Wiring Stereo Speakers

makingplansfor

makingplansfor

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I am planning on having an extra set of speakers on a wandering lead so I can get music where I want out on deck. I am using a specific speaker connector which has 4 terminals marked +1 -1 +2 -2 which I assume the + to be signal and - the return. I bought 15 M of 2 core speaker cable from Maplin's and was surprised that the screen on each core was touching and therefore shorting.

I have no knowledge of sound systems beyond normally having 2 separate 2 core cables, one for each speaker. Is it normal that the returns for stereo speakers are common??

Thanks in anticipation....
 
regarding the "-", some radios do use a common negative (Cheaper ones usually) it is essential to make sure that the +&- of each speaker is connected to the correct tag, otherwise distortion will be heard especcially with speech.
 
No, you wont get distortion. What you will get is one speaker 180 degrees out of phase with the other. Ie... It will be pulling, when it should be pushing... And vice versa...
If you have distortion, then you have another problem.
 
As said if the output connections do not have a common -ve then you may cause problems by connecting the 2 negatives together.
A low powered audio amp or radio is probably OK (ie claimed 8 watts or so per channel)

To get more power from the usual complementary symetry output amplifier from a 12v supply involves all sorts of jiggery pockey which can leave the 2 speaker output lines above earth. So potentially different to one another.
So unless it is just a cheap car radio I would make sure that the negatives are isolated one from the other. So you need a 4 wire cable. A piece of ethernet (is it called cat 5?) cable will provide enough insulated conductors. Or use 2 wires of 1 pair each.
No it does not need to be screened although no problem if they are screened provided you can insulate the 2 screens. good luck olewill
 
I wouldn't recommend using ethernet cable to connect speakers, especially if it's for movable ones - ethernet cables are solid core and don't like to be flexed too much, and the cores are quite thin. Best to use 1.5mm speaker cable - most 4-channel car-type stereos are 40W per channel, so the speaker cable needs to handle at least 3.5A of current. Bigger cable is better! If you have screened cable, Maplins sold you the wrong stuff...:(
 
greenalien said:
I wouldn't recommend using ethernet cable to connect speakers, especially if it's for movable ones - ethernet cables are solid core and don't like to be flexed too much, and the cores are quite thin. Best to use 1.5mm speaker cable - most 4-channel car-type stereos are 40W per channel, so the speaker cable needs to handle at least 3.5A of current. Bigger cable is better! If you have screened cable, Maplins sold you the wrong stuff...:(
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Have you ever put an ameter across the back of a hifi... I doubt you would see anywhere close to 3.5 amps
 
Thanks all, I am beginning to think that Maplin have sold me the wrong stuff. As I am keen to have all cores in a single cable, would a simple 4 core cable do the trick or are there any other considerations?
 
greenalien said:
I wouldn't recommend using ethernet cable to connect speakers, especially if it's for movable ones - ethernet cables are solid core and don't like to be flexed too much, and the cores are quite thin. Best to use 1.5mm speaker cable - most 4-channel car-type stereos are 40W per channel, so the speaker cable needs to handle at least 3.5A of current. Bigger cable is better! If you have screened cable, Maplins sold you the wrong stuff...:(
Click to expand...
Actually ethernet cable can make pretty good speaker cable, it certainly out-performs the sort of speaker cable Maplins sell.
 
makingplansfor said:
Thanks all, I am beginning to think that Maplin have sold me the wrong stuff. As I am keen to have all cores in a single cable, would a simple 4 core cable do the trick or are there any other considerations?
Click to expand...

If you are having all the cores together, do you need two speakers?

I can't think of less appropriate cable to use than Ethernet cable, the cores are far too thin, and are solid.
 
bedouin said:
That is exactly what makes it a great speaker cable...
Click to expand...

Being far too thin, and a solid core is good for speaker cable? You are having a laugh, surely? The best speaker cable has hundreds of cores, as the high frequencies travel only on the surface of the conductor. They are also normally huge, at least 2.5mm² and made with Oxygen Free Copper (OFC).

[EDIT]

Here is a "mid-range" type at a very low price: http://www.amazon.co.uk/exec/obidos/ASIN/B0086X6VHO/dolcetto-21
 
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bedouin said:
That is exactly what makes it a great speaker cable. Wouldn't recommend it for a mobile installation though.
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Like a boat, for example? (see OP)

Ethernet cable is far too thin and fragile to use for speakers.

Cable should ideally be multi-strand of at least 1.5 square mm per core. 2-core mains cable works quite well for low-powered systems, but Maplin, etc. sell suitable speaker cable - the only difference is that the cores are coloured red and black rather than blue and brown, to avoid confusion.

The connectors the OP refers to sound like "Speakon" connectors. For a single speaker, you would normally wire the red core to 1+ and the black core to 1-. If both speakers wired to the same connector (not normally done) then wire the left one to 1+/- and the right one to 2+/-.

