I think what Winter was assuming was that everyone was bearing in mind that the signal is isolated from the shield on these types of cables. Most systems actually run the shield to a ground, which typically keeps the induced noise isolated from the signal all the way from source to reception. Some systems also use a Balanced Line Driver application to reciprocate and therefore cancel out the induced noise.
Your statement is correct, but it goes under the assumption that the installer is going to isolate the UTP cable from sources that commonly induce noise. Ideally, ALL signal cable will be completely isolated from ANYTHING that will induce noise, but we all know that, in some cases, this is almost impossible.
Eliminating points of contact with possible noise sources is the best method of eliminating induced noise. If this is impossible and the signal must come into close proximity with a potential source of noise, using a decent shielded cable that keeps the signal isolated from the shield will help to minimize the possibility of induced noise. Also, minimizing the points of contact between the signal and noise as much as possible will keep the possibility of induced noise at a minimum.
Sorry for any confusion.

 

^^
thankyou UV7

i didn't have the need to explain in detail as to how a proper shielded wire worked other then the fact that are designed specifically to resist and or effectively cancel out signal noise.

the shielding material is normally ran directly to the main amp ground and is isolated within the amp so that it is to never come near any of the processing being done so that it keeps signal noise to the most minimum possible points. even a system that is completely shielded from all noise will still have noise, you just wont hear it.

 

Glad to see you seem to understand the topic, unlike Winter.

I agree a balanced design is definitely best for noise rejection & prevention, but my comments only pertained to standard implementations. Most people don't use balanced cables due to the additional cost & complexity of such systems (compared to non-balanced), and because they're not usually needed in most modern vehicles.

Routing of cables used to be very important (as you indicated), but it's much less so now. I do have to question one of your statements, "...it goes under the assumption that the installer is going to isolate the UTP cable from sources that commonly induce noise", because it leads me to believe you may not understand that the twisted-pair design itself is noise-resistant. The thing is, shielded cables cost more and they're not needed to ensure a noise-free install in our Scions. I'm personally using inexpensive unshielded twisted-pair and don't have noise, and there are many others who've done the same, so there's no need to recommend that people buy shielded. The entire car body is a big ground, my UTP cable is right up against it (and all those moving electrons) all the way from the dash to the hatch, yet I don't have noise, so why buy, use or recommend shielded or balanced-line for our vehicles when it's not needed?

That was the only real point I was trying to make in that initial post in this thread. At least now some of the newbs have more info to ponder, and can make up their own minds about which type of cable they choose and why. I just get concerned when I see misinformation (incl. incomplete info) and recommendations that people who don't know any better might act upon.

 

ok, so my schooling was wasted time in my life and the experience i've had is also a waste...

didn't realize we were targeting each others opinions... different experience gives different opinions. my experience is from the live field, not car audio. so for you to target me and say i don't understand is ridiculously.

whatever... believe what you wish to. i'll go on doing what i've always done because it's never failed on me.