How important is EMI and RFI rejection?

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.

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.

Enjoy,

Dan

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...

http://www.bluejeanscable.com/articles/humrejection.htm

...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 :)

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.

Have you tried putting a ferrite core around the power cord and interconnect ends right where it plugs into the equipment? You can try it very inexpensively and will block all RFI from entering your system, no matter which cable you are using.

"Then again there are people like Charles Hansen of Ayre who have a totally different view on grounding."

OK, I'll bite :) Where can read up on Charlie's view of grounding? Thanks!

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.

Hi Clio,

Assuming RFI is the issue a .01uF ceramic bypass capacitor connected between the floating ground and real ground will shunt all the radio frequency energy away from the audio system and to real ground.

Dan

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.

Looking forward to hearing how these changes work out or you. One correction though - good grounding is not a tweak. It is the foundation on which every great system is be built.