Shielding components from EMI/RFI... Help please

Thanks, ladies and gents. The TI Shield looks very interesting. I think I'll order some to experiment with. And I will get myself a meter posthaste.

Bryon

Did I forget to mention that I already rebuilt my listening room?

bc

That is good advice, Sarcher. I had a similar journey with analog interconnects. After trying a number of different shielded interconnects from well respected manufacturers, I settled on an unshielded pair. As you describe, the sound was more open and airy with the unshielded cables. I've also experimented with shielded and unshielded power cables, and found that I preferred them unshielded or minimally shielded.

I guess I'm learning that I have a different attitude about shielding analog signals and power cables vs. shielding digital signals and digital circuits. The digital interconnect I settled on is double shielded. Very happy with it. As I mentioned in the OP, I have 3 digital devices with high speed clocks and switching mode power supplies. I've built complete shields for 2 of the digital devices, and a partial shield for the other. I recently removed the shields to make some other changes and I discovered that I definitely prefer the sound with digital devices shielded rather than unshielded. It wasn't so much a matter of audible noise as it was a matter of high frequency grain and glare. I guess that I could sum up my (admittedly limited) experience by saying that...

Shielding analog cables and power cables tends to reduce openness and air :-( whereas shielding digital cables and digital circuits tends to reduce grain and glare :-)

I have no idea if that is generalizable.

bc

I also use ethernet. My understanding is that most (all?) ethernet protocols employ a variety of error detection/correction techniques that ensure perfect or near perfect data transmission.

If that is true, then I would imagine that additional shielding on ethernet cables would have little or no effect. But what do I know? Maybe it would have some effect. Stranger things have happened in the world of audio.

Maybe someone who knows this stuff better will weigh in.

Thanks, Al. That's what I suspected, but it's good to hear from someone who actually knows something (in this case, both you and Steve).

On the issue of ethernet cables themselves releasing EMI/RFI... I have no idea whether my ethernet cables are shielded. Is there a way to determine that without cutting into them?

Thanks, Al. My Cat 5 cables are unshielded. I just ordered some shielded Cat 6.

Yesterday I received the materials to complete the DIY projects described in the OP. Hopefully there will be some results. I will report back.

bc

Thanks, Sarcher. Interested to hear if the Cat6 makes any difference.

I have an update...

I have installed 7 copper plates inside my preamp/dac. They are each 16 gauge, or .06", which is fairly thick. I grounded each plate to the chassis. I bolted 3 plates around the analog output stage, 3 plates around the power supply, and 1 large plate to the underside of the lid.

The results are surprisingly good. The noise floor dropped noticeably. The resolution increased slightly. The high frequencies got smoother. I can turn the volume up about 3dB with the same comfort level.

I've tried quite a few tweaks and mods, and this is one of the most audible. The results are much more obvious than when I recently added ERS cloth to the preamp/dac. Total cost for this mod: about $100 in copper from an online retailer, who also cut the plates to exact sizes.

Next up: I'm building a copper/aluminum enclosure for my reclocker. The enclosure will be grounded to a dedicated ground rod I just buried under the house...

...to be continued.

Bryon

Sounds like the Cat6 experiment has produced uncertain results. I've already ordered shielded Cat6 from Amazon, so when it arrives I will let you know if I hear any difference. In the meantime...

I can now report that my shielding experiment has produced fantastic results. I hesitate to use the word 'fantastic,' because I don't want to diminish my credibility by overstating the facts. But the fact is that the addition of shielding has produced very impressive results.

I had an audiophile friend over who is familiar with my system and he said "It sounds like a different system." THAT might be an overstatement, but it is fair to say that the system sounds MUCH improved. Two improvements are particularly noticeable: Greater resolution and less high frequency grain and glare. The difference in these two categories is so pronounced that you can literally hear the improvements from the next room.

Here's everything I've done so far:

-Custom cut 16ga. copper plates around the Meridian G68's power supply, analog output stage, and the entire underside of the lid. All plates are grounded to the chassis.

-An aluminum/copper enclosure around the Empirical Audio reclocker. The enclosure is grounded to a dedicated ground rod under the house, and the reclocker is electrically insulated from the enclosure.

-An aluminum/copper enclosure around the Sonos. The enclosure is grounded to the dedicated ground rod, and the Sonos is electrically insulated from the enclosure.

The biggest gains were achieved by adding copper plates inside the Meridian preamp/processor. I added plates in three separate stages, and each time there was a clearly audible improvement. Apparently, in this case, more is more.

