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Answered Speaker cable length & gauge

madfiddler

Active Member
Hi all

I’m wanting to replace some old speaker cable that runs around the edge of my room under skirting board etc. but there’s limited space. I’ve been reading a few guides on gauge and length etc but read a few different things that’s seem to conflict so hope you all here can help. I guess for some it will be a simple question to answer!

So 24ft/7.32m, 4-8 ohm is what I am looking to cover

My old stereo integrated amp is only 30w into 8 ohms
I also have a Cambridge audio receiver that which is 100w rms at 8 ohms when driving two channel
Am considering replacing both with a single integrated amp (perhaps Audiolab 6000a)

Speakers are 100w, 4-8 ohm sensitivity 90db

I know that advice perhaps would be go to a higher gauge cable to future proof, but with the limited cabling space can anyone confirm I am correct in assuming 1.5 mm sq. (awg 16?) is sufficient at that distance please? Thanks
 

dannnielll

Well-known Member
Nothing wrong with 1.5 mmsq, but of course 2.5mmsq will be marginally better. I suggest you look at some of the ribbon cable types. ..not for the alleged sonic benefits but that a bigger cross sectional area can be accommodated in a narrow gap.
 

Sam Vimes

Active Member
I'm intrigued to know where, why and when, worrying about speaker cable guages came about.
Beyond being able to hide it effectively, the guage of a cable has never even crossed my mind. Speaker specs also wouldn't have any real bearing on the speaker cable I chose. It's all about the sound, the electrical differences between the same structure of cable of different thickness are not worth worrying about. It would take some remarkable equipment and ears to hear the difference.

I've known of full on multiroom systems to be wired with the likes of Chord Rumour install, which is just a pair of simple (AWG 16/1.31mm2) cables with no outer sheath.
 

ChuckMountain

Distinguished Member
It's not to do with difference in quality per say but the electrical resistance of cables. A thinner cable from the same manufacturer will have a higher resistance.

In short runs that's not an issue so long as you don't have stupidly high powered speakers.

However over longer distances this can become an issue so you need to move to the next gauge up to minimise losses and give the amp an easier time.

Most household distances and speakers won't suffer from this.
 

Sam Vimes

Active Member
It's not to do with difference in quality per say but the electrical resistance of cables. A thinner cable from the same manufacturer will have a higher resistance.

At the distances that the overwhelming majority of domestic users will be running cables, the differences are academic.
 

ChuckMountain

Distinguished Member
Yes that's what I said in my last sentence...

I have some 20m+ runs and the 1.5mm^2 would have been close to the limits so I went higher to 2.5mm^2
 

madfiddler

Active Member
Thanks..I guess I’m coming from fact that what is in place already looks not much better then bell wire.....cranking up the volume tends to stress out the Cambridge amp fairly easily
 

dante01

Distinguished Member
The wire thickness simply reduces the impedance being imposed over a given length of wire. The thicker a wire or the lower the AWG, the less resistance. It is a combination between speaker impedance, the length of wire needed length and its thickness that affects the resistance imposed. You should theoretically try to ensure that your speaker wire has a resistance less than 5% of your speaker’s nominal impedance. You'd hear no improvement if using thicker wire over short distances and there's no reason to use thicker wire which will cost you more unless you intend using cable runs long enough to warrant such wire. The wattage the receiver outputs woudn't have any bearing on the thickness of the wire.

speaker-cables.png


As you can see, 2.5mm covers most eventualities and you'd only really ever need wire thicker than this if the cable runs were exceptionally long. Even 1.5mm wire would in your case suffice and may be easier to conceal if wanting to tuck it under your skirting and or carpeting?
 
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madfiddler

Active Member
The wire thickness simply reduces the impedance being imposed over a given length of wire. The thicker a wire or the lower the gauge, the less resistance. It is a combination between speaker impedance, the length of wire needed length and its thickness that affects the resistance imposed. You should theoretically try to ensure that your speaker wire has a resistance less than 5% of your speaker’s nominal impedance.You'd hear to improvement if using thicker wire over short distances and there's no reason to use thicker wire which will cost you more unless you intend using cable runs long enough to warrant such wire. The wattage the receiver outputs woudn't have any bearing on the thickness of the wire.

