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33 foot speaker cable capacitance

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Posted on February 6, 2016 at 11:05:50
mobiasloop
Audiophile

Posts: 100
Location: SW Missouri
Joined: August 14, 2014
I'm hiding my speaker cables under my house to satisfy my better half. I know it's best to keep cable capacitance to a minimum. But what would be the optimum and never to exceed limit in capacitance on a 33foot run. I'm hiding all the components in a closet and the speakers are a minimum of 33 feet (allowing for up and down) to each speaker wall terminal. I'm choosing twin twisted pair coas that is braid shielded because I have to cross the 220 service entrance power to the house run which is under the house also. I was told if I twist the two 20AWG conductors together I will achieve lower capacitance. Thanks, Jim
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare

 

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RE: 33 foot speaker cable capacitance, posted on February 6, 2016 at 15:11:06
Triode_Kingdom
Audiophile

Posts: 10012
Location: Central Texas
Joined: September 24, 2006
Speakers represent a very low Z load in relative terms, so any reasonable amount of capacitance will be swamped by that. I think it's not likely to be an issue unless the amplifier is operating on the verge of instability. Twisting will require more unit length of wire to reach from point A to point B. I don't see how that would reduce capacitance.



 

RE: 33 foot speaker cable capacitance, posted on February 6, 2016 at 19:56:33
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
I think you want to revise the AWG of the speaker runs at 33 feet. 20 AWG will be VERY lossy, terrible !!!

I would use three, maybe even four runs of 12 AWG in parallel, to equal ( 3 is ) about 8 AWG, and ( 4 is ) about 6 AWG . Then, you will have proper PEAK current capability,, and great, really good transfer-efficiency !!

Reasonable-in-cost 12 AWG would be military surplus, copper stranded, and silver plated in a Teflon jacket, Apex Jr, etc has it, ask for Steve and tell him I sent you.

Jeff Medwin

 

RE: 33 foot speaker cable capacitance, posted on February 6, 2016 at 21:53:47
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
Something like Canare 4S11 is 146pF per meter, so you're looking at roughly ten times that. 1500pF of capacitance on an amp with a 1 Ohm output impedance will be bandwidth limiting somewhere over 1mHz.

I don't think you're going to have any problems crossing your power feed.

 

Thanks! nt, posted on February 7, 2016 at 07:10:13
mobiasloop
Audiophile

Posts: 100
Location: SW Missouri
Joined: August 14, 2014
nt
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare

 

RE: 33 foot speaker cable capacitance, posted on February 8, 2016 at 10:16:40
Lew
Audiophile

Posts: 10911
Location: Bethesda, Maryland
Joined: December 11, 2000
I am not as extreme about gauge as is DLM, but I would have to agree with him in this case, in that 20AWG just does not "feel" like it's enough wire thickness to go 33 feet without some losses. (Resistance of 33 feet of 20AWG = 0.335 ohms.) Four runs of 20AWG in parallel would give you around 14 gauge, I think. That should be "enough". I'm ashamed to admit I would shoot for a net of 12ga total, even though the math would suggest it's overkill. Parallel runs of smaller gauge wire (e.g. 20ga), where each of the wires is insulated from the others in the bundle, is how I would do it. I freely admit my thinking here is more touchy feely than scientific.

 

Thanks Lew nt, posted on February 11, 2016 at 07:54:01
mobiasloop
Audiophile

Posts: 100
Location: SW Missouri
Joined: August 14, 2014
nt
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare

 

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