I don't know how generalizable my results are to other preamps, because my Meridian G68 is undoubtably much noisier than the typical audiophile preamp. But my G68 is also my dac, and I suspect that similar results could be achieved with other dac's or players.

It bears repeating that I am not an ideologue when it comes to shielding, as you can see in this thread. My (admittedly limited) experiences have led me to prefer unshielded or minimally shielded analog interconnects and power cords.

But digital interconnects and digital circuits are another story. For a while I've suspected that shielding most (all?) things digital is a good idea, and the results of this experiment confirm that suspicion. Of course this is a sample size of 1, so I recognize that YMMV.

Bryon

01-30-13: Camb
What do you think the sonic benefit of all the shielding in your G68 is? Protecting it's internal components from external EMI or protecting your other equipment from EMI generated by the G68?

IME, the biggest gains in SQ were made by shielding the G68 from ITSELF. In other words, shielding the analog board from the digital boards and shielding the power supply from both the analog and digital boards.

Bryon

Sean - I think my results, if they can be generalized, point to the value of extensive shielding in dac's and cd players, all of which have clocks, and many of which have noisy power supplies. I agree that it's strange that you don't see extensive shielding more often. The copper for the shielding in my G68 cost me about $100. That's a very small fraction of the current $12K msrp.

Jim - The ground rod wasn't based on magical thinking. It was based on the belief that the ground for a Faraday cage should be different from the ground for the equipment inside the cage. I gather from your comments that that is incorrect.

When I installed the copper shielding inside the G68, I grounded it to the G68's chassis. The dedicated ground rod was used only for the 2 enclosures - one for the reclocker and one for the Sonos. I have disconnected the ground rod and connected the enclosures' ground cables to a conductive spot on the G68's chassis. My initial impression is that I can hear no difference between that arrangement and my previous one.

Bryon

After more extensive listening, I've concluded that grounding the new enclosures to the Meridian G68 resulted in sound that is slightly worse, particularly in "listening ease" at loud volumes. Here are the 3 arrangements I've tried:

1. Enclosures grounded to ground rod.
2. Enclosures not grounded.
3. Enclosures grounded to G68.

I can say with some degree of confidence that (1) and (2) sound better than (3), but I cannot say with much confidence whether (1) sounded different from (2). So maybe the ground rod is adding nothing other than additional risk.

As for why (3) sounded worse than (1) and (2), I don't know what to say. Maybe grounding the enclosures to the G68 made the enclosures act like antennas collecting RFI, and that RFI was then transmitted into the G68? I don't know. I'm out of my depth. Maybe someone has a theory.

bc

Thank you, Al, for your help. In light of Jim's advice, I've abandoned the idea of using a dedicated ground rod. Even though I live in Southern California where lightning is rare, there's no good reason to take the risk. It's really no sacrifice anyway, because I could not hear a difference between the enclosures grounded vs. ungrounded.

The improvement from adding the two additional enclosures (whether grounded or ungrounded) was perceptible but not dramatic. The big improvement came from adding shielding INSIDE the G68 (grounded to the chassis). With that in mind...

I've been reading that copper is effective at shielding high frequency RFI, but not particularly effective at shielding low frequency EMI. So I'm thinking about adding a layer of STEEL shields around the G68's power supply, bolted directly to the copper plates that are already in place.

bc

Question...

Looking inside the Meridian G68, I see that the power is grounded to the chassis at TWO points. A ground wire connects the IEC input to the chassis. A second ground wire connects the power supply to the chassis.

The unit has been modified extensively, both by me and by a professional modder, so I don't know how it was grounded when it came from the factory.

Is it okay for the power to be grounded to the chassis at two points? Or am I creating a ground loop?

Thanks,
Bryon

My suspicion would be that the connection from the power supply is connecting the ground on the DC output side of the supply to chassis...

You may be right, Al, although the ground wire on the power supply is right next to the power INPUT. Here are some pics...

Modded PSU photo 1

Modded PSU photo 2

Modded PSU photo 3

Stock PSU

The power input is the blue/red wires in the top left of photo 1. The ground is the green wire in the bottom left of photo 1.

Can you tell from looking at those pictures whether the ground is on the AC side or the DC side? Can we infer from its physical location that it is on the AC side?

Thanks, Al. I will leave both ground wires in place. There is something else strange to report...

I installed a shielded Cat6 cable today, replacing an unshielded Cat5 cable. I expected to hear no difference whatsoever. Much to my surprise, there was a BIG difference. I know that sounds crazy. I don't understand it at all.

