# Twisted speaker cuts down on possible noise



## itsblown (Dec 6, 2011)

Is it true that twisting the negative and positive runs of speaker wire around each other cut down on possible noise?


----------



## Candisa (Sep 15, 2007)

In theory: yes, because twisting makes sure all the noise induced will be induced to the negative and positive wire equally, cancelling out at the end...
This is how most balanced signal-cables are built and it actually helps...

But speaker-level signal is a LOT stronger than line-level, so the noise induced by the speaker-cables will be a lot less compared to line-signal cables when you compare it to the actual signal. 
Result: it becomes inaudible (if it isn't, it's because you laid the speaker-wires next to something that gives a LOT of electromagnetical noise, meaning you'd better re-route the speakerwires).

I think twisting the speakerwires will have more effect on the noise *coming from* the speakerwires, than on the noise *induced by* them. I mean, if you put speakerwires that transfer very high power right next to insufficiently shielded RCA-cables, the RCA-cables might induce some unwanted electromagnetical noise from the speakerwires, which might me decreased when the speakerwires are twisted...

I doubt anyone would expect problems when using proper (not $100,-/ft treated with snake-oil, just normal good quality stuff) RCA-cables and carefully routing the cables.
A shielded main-power-cable will have a lot more influence, if any, when running a powerfull system and all wires (RCA, speaker, power) in just 1 bundle, but there are many people out there that do this without using shielded power-cable and have no problems at all...

Isabelle


----------



## minbari (Mar 3, 2011)

Candisa said:


> *In theory: yes, because twisting makes sure all the noise induced will be induced to the negative and positive wire equally, cancelling out at the end...
> This is how most balanced signal-cables are built and it actually helps...*
> 
> But speaker-level signal is a LOT stronger than line-level, so the noise induced by the speaker-cables will be a lot less compared to line-signal cables when you compare it to the actual signal.
> ...


this only works if you have a balanced line system. the unbalanced nature of RCA or amplifier outputs does nothing with twisted pair.

I will agree that the relatively high voltage level of speaker level means that small voltage noise (in the mili-volt range) wont be heard.


----------



## Candisa (Sep 15, 2007)

It doesn't have anything to do with being a balanced signal or not: A speaker is powered by the potential difference between the positive and negative speaker-wire. 
If noise is induced equally on both the positive and negative wire, it will cancel out where the ends meet the speaker...

There are actually twisted, non-shielded RCA-cables out there that do a great job transporting a non-balanced line-level signal...

Isabelle


----------



## CaptainMorgan (Jan 13, 2012)

Candisa said:


> It doesn't have anything to do with being a balanced signal or not: A speaker is powered by the potential difference between the positive and negative speaker-wire.
> If noise is induced equally on both the positive and negative wire, it will cancel out where the ends meet the speaker...
> 
> There are actually twisted, non-shielded RCA-cables out there that do a great job transporting a non-balanced line-level signal...
> ...


They may work alright in an ideal installation, but twisting RCA cables is hilariously illogical (for unbalanced signals). It will do absolutely nothing, and in the horrible environment of a car not having any shielding isn't too smart either. The most benefit that you could do with twisting RCAs for an unbalanced signal would be to give yourself slightly closer to equal noise into each channel. It won't reduce anything, at all.

There is a reason all pro gear uses balanced signals. Unbalanced for noise rejection sucks and requires voltages that are much higher to separate a signal from a noise floor. The only time at my work (broadcast television installations) that we use an imbalanced audio signal is when adapting consumer grade gear into the truck like the DVD/CD and IPOD integrations. Even then, they go immediately to a converter that changes the signal over to a balanced one before it gets sent anywhere else.

I'm honestly surprised that more SQ decks and amps for us haven't gone balanced. It would be so far superior for our needs and make more of a difference in a car than half the crap they pour money into.


----------



## chad (Jun 30, 2005)

CaptainMorgan said:


> Unbalanced for noise rejection sucks and requires *voltages that are much higher to separate a signal from a noise floor.* The only time at my work *(broadcast television installations)* that we use an imbalanced audio signal is when adapting consumer grade gear into the truck like the DVD/CD and IPOD integrations.


ummmmmm, no, Nominal Consumer unbalanced is at approx -10dBV Whereas pro audio is at +4dBu

-10 being .316V
+4 being 1.228V

And I don't think much has changed since yesterday but a metric ****ton of Broadcast gear is at higher nominal voltages with a bunch being at +8dBu

Candisa, for any sort of cancellation to work in a twisted pair line both lines MUST have the same impedance characteristics, this means it may only come close to working when being driven with a bridged amplifier as both lines would have nearly the same output impedance.

It's a pretty rare instance that you have noise induced upon a speaker line, although possible.

I'd be more concerned with keeping the speaker line from RADIATING upon a line I don't want it to. I've seen installations, with very long runs, where that can cause oscillation and instability in a system.


----------



## Genxx (Mar 18, 2007)

It appears I must just be one lucky motherfucker. Since 1989 when I did my first system, I am 25 of 25 with regular RCA cables and no noise issues, in 25 different vehicles. I have two vehicles that run balanced with Zapco. So total of 27 full systems never any noise issues. Out of those 27, 6 have been full active mult-amp systems with some form of digital processing or analog x-over and EQ's.

I see no reason to have balanced in an aftermarket stereo system, especially to the average consumer. 

IMO people underestimate just how hard it is to induce noise into a set of good quality RCA cables. I have seen it done due to a faulty piece of equipment in the chain but never induced from cables sitting in a car next to other cables.


----------



## CaptainMorgan (Jan 13, 2012)

chad said:


> ummmmmm, no, Nominal Consumer unbalanced is at approx -10dBV Whereas pro audio is at +4dBu
> 
> -10 being .316V
> +4 being 1.228V
> ...


