I haven't heard any big improvements from shielding the XLR interconnect. But when I properly shielded the speaker cable I got HUGE improvements in dynamics and low-level detail.
http://forum.stereophile.com/forum/showf...&PHPSESSID=

As a general rule, speaker level signals are considered high enough above the intrusion level (in voltage) of RFI/EMI signals. There can, of course, be exceptions to this rule but they would be considered special cases where good cable design and appropriate cable dressing can't achieve the desired levels of rejection. Twisted or braided conductor legs will minimize pickup from outside forces. However, almost anything the designer does to minimize RFI/EMI pickup - and most especially shielding the cable with a braid or foil - will increase the capacitance of the cable which might then make the shielded speaker cable a not so good choice in certain applications.

The above responses are good, just wanted to add that with SS, they should be stable enough, but with tube amps and trannies, the core material itself helps to minimize the problem, esp as the frequency rises.

Another problem, though, is the cable capacitance reflects back to the primary, loading the source (output tube) and reducing the high frequency response.

Hope this helps.

In a capacitor, there is usually two plates and an insulator sanwiched in between.

The added shield becomes another "plate" with a large surface area. The jacket is the sanwiched insulator between the internal wires and the shield.

Hope this helps.

Let's discuss what you're trying to achieve. Speaker cables seldom pick up RF/EM interference. When they do, dressing the cables to keep them away from the source of such interference typically resolves the problem. Since it's very difficult to get a 100% coverage with the methods you describe, there are probably better ways to minimize noise in your cables.

Interconnects are far more susceptible to RFI/EMi pick up than speaker cables. If you're having a problem, this is where I would suggest you begin making corrections.

Have you determined where the noise is entering the system? Have you tried other methods of noise reduction?

Without those answers, the best I can say is; try the shield.

I would tend to think the best approach is as the article suggests, simply unplug the offending AC cable.

Patrick82 wrote:
I haven't heard any big improvements from shielding the XLR interconnect. But when I properly shielded the speaker cable I got HUGE improvements in dynamics and low-level detail.
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Question:
did you ground the shield? if yes where?

Grounding of shield is sometimes necessary. Without grounding, signal can actually become worse because shield can behave as an antenna.

Excuse me, but as an experienced electrical engineer who has been an audio enthusiast for 50 years, I have never read so much nonsense in my life as I see in this thread. Anyone who claims they have heard a difference from shielding speaker cables is in my opinion not credible.

Speaker cables carry a fairly large current and are driven by an amplifier which has a very low output impedance. Almost NOTHING will influence or change the signal in them materially.

They are immune to any significant interference because their current is too large and their impedance is too low to be materially influenced by any other electrical signals that could influence them in the environment. Any competent engineer can do the math and prove it.

That is like suggesting that the current in the Mississippi River will need to be protected against the disturbance of the air due to passing birds that might modify the flow.

The ONE exception to this would be if you were within 100 yards of a VERY powerful radio transmitter AND your speaker cable length was the EXACT length to form a tuned antenna at THAT EXACT TRANSMITTER FREQUENCY. The chance of all of this happening is about a million to one.

The idea of shielding speaker cables is absolutly ridiculous.

Also:

ANY correctly constructed balanced (XLR) connection (cable) has an inherent noise rejection of 50 db or more when terminated in the usual appropriate circuits at both ends. It has a balanced design which totally rejects common-mode (noise) signals, and it is already shielded. Trying to add another useless shield is redundant and makes no sense at all.

Until you get a degree in electrical engineering and can understand the basics of what you are talking about, you might want to stick to discussing another subject. Trying to discuss something you have NO understanding of is useless and often counterproductive.

Wow, if i could have EVER hoped for a clearer explanation. .. Thank you "commsysman"

Now to properly connect my speakers to my Lava Lamp!

commsysman wrote:

Excuse me, but as an experienced electrical engineer who has been an audio enthusiast for 50 years, I have never read so much nonsense in my life as I see in this thread. Anyone who claims they have heard a difference from shielding speaker cables is in my opinion not credible.