I know that the shielded cable might keep out EMI/RFI, but that doesn't seem to explain what I'm hearing, which is significantly more resolution. It's dramatic enough that it seems difficult to explain as simply less EMI/RFI. The difference sounds similar to the kind of resolution jump you get when you go from 16/44.1 to 24/96. In other words, it sounds like more information is reaching the system. But how could that be, if the ethernet protocol utilizes error detection/correction? I'm confused.

The old configuration was...

iMac -> 50' unshielded Cat5 -> Apple Airport Extreme -> 50' unshielded Cat5 -> Sonos -> S/PDIF -> Reclocker -> S/PDIF -> Meridian G68

The new configuration is...

iMac -> 50' unshielded Cat5 -> Apple Airport Extreme -> 25' shielded Cat6 -> Sonos -> S/PDIF -> Reclocker -> S/PDIF -> Meridian G68

So only ONE link in this chain changed: a 50' unshielded Cat5 was replaced with a 25' shielded Cat6. And the result was a big jump in perceived resolution. I'm scratching my head...

bc

Al, I think you may be right in your speculation that the reduction of EMI/RFI provided by the shielded cable is resulting in less jitter. That is consistent with the change in sound quality. If that theory is correct, the system now has a LOT less jitter.

I spent a couple hours listening last night and I continued to be stunned by the difference. I have NEVER experienced anything like this with any other cable. In the past, I've had two different $2k analog interconnects in the system, and they didn't have anywhere near the effect I'm describing. I currently have about $4k in power cords in the system, and they didn't result in a fraction of the improvement of this $7 cable. It's mind blowing.

FWIW, I very seriously doubt that other systems would be similarly effected by a shielded ethernet cable. My setup is so idiosyncratic that my results are most certainly not generalizable.

I'm inclined to conclude that there was a significant PROBLEM in the system that the shielded Cat6 cable has rectified, a problem that has gone undetected by me for years. Things have sounded pretty good, so when I listened to the system, it didn't sound like there was a problem. But this is such a dramatic effect, I must have been listening to/through this problem all along.

As a footnote, it's interesting that you mention intermodulation, because when I added shielding around the analog output stage, walling it off from the digital circuitry, I said to a friend: "It sounds as if there is less intermodulation." I'm not even sure I know what I meant by that, but that was the concept that immediately came to mind.

Bryon

Jea - Thanks for the advice. I will poke around on Tweakers and see what I discover.

Kijanki - Thanks for the help. You are always a good source of information. Much appreciated.

MuMetal is good suggestion - it works much better than plain steel.

I already ordered custom cut regular steel from an online retailer. :-( You think using regular steel is a waste of time?

Your magnetic fields are most likely very weak but just in case don't place MuMetal close to the source (transformer etc.).

Again, what if I use the regular steel I already purchased? It's T-304, which I believe is non-magnetic. If that's true, do I still have to be careful how close I get it to the power supply? How close is too close?

Bryon

Now that I think about it, if the steel I purchased is indeed non-magnetic, will it work for shielding EMI at all?!

bc

Thanks, Kijanki, for that detailed response. I will follow your advice and add the regular steel shields to the copper shields already in place. I will report back with the results.

I think you and Al must be right that the Cat6 cable has reduced system noise, and thereby reduced jitter. It's the only plausible theory that also explains the dramatic change in sound quality.

It's worth noting that whatever the jitter-inducing system noise was, it was not audible as a NOISE FLOOR, i.e. hiss, buzz, and other grunge audible when playing music. The system has been very "quiet." Because of that, I (falsely) believed that the system didn't suffer from any significant noise problem. But now I see that my reasoning was flawed. Apparently, not all detrimental noise is audible as a noise floor. I wish I'd known that!

Bryon

Rodman - At your suggestion, I've been reading about the TI shield. It looks like a very interesting product. I think I will order some. Thanks.

Bryon

My TI Shield arrived yesterday. I was thinking about placing it around the switching mode power supply in the G68. I think Kijanki warned me not to get magnetic materials too close to the power supply.

Anyone know how close is too close? And what would happen?

Thanks,
Bryon

Update… Things are winding down. Here’s what I’ve added to the system:

--A total of 11 shields to the Meridian G68. Each shield is a sandwich comprised of 16 gauge copper, 22 gauge steel, and TI Shield. I placed shields around the power supply, the analog output stage, the clock, and the lid. All shields are grounded to the chassis. You can see a picture of some of the shields here.

--Aluminum enclosures around the Empirical Audio reclocker and the Sonos. I reinforced both enclosures with 16 gauge copper and 22 gauge steel.

--A sheet of ERS Cloth inside the G68, and 2 sheets inside the door of the breaker panel.

--A 22 gauge steel plate under the Pass amp.

--A 22 gauge steel plate on top of the Hydra power conditioner.

