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RF / EMI Interference, etc...

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Seems like I/we could benefit from a discussion on how best to avoid RF, EMI, grounding, and other types of issues that can interfere with sound, unnoticed until they disappear.


First I'll admit that I have no clue, other than a nagging suspicion, how much damage is being caused (or why) by the mess of cables, multiple wireless networks, and plethora of devices connected to two AC circuits in an apartment building.


Said another way, I am probably a worst case scenario.


How is this related specifically to computer audio? The merging of audio systems with wireless computer gear into the same small space (and same circuits) surely compounds the problems.


Hopefully I_S, CG and others can share the fundamentals of RF / EMI avoidance, and how best to eliminate potential grounding issues, and perhaps other topics I don't even know exist.


Notably, when Jone Reichbach (of Amarra) was asked what is mote likely to have a negative effect on computer audio, he said "Bad software", understandably, and 'Bad RF".


Most can stop reading here, but I'll share the details of my 'worst case scenario', for those who like gore and carnage.


I am temporarily living in an apartment in NYC, think small, and surely bombarded with all manner of wireless networks, etc... although no microwave.


My computer gear consists of Apple Extreme router (running N) with WD Mybook 1TB drive connected (Airdisk) for wireless access to most of my music files. I also have Airport Express (running G) as a separate network for use with non-N-capable laptop and wireless printer connection, and a separate Airport Express for routing music to a pair of AudioEngine A2s in the bedroom.


I also have an Apple TV, which I use as an Airtunes client, for routing music wirelessly to my DAC (Metric Halo ULN-2) via Toslink.


My source computer is MacBook Pro (2005 model), connected via Firewire to the ULN-2.


My purely audio gear is all heat generating, and potentially a donor/receipient of hazards in question - a Nelson Pass designed Class A power amp (Aleph 30), and Dehavilland Ultraverve tube preamp, driving Audio Physics Virgos.


The poweramp is plugged into one circuit (along with printer, and WD Mybook). The rest of the gear mentioned, along with cable box, and Sony HD LCD panel, are all plugged eventually into one wall circuit (two outlets). The exception is that the laptops are charged on another circuit across the room.


The cables are a veritable birds nest, with the singular exception of the Firewire, which has a relatively isolated run to the DAC. Wireless iPhones abound, etc., etc. I have never considered power line conditioners. My interconnects, speaker cables and power cables are all by Analysis Plus, bought used (think cheaper AND already 'broken in'). An Arcam FMJ CD23 sits in a corner gathering dust that falls from the unused CD rack just above.


Like I said, a worst case scenario.


On a slightly positive note, my computer to DAC connection is Firewire (4.5 m), presumably more immune to airborne interference than say, S/PDIF. My Apple TV to DAC connection is Toslink (which occurs at ground zero). My landline is NOT wireless. I keep my Oppo DVD player in standby mode until needed. I switched (no pun intended) the switching powersupply on my ULN-2 to a linear (aka HOT) power supply.


I"m sure there are issues that are preventing me from the best that computer audio has to offer. The big clue was that the Amarra demo did not 'rock my world' as I had expected. I could hear a difference but not to the extent that others have noted, possibly not even ABX-able.


Apologies for the length of this post, I didn't have the time to make it shorter.


Thanks in advance for any help. Did I mention this was a 'worst case scenario'? :)








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I plug all my audio/video/computer into my Torus Power Supply/Conditioner. Much quieter than my previous Rotel RLC-1040 Power Conditioner (APC built). The clean and readily available source of power is the big advantage. Especially the impedance problems, (from Torus site)"Torus power isolation units present low impedance to any electronic device that is connected to them. A Single 20 amp Torus PIU has an output impedance of 0.2 ohms and can deliver 400 amp peaks (instantaneous current). The 100 amp unit only has .04 Ohms of output impedance. A typical 200 watt audio power amplifier demands 10 amps RMS current from a 120 volt line (1200VA) but may demand up to 50 amp instantaneous peaks. The standard residential wall receptacle can't supply the 50 amp peaks because they typically have higher nominal impedance. A Torus 20 amp PIU plugged into the same wall plug can supply these peak current requirements quite easily."

