After nearly a year of gathering parts and testing room arrangement I'm about to put my surround speakers on walls, rather than sitting on top of something. The speakers can be biwired, and I may experiment to see if they sound better that way.

If I go with biwiring I will put double runs of 2-wire cable in the attic to each speaker, but I don't want to do double runs from my 1070 to the wall plate where the cables ascend to said attic.

I know that if you double the diameter of a pipe the volume of fluid it can carry quadruples. Is the same true of a wire? If I use double runs of 12 guage cable to the speakers, how big should the cables from the 1070 to the wall be?

Thanks, Bob

Bob,

Please check out this site for a guide on choosing wire sizes.

Bob,

Doubling the diameter of the pipe increases the cross sectional area by a factor of 4. It increases the flow volume at a given head (differential pressure or pressure drop) by a factor of 16.

Wire is different. Resistance is directly proportional to length and inversely proportional to cross sectional area (neglecting skin effect). You must choose how much resistance you are willing to tolerate between your amp and speakers and this will determine the wire size you need to use.

Well, if I could have done all tbat math I might have gone to engineering or medical school. Because I couldn't I ended up in law school.

I estimate my cable runs from the wall to the speakers will be 35 feet and the run from the 1070 to the wall 6 - 8 feet. My surround speakers are B&W CDM Snts which are 8 ohms. It would appear that 12 gauge cable would be more than sufficient for the total, less than 50 feet.

So my question is, what gauge cable from the 1070 to the wall best maintains resistance consistent with the cabling in the wall? Will a 12 gauge cable work, even though it is then doubled in the wall to biwire the speakers?

Maybe it doesn't matter and I should just make a set of jumpers for the speakers.

All thoughts gratefully accepted.

I'll spare everyone the pipe sizing analysis (believe me, you're glad I did ). I would agree that 12ga wire should be fine for your application.