--2 shielded Cat6 cables to replace the unshielded Cat5 cables.

--A shielded Netgear ethernet switch to replace the Apple Airport.

--VH Audio’s 10 gauge cryo’d romex for my dedicated line to replace standard 12 gauge romex. I rerouted the line to minimize the distance to the breaker and to avoid crossing any other lines.

The only other thing I have yet to do is install a new outlet. I've ordered a Maestro outlet to replace my Synergistic Research Teslaplex, which I've just discovered has a magnetic backstrap.

The results of all these changes are excellent. Greater resolution, better harmonic accuracy, better bass definition, and more precise imaging. Overall, things sound more natural and less “hifi.” I am pleased.

Thanks to everyone for your help.

Bryon

Hey Sean - You can see a picture of some of the shields I added to the Meridian G68 here. I haven't taken a picture of the other enclosures yet.

Bryon

Follow up...

I bought this ethernet switch to replace my Apple Airport and it works great. But when I got around to grounding it yesterday, I discovered that there is no obvious way to ground it.

I thought there would be a grounding tab on the chassis, because a friend owns a slower version of the same switch and it DOES have a grounding tab. Does anyone know...

Can I simply drill a hole in the chassis of the ethernet switch and attach a wire to some point on the system I know to be grounded? Or do the ethernet PORTS themselves have to shielded/grounded in order to pass the benefits of grounding on to the cables?

Bryon

P.S. The component immediately downstream from the ethernet switch is the Sonos, and it isn't grounded either.

Thanks, Al.

Camb -- Digital components are noisy, and analog components are sensitive. Putting them together makes for an unhappy marriage. IME, shielding works, but the DIY approach requires lots of experimentation. I find the process of experimentation fun, but then again I am crazy.

:-)

bc

Thanks, Al, for that detailed response. I'm in the middle of a long series of tests, trying to determine the best grounding arrangement. I will report back when the results are in.

Bryon

Here are the results of my experiments with grounding…

THE SETUP

COMPUTER ->
50’ shielded ethernet cable ->
ETHERNET SWITCH ->
1’ ethernet cable ->
SONOS ->
s/pdif cable ->
RECLOCKER ->
s/pdif cable ->
MERIDIAN G68 ->
analog interconnect ->
PASS AMP

THE EARTH GROUNDS

computer: grounded to circuit #1
ethernet switch: NOT grounded
Sonos: NOT grounded
reclocker: NOT grounded
Meridian G68: grounded to circuit #2
Pass amp: grounded to circuit #2

Other than the computer, all the above components are plugged into a single Shunyata power conditioner, which is itself plugged into circuit #2 (a dedicated line).

THE EXPERIMENT

I manipulated 2 variables. First variable: grounding vs. not grounding the ethernet switch. Second variable: using a shielded vs. unshielded ethernet cable for the 1’ run between the ethernet switch and the Sonos. I tested 4 arrangements:

1. UNGROUNDED switch + UNSHIELDED cable

2. UNGROUNDED switch + SHIELDED cable

3. GROUNDED switch + UNSHIELDED cable

4. GROUNDED switch + SHIELDED cable

I tested for continuity (from the ethernet switch to all other components), and I also did listening tests for each arrangement.

Important point: For ALL arrangements, the 50’ ethernet cable between the computer and the ethernet switch was SHIELDED. I only tested the shielded vs. unshielded ethernet cable for the 1’ cable between the ethernet switch and the Sonos, which as you will see, changed both the continuity results and the listening results.

THE CONTINUITY RESULTS

1. UNGROUNDED switch + UNSHIELDED cable

Ethernet switch to Sonos input… NO continuity
Ethernet switch to Sonos output… NO continuity
Ethernet switch to reclocker input… NO conitnuity
Ethernet switch to reclocker output… NO continuity
Ethernet switch to Meridian G68… NO continuity
Ethernet switch to Pass amp… NO continuity

2. UNGROUNDED switch + SHIELDED cable

Ethernet switch to Sonos input… continuous
Ethernet switch to Sonos output… continuous
Ethernet switch to reclocker input… continuous
Ethernet switch to reclocker output… NO continuity
Ethernet switch to Meridian G68… NO continuity
Ethernet switch to Pass amp… NO continuity

3. GROUNDED switch + UNSHIELDED cable

Ethernet switch to Sonos input… NO continuity
Ethernet switch to Sonos output… NO continuity
Ethernet switch to reclocker input… NO continuity
Ethernet switch to reclocker output… continuous
Ethernet switch to Meridian G68… continuous
Ethernet switch to Pass amp… continuous

4. GROUNDED switch + SHIELDED cable

Ethernet switch to Sonos input… continuous
Ethernet switch to Sonos output… continuous
Ethernet switch to reclocker input… continuous
Ethernet switch to reclocker output… continuous
Ethernet switch to Meridian G68… continuous
Ethernet switch to Pass amp… continuous

THE LISTENING RESULTS

1. UNGROUNDED switch + UNSHIELDED cable

Lacking pitch definition in bass.

