Electronics > Projects, Designs, and Technical Stuff
Speaker Wire and Calculating Guage
DW1961:
How do you calculate what size wire you need for speakers and amps?
I am familiar with this site http://www.roger-russell.com/wire/wire.htm#wiretable
However, when I ran my original speaker wire, I didn't know it was CCA wire (Amazon brad), so now I want to redo my calculations. Also confounding my calculation is , how do I know what the resistance is for CCA wire? I've read that the skinning affect actually reduces resistance is CCA wire (since there is some copper on the outside) so it's not just like calculating for copper or aluminum.
bob91343:
Don't overengineer it. Just use a heavy enough gauge to avoid adding too much resistance to the circuit. After all, it's often an 8 Ohm setup so any resistance greater than a half Ohm or so begins to take away from the output power. Skin effect is seldom important.
16 AWG is about 0.004 Ohms per foot. So 100 feet of cable has 200 feet of wire in it, for a resistance of around 0.8 Ohm. That is beginning to be significant but you are unlikely to hear any difference.
themadhippy:
--- Quote ---How do you calculate what size wire you need for speakers and amps?
--- End quote ---
Either use ohms law , work out the current the cables handling,decide on the maximum acceptable volt drop,with these you can calculate the maximum acceptable cable resistance and use the resistivity of the desired cable material to find the cross sectional area of the cable that meets that. Or just chuck in the biggest lump of copper you can find/afford,no need to go exotic,plain old 2.5mm twin n earth* is just as good as virgin free oxygen dusted audiograde cable
*romex i believe is the equivalent in foreign parts
DW1961:
--- Quote from: themadhippy on July 20, 2020, 11:03:21 pm ---
--- Quote ---How do you calculate what size wire you need for speakers and amps?
--- End quote ---
Either use ohms law , work out the current the cables handling,decide on the maximum acceptable volt drop,with these you can calculate the maximum acceptable cable resistance and use the resistivity of the desired cable material to find the cross sectional area of the cable that meets that. Or just chuck in the biggest lump of copper you can find/afford,no need to go exotic,plain old 2.5mm twin n earth* is just as good as virgin free oxygen dusted audiograde cable
*romex i believe is the equivalent in foreign parts
--- End quote ---
HAHA, yeah Romex would be fun to work with! lol Romex in the US is solid core plastic PVC coated wire. Nasty stuff unless you are running house wires.
james_s:
I've never bothered to calculate it. 16AWG lamp cord works fine for the sort of lengths you'll find in a typical house at the sort of power levels I'd ever be interested in having. If you're dealing with unusually long lengths, really high powers or something exotic then you might want something heavier. These days amplifier power is cheap and typically the RMS will be only a few watts, I know audiophiles will cringe when I say this but a bit of loss doesn't really matter. Just don't use ridiculously thin wire like the stuff that comes with a lot of cheap consumer gear and you'll be fine.
Also, CCA is garbage. I got screwed a while back when I ordered a box of CAT5e thinking "wow this stuff has gotten cheap!" and then realized after I went to use some that it's CCA which doesn't even meet the spec to be called CAT5 in the first place. I probably should have complained and sent it back to Amazon but I never got around to it.
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