo to the earth stud on the body the earth point of the car not the negative post of the battery

So Gaffer are you training to be a doctor and hope the above helps you

 

[Philipmadden87]

Hi Gaffer, I know this was a couple of years ago but I don't suppose you have the solution to the problem do you? I've had a good read through this and I'm having the exact same problem (indicators, brakes and alternator whine etc) it only seems to be when I indicate right which I thought it could have been something to do with the rear right light cluster. Just given it a great earth and used contact cleaner on the Bose amp. Any help would be much appreciated. Thanks. Phil

 

[easy going Si]

hi yer Phil

is there still a problem with the sound, did you take the earth from the rear light cluster earth ???

Alternator whine is being generated by the alternator the quickest solution to this is to fit a suppressor to the alternator

check the negative wire from the battery post to the stud on the body make sure the area around the thread is clean

work most car audio noise comes from poor earthing

could you give me a description of your car and any details or progress you have made

regards Simon

 

[Philipmadden87]

Hi Simon, I checked the earth to the aftermarket amp and relocated it as it did seem a bit naff, sanded all around the hole and made sure it's nice and tight, it's earthed directly to the body. I sprayed contact cleaner in the Bose amp and connector. And I checked the battery earth cable and all seems ok. Would it not have a suppressor on the alternator already? Would a suppressor fitted to the aftermarket head unit help?
Thanks for any and all your help mate it's much appreciated.
Car is a 62 plate Audi A3 S-line Sportback black edition

 

[easy going Si]

Hi yer Phil

Negative electrons are the things that do the work Voltage is a positive force the pushes electrons along a cable Ampage is a measure of how many electron's are being used to do a certain amount of work, Silver ( number 1) and Copper (number 2) are fantastic conductor's but carbonised Iron ( Steel ) (number 23 in the list of electrical conductivity) it is not a poor conductor of electricity but no where near as good as copper or silver

1) Make sure the cable to your amp's negative connection is at maximum 12 inches long 15 inches is the longest I would ever fit the shorter the better if the cable is longer than this you will have the Amp hunting for earth which will cause voltage drop and Ampage starvation which makes the Amp gulp current in and not have a constant flow of current which it needs, makes sure you seal the earth point with grease I would use LM grease like you use on battery terminals to stop electrolitic corrosion

2) Contact Cleaner does no harm what so ever but will only cure electrical corrosion on the Amps terminals some people think this a cure all for all electrical problems

3) I want you to look at you tube and look for some thing like what the Amercian's call car earthing the big three ( 3 ) they will normally start by laying in 300 amp to 415 amp negative cable to increase the flow of electron's in the car body when I did my car stereo wiring I realised very quickly that the single earth cable ( around 100 amp to 150 amp cable ) from my negative battery post to the negative stud on the car body was totally inadequate for the power demands I was going to place on the electrical system

4) So I went to Halfords they do a 6 way battery post for the negative battery post and installed 6 x 170 amp cable 3 of these replaced the single negative cable that went to the stud 2 went direct to the starter and 1 went to the engine block If you give me some idea of length to replace I could make up some cables for you I can crimp ( I can crimp up to 300mm round cable with my hydraulic crimper) or solder connectors on for you in either 6mm or 8mm lug crimps and make all you car stereo's earth connection's to the stud on the body not the battery terminal as this is where most of the electrical noise is generated ( I order my cables from AES car electrical so you can see the drum or meter price of cable )

5) Remember Phil that the electron flow comes from the negative terminal and the voltage comes from the positive connection this is a very simplified view of a far more complex electrical process but both negative and positive work in balance if you have 6 x 415 amp cables from the battery positive and only 1 x 100 amp cable from the battery negative in simple terms the maths of electricity isn't in balance

6) the suppressor fitted to your alternator by the manufacture is a very low value and outside suppressor is made by durite and is not that expensive but can you look at the above before looking at a suppressor

Phil I tried to make this as none technical as possible with simple to understand descriptions of complex electrical process

Hope it helps I can send you pictures of my stereo and cabling install if you like

 

[Gaffer]

Hi again.
Nope, the problem still there but over the past many months I have confirmed it is indeed that blasted connector (noise appears intermittently although I have made it go away for weeks at a time by jiggling the connector a bit)

I intend to try something more definitive next week and report back


Sent from my iThingy using Tapathingy

 

[Gaffer]

************ Found the Cause *****************


So after investigating again, no amount of fiddling with the connector would help. Then I stumbled across another temporary fix.
The only reason the connector has an effect is because it's moving the audio wiring loom but I still tried to see if I could fix the connector in place slightly differently. I initially sprayed WD40 into the connector (both male and female parts) which had no effect, nor did pushing the connector itself. However, after moving the loom slightly, the noise stopped. By pushing the loom around, I think certain wires within are being moved further away or closer to the phono's I have spliced in -> which are introducing a ground-loop-like effect due to electromagnetic interference with the wires they're sandwiched next to.

The loom has to be pushed a specific way to stop the noise (in my case to the side/lateral wall of the car probably because of where I have soldered into the loom). If you splice in to a different position, the direction you need to push the loom to eliminate the effect may be different.

So the Blue wire is the remote on for the subwoofer's digital amp. The sub phono input +ves travel to the loom and are soldered into the R & L preouts. The -ve from the phonos is separated out and instead gets routed down to the boot floor to be earthed along with the sub earth/return wire.

By placing a wedge between the side and loom as shown, I am in effect pushing the wiring loom slightly laterally towards the right wall of the car --- just enough to completely eliminate the whine (need to obviously have the car switched on to hear the whine - I also had the hazards on so I could clearly hear the buzzing and then hear it get "fixed" by dissappearing).
The bad news: This is only a temporary fix but I have taped the wedge in as well for a better hold so that when I go over bump it won't dislodge. I expect it to last 4 or 5 months or so before becoming loose enough that i have to redo it.
The good news: It literally is so easy to do it takes about 10 minutes or so - so not too terrible if you end up having to do it 2-3 times a year.

 

[easy going Si]

Hi yer Gaffer
I have now exactly the same problem as you I laid in 3 x 25mm positive power cables down the drivers side with 2 switch on wires but the 3 power cables were routed slightly differently with the 2 switch on wires loomed near the seat loom one red and one blue I connect the red no noise but when I connect the blue I get a buzzing sound on the front speakers ???????

Have you tried inline ferrite choke at each end of the cable ????? they have worked in the past for me around big power wires but I put a choke at each end of the cable at least these could be a cheap and easy solution

Regards Simon