Isolation of digital gear from each other is another plus.

A big difference is with your amp which becomes faster and can handle complex passages or alot of bass much more easily.


Note: I live in the downtown of a large city so RF/EM issues are a real problem. So NY must be quite difficult!



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All add to this questioning the value of Voodoo RF/EMI audiophile equipment such as Shakti Stones and ERS RFI sheets, etc. Anyone have experiences to offer? Educated perspectives, raised eyebrows, looking straight down your noses, all is appreciated.


- Rand


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but not really! I am going to assume (big assumption) that you live in an older building. I am also going to further assume that they used pretty good wire in metal conduit. Wire in a metal conduit is good even in buildings! These days most new construction is romex in single family homes and this is junk. They cant use it in buildings, so they have some other cheap stuff of choice called mc (I think) its a little better, but still junk. Anyway if my two assumptions are correct....big plus over the other cheaper alternatives. My home is romex and my audio buddy made me wire a dedicated outlet (wish I had done two). I did not use metal conduit (oh well it far from other lines anyway), but I did used heavy #10 cables. I also installed a heavy duty outlet (20 amp type) that is a cheap upgrade. Look for the ones that saddle the wire and are usually a gray color. Or a hospital grade outlet in 20 amp is also good. I use the Rotel 1040 noted above and I love it. PS that was also my audio buddies doing and I am glad I did it. I cann't compare to others things, but its great for the price. I have the amp direct to the bottom of the outlet and the rotel conditioner direct to the top of the outlet. The only upgraded cable is the amp cable. All my other equipment goes to the conditioner even the video side of things. The computer is still on a typical wall outlet for now until I finalize the build and then its also getting plugged in to the rotel. I'm going to ask my audio buddy (electrical engineer) and let you know what else he says as well.

Let me know if my assumptions were correct.


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seeing as RF is very implicated in jitter, proprietary Firewire and master clocking will only do so much.....It can't fix so called inherent jitter.

I agree with Amarra the os/platform/hardware and playback software is paramount.

The Amarra SW sounds, or so my understanding goes, awesome when you buy their custom optimized OS-X on SSD ($2500). Otherwise you still have OS-X still doing all the things it does that have nothing to do with playback, increase baseline cpu, ram and bus port usage all adding to more power being used which inc RF etc.


There is no magic to it - just optimize your OS for playback and get the best hardware you can. Mac doesn't give you a choice with hardware (and most people don't have enough knowledge to chose the right mobo's anyway) so all you can do is muck around with the os: which in OS-X is both difficult and not for faint of heart. Personally whatever Amarra charge for that experience they are welcome to.


Most of the Windows players do that eg CPlay, XX High End Utter PITA.. Linux of course does it out of the box (there's that box again Clay...) which makes it entirely a suitable option for the lazy like me. Of course then you run into compatibility issues (common Daniel - get writing that Dac 2 Linux 1394EEE driver) with hardware ...except USB.


Bit perfect means stuff all if those bits are jittery as hell, not from crappy clocking but everything else going on in your puter: which is a much over looked aspect of the async USB discussions....


Just my 2 cents...




Best Wishes


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The Rotel RLC 1040 is a great unit but it is not a power supply as well as a line conditioner. My son bought it from me as soon as he heard I was getting the Torus.

If you are referring to my building ( and not Clay in NYC) it is 25 years old. The sales pitch is that there are numerous causes of RF/EM/digital hash. Prob.1: a lot of digital noise is already present in the power supply before it enters one's home due to the many computer's, switching power supplies, flourescent lights, digital info deliberately put into the electricity by power company...

There are numerous sources of RF/EM/digital noise according to the engineers at Torus.

I do know that the Rotel(APC) lowered the noise floor to a large degree and the Torus provides an even blacker back ground + it is a big honkin' power supply as well.





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I looked and that is some serious equipment. I didn't dought that it was better and I trust your comparison. I was refering to Clays apt....trying to give him moral support, so he doesn't turn into a jumper...hehehe.

I understand the special issues associated with living audiophile in buildings. I would venture to say that his entire building is on one large tranformer, so that can be alot of people on that system. I rarely see one transformer per floor, but it could be.