2. UNGROUNDED switch + SHIELDED cable

Lacking pitch definition in bass. Little or no perceptible difference from arrangement #1.

3. GROUNDED switch + UNSHIELDED cable

Excellent. The best arrangement by a considerable margin. Very good pitch definition in bass.

4. GROUNDED switch + SHIELDED cable

Better highs than arrangement #1 or #2, but like #1 and #2, still lacking pitch definition in bass.

MY INTERPRETATION OF THE RESULTS

I suspect that grounding the ethernet switch resulted in significant benefits because it grounded the shield for the 50’ shielded ethernet cable running between the computer and the switch. I suspect that using a shielded ethernet cable between the ethernet switch and the Sonos resulted in poorer performance because, as you speculated Al, it defeated the galvanic isolation in the reclocker.

It's worth pointing out that I did NOT hear a difference in the noise floor among ANY of the arrangements. I tested this by turning up the G68's volume to max and putting my ear to the tweeter. Because of this, I suspect that the main audible variation I heard – pitch definition in bass – was attributable to differences in jitter levels among the various grounding arrangements. I believe I have read that jitter can be audible as a lack of bass pitch definition. That could have been from Steve N., or some other source, I’m not sure.

This has been an informative experiment for me. For one thing, I didn’t expect to hear a difference in bass response at all. Also, before the experiment, I would have guessed that arrangement #4 (grounded switch + shielded cable) would yield the best results, because I naively assumed that the more grounding/shielding the better. That was true only up to a point.

Bryon

Thanks again, Al. A few final questions...

You mentioned a couple times that a ground must have an "effective path." I don't really know what the factors are that make a ground path effective.

To ground the ethernet switch, I drilled through the metallic housing of the block of ethernet ports and connected a 14 gauge wire. The wire runs to an aluminum screw that passes through the switch's housing. You can see a picture here. A second 14 gauge wire runs from the switch to a screw on the power conditioner. Does that seem like an effective path?

Also, you mentioned that the shield of the 50' ethernet cable is grounded at the computer end. I couldn't find any information about that online. How can you tell?

Bryon

Hi Al - I checked for continuity between the tabs in the computer's ethernet port and the computer's IEC ground pin. You were right, the port is grounded.

Correct me if I am wrong, Al, but that seems to help explain something that puzzled me at the time: the dramatic improvement I heard when I first replaced the unshielded ethernet cables with shielded ones. In my posts on 2/16, I was mystified about how a $7 cable could make such a difference. You offered me a speculative explanation at the time, but I was left with a certain amount of puzzlement. What I didn't know at the time (but you did) was that the shielded ethernet cable was also grounded. Knowing that now, it seems to help explain how I could have heard such a dramatic improvement.

There is one other point I've been wondering about with respect to ethernet grounding, and that is: Is it better to ground an ethernet cable at both ends? I poked around a little and I found a discussion of this topic, in which an evident expert said this...

In high-speed digital applications, a low impedance connection between the shield and the equipment chassis *at both ends* is required in order for the shield to do its job...

In high-speed applications involving low-impedance circuitry, most of the near-field energy surrounding the conductors is in the magnetic field mode, and for that problem, only a magnetic shield will work. That’s what the double-grounded shield provides. Grounding both ends of the shield permits high-frequency currents to circulate in the shield, which will counteract the currents flowing in the signal conductors. These counteracting currents create magnetic fields that cancel the magnetic fields emanating from the signal conductors, providing a magnetic shielding effect.

For the magnetic shield to operate properly, we must provide means for current to enter (or exit) at both ends of the cable. As a result, a low-impedance connection to the chassis, operative over the frequency range of our digital signals, is required that *both* ends of our shielded cable.

One thing I'm still unclear about is whether the grounding I've created at both ends of my 50' ethernet cable is "operative over the frequency range of [the] digital signals." I know you said that...

the inductance of a plain piece of wire will cause it to have a significant impedance at the high RF frequencies that constitute the spectral components of the ethernet signals.

...which, in combination with the information I quoted above, seems to suggest that grounding the ethernet cable at both ends should have no additional benefit. But I DID hear an additional benefit when grounding it at both ends. Perhaps that is because, as you said...

the resistance of the very long run presumably lessens the effectiveness of that ground from the perspective of the switch.

