Cable Design Ideas
Jun 21, 2010 at 3:47 PM Thread Starter Post #1 of 10
weibby

weibby

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By design I don't mean aesthetics but rather functional ones, what are the impending problems and what are the engineer design in place to resolve it?
I hear alot of talk about "well designed" cable by XXX, some with floating ground and shielding/twisted with some kind of explanation for capacitance and Inductance.
 
How do you test for that?
 
Anyway form of ideas from an engineer stand point is welcome.
 
Jun 21, 2010 at 3:56 PM Post #3 of 10


Quote:
momomo6789 said:
wires all test the same unless their totally screwed up.
Click to expand...


Comments like that mean so much more when linked to evidence, though I do agree with you.
 
The issue with this is that so many claims are made by cable makers, but they cannot be correlated to sound quality. Proof of that is found through out this and all other audio forums where some report no difference, others report differences, but different differences even with the same cable. Blind/ABX tests find that people cannot reliably pick out different cables and have even claimed to hear a difference when identical cables are disguised and then listened to. 
 
To me well designed means it works and is made safely to a good standard. Pretty is good to, but that is obviously very subjective.
 
Jun 21, 2010 at 4:15 PM Post #5 of 10
 
Quote:
weibby said:
some with floating ground and shielding/twisted with some kind of explanation for capacitance and Inductance.
 
How do you test for that?
Click to expand...


Sorry for the smart answer:
You use a capacitance or inductance meter. It usually needs to be fairly sensitive, or you need a longggg cable.
 
As with anything, a measurement without determining what matters is meaningless.
 
there are a few reasons either of those thigns could matter.
 
Parallel capacatance can be killer in interconnects, as well as to certain speaker amps. When multiplied by the length of the cable (parallel capacitance for commercial cables is given in "XXXpf/m" (or pf/foot)) you can determine the total capacitance of the cable. As you can imagine the capacitance of a long (like more than 20-50ft) can be exceptionally high, and will present a difficult load for the preamp. This is an important piece of information to consider if you are building very long cables, or have a source that you know does not deal well with excessively capacitive loads. 
 
Inductance also matters. Inductance is more important on speaker cables, where too much inductance in series with the driver creates a low-pass filter. Fun Fun.
 
Dismissing the measurable effect of a long cable out of hand is a little off... The effects are smaller for shorter cables, such as found in a home hi-fi system, but can quickly creep back at you if you use certain equpment. Sources with high output impedances are particularly sensitive to cable capacitance, and amplifiers with exceptionally wide bandwidth are not known for playing nice with highly capacitive cables either. 
 
Jun 22, 2010 at 11:35 AM Post #8 of 10
The only issue that has any definite effect IMO is attenuation, which is a means of reducing the voltage from the source to match the receiver. Sometimes attenuation is built into cables, such as Russ Andrews Kimber or else you buy plugs that go on the end of interconnects such as by Rothwell or Goldenjacks. In a cable alone, you would need very long lengths before there is an issue.
 
 http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/attenuation.htm
 
The result of such is that you get far more volume control with the amp or pre amp, which means clarity and dynamics start from a low volume and go higher before distortion sets in. 
 
 
Jun 23, 2010 at 8:21 PM Post #10 of 10
Some things you might want to check out when considering home building interconnection cables...
 
Capacitance
Microphonic signal generation
Shielding from airborne electromagnetic interfearance
Temperature effects
Physical protection from chafe, crush and cut
 
The vast majority of equipment loads (amp input stages for example) will require less than 1 mA, and almost never more than 3 mA, so current capacity is not going to be an issue.
 
Remember to consider the connectors, as dimensional accuracy, surface material and surface condition are all significant.
 
 
'till later
: )
 
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