Speaker cable runs - how far?

[Danno13]

Hoping someone can help with this....

How far is it possible to run speaker cables without experiencing a significant loss? Is there any way to calculate how much you'd loose? I expect diamter of cables would be a factor and possibly some specification on the amp as well?

[theoloyla]

The thicker the cable the further you can run it.

[Danno13]

Yep.. thats what I thought, but I was after some real measurements for say 2mm or 4mm cable - how far is too far? 30m? 50m? 150m? Oh.. and run at 4ohms most probably.

[TonyB]

This page may help http://www.roger-russell.com/wire/wire.htm.

It depends on the thickness of the wire but the maximum with the thickest wire seems to be 50ft.

[Danno13]

Thanks Tony, useful info there.. although I can't work out how the AWG rating coresponds to the diameter of the cable.. the Wiki article on it just confused me even more!

Oh, hang on.. I think i've got it 3mm^2 cable is roughly 12AWG and 1.5mm^2 cable is around 6AWG.. although that makes no sense, as according to the table on the link you posted, the lower the AWG the longer the run can be!

[jimboylan]

As the AWG goes lower the mm2 goes higher.
Table here

Jim

[Andy Westcott]

Also, if you can run at 8 ohms the losses will be a lot less. And if you can run into 16 ohms, even better.

What exactly is it you wish to do?

[Danno13]

Its for PA at an outdoor fete.

[Andy Westcott]

To be completely realistic, if you are using 2.5mm CSA wire, you can run it pretty much as far as you like within reason.

There will be some slight power loss, and less of what we call 'damping factor' due to the cable's resistance, but in this application I really don't think that matters - no-one is going to expect hi-fi standards of bass control.

As an example, if the total cable resistance measured a whopping 4 ohms (that'd be a pretty long run) the speaker's output (assuming it was a 4 ohm unit) would drop by about 6dB - hardly earth-shattering in outdoor PA terms. An 8 ohm unit would drop less than this.

Go for it, and don't worry about it - it isn't a big issue. Just have a reasonably powerful amplifier so you can shove some decent voltage down the line to allow for the slight drop.

[Danno13]

Cheers Andy,

It's most probably going to be in 4ohm and I'll run two speakers on each side of the amp, one about 20m away, then another as far aware as I can manage! Would it be a good idea to wire them in parallel to get 16ohm instead? Or would the benefits be counteracted by the fact the amp will supply less power?

Channels of amp power avaliable are 4 x 400w (8ohm) 2 x 250w (8ohm) and 2 x 450w (8ohm).