View attachment 1120597

As you can see, 2.5mm² covers most eventualities and you'd only really ever need wire thicker than this if the cable runs were exceptionally long. Even 1.5mm² wire would in your case suffice and may be easier to conceal if wanting to tuck it under your skirting and or carpeting?

Yes that actually was the first table of info I looked at from the Cambridge audio web site, then subsequently seen some places selling 1.5mm² wire as 16 AWG and others as 15 AWG. Then a lot more talk about using 2.5mm²....
 

BlueWizard

Distinguished Member
Here are some reference guides I've created for Speaker Wire -

Cable Length as a Precent of Speaker Impedance Table

For Speaker Wire, it is generally regarded that 5% signal lose in the cable is acceptable, though you can usually do much better than that -

Here is the 3% chart as an example -

threepercentcablec-jpg.560674


These charts account for both Wire out to the speaker and back.

Here are additional Calculations for relating Power Handling Capability relative to Speaker Gauge.

Speaker Wire in Prespective -How much is Enough?

For example -

14ga wire (2.08mm²) would look like this -
* 279 sustained watts of power
* 1800 peak working watts of power
* 8192 max peak watts of power


There is another long thread, if you are interested, where I calculated Inductive and Capacitive loss for various degree of loss, and generally under 50ft it was never an issue. So, really little to no need to regard those aspects.

Speaker Cable Debate in Perspective - AVS Forum | Home Theater Discussions And Reviews

This gets pretty Mathy, but the conclusion, if you want to cut to the chase, is don't worry about it.

Steve/bluewizard
 
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BlueWizard

Distinguished Member
...by don’t use poxy “bell wire”
Can I assume that is - BUT don't use proxy "bell wire"?

Any Copper wire is probably fine. Though for Audio most prefer OFC (Oxygen Free Copper) of 99.99% purity, though that is not that hard to find nor is it that expensive.

In fact, very affordable.

https://www.amazon.co.uk/KabelDirekt-speaker-2x2-5mm²-Transparent-polarity-copper/dp/B01C79Z1FU/

https://www.amazon.co.uk/Fisual-S-Flex-Studio-Grade-Speaker-White/dp/B00JVSE5S0/

While it is wire, so it will work, most advise AGAINST CCA (copper clad aluminum). If the wire doesn't specify what it is, just move on, there are plenty of sources of wire out there.

Of the wire is going to be inside some type of raceway or conduit, or inside walls, then it needs to be CL2 or perhaps CL3 Fire Rated. But that is still not that expensive or uncommon.

https://www.amazon.co.uk/Mutec-Cable-Speaker-2-5mm²-Listed-Installation-White/dp/B00EO0912U/

https://www.amazon.co.uk/Monoprice-102821-2-Conductor-Oxygen-Speaker-White/dp/B001WHZ9K6

Just a few additional facts.

Steve/bluewizard
 
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ChuckMountain

Distinguished Member
As you can see, 2.5mm² covers most eventualities and you'd only really ever need wire thicker than this if the cable runs were exceptionally long. Even 1.5mm² wire would in your case suffice and may be easier to conceal if wanting to tuck it under your skirting and or carpeting?

Erm, your units are diameter not area?
 

Biryets

Standard Member
One thing to be aware of is how rare pure OFC coper cable has become.
While I’m an advocate of not paying over the odds for what is essentially a comodity.
Most cable on Amazon / ebay or even supermarkets is will definitely not pure copper.
That could explain why some of the gauge recomendations are conservertive for joe blogs.
Alot of speaker cable out there is copper clad aluminium (CCA). You cannot tell it apart with a naked eye.

Video below on how to tell CCA from Copper cable below.


