Not important on power cords and speaker cables. Important in IC's if the system components have poor design. Another words it's mostly component's fault to pick up RFI.
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EMI is usually 60 cycle hum that is picked up from power cords into your audio components. This is usually fixed by moving the power cord away from the component that is picking up the hum. Another "trick" is to make sure interconnects are not to close (six or more inches) from the power cord and are perpendicular to it (ie not running right beside it).
RFI is usually not an issue unless you live near a radio station, your neighbor talks on CB or HAM radio, or you put your WiFi brouter next to your turntable (ouch!).
That said, a well designed interconnect will likey take care of both issues. Blue Jean Audio provides cables that excel at EMI and RFI rejection. They have some good articles to read on the topic, too.
You can also block RFI from entering your system from the wall with a ferrite core that clamp over your power cord. Radio Shack carries these.
Finally, make sure all your equipment is grounded.
Well I'm confused....
I asked this question because somebody on another forum said NBS cables were all about EMI and RFI rejection....I use NBS and like them....
After seeing the responses so far....I found this on the NBS website...
"Noise, in a cable, can and will affect the audio frequency range and interfere with an audio signal. The most common noise, Radio Frequency Interference (RFI), affects a cable directly in the audio range. RFI presents itself as hiss, commercial radio broadcasts, intercom broadcasts, or any other radio signal broadcast in the audible range.
Another source of noise is Electromagnetic Interference (EMI). Whenever electricity, i.e., an audio signal, passes through a wire, it produces inductance that creates an electromagnetic field. Because EMI manifests itself at a high frequency, it is commonly believed not to interfere with the audible range of frequencies. However, all frequencies demonstrate harmonic structures. Even if the cause of EMI is outside the audible range, the upper and lower harmonics of a given frequency often present themselves within the audible range. At the very least, EMI causes degradation of audio frequencies."
So I guess it still open....
NBS definitions of EMI and RFI are wrong. Clearly RFI is due to Radio Frequencies Interference which we cannot hear. EMI does come from inductive coupling, as I also said, which is most likely 60 cycle hum in the US, and you can hear it.
Perhaps NBS is jumping to the symptoms - you can hear the modulated signal from RFI related problems. This is called rectification. No idea regarding their EMI description?!
Based on 40 years of working with radios and audio I know the descriptions and remedies listed at Blue Jeans Cables are correct...
...as are my recommendations for remedying them with your existing cables above.
This doesn't mean NBS cables are bad (I've never heard them or Blue Jeans cables for that matter), but you really have to separate technical from marketing.
If you like NBS cables and you have no EMI or RFI problems, then that's great. If you do, you should check out BJC and/or employ my remedies above as both solutions are very inexpensive (some even free :)
I have no problems with NBS. I have recently tried other brands and while having excellant sonic qualities....their "blackness" were not equal to my NBS. Since the NBS were said to have these rejection qualities...I was wondering what cables excell in EMI & RFI rejection. Or maybe I should just ask what cable brands have the blackest background?
Not sure there is a technical measurement for blackness :) I was just responding to the original question and when I see stuff like: "Radio Frequency Interference (RFI), affects a cable directly in the audio range" it's just flat out wrong.
I've been looking for some new cables and liked the design philosophy of BJC for unbalanced audio cables. Why? Because their audio cables are based on video cable stock. Therefore, you know they have the best possible RFI rejection as this is a primary design criteria for delivering radio frequencies. Do they sound good? I have no idea. But I'm am confident they provide extremely high RFI rejection as all high quality video cable will.
Good luck w/your search.
JPS that's good to know....as I have auditioned a few PC's and found them lacking as to silent background. I always knew my cables had a silent quality but never realised how much of a difference it made in the overall sound quality. I find that PC's can have excellant detail...but if it lacks the quiet background it doesn't matter....it makes the whole system sonics degrade. Experience here is about the only way to find out if different cables are compatible or just stick with one brand.... atleast that's what I'm finding out.
Proper design in cables alone will not completely get rid off EMI noise and in some cases even RFI. This is because so called high end audio components today are not built properly, poor grounding, poor shielding etc. Yes, you want to have good qiality and properly designed cables that will help not introduce more junk into the components but most components will inherently have some. I was made aware of this when I started looking at properly grounding my components and was further astonished when someone introduced me to a passive filtration device called "Troy" from tripoint audio. After grounding my amps, preamps and Turntable to the tripoint audio box, the level of darkness, clean upper frequencies and just overall space and music flow was jaw dropping. I am an importer/dealer in the South Florida area and I invite any of you to come by and listen to an A/B demo.
After reading the Tripoint website...
"Come experience the holographic transportation of the real musical event with our proprietary passive filtration that eliminate EMI/RFI from the signal and impulse signal flow. Hear what your electronics, room, and vibration control really sound like."
My preamp a accuphase unit is very well made and shielded...also my Vac 140's have a 3 setting ground adjustment that produces a noticeable improvement in transparency and blackness along with a holographic soundstage.
Thanks for pointing out the EMI/RFI connection to grounding...
I might have to consider a troy someday....