...but I'm not sure I completely understand how that works. In other words, I'm unclear about how the following 3 things can all be true at the same time:

1. The effectiveness of a ground method for an ethernet cable's shield depends upon whether the ground method operates over the frequency range of the ethernet signal.

2. The ground method I provided my ethernet cable (at the switch) is ineffective at the frequencies range of the ethernet signal.

3. I heard an improvement when grounding the ethernet cable at *both* ends.

Assuming I'm right about #3, maybe you can say a few more words about how those things can all be true. Thanks!

Bryon

Thanks, Al. Everything you said makes sense. It's interesting that you took Dr. Johnson's course. It looks very interesting, although most of it would go way over my head.

Let me take this opportunity to say that, during this process, you've been an invaluable source of information, advice, and support. It is VERY appreciated!

I will now resume the rest of my life. My wife is expecting our first baby any day now, so I finished this experiment just in the nick of time! :-)

Bryon

I've been putting the finishing touches on reducing the effects of EMI/RFI by putting ferrites on things.

I've put some ferrites on power cords in the system (only on components whose performance is not affected by current draw).

I've also been wandering around the house, putting ferrites on things that dump RFI onto the power lines.

Question: Would it be effective, and is it safe, to put a ferrite on the GROUND WIRE of the system's dedicated AC line?

Bryon

Thanks, Al.

Update. Three things...

1. After further experiments with additional ERS cloth, placing it in every location I could think of, I have come to the conclusion that, in my system, to my ears, it is harmful more than helpful about 90% of the time. Some folks predicted I would say that. You were right. It has a tendency to make things sound strangely "muffled." I find that just as puzzling as my initial impression that, in my dac, it resulted in a slight improvement in sound quality. I have not yet removed it from the dac to see if my impression might have changed. That is certainly possible, especially in light of the extensive tweaks I've made to reduce RFI/EMI in the system since I initially installed the ERS.

2. I am happy to report that, with the loving support of my wife and timely medical intervention, I have overcome a three week addiction to ferrites. :-) There are now approximately 50 ferrites all over the house. I attached them to things that pollute the power lines, as well as to some of the cables in the system, including the ethernet cables. I did NOT attach them to the system's interconnects, speaker cables, or power cables. I must say, they really work, provided you don't put them in the wrong place.

3. Among my final experiments with ferrites was to create two RFI pigtails. They look like this. I attached one pigtail to the chassis ground of the Meridian G68 and a second pigtail to the signal ground of the amp (which was made easy because Pass includes a signal ground binding post on the rear of the amp, for reasons that are unclear to me). I have no idea whether the RFI pigtails make a difference. I probably should have posted this part in the thread on Magic. Perhaps someone can comment on whether the whole idea of an RFI pigtail is preposterous.

Bryon

Thanks, Al, for your explanation of the signal ground binding post on the amp.

Your hypothesis about the ERS is interesting. I plan on removing it from the G68 temporarily to see if things get better or worse, now that I've made so many other changes to the G68 and the rest of the system. I will report back the result. I might post my findings in the Magic thread, since (I now recall) that's where most of the discussion of ERS occurred.

RFI pigtails can IMO be placed somewhere close to the border separating the remotely plausible from the totally preposterous.

That made me laugh. And I'm not surprised to hear you say it. I suspected as much. It's strange the things you will do when in the grip of addiction. :-)

I looked at the thread you linked. An interesting discussion of another Magical device, if you can call a piece of wire a 'device.' All your skeptical comments make perfect sense. Still, after reading that thread, I want to try it.

One day at a time. One day at a time.

Bryon

03-25-12: Almarg
Bryon, an additional point occurs to me regarding the ERS cloth... its presence could affect the amount of stray capacitance between arbitrary circuit points.

That's an interesting hypothesis, Al. The mystery of ERS deepens. :-)

03-25-12: Lewinskih01
I understand ferrites need to be carefully chosen by frequency. Which ferrites did you choose and why, and which were the most effective places for them?

Hi Lewinski - I didn't select ferrites based on frequency, because I don't know the frequencies of the RFI I'm trying to reduce. So I took the shotgun approach and bought several different sizes like these from Parts Express. For some cables, I used multiple ferrites of different sizes in an attempt to cover a wider range of the frequency spectrum.

I was a bit more scientific about where I placed the ferrites. I put them on...

1. Anything in the house that might pollute the power line... anything with a microprocessor, a switching mode power supply, a motor, a fan. So all appliances, tv's, computers, routers, dvr's, etc..