Funny thing happen to me. After doing my electrical upgrade my neighbor moved his ac to my side of the house...go figure. Who moves thier ac right...this guy did. I wanted to kill him, but what can you do.


Clay, funny how the PS Audio ad points right at your post ;) Anyway, I read your post again in detail. I have a few points that you may already be doing, but just in case. Turn off the tv and the cable box. Both use to much power and are sources of more trouble. Turn off the apple tv when connected to the metric halo via the laptop. That input acts like an antenna if you not using it at that moment. If its on it feeds signals into the halo for no reason. Also, looks like your apt is a huge wireless center...hehehe. Can you hardwire as a test and turn off all your wireless.


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Thanks to all who've responded this far.


Looks like I do need a PLC, although I must admit that their rationale (the competitive positioning portion) are even more suspect than cable manufacturer claims, e.g.:


"There were three major components within the black, unassuming box of [Audio Magic] Stealth Mini Reference. One was the IPF module, which consisted of caps and coils, working together to curb RF and EMI interferences. The other parts were a Quantum QRT module and also a Quantum Physics Noise Disruptor. "


This is where I'm hoping someone can help explain what one really needs. :)


According to Barry Diament, I need to properly 'dress' my cables and condition my power before worrying about vibration influences.




As some may have surmised, I lend more credence to recording engineers than I do to audiophile reviewers.


Half-joking (he asks), do any of the power line conditioners have remote on-off feature? Airport Extreme has no remote on-off, Apple TV does, but requires turning the TV on & navigating to the Apple TV source. It'd be nice to turn off every interfering device with one click, yes?


But first, does Wifi really interfere, and I mean from the pragmatic standpoint. I'll grant that it probably will have an impact in the 'everything matters' point of view.


thanks again,






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RF (radio Frequency) is all about us. Unless you live within 20 feet of a radio transmitter, then the effect of the large waves, is RFI (radio frequency interference) is not going to bother you.

EMI (Electromagnetic Interference) is locally produced by just about anything that contains a switch mode power supply. Various standards around the world have "tried" to keep a lid on the compatibility between the source of the noise and the victim. To comply with standards (CISPR11 and others), the equipment can emit EMI, provided the level is low enough for a victim to survive. The victim must also have a level of immunity from EMI to counteract the rubbish it receives to comply to the standard.


As we know, electronics is built to a price and noise does escape, fact. Even though the device may be built to a standard, it doesn't necessarily imply that it's an angel and won't emit any noise. This noise is picked up by interconnects, mains leads, poor shielding in computers, the list goes on and is usually emitted by the mains lead as an antenna, or in our case interconnects. This is NOT JITTER, it's worse. EMI is at a higher output level and is very audible, like monkey chatter, random noise, like FM hash, varying in frequency.


One way to reduce the effect of the noise is make all the components in the audio chain at the same level reference. A typical setup of an audio chain, is the source (computer), DAC, amplifier, power amplifier. If you plugged each one into the mains power, the zero Volt (the metal common around the RCA plug) will be at a different potential to each other. This means noise has found a path! This potential is small, but added up, especially in an amplifier, can create some pain.


Remember the days of the turntable where if you had hum, you would connect a ground wire to the amplifier and the hum would go away. Nothing has changed, in the world of digital as far as noise is concerned, so grab some 12 or 14 gauge wire (actually flat braid is best), and run this wire from each of your sources to the one point, usually the GND or ground point on your pre-amp or the device where you do the switching.

Desktops can be connected on any metal, preferably the rear expansion slots, notebooks are a little trickier, the small hole used for the VGA cable clamp out will work.


The wiring system will represent a star system, or radial feeds from the one point. NEVER loop the ground wires from one component to the other and daisy chain, bad idea.

Some audiophiles insist to run a separate ground from the amplifier to a stake in the earth, but for safety, this is not recommended and dangerous in the event of a short circuit on the mains power. The standard ground connection should suffice in the amplifier very well.


Even though you might think that noise is induced in the ground wires and could make things worse, but the noise actually likes to travel on the braids because it's the path is of least resistance to the noise, and electricity is lazy, it always finds the easiest route. Remember noise can be several hundred MHz, so it's nature is different to audio frequencies. So let it find the easiest route and let it mull around the star point, and let the audio be clear of noise for a change.