I should say that the voltages I made a mistake in my post in the voltages I was referencing. I wasn't thinking in terms of what the signal voltages are that I actually work with, but more so in line with what can be pulled off with balanced signals in something like a high quality mic cable in a long run. My apologies for that previous post, I didn't intend to speak as to something I wasn't knowledgeable about.

I still hold the premise that while what you responded to wasn't correct that twisting an unbalanced cable is pretty useless.


----------



## PaulD (Nov 16, 2006)

I once tie-wrapped my RCA's to the amp power wire (about 10-12 ft) to see what would happen, no noise issues.


----------



## chad (Jun 30, 2005)

CaptainMorgan said:


> I still hold the premise that while what you responded to wasn't correct that *twisting an unbalanced cable is pretty useless.*


Useless as tits on a snake :thumbsup:


----------



## 24th-Alchemist (Jun 16, 2011)

> for any sort of cancellation to work in a twisted pair line both lines MUST have the same impedance characteristics


I'm not sure this is true. I think with an unbalanced source driving a balanced receiver (resulting in unequal impedance among lines) a twisted pair could help with inductively coupled noise reduction (i.e. reduce noise from high current flow in nearby wires).

The possibility hinges on the fact that receiver input impedance is typically much higher than source output impedance. For example a person could have a 20 or 200 Ohm source output impedance and a 20k-Ohm receiver input impedance, resulting in a hundred-fold impedance difference even for the 200 / 20k case.

Suppose for example there's an inductively coupled current _i_ in the signal lead. At the source with an output impedance _Rs_ there's a voltage change (noise) of _Vs = i * Rs_. If the leads are twisted then the same current _i_ flows in the ground lead, resulting in current cancellation at the balanced receiver impedance _Rr_ and no additional noise added to _Vs_. Now suppose the leads are not twisted and there's the same current _i_ induced in the signal lead, but there's a current _difference_ of _d_i_ (due to untwisted) between the signal and ground leads. Then in addition to the noise voltage _Vs = i * Rs_ from the source, there's added noise _Vr = d_i * Rr_ at the receiver. In such a case if the receiver impedance _Rr_ is a hundred times larger than the source impedance _Rs_ (not necessarily atypical), and the current difference _d_i_ (due to untwisted) is a mere 1/10'th of the signal lead current _i_, then the resulting noise voltage at the receiver (_Vr_) is 10X larger than the noise voltage at the source (_Vs_) with untwisted. (But the receiver voltage is rejected to zero with twisted). 10x less noise in that example would result in an audible difference. And if the source output impedance were 1000x smaller than the receiver's output impedance (e.g. 20-Ohm source and 20k-Ohm receiver), then the reduction in noise in moving from untwisted to twisted would be 100-fold for a 10% difference in induced currents in untwisted pairs. (i.e. for unbalanced source driving balanced receiver untwisted noise is _i * Rs + d_i * Rr_ whereas twisted noise is only the first term _i * Rs_ because twisting forces _d_i_ to zero; thus the situation for whether twisted reduces noise seems to boil down to whether the ratio _d_i / i_ is smaller than the ratio _Rs / Rr_).


----------



## thehatedguy (May 4, 2007)

PaulD said:


> I once tie-wrapped my RCA's to the amp power wire (about 10-12 ft) to see what would happen, no noise issues.


When installing for a living, you probably will find most retail installers run rcas with power wire just to save time. The literally thousands of amp installed I have done this way had no noise from that.


----------



## cmayo117 (Aug 14, 2009)

PaulD said:


> I once tie-wrapped my RCA's to the amp power wire (about 10-12 ft) to see what would happen, no noise issues.


You wont induce any noise from a DC power cable. The current has to be changing quickly to induce anything. This is why transformers only work with AC.


----------



## thehatedguy (May 4, 2007)

Nevermind no matter where you place the rca cables in the car that they will never be isolated from noise since the entire chassis of the car is the return / ground plane. Whatever noise is on the power wire will be on the ground side too.


----------



## chad (Jun 30, 2005)

24th-Alchemist said:


> I'm not sure this is true. I think with an unbalanced source driving a balanced receiver (resulting in unequal impedance among lines) a twisted pair could help with inductively coupled noise reduction (i.e. reduce noise from high current flow in nearby wires).


Sure it will HELP but the CMRR will still suck.

But I think we could probably agree that amp manufacturers should just stick balanced inputs on their amps and call it a day.


----------



## The Tube Doctor (Nov 24, 2009)

I was pretty choked when Audison's clever balanced line never achieved broader commercial recognition. (ABS system) The produced a great-sounding passive, balanced line converter, as well as an active box, either of which could go behind the source unit. The ABS connectors were unique, in being compatible with balanced or unbalanced input signals.
I've still got their balanced preamp, both variations on the balanced converter, and a few amps
in my collection. Definitely ones that I'll keep.


----------



## xtremevette (Apr 14, 2011)

For those saying you installed a ton of systems and never had any noise. Try working on a vette then chime back in. You'll more then likely have noise the very first time.


----------



## chad (Jun 30, 2005)

Nope. Didnt. 

Sent from my Sony Tablet S using Tapatalk 2


----------



## jguthrie (Nov 14, 2011)

So do it or skip it?


----------



## DirectionsAndConnections (Nov 21, 2012)

When I was an installer, I always twisted speaker wire. But it had nothing to do with noise. It makes the install cleaner and easier, and single lead wire is way cheaper to use than the paired speaker wire. That's it. Like others have said, any noise is going to come from the RCA's, because the signal level is lower, and all of that noise is going to be amplified.

I say do it, but just because your install job will look neater.


----------