I have no interest or ties to the company....just listed the link for copyright issues.
You're welcome, Wavetrader. Please note that I mentioned grounding in my initial response. IMO, (no interest or ties to Tripoint) you'll be paying them to implement my low cost suggestions in a beautiful box with margins that boggle the mind. There is no magic here, EMI/RFI are well understood electronic phenomena that are usually simple and inexpensive to fix.
I compared the Ground Zero model#501 to the Tripoint Apollo. The ground zero effect is subtle at best, better focus with more stable images in the soundfield, but didn't compare with Tripoints expansive soundstage and added body to the music. Tripoint was much more quiet and resolving. The much pricier Tripoint is what I call grounding on steroids and worth the price of admission.
I don't doubt the Tripoint is better. I know Miguel and he has been playing around with grounding schemes for a while. I don't doubt he is on to something with the Tripoint. However, not everyone can drop $8k on such a device. As Danmyers said you could do it a lot cheaper and get good results.
Then again there are people like Charles Hansen of Ayre who have a totally different view on grounding.
Go over to Audio Asylum. Do a search there. He's posted his views many times. Ayre uses double insulated chassis' in their design so you can float the ground without the danger (according to Ayre anyway). Charles also lives in an old home where none of the outlets are grounded. I believe he floats all grounds in his system.
Here's on thread where Charles comments:
Based on what they're experiencing it appears that floating grounds has similar sonic effects to the Tripoint.
I have found that on my system that consists of Magnepan speakers (20.1) Krell FPB 600 amp, Accustic Arts DAC, Sim audio moon eclipse cd player(used as transport) BAT 52 SE preamp, ps audio power plant premier(ac to dc to ac generator)dedicated breaker box, shielded ac wiring,dedicated sockets, 6 foot ground rod in the earth,that I could not live without cables that were not efi sheilded. When you get cables that are well shielded you will get rid of a glare and blanket of music robbing junk. I use Purist Audio Design cables exclusively. If any one tells you they don't make a difference in performance then they sould talk to NASA and see what they say about EFI and EMI. Better yet do an A,B comparison and you will hear the music come alive. I have enjoyed the improvement for years now and no one can tell me after all the improvements that noise does not enter through cables. Just by nature they are antenas. Also if you want to hear another product that gets rid of EFI andEMI by the power of ten then check out Tripoint Audio you will be shocked.
Thanks for the AA link. I see he's basically saying he prefers a floating ground vs actual ground. I'd say that's fine - most of the time. The goal of good ground design is to get all the equipment at the same negative voltage level. For actual ground this is 0 volts. In a floating ground it can be... well anything really but usually a few millivolts. The main thing is that everything is at the same voltage level. The "usually OK" part is if you really do have EMI/RFI problems. This is because the other goal of good grounding is to shunt excess energy away from the system. In a floating system, there is no where for the excess energy to go. This can still be fixed with a five cent capacitor.
Booboobaer, no one has said well designed cables that shunt EMI/RFI to ground don't make a difference. Or that grounding isn't important. Or that you can't hear a difference. To the contrary, it is all extremely important. It just isn't expensive.
This is because the other goal of good grounding is to shunt excess energy away from the system. In a floating system, there is no where for the excess energy to go. This can still be fixed with a five cent capacitor.
Danmyers, how would you fix it with a five cent capacitor?
Or, one could lift the ground from the component chassis (has to be 3 inches from the IEC socket to conform to UL codes), and ground back to the original earth ground (where all the components plug into so you have 1 ground to meet UL codes), via a wire configuration. I have begun this process with good results-after 40 years in this hobby I am learning just how critical it is to properly ground your system.
Powder, I'd be interested in learning more. Feel free to email me offline to describe what you are doing.
I have a couple of components where the manufacturer does not have the ground connected at the IEC inside the components. Says it is a huge source of noise. Not sure how the grounding was addressed if at all. Never had any shocks and it sounded great.
What Powder is describing sounds like normal (and what I would recommend) grounding to earth ground. Clio, your question was regarding floating ground and the bypass cap will work and still maintain a floating ground.
But as everyone on this thread agrees, good grounding is essential to shunt any RFI energy away from your system. The shield on your cables and the metal around your components will shield them from RFI BUT (and it's a big BUT) you have to move that RF energy away from your system or it will find another way in.
The way electricity works is it flows down the path of least resistance. So you need to provide a super-highway for the RF energy to travel on that moves it away from your system. If you do, you'll never hear the RFI. That is one of the main purposes of grounding. RFI has some other characteristics that we can use to whisk it away. Without going into the details it's to use wide and flat grounding straps and bypass capacitors to "widen" the super-highway for RF energy. We can also use ferrite beads to absorb the RF energy before it enters your system.
So far, this the only money we've spent is probably $20 for flat/wide copper braid ground straps and $1 on bypass caps. Connect the braid to each of your components keeping the lengths as short as possible (use a "star shaped" configuration). Then run some braid from the center of the star to earth ground (the roundish hole in your electrical wall socket). You should also buy some ferrite beads and put these around your power cord and each end of your interconnects. This will add another $15 to your bill. A final remedy for RFI is shielding. Not in the cable, but shielding the entire component from either radiating or receiving RFI. You can do this with heavy aluminum foil and some of that flat/wide copper braid (ie the aluminum foil has to be grounded to be an effective shield).