2. Some of the power cables in the system. I started with all the power cables for equipment whose current draw is either relatively constant and/or unrelated to performance. So I put ferrites on the power cables for the computer, the disk drives, the Sonos, the reclocker, the ethernet switch, but NOT on the amp or the preamp.

3. The ethernet cables.

4. Some of the equipment grounds, including the chassis ground of the preamp and the signal ground of the amp. For this I made two RFI pigtails, which as Al and I discussed is probably nonsense, but they didn't do any harm and they were fun to make.

5. The ground wire of the Romex for the dedicated line to the system. Again, probably Black Magic, but with no ill effects.

I also tried ferrites on the S/PDIF cable connecting the Sonos and the reclocker. That sounded bad. It made things sound hard and glassy. I suppose it elevated jitter.

I did not try ferrites on the analog interconnects or the speaker cables. That seemed like a bad idea.

Altogether, the ferrites resulted in a small but significant improvement in the system's noise floor, harmonic accuracy, and overall musicality. But be warned: Once you start, it is hard to stop.

03-26-12: Sabai
Neodymium magnets are among my favorite tweaks. I place them on or under components near transformers to draw off EMFs. The effect can be to increase the focus of instruments and voices and to provide a clearer sound than without the magnets in place.

Hi Sabai - This is new to me. Where do you put them? What size/shape/material? Do you know why they make a difference?

Bryon

The Meridian G68 has a ground wire running from the IEC input to the chassis. As discussed in earlier posts, the G68's PSU has a SECOND ground wire that is also connected to the chassis, but at a different point. You can see a diagram here. You can see a picture of the PSU's ground wire here.

Yesterday, while upgrading the AC wires running from the IEC input to the PSU, I removed the ground wire connecting the PSU to the chassis. The ground wire connecting the IEC input to the chassis is still in place. Works normally, but...

Have I created a safety hazard?

Thanks,
Bryon

Another update from my crusade against EMI/RFI...

A couple years ago, I relocated all my equipment to a closet, which you can see here. To reduce heat buildup, I installed a large fan in the ceiling of the closet. Today, I finally got around to DIY'ing an EMI/RFI fan filter, which you can see here. It's made from steel and copper mesh, and it covers the entire ceiling of the closet.

Obviously, I don't have much of a life. But that's not the point. The point is: it works. Definitely an improvement in SQ. I was surprised. Again.

Bryon

Hi Al -- I didn't realize from our earlier discussion that removing the PSU ground wire would reduce the level of noise filtering. Back it goes!

Hi Mapman -- I've looked at Mu metal a few times. It seems like an interesting product. I elected to use TI Shield instead, along with regular old copper and steel. But I'll keep the Mu metal in mind for future diy projects. Thanks.

Bryon

03-04-12: Almarg
...for shielding to be effective at high frequencies, as Dr. Johnson indicated the shield should be grounded at both ends. But I believe that the key element of what he is referring to by "grounding" is a connection at each end between the shield and the metallic structure of the component, rather than a connection to some external ground point. I believe that circulation of noise currents from the cable shield into the metallic structure of the components will dissipate their energy significantly, although perhaps less so in the case of the network switch due to its small size.

I've been giving more thought to this, and I decided to experiment further with an alternative grounding scheme. I disconnected the ground wire between the ethernet switch and the power conditioner (thereby removing the switch's connection to earth ground), and I added a braided grounded strap between the ethernet switch and a 6" x 12" aluminum plate. My hope was that, by "enlarging" the surface area of the ethernet switch, it would provide more adequate dissipation of RFI or other noise picked up by the long ethernet cable between the computer and the switch.

The results are at least as good, and possibly better, than the result of grounding the ethernet switch to the power conditioner (which, in turn, was grounded to the preamp, the amp, and earth).

Bryon

Yes, Al, the plate is directly under the switch. I placed it there to keep the braided ground strap as short as possible, to minimize any antenna effect. Out of curiosity, is there another reason why it should be directly under the switch?

Also, I neglected to mention that I also changed another variable: I replaced the 1' unshielded ethernet cable between the switch and the Sonos with a SHIELDED version. So prior to this change, the configuration was...

computer -> 50' shielded Cat6 cable -> ethernet switch (grounded to power conditioner/earth) -> 1' unshielded Cat6 cable -> Sonos -> reclocker...

And my continuity results were...

Ethernet switch to Sonos input… NO continuity
Ethernet switch to Sonos output… NO continuity
Ethernet switch to reclocker input… NO continuity
Ethernet switch to reclocker output… continuous
Ethernet switch to Meridian G68… continuous
Ethernet switch to Pass amp… continuous

So the break in continuity was due to (a) the galvanic isolation in the reclocker and (b) the UNSHIELDED ethernet cable between the switch and the Sonos.

