# Shield speaker wire?



## diynube (Feb 27, 2011)

Hi,
I found that my system produces a nasty noise on the the front left tweeter. Interestingly, it produces the noise for extended periods of time, but there are times that it doesn't produce the noise.
I have an MS-8 with a 4-channel amp powering a 2-way active front stage. Disconnecting the RCA's at the amplifier affects the noise very little. The only way to kill the noise is to disconnect the tweeter from the amp. I'm guessing that induction from something under the dash area is causing the noise.

I want to shield the speaker wire to see if that helps.
What suggestions do you guys have?
I have thought of the following:
1. Aluminum tape wrapped around the speaker wire.
2. Aluminum foil wrapped with tape.
3. Pre-fabbed metal shielded speaker wire of some sort.
4. Use RG-6 for speaker wire.

I may splice the wire right before it goes into the door, but I may just pull the door card off and run all new wire. I am open to suggestions.
Thanks


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## minbari (Mar 3, 2011)

if induction was causing it, then it would still do it once you removed the wire from the amplifier. in fact it might get louder since it would not have the amplifier to dampen it.

this is not likely the problem. reverse the tweeters wires, left to right. does the weird noise stay on the left or switch to the right?


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## nick650 (Feb 7, 2011)

Avoid all power wire from speaker wire. Learned that the hard way!


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## diynube (Feb 27, 2011)

minbari said:


> if induction was causing it, then it would still do it once you removed the wire from the amplifier. in fact it might get louder since it would not have the amplifier to dampen it.
> 
> this is not likely the problem. reverse the tweeters wires, left to right. does the weird noise stay on the left or switch to the right?


I am kicking myself for not swapping tweeters. Are you sure that disconnecting the wire would cause more noise? It seems counter-intuitive because the circuit would be open, and current could not flow...



nick650 said:


> Avoid all power wire from speaker wire. Learned that the hard way!


Yeah, I was messing with the distances from the power wire to speaker wire, but they really aren't that close. I think I was able to separate them by 6" or so. I also made them touch and I couldn't tell if there was a difference at all.

I am beginning to wonder if it is a bad amp. I obviously have some more testing to do...


I attached a WAV recording the tweeter. The mic was about 1cm from the tweeter. I renamed the WAV file to a PDF file so I could upload it.
View attachment 2012-05-09_13-15-23.pdf


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## MarkZ (Dec 5, 2005)

Power wire has no effect on speaker wire. It's a low impedance circuit.

I think you're barking up the wrong tree here. Of course the noise will disappear when you unplug the offending tweeter!  If you think it's coming from the tweeter line, you could unhook the tweeter (and the wire!) and measure the noise at the output of the amplifier with a meter. That would at least isolate the source. Minbari's right that you should switch speaker wires and see if it follows the amp or follows the speaker. If it follows the amp, that could indicate there's something wrong with the amp. If it follows the speaker, that could indicate the tweeter wire or terminal is grounding out somewhere. When that's the case, it usually squeals.


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## Neil_J (Mar 2, 2011)

I can't open up the wav from my phone via tapatalk, but is it a periodic clicking noise, by any chance? I have the same thing in my car right now, it sort of comes and goes. Haven't found what was causing it, but as MarkZ said, it is certainly not the speaker wires receiving the interference.


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## minbari (Mar 3, 2011)

diynube said:


> I am kicking myself for not swapping tweeters. Are you sure that disconnecting the wire would cause more noise? *It seems counter-intuitive because the circuit would be open, and current could not flow...*
> 
> 
> 
> ...


if the noise was being induced from an outside source, then it is being induced in addition to the amplifier signal. disconnecting the one source (the amplifier) would not stop the noise from the other source. that being said, I highly doubt this is what you are seeing. inducing enough noise into a very low impedance circuit (as markz said) to be audible would require a TON of current to be moving in an adjacent wire and that current would have to be constantly changing. ( this is essentially how a transformer works )

more than likely this is the amplifier doing it, the RCAs going to the amplifier or the HU. start by swapping the speaker wires, then swap the rcas. if either of those cause the noise to swap sides. its not the tweeters or the wire causing it.


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## chad (Jun 30, 2005)

diynube said:


> I am kicking myself for not swapping tweeters. Are you sure that disconnecting the wire would cause more noise? It seems counter-intuitive because the circuit would be open, and current could not flow...





minbari said:


> if the noise was being induced from an outside source, then it is being induced in addition to the amplifier signal. disconnecting the one source (the amplifier) would not stop the noise from the other source.


