Why does shielding matter?

msg

Was just reading another post moments ago ( @tonyb 's post re: 75Ω vs 110Ω digital coax) and a question came to mind after reading a response from @OleBoot mentioning experience with using a non-shielded cable, noticing detailed, but thin performance.

Why does shielding matter? What is its function?
And is loss of bass and empty midrange to be expected without proper shielding?
If so, how does this happen? Inbound contamination? Signal escape? Both?

tonyb

Noise rejection basically. Why some sound better unshielded, I dunno, but imagine it has something to do with the material used and it's effect of the signal. Somebody may chime in with a more technical reason, but personally I've never experienced a difference in either.

Let me re-phrase that, I've never had the same cable, one shielded and one not. I have used both types before but not the same exact cable. Could not tell a difference noise wise.

OleBoot

msg, my reply to tonyb was was more a generalized example of using an "out of spec" cable for digital interconnect than it was a comment about screened vs unscreened cable. Unless you want to place your interconnects next to your power cables or on top of the power supply in your amp, or you live next door to a sub station or SETI, I doubt if there's an inherent difference. On the other hand, I do think that I notice a difference in sound quality when my wireless internet fridge is messaging my wireless internet toaster.

msg

OleBoot wrote: »

my reply to tonyb was was more a generalized example of using an "out of spec" cable for digital interconnect than it was a comment about screened vs unscreened cable. Unless you want to place your interconnects next to your power cables or on top of the power supply in your amp, or you live next door to a sub station or SETI, I doubt if there's an inherent difference.

sure, sure, I understand. it was the bit about your perception of the sound quality, specifically - thin and weedy - that caught my attention, and just got me thinking and wondering what shielding is for, and whether my use of cheap (possibly unshielded?) cables is/was the, or contributing, cause of what could be better bottom end and richer mids issues. until recently, I'd been neglecting cables altogether; I just couldn't see it making that much of a difference. that was until I tried it for myself and began to notice some not-exactly-subtle differences, so now I'm trying to learn about cables designs and why some sound more detailed than others, but may lack bass and mid presence, while others seem more balanced across the range, which ultimately is my goal for system sound quality.

btw, how would you describe a weedy sound? still feeling my way through these sound quality descriptions. would that be congested?

On the other hand, I do think that I notice a difference in sound quality when my wireless internet fridge is messaging my wireless internet toaster.

haha, Skynet in your home. nice.

Speedskater

Remember that EMI/RFI interference will be situation specific and often time specific. Any new item that you purchase and plug into AC power has the potential to generate interference. That's new lights & lighting systems, appliances, communications, entertainment and wall-worts. While many shields are connected at both ends, not all are.

kevhed72

Why is the coax for my satellite tv service double-shielded....just curious, unless we are talking about different things here...

F1nut

For the same reason other signal cables are, to help prevent EMI/RFI interference.

Conradicles

It is huge in the RF world. In the audio world it is not so huge, but a factor.

CoolJazz

In the RF world, very important is the loss and stable impedance characteristics. Not that noise doesn't have impact.

In the satellite system, it's all about the losses at the high frequencies involved. It wasn't until much of the frequency downconversion was moved indoors, before such cable could even be used at all. The home systems use 950-1450mhz for what's known as L band.

CJ