Now the configuration is...

computer -> 50' shielded Cat6 cable -> ethernet switch (not grounded to power conditioner/earth, but grounded to the "grounding plate") -> 1' SHIELDED Cat6 cable -> Sonos -> reclocker...

And the continuity results are the "OPPOSITE"...

Ethernet switch to Sonos input… continuous
Ethernet switch to Sonos output… continuous
Ethernet switch to reclocker input… continuous
Ethernet switch to reclocker output… NO continuity
Ethernet switch to Meridian G68… NO continuity
Ethernet switch to Pass amp… NO continuity

So now the upstream half of the system (computer, ethernet switch, Sonos, reclocker input) is discontinuous from the downstream half (reclocker output, preamp, amp).

In this new arrangement, the high frequencies are improved, which is consistent with my listening results from 3/3, where the presence of a SHIELDED ethernet cable between the switch and the Sonos produced the best high frequency results. At the time, I didn't go with a shielded ethernet cable between the switch and the Sonos because the bass was lacking pitch definition with that arrangement. But with the "grounding plate" for the switch in place, the bass pitch definition is excellent.

My conclusions...

1. The variation in the bass was a function of grounding the ethernet switch to a sufficiently large chassis, which was originally provided by the power conditioner and is now provided by the grounding plate. The variation in the bass was NOT due to the presence or absence of EARTH grounding, as I originally believed.

2. The variation in the highs was a function of the presence or absence of shielding in the ethernet cable between the switch and the Sonos. I suspect that shielding that cable reduces noise, either...

(a) noise transmitted from upstream components (computer, switch) through the ethernet cables, or...

(b) noise transmitted from nearby components (amp, preamp, Sonos, reclocker) through the air, or...

(c) noise transmitted from downstream components (preamp, amp, power conditioner) through the ground wire between the switch and the power conditioner (that ground wire is now gone, but it was present on 3/3, when I experienced the same variation in the high frequencies).

Not sure which of these was the culprit.

Bryon

I agree that the current configuration seems to maximize the benefit of the reclocker's galvanic isolation.

I have a follow up question for you, Al, about the dissipation of noise in an equipment's chassis... Is the dissipation potential of a chassis determined by its surface area, its mass, its material, its conductivity, its magnetism...? Several of the above?

bc

Thanks, Al. That looks like a great reference guide, though much of it is over my head. I think at some point I'll take a course in electronic engineering, to get a firmer grasp on some of the more difficult concepts.

I read a few of Ott's articles and tech tips on his website. I particularly enjoyed this one.

bc

Question...

When I went around placing ferrites on everything in sight, I put a number of ferrites on wall warts with DC outputs. Do ferrites have the same effects on DC as AC? Are ferrites appropriate for DC?

Bryon

Thanks, Al.

Hi Dave - Thanks for those links. They are very informative.

As far as A'gon rejecting your post because it was "too short," that is just strange. And arbitrary. My last post on this thread was two words long.

What's more, it seems like I've been hearing more and more A'gon stories of people whose posts are being rejected for one reason or another. Maybe there is new management in Moderatorland.

While I certainly understand the need to moderate forums for content that is truly objectionable, one of the things I always liked about A'gon is that it erred on the side of permissiveness rather than censorship. Not long ago, I joined another audiophile site, where 3 out of my first 15 posts were edited by a moderator. It was creepy. I stopped posting there altogether.

Whether it's in the virtual world or the real world, the excessive control of speech has a chilling effect on the exchange and progression of ideas. Let's hope this trend doesn't continue.

Bryon

Update for anyone still interested in my adventures in EMI/RFI reduction...

Three more changes:

--I replaced the unshielded power cords for the power conditioner, the preamp, and the amp with shielded power cords. An improvement, even though I went from three $1100 cords (Shunyata Pythons) to three $100 cords (Pangea AC-9's).

--I added copper "sleeves" to the ends of all power cords in the system, as described here.

--I wrapped the external hard drive where my music is stored with TI Shield.

All three were improvements, but the biggest and most surprising improvement was wrapping the external drive with TI Shield. Don't know what to make of that.

FWIW.

Bryon

Yes, Onemug, I did notice a small improvement after they had about 100 hours on them. I am very impressed with the performance of the AC-9's. Remarkable for the price.

The fact that I preferred the very affordable AC-9's to the very expensive Pythons illustrates a point Al has made many times... in the world of cables, the correlation between price and performance isn't that strong.

Bryon