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#1
Posted to rec.audio.pro
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Conductive PVC Shield
Out of curiosity, I just stripped the jacket off of a cheap microphone
XLR cable that came with an Audio Technica ATR2100 microphone. There is a second jacket inside the outside jacket. If the cable is the same as the one at the link below, the inside jacket is a "Conductive PVC Shield." https://www.bhphotovideo.com/c/produ...ies_XLR_M.html How effective is the conductive PVC shield? I assume it's crap, but can it be quantified? Is it 50% as effective as a foil or 100% braid shield? 30%? 80%? I used one of these cables in a pinch and was surprised when there was a little noise in the system. It will be interesting to see whether a real cable will clean it up. Bonus question: What's your favorite bulk XLR mic cable (other than star quad types?) |
#2
Posted to rec.audio.pro
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Conductive PVC Shield
On 10/1/2018 5:44 PM, mcp6453 wrote:
How effective is the conductive PVC shield? I assume it's crap, but can it be quantified? Is it 50% as effective as a foil or 100% braid shield? 30%? It's just fine. The percentage that you sometimes see related to a shield has to do with how tight the braid weave is, but since there's no braid in this type of cable, there's no number. If the microphone output is balanced and it's going to an amplifier with a differential (most say "balanced") input, nearly all of the hum rejection is done by the balanced connection. The shield helps with high frequency noise. Bonus question: What's your favorite bulk XLR mic cable (other than star quad types?) Star quad is kind of a special purpose cable - good to use when you know you're going to have an EMI problem, but otherwise better to use something else that has lower capacitance. Belden 1800F makes good mic cable, and it also has a characteristic impedance of 110 ohms, so it's designed to work with AES3 digital audio connections when you want to do it right. -- For a good time, call http://mikeriversaudio.wordpress.com |
#3
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Conductive PVC Shield
mcp6453 wrote:
Out of curiosity, I just stripped the jacket off of a cheap microphone XLR cable that came with an Audio Technica ATR2100 microphone. There is a second jacket inside the outside jacket. If the cable is the same as the one at the link below, the inside jacket is a "Conductive PVC Shield." https://www.bhphotovideo.com/c/produ...ies_XLR_M.html ** The Pearstone cable has a spiral, copper grounding shield - says so the "overview". It also states the purpose of the conductive PVC shielding is to reduce electrostatic ( ie handling ) noise. How effective is the conductive PVC shield? ** Very effective at the stated purpose. ..... Phil |
#4
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Conductive PVC Shield
On 2/10/2018 4:22 PM, Phil Allison wrote:
mcp6453 wrote: Out of curiosity, I just stripped the jacket off of a cheap microphone XLR cable that came with an Audio Technica ATR2100 microphone. There is a second jacket inside the outside jacket. If the cable is the same as the one at the link below, the inside jacket is a "Conductive PVC Shield." https://www.bhphotovideo.com/c/produ...ies_XLR_M.html ** The Pearstone cable has a spiral, copper grounding shield - says so the "overview". It also states the purpose of the conductive PVC shielding is to reduce electrostatic ( ie handling ) noise. How effective is the conductive PVC shield? ** Very effective at the stated purpose. .... Phil And exceptionally good value, especially if those are real Switchcraft connectors. geoff |
#5
Posted to rec.audio.pro
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Conductive PVC Shield
Phil Allison wrote:
mcp6453 wrote: ** The Pearstone cable has a spiral, copper grounding shield - says so the "overview". It also states the purpose of the conductive PVC shielding is to reduce electrostatic ( ie handling ) noise. How effective is the conductive PVC shield? ** Very effective at the stated purpose. Agreed. Cables that use just the conductive plastic tend not to perform that well, because the thickness of the plastic (and therefore the resistance) is different in different directions. There are a couple European manufacturers making cable like this. But cables that use conductive plastic combined with a proper shield do very well, and the plastic almost eliminates handling noise when used for high-Z connections. For pro audio where everything is 600 ohms or lower, handling noise should not be a huge deal, but it still occasionally is, and the conductive plastic is cheap insurance. It beats graphite, which works well for reducing tribo noise but makes a mess when you terminate the cable, and which can cause leakage resistances if you don't clean the mess up. I am curious though whether the PVC increases the ruggedness of the spiral shield. I never liked spiral shields because they are much easier to damage than braid shields, but I'd think that PVC layer might hold them in place better. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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