Now assuming your interconnects aren't completely horrible (they must be shielded if you are having RFI problems) your system will be properly grounded. It will sound like it's on steroids with incredible inky blackness and the notes appearing in space out of nowhere with no hum or hiss and holographic realism that will rival the big buck systems! WOW! INCREDIBLE!
As a final note, I'll add that most people do not have either RFI or EMI problems. Only those who live near a radio tower or some other structure/device that generates RF. This is why most people can just use regular wire and not flat/wide copper braid to ground their systems and get WOW fantastic inky black backgrounds for $3 instead of $35 (most people don't need the bypass caps or the ferrite beads either). But they don't hurt and they are inexpensive so better safe than sorry.
I think that covers it... did I leave out anything? Probably, but these are the basics of the simple, inexpensive, things anyone can do to properly shield their system from RFI. There are a few more things for extreme cases and EMI like BALUNs and chokes, but these are inexpensive, too.
So take some time to learn and implement these basics yourself. Or buy a beautiful box for almost ten thousand dollars and more cables at three grand per meter. Another option is to hire an electrician to come out and properly ground your system. That will probably cost you a few hundred dollars, but you'll know it's done correctly. I can describe the science, but the art and pride of ownership is certainly worth something. How much is your choice.
"The way electricity works is it flows down the path of least resistance. So you need to provide a super-highway for the RF energy to travel on that moves it away from your system. If you do, you'll never hear the RFI. That is one of the main purposes of grounding. RFI has some other characteristics that we can use to whisk it away."
Take a bow Dan,take a couple. I have my super highway almost done. I did the preamp,dac, and transport, have the amplifiers to do,all four of them. Should I tie them all together and then wire to the preamp?
This has been a real humbling experience. One of my favorite Cd's is "Music from Hollywood" a recording done at the hollywood bowl in 1963. I have listened to this disc a hundred times,tonight....I don't want to turn my system off.
Pictures would be great. Funny, I was wondering the same thing about how to work it out on my VAC amps.
Just another note. I just had a friend remove the ground wire from the chassis IEC inside his transport and noticed an improvement. I'm wondering if its worth it or even makes sense to mix the two concepts together: floating grounds and the chassis grounding scheme.
I did my 2 sub blocks and they have never run this quiet. After looking at the vacs closely the only chassis screws are underneath and at 100Lbs a piece there has to be another way. The vacs have a adjustable grounding switch anyway,but I would still be tempted to see if there is a difference.
Floating grounds and this treatment? You better ask a opinion of a expert. I am way over my head doing this, I can't beleive it worked and it sounds great today too. Inky black and the speakers are alive. I never thought I had a grounding problem as all my stuff looks to be well shielded.
So too get a grasp on what we are actually talking about performing here Please explain what your doing to mod your grounding scheme? It seems that basically the explanations above is going into each component of the system and actually disconnecting the IEC ground pin and then straping a new ground via wire or braided strap to the chassis (similar to a phono stage to a cartridge in a turntable) and then bringing them all directly to a single ground via example connecting them all to one open outlet on your wall gaining a single star ground to earth (of course only using the ground pin on that outlet maybe using an old 3 prong plug but taking care to make sure hot and neutral are paralyzed and not used accept for the pins to mechanically help plug it to the wall) ?
Here is my question, is not the ground collars on all the RCA jacks and PIN #1 on an XLR connecting components to each other already giving a common ground back to each component? And would this not be the same Chassis ground already simply putting you in a position to just make One single ground strap to connect back to an earth ground at a single outlet after removing the ground from all IEC's?
Also I don't really understand the whole "Floating ground" concept with or without capacitors accept floating ground normally means simply removing ground from a component causing a hum in the system.
If someone can please specifically explain what steps are taken to try and get this same negative ground voltage matched up to all components, I understand the Star ground etc And it would seem you do have to make sure each component would be isolated from having a second ground hooked up thru your various power cables going to different outlets which normally has the 3 ground pin connected via the cable to the wall, however would it not be a better idea to just making sure ONE of the power cables in the system has the ground attached to its IEC and just connect all other components chassis to that one Chassis with an IEC earth ground already connected?
But from my understanding the whole system including the amp is still common grounded because all the interconnects still give it a common ground, and if the amp was to surge or something it would simply ground itself thru the preamps RCA's which are of course hooked to the chassis ground which is still hooked to earth ground at the outlet etc
Anyway please explain the professional way to go about it, and also is there anyway to test for this hum with a type of voltage differential test or something between components with a basic multimeter or something?
If you cross power cables and audio cables at 90 degrees and keep power cables 4 to 6 inches away from each other you should have few problems.
As far as I know the only way to stop EMI considering it is EMF causing the problem is to use shielded cables and ground at only 1 end, preferably to the wall outlet screw not your equipment.