After buying and returning a few cables. I settled on Konig speaker cable which is the real deal and you are not paying over odds for the fancy packaging or marketing
 

DT79

Distinguished Member

madfiddler

Active Member
Of the wire is going to be inside some type of raceway or conduit, or inside walls, then it needs to be CL2 or perhaps CL3 Fire Rated. But that is still not that expensive or uncommon.

So I’m tucking this under skirting boards and as I have a hard wood lamimate flooring there is edging/beading then down between it and the skirting that will hide the cables. Is the CL2 really necessary? There seems to be plenty of slim cables around that are advertised as suitable for that or even under carpet and other flooring but I haven’t seen that any of it is CL2/3...

If CL2 isn’t that expensive why not make it all that way?

I was looking at picking up one of these mutecpower cables and some extra banana plugs so I could split it into 3 (unfortunately they don’t have sizes between 5m and 30m it seems). https://www.amazon.co.uk/MutecPower...&sr=8-7&keywords=mutecpower+banana+plugs&th=1
 

BlueWizard

Distinguished Member
Erm, your units are diameter not area?
Um ... no pretty sure they are Cross-Sectional Area.

2.5mm² is very common wire closest to 13ga (2.62mm²). It is overkill for most needs but cheap enough, so that's what people use.

1.5mm² is still fine for a majority of amps at common lengths, and is the equivalent of 16ga (1.31mm²). I bit cheaper if you must save money.

14ga (2.08mm²) will sustain 279 watts pretty much all day long.

13ga (2.62mm²) will sustain 438 watts pretty much all day long.

As are can see both are more than adequate -

Speaker Wire in Prespective -How much is Enough?

Steve/bluewizard
 

BlueWizard

Distinguished Member
If CL2 isn’t that expensive why not make it all that way?
...

CL2 and CL3 are about the insulation used, not the actual wire. CL2/CL3 is Low-Toxicity when burning and flame resistant to keep you walls from starting on fire or choking you to death in a fire. But that only applies to in-wall or in conduit/raceway wire. Wire in the open does not have this restriction.

The likelihood of you having that problem are slim, but if the Building Inspector comes in, he might not be happy about it.

Steve/bluewizard
 

dannnielll

Well-known Member
Erm, your units are diameter not area?
Wire gauge is a diameter measure, whereas mm sq is the cross section area. The distinction is important because there are plenty of flat cables, both for loudspeakers and enternet with a broad but very flat profile. That makes them very suitable for under carpets, and behind skirting boards.
 

dannnielll

Well-known Member
Yes that actually was the first table of info I looked at from the Cambridge audio web site, then subsequently seen some places selling 1.5mm² wire as 16 AWG and others as 15 AWG. Then a lot more talk about using 2.5mm²....
The cost of wire is the cost of the metal and the cost of the plastic insulation. The cost of insulation is about the same for 2.5 mmsq and 1.00 mmsq ,so getting the thicker wire does not carry much of a premium. When one gets to 3.5 or 6.5 mmsq,the insulation price is a constant,but the volume of metal is rising rapidly...
 

ChuckMountain

Distinguished Member
Um ... no pretty sure they are Cross-Sectional Area

Yours are but Dante's are not the table only quotes diameter and then compares those against a cross section value. My point is that you need to make sure the units are the same when doing the table lookup. You need to do a little bit of maths, albeit simple, but it's not a straight look as I read the post.
 

dante01

Distinguished Member
It was a mistake on my part and I was refering to the diameter as opposed to the area :)



The post has been edited accordingly to avoid any further confusion.
 

dante01

Distinguished Member
THe mistake does give rise to an interesting point though relating to flat cables or cables whose form doesn't conform with the norm. You'd still want these cables to have the same or similar cross sectional area to the conventional cables which express their gauge using AWG (American Wire Gauge) or as a diameter. The following may help in regards to this:

snapshot001.jpg

Wire Gauge Converter - AWG versus square mm
 

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