Speaker cables carry a fairly large current and are driven by an amplifier which has a very low output impedance. Almost NOTHING will influence or change the signal in them materially.

They are immune to any significant interference because their current is too large and their impedance is too low to be materially influenced by any other electrical signals that could influence them in the environment. Any competent engineer can do the math and prove it.

That is like suggesting that the current in the Mississippi River will need to be protected against the disturbance of the air due to passing birds that might modify the flow.

The ONE exception to this would be if you were within 100 yards of a VERY powerful radio transmitter AND your speaker cable length was the EXACT length to form a tuned antenna at THAT EXACT TRANSMITTER FREQUENCY. The chance of all of this happening is about a million to one.

The idea of shielding speaker cables is absolutly ridiculous.

 

Also:

ANY correctly constructed balanced (XLR) connection (cable) has an inherent noise rejection of 50 db or more when terminated in the usual appropriate circuits at both ends. It has a balanced design which totally rejects common-mode (noise) signals, and it is already shielded. Trying to add another useless shield is redundant and makes no sense at all.

Until you get a degree in electrical engineering and can understand the basics of what you are talking about, you might want to stick to discussing another subject. Trying to discuss something you have NO understanding of is useless and often counterproductive.

I had to make a post here to refute some of what commsysman is spouting. I'm currently dealing with RFI AM transmissions coming into my speaker cables and playing through my speakers as I live within the shadow of 4 very large AM broadcasting towers. All speaker cables are different lengths and every one of them acts as an antenna. I've reduced about 50% of the RF signal bleedthru by running shielded rg6 as speaker wire and loop grounding the two braided shields that go to each speaker, but when I push the volume, I still get bleedthru. Speaker wiring is suspended in the attic and isolated from any other EM/RF signal sources by at least a few feet. I've tried multiple AV receivers, have pounded a 12'x1" copper rod into the ground and isolated every other lead other than the speaker lines narrowing it down to just them. The cables I ran prior were cat6e plenum shielded. If I use more than 4' of ANYTHING cable wise, I get AM radio bleedthru. If commsysman or anyone else can come on over and completely eliminate the bleedthru, I'll pay $500 plus a round trip airplane ticket. The KVAN-AM engineer spent 8 hours here at the house a few months ago, and is completely baffled as well.

I have been a ham radio operator for 30 years and although I am not an electrical engineer I did complete 2 years in electrical engineering technology. The problem you are dealing with is actually quite simple. I have dealt with this on many occasions. Everything connected to your receiver/amplifier is acting as a path for RF. despite what you have read here, it does not take 50KW Am transmitter to cause this problem. I have a 1KW HF broadcast station in my basement and on certain frequencies I was in fact experiencing RF getting into my receiver. The first thing to do is to unplug everything except your front speakers and a Digital input - A dvd will work for this troubleshooting. Make sure all of those disconnected cables are away from the receiver. Ground all of them if possible. See if you still have RF coming out of the speakers. If you do then you are likely getting RF infiltration from the power cord. You will need a choke. Filters are useless in this case. There are many compounds and ferrites that are specifically designed for certain frequency ranges. I would recommend you reach out to Palomar engineers for guidance on which would works best for your situation. These chokes will work by bleeding the RF off of the power cords an speaker lines. You may need to install more than one toroidal choke to eliminate the problem. I had to install these on every cable that got plugged into my receiver - including all HDMI cables. A finer note about your grounding. A single 12' rod is not likely all that efficient depending on your earth ground resistance. In order for me to obtain an earth ground of suitable low resistance (less than 10 ohms) AND low induction, I had to drive a ground rod almost 50' deep (six 8' ground rods coupled together0. I used a demolition hammer with a cup bit to drive them to this depth. I did not have a real ground tested so I used ohms law and a current reading multi meter in series as I fed 120V into the ground through the meter. I do not recommend you try this as it is dangerous and you could get electrocuted. My antenna farm is relatively efficient and in very close proximity to my house (less than 50' away). I was able to eliminate all of my RFI. Hope this helps.