If you want, Google "ground loop, instrumentation" and you'll find books and books on the subject.

The best way to avoid all this is to used a balanced system of audio (as the pro audio market has embraced for at least 40 years++++), since a balanced interconnect cancels out any noise, since the signal works on a differential only and not a single ended design as in the humble RCA (or cinch).


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One and a half has summed up things very well, so I'll just add in my tuppence worth, which is:


Firstly, in a digital system, the effects of random noise in the environment are much less than using a vinyl front end (as an example). This is because in a digital system, the point at which the signal becomes analogue, and most susceptible to outside influences, is inside a hopefully well shielded box, which is of the order of 2V or so. Compare this to the input to a phono stage of a pre-amp, which will be of the order of millivolts, where you do get effects such as picking up local radio stations. I'm not saying that there is no effect, but that traditional rules don't necessarily apply to the same extent, and we should have a sense of perspective. It's a bit like most high-end transport manufacturers use similar damping schemes to turntable manufacturers, even though the problems are completely different.


Having said all that, you don't tend to have a PC connected to a turntable :)



your friendly neighbourhood idiot






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Thanks to all,

A lot to digest here. I'll respond in more detail later.


One question that is still not clear in my mind, should one worry significantly about interference from wireless network activity in a) close proximity to a dedicated music server (Mac), or b) wireless access to music files by the music server?


Asked another way, is this much more than a theoretical concern?

Is a switch to ethernet in order (assuming I get the rest of the environment fine tuned)?


thanks much



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"I was refering to Clays apt....trying to give him moral support, so he doesn't turn into a jumper...hehehe"


Thanks for that. If only jumping would help me, I'm too close to the street for that to cure anything, and therefore suffer other audio indignities - street noise, and even the occasional airborne interference from passing vehicles.


"Clay, funny how the PS Audio ad points right at your post ;)"


Yeah, funny that, although not surprising. :)


In my earlier days, I had a much cleaner environment - relatively new house in the suburbs (but with Romex instead of metal conduit), different rooms for computer gear / video gear / audio gear, reasonably clean AC - which is one of the reasons I know NOTHING about this stuff.


Ironically, the apt building just totally replaced my bathroom last week, and with the walls ripped out, I do recall seeing metal conduit.








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it your feeling lucky and brave you could possibly pull the wires and replace then with heaver ones. Pretty cheap upgrade to pull two #10s back to the panel. You could run into problems it not a direct run, but might me worth a try even if its not your place.


I have to tell you I am glad you started this post as rf and emi have been a concern of mine for a while! I got the power cables in my pc and braided them or at lease the ones I could due without much fuss. Crazy huh....I guess I was bored.


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So I proposed this question to Alan Maher over on AudioCircle and he responded with all of the tweaks he does with his system, which is a combination of his own products (which I'm a fan of, but in no way affiliated with of course) and other products and prudent techniques. So hopefully Chris is okay if I insert the pointer here to that forum as he provides some great ideas and tweaks, including some inexpensive ones (i.e., ERS paper, CAT7 cables, his infinity products, shakti onlines, small Quantum Physics Noise Disrupters, etc.):




go to reply # 1164/1165


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Like any other component, the phono pre-amp ground should go to the pre-amp, as the point on the pre-amp is usually earthed. The tricky part now is the TT ground. I would connect the TT ground to the Phono preamp, since the phono preamp has facilities to connect the ground directly, and may include filtering to provision for hum rejection in this case.

I would still add a ground braid from the phono preamp to the main amp.



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Over at Empirical Audio, their white paper on mains cables dismissed the idea that shielding mains cables was not the most effective to "make the sound better".

While using shielded cable *from* the wall where it may not be shielded *in* the wall at all is a waste of time, for sure. However to use proper EMC cabling where the mains conductors are wound with a specific shield does have the advantage that EMI is contained within the shield and not the internal conductors of the cable.

Metallic conduit is in the "good" category as far as EMI is concerned, but it was never designed to be a collector of noise, rather than provide for a mechanical protection system for the cables for which it is ideal.


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