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Discussion Starter · #1 ·
HI ALL


I will be doing a speaker wire DIY project soon.


2 months ago I came across a site that offered a good correlation between capacitance vs induction when the conductors are moved either "closer to" or "further from" each other.

This site suggested a design solution which was to give low inductance + low capacitance to a speaker wire.


I FORGOT TO BOOKMARK THE SITE:( :(


Does anyone know the link???



brian
 

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Discussion Starter · #3 ·
Quote:
Originally posted by Bill Lummus
greater space= higher inductance + lower capacitance

smaller space= lower inductance + higher capacitance
YEA! U BET

In order to get the best of both worlds the site offered some kind of design solution with this fact in mind.

It beats the heck out-of-me as to what the solution was. :confused:


Thanks
 

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Discussion Starter · #5 ·
Quote:
Originally posted by Bill Lummus
Search on Yahoo for Jon Risch.


He has a low capacitance, low inductance twisted pair coax recepie. I use it, it is excellent.
BILL

Funny that you suggested Jon Risch


Today I received a reply to a similar posting I made over on the Audioholics Forum.

And included was a comment from one of their staff members that caught my eye.


Only for what it is worth I guess.

The guy slammed Jon


brian
 

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Because you loose all shielding, and increases pair-to-pair capacitance dramatically. So this cable COULD cause a power amplifier, especially a valve or tube amp to oscillate, and may cause frequency response roll-off. It would be better to just use zip-cord.
 

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I disagree-


Most speaker cables- including zip cord- is not shielded so the lack of shielding is of no consequence.


Secondly- the pair-to-pair capacitance of this cable is much lower than other high-end speaker cables on the market including any sort of braided configuration. Most speaker cables are designed to be low inductance and this generally occurs at the penalty of fairly high capacitance. Certain companies like Nordost have created some cables with fairly low inductance and capacitance but the higher capacitance seems to have very little, if any, negative audible consequences. The cross-connected coax has a measured capacitance of 49pf/ft, Zip cords usually run about 20pf/ft, but Goertz AG-3 has a capacitance of 1.5 nf/ft (which is 1500 pf/ft) and this is considered an excellent cable for many systems. Many of the speaker cable designs on the market use a braided or twisted pair geometry (for example- Kimber) and these will all be higher capacitance than the cross-connected coaxial construction.


Unless you use runs of more than 100 feet or use and amplifier with an op-amp for an output stage the difference in capacitance between the coaxial design and zip cord is inconsequential and shouldn't drive any modern amp into oscillation.


What sort of frequency roll-off do you think this is going to cause?
 

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Bill;


You raise valid points. However, I also wouldn't recommend using coax cables as speaker cables. The DC resistance is still too high and the pair to pair capacitance would be over 50pF/ft as you alsoconfirmed. resulting in a difficult load to many amplifiers if cable lengths are reasonably long, say over 50ft. I really think audio people tend to play down the importance of a cable with low capacitance just to reduce inductance. I wouldn't give amp companies, especially tube amps, too much benefit of a doubt regarding their margin of stability they design into their products.


The high capacitance may cause problems of overshoot or ringing more than traditional rolloff. Also, the added DC resistance will result in more than 0.2dB loss througout the audio band into a low impedance speaker load compared with ordinary 12AWG zip cord.


I really think DC resistance is primary, inductance is secondary concerning speaker cables.
 

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50ft x 50pf/ft =2500 pf. That is equivalent of less than 2 feet of Goertz AG3. I've prevously used a DIY braided design with a measured C of >7000 pf with no problems on amps from B&K, BEL, and Krell. The generally accepted values are
 

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Nice answer Bill. While I am a tweaker and a wire nut myself, there are FACTS out there that outweigh hype and paranoia. Sometimes, as you state above, we know what to measure, sometimes we don't. Listening and trial and error still reign supreme.
 
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