Long run of speaker cable?

[Gaz]

Due to a sudden reconfiguration of room layout bt SWMBO one of my speakers has found itself partially hidden behind a sofa, something that is far from ideal.

The only solution I can think of is to relocate both speakers to the other end of the room, unfortunately the rest of the system has to stay put. This will mean approx 11m runs of speaker cable (the room is about 7m but the cables will go under the carpet and one will need to go across the room as well as along it)

What guage of cable should I use for this kind of length?
I'm not interested in discussions about brands or materials, whatever I use will be the cheapest copper cable of the correct thickness I can find, I've tried fancy cable in the past and heard no difference whatsoever.

Thanks

[Firebottle]

With an 8 metre run of 2.5mm squared cable I measured 0.125 ohms per conductor, so that was 0.25 ohms for the rum there and back.

With your longer run I would use 4mm squared, something like this https://www.ebay.co.uk/itm/electrosmart-10m-2x-4mm-Loud-Speaker-Cable-Wire-Multi-Strand-540-2x-270-Strand/331231435087?hash=item4d1eee994f:g:u6UAAOSwjDZYb3E j

Message them to see if they can supply 2 x 11 meter runs. There are plenty of other suppliers.

[Gaz]

Thank you

[blackmetalboon]

With an 8 metre run of 2.5mm squared cable I measured 0.125 ohms per conductor, so that was 0.25 ohms for the rum there and back.

That measurement seems quite high. I’d expect it to be around half that.

[Macca]

Or maybe 0.025?

[blackmetalboon]

2.5mm² copper cable has a resistance of 7.41mΩ/m, so the loop resistance for a 8m cable should be around 0.118Ω.

[struth]

Would have expected 2.5mm dia cable to be in the thousands of an ohm per metre, dc resistance

[Stryder5]

* thousandths *?

Gary

[Firebottle]

My measurements were made at 120Hz, not DC, so would include some inductive reactance.

[Macca]

Handy chart here showing the thickness of wire required for the length of run if you don't want to get roll-off

https://i.imgur.com/TJLJRMa.jpg



So over 11 meters you should be fine with 14awg, 12 awg if you want to be sure.

[blackmetalboon]

American Wire Gauge (AWG) to mm² conversion chart.

http://gemsaid.com/images/Conversi%C3%B3n-AWG-MM2.jpg

[Barry]

In order to maintain a decent damping factor, the rule of thumb is that the loop resistance of the speaker cable should be no more than 5% of the nominal impedance of the speaker. Don't worry about the ohmic loss - it will be negligable; as shown by the graph in Martin's post above.

[Gaz]

Thank you all for the advice

I've order a 25m reel of 4mm cable now.

Thanks again

[Gaz]

Cable arrived yesterday and speakers successfully relocated away from offending furniture.

As the speakers are now in a different location it's impossible to say if the cable has made any improvement, it's twice as thick but also twice as long as the old cable.

Just under £1 per metre Inc delivery