The circuit has to be closed for the noise to be induced. It's currently being closed by the uber low output impedance of the amp, if he disconnects the speaker from the amp then it's no longer closed, if he disconnects the speaker from the amplifier and shorts the speaker leads then it's closed again.

Transformers work on induction, this is a crude transformer. If you have a primary coil inducing energy onto a secondary then the current thru the primary is very low until you put a load on the secondary, energy is not being transformed, no reactance.

Saying that the open speaker line would work would be like saying you only have to hook up the positive lead to to tube amplifier with a transformer.


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## minbari (Mar 3, 2011)

ok, you are right. it is still not likely the issue, even when connected.


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## chad (Jun 30, 2005)

It happens, had a member here chase it forever. IIRC the 1980's jimmys were notorious for this too.

It's very rare and often times I feel that it may happen in the amps feedback so shorting the lead would not replicate it.... but it happens.


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## diynube (Feb 27, 2011)

Well, I think its the amp. I noticed that the right tweeter channel produces much more hiss than the left tweeter channel.
The left tweeter channel does that crazy noise, but only sometimes. Otherwise the left channel has a low noise floor.
Both of the mid-bass channels produce equal, expected hiss. I measured with FFT.

I switched RCAs, and the right channel still makes the same fairly loud hiss. Interestingly, it only makes the louder hiss when an RCA is connected in general, but I confirmed the hiss is not coming off the RCAs because I did the swap.

The amp is an Infinity Kappa Four and I purchased it in April last year. I would think its out of warranty and I'm probably hosed...


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## 14642 (May 19, 2008)

I think Kappa is a 2-year warranty.


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## diynube (Feb 27, 2011)

Andy Wehmeyer said:


> I think Kappa is a 2-year warranty.


It appears to be one year, but I'll call them and see what they say. I dig the amp otherwise, nice and compact.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

diynube said:


> Well, I think its the amp. I noticed that the right tweeter channel produces much more hiss than the left tweeter channel.
> The left tweeter channel does that crazy noise, but only sometimes. Otherwise the left channel has a low noise floor.
> Both of the mid-bass channels produce equal, expected hiss. I measured with FFT.
> 
> ...


I have/had been chasing my tail trying to find my noise issues... I thought I had the same/similar problem... Was totally random and I couldn't do anything to reproduce it... 

I've been questioning the cars electrical system/alt because of it... took my old and new alts in and had them properly tested... no issues... My car has had issues data-logging (highly tuned) so I thought noise coming from somewhere... maybe a janky connection or something, as some of the wires in the car are shielded.. 

Then during level setting it reared it's ugly head, I had the RCAs unplugged and I herd it... 




Up to that point I had never herd anything with the RCAs unplugged.. but maybe I wasn't up front at the time..


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## diynube (Feb 27, 2011)

Aaron'z 2.5RS/WRX said:


> I have/had been chasing my tail trying to find my noise issues... I thought I had the same/similar problem... Was totally random and I couldn't do anything to reproduce it...
> 
> I've been questioning the cars electrical system/alt because of it... took my old and new alts in and had them properly tested... no issues... My car has had issues data-logging (highly tuned) so I thought noise coming from somewhere... maybe a janky connection or something, as some of the wires in the car are shielded..
> 
> ...


You are saying it was the amp, right? I measured my high-output alternator with my Fluke 77 Series II and found there was moderate RMS "ripple", 0.015V. The thing is it measures the same amount whether I was getting the noise or not. I'll have to do some more measurements at different RPMs just for the sake of science, but I'm confident the amp is the culprit in my case.


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## chad (Jun 30, 2005)

Geiger counter.


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## Richv72 (May 11, 2012)

cant you just disconnect it from the wire you are using and test it right at the amp to verify if it is the wire or not?


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

diynube said:


> You are saying it was the amp, right? I measured my high-output alternator with my Fluke 77 Series II and found there was moderate RMS "ripple", 0.015V. The thing is it measures the same amount whether I was getting the noise or not. I'll have to do some more measurements at different RPMs just for the sake of science, but I'm confident the amp is the culprit in my case.


 
Yes... It could totally NOT be your alt is what I'm saying... 


Try a quick set of speaker wires routed a different way maybe? Set a silly coax on your dash, with speaker wire running up the middle, see if THEY do it... 

If so, you know, if not, you know...


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