By the way, don't do as someone earlier suggested - connect an ammeter across the terminals - chances are you might damage the amplifier. If you really want to measure the current, connect the ammeter in series with the speaker. However, current carrying capacity isn't the only reason to use heavy gauge cable for speakers (although, if you deal with PA systems it becomes important!) - for best sound quality, there needs to be a low resistance connection between the amplifier and the speaker, the lower the better!
 
nigelmercier said:
Being far too thin, and a solid core is good for speaker cable? You are having a laugh, surely? The best speaker cable has hundreds of cores, as the high frequencies travel only on the surface of the conductor. They are also normally huge, at least 2.5mm² and made with Oxygen Free Copper (OFC).

[EDIT]

Here is a "mid-range" type at a very low price: http://www.amazon.co.uk/exec/obidos/ASIN/B0086X6VHO/dolcetto-21
Click to expand...
I'm guessing you've never tried listening to them - if your speakers are bi-wireable then they are particularly good for the tweeters. Massive number of strands may be good for subwoofers but they just don't do it for treble.
 
bedouin said:
I'm guessing you've never tried listening to them - if your speakers are bi-wireable then they are particularly good for the tweeters. Massive number of strands may be good for subwoofers but they just don't do it for treble.
Click to expand...

Wrong again.

Subwoofers may need the high current "grunt" hence large copper area, but the "skin effect" Nigel refers to is a high-frequency effect and applies particularly to tweeters.
 
mikefleetwood said:
Wrong again.

Subwoofers may need the high current "grunt" hence large copper area, but the "skin effect" Nigel refers to is a high-frequency effect and applies particularly to tweeters.
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So have you ever listened to them? I'm guessing from your comments that you haven't so how can you be so sure?

Don't forget CAT6 cable is designed to carry signals up in the GHz range - it is much better at carrying high frequency detail than massive wads of copper.

In fact the "skin effect" means that the high frequency current is actually largely carried in the insulation rather than the copper itself, so the individually insulated strands in CAT6 cable are much better than a mass of uninsulated strands.
 
bedouin said:
That is exactly what makes it a great speaker cable......
Click to expand...

Huhh:confused: Only if you like the sound of distorted music, which of course most audiophiles do;) (Lights blue touch paper...............)

You are best using a 2-core cable with a cross sectional area suited to your speaker power rating and length of cable run. Use a separate cable for each speaker. Any low cost, flexible cable (preferably tinned to protect it from the marine environment) will do. You can also use single core cables which might be a cheaper option.

There is no harm in using screened cable but there is no point either and it will cost you more.

If you use a common 0V (earth/ground) core you will induce some inter-channel modulation (distortion) even if they are connected together in the radio itself.

Some radios use class D amplifiers which have a push-pull mechanism for the + & - connections. In that case no speaker wire is common with another or 0V and your system will not work correctly if at all.

So to make some assumptions;
Radio power supply = 12V
Speakers 4 ohms, 40W.
Cable length, radio to speaker. 4m.

Peak speaker current = 12V / 4ohms = 3A

Your cable resistance should be significantly less than the speaker, say 10 times. So for a there and back length of 8m (2 x 4m) the cable's resistance should be less than 0.4 ohms.

0.4ohms / 8m = 0.05ohms per meter.

Now we can calculate the CSA for a copper cable that will give use no more than 0.05 ohms per meter.

CSA = Resistivity of copper / 0.05 ohms = 0.65mm2

Now if you don't expect to run your system flat out, your cable run is shorter, your speakers are lower power you can use a smaller CSA.

So there are 3 important things for the cable specification;
1. CSA, so that the power is delivered to the speakers and doesn't just heat the cables and cause distortion.
2. Multi-strand so that it is flexible and doesn't break.
3. Tinned so that the salt air and damp don't corrode the copper.

There is no harm in using a bigger CSA.

Finally and as mentioned by others, make sure your speakers are "in phase". IE, the + terminal on the left channel is connected to the same terminal on the left speaker as the right is on the right hand speaker. It doesn't matter which way around they are, just that they are the same.

It is true that an ammeter connected in your speaker cable will never show the large currents; that is because the peaks are transient and much too short for a multi-meter to register. Also a multi-meter on any setting less than 10A will increase the cable resistance significantly and so reduce the current. We are sizing the cable to handle the peak, not the average or RMS currents.
 
bedouin said:
In fact the "skin effect" means that the high frequency current is actually largely carried in the insulation ...
Click to expand...

Please can you stop talking nonsense so we can try to help the OP with sensible suggestions.

I repeat my earlier question, as it has become hidden by the dross:

If you are having all the cores together, do you need two speakers? If not, you can wire them as a mono-mix very easily.
 
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