It really depends on alot of factors..
There are alot of power cords that are not shielded...
If there is shielding in power cords, it is usually small amounts of wrapped aluminum/tin or braided tin...
I have found that in power cord construction, shielded vs unshielded may make a difference for longer runs but short runs, musically, the unshielded cords tend to sound better. The sheathing, whether pvc or rubber etc makes a difference... The internal dialectrics make a difference.. The coating on the conductors inside the cord make a difference... There are many flavors of cords... Being a small manufacturer.. I have developed a line of cords that use Ferrite core rfi blockers by TDK to eliminate any noise..so to speak... Shielded or un shielded, there wasnt much of a difference... For digital components.. one may want a smaller gauge, shielded cord or filtered cord..
For power amps, and high current applications.. one may want to try a larger gauge cord with better internal dialectrics and heavy duty connectors for maximum signal transfer... On the other hand, some environments and systems are just prone to bad power ... ie, rfi in the area emi in the lines, and bad synergy with the interconnects and cable tv wire... So there is no right or wrong...
Choose a cable that suits your needs, and follow your cable manufacturers recommendations...Different cords may and will work better in some situations than other...
Just my 2 cents.
Joe DiMonte
Custom Audio LLC |
No technical reason to shield power cords or speaker cables. These are low-impedance output drivers, so crosstalk is not really a concern. The only advantage might be if you wnat to run power cords side-by-side with unshielded interconnects. Then the power cord may crosstalk to the interconnects. This is fairly easy to avoid with minimal spacing however. Shielding just adds unwanted capacitance. |
A shielded cord will always perform in superior fashion to an unshielded cord of otherwise identical design. If it does not, some simple yet almost always overlooked design criteria were not taken into account during the construction of said cord.
The lack of design integrity with the shielded cord would become more apparent when using devices that produce high current demands on the power cord / wall outlet i.e. power amps, etc... That is why many people have better luck using shielded cords on low current devices ( digital, line level sources, preamps, etc.. ) but run into problems using shielded designs on power amps. I don't know of any commercially designed power cords that take such criteria into account. Those that are smart and / or familiar with magnetic fields will understand what i am hinting at. Sean
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I might be over taking too simple of an approach here, but I took one of the little pen things that detect current/voltage(hot leads) and went around my system with the supplied(careful wording here...) and it went nuts.
With my DIY adventure, the pen no longer goes off, as much. It is pretty hard to shield a tv....:)
I think I was thinking of a more "global" approach, basically reducing the junk jumping into the RCA ic's.
I am not wanting to start a gripe thread... But I have no choice but to use single ended ic's on some equipment. Simaudio Stellar to the Simaudio Attraction can only be hooked up in one of two ways... Digital coax or RCA's. No balanced inputs on the Attraction.
The field an unshielded pc give off seems to be large, at least 12 inches.
Thanks all
Marty |
Hi Marty: Good question! As with IC's there is a division regarding the necessity of sheilding and to what degree/method of sheilding is best. As always, ensure that all cords are FULLY burned-in. Even when fully settled (burned-in), when the cord (IC, speaker wire, PC --any cord) is physically moved, I would give it 1/2 hour to re-settle, so-to-speak. It may sound strange, but listening sessions over many years confirms/supports these recommendations. I wish I could state firmly what the best approach is, but it's difficult (at times)to confirm a particular manufacturer's design/sheilding and therefor deduce what exactly makes one PC sound better/or different than another. The desired PC (like all other components) is simply a matter of taste and what characteristic(s) one desires most.
As IC's, PC's do contribute significantly to a component's performance capability. Give a few a listen (bearing in mind the above caveats)and you'll discover one that suits your tastes and defintion of a marked improvement.
peter jasz |
Marty, your "DIY research" has exposed more "truths" than many manufacturers / engineers will ever come to realize in a lifetime. The reason for this is that you can't find the "hands-on" results that you experienced first hand in a text book sitting at a desk or bench. This is NOT a poke at Steve aka Audioengr but a generic comment. I hope that he understands this and does not take it personally. I know that Steve is working very hard to do the best he can and does so with both hands-on testing and using very high grade test equipment. Quite honestly, i know first-hand that Steve has more advanced test equipment than most of the other cable manufacturers out there and knows how to use it. I am not endorsing his products as i have never used them, but i don't doubt that they perform well based on REAL scientific research and listening tests. Sean
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David Blair at Custom Power Cord Co. in Skokie IL uses heavy liberal shielding for all of his AC cords with great results; evidence that this can in fact be done to good effect when properly engineered.
Now take another look at shielding from a somewhat radical perspective: specifically, the Synergistic Research "active shielding" approach. The applied DC voltage potential on their cable shields (which are out of the signal path) is said to saturate the insulation dielectric such that it won't leach electrons from the signal carrying conductors. I admit to healthy skepticism when I first read about this unique shielding system, & was still rather doubtful regarding its benefits when I first auditioned it with some decidedly mid-fi componentry. Yes I heard an improvement with the active shielding power supply energized, but not enough difference was perceived to justify the expense.
Later on, after significantly upgrading my rig to better quality components, I decided to incorporate the active shielding system. Now I could really hear a significant difference between the active shielding vs. passive shielding; this system really does work. Proof that this effect is not just psycho-acoustic came to me a few months later, when the rig was shut down during a storm. Wife had powered the system back on the following day, but had neglected to turn on the shielding power supply (they call it a Master Control Center - but it really doesn't control anything). I came home from work & even casual listening revealed a deficiency, but I couldn't quite quantify the actual problem. Bass was lacking, dynamics were softened, highs just weren't what they should be, staging was constricted. I suspected the disc that she was playing, until other more familiar material didn't measure up either. Sitting in the living room, I was gazing at the rack & then realized that the tiny blue LED AC power indicator for Master Control Center was not turned on. Turned on the power switch & everything fell right back into place. That's proof enough for me; I'm not "imagining" these effects.
Synergistic has since incorporated active shielding into their AC cords & even speaker cables. Currently, only my Synergistic interconnects have the active shielding, but I now plan to retrofit my AC cords. I don't use their speaker cable so I can't really comment on that; however I remain convinced. |
I agree with audioengr, shielded power cords are unnecessary. The extra ground capacitance and dielectric distortion is undesirable. |
Bob's not going to like this,
I wonder how one could do a DIY active shield? Put a dummy load on a small DC transformer and shoot the current up the shield, or wrap the wire around the cable?
I must say that with my limited, yes very limited tester, the shield and drain on the wire I used seems to work very well.
Thanks all,
Marty |
Marty9876 wrote: The field an unshielded pc gives off seems to be large, at least 12 inches. The fields may be large depending on the construction of the power cord. Many cord designs are field-cancelling, and they are not shielded. I dont doubt the you measured larger fields with unshielded power cords, but what about the ROMEX in the wall? Did you shield that too? This ROMEX is usually substantially longer than the power cord. Also, did you have more noise with the unshielded power cord than the shielded one? The reason that I ask is because I have seen many audiophiles chase their tails trying to eliminate noise with shielding on IC's, power cords and even speaker cables when the problem turned-out to be a ground loop. Since your system is all single-ended, this is more likely. Using more than one circuit outlet to plug all of the components also increases the likelyhood of a ground-loop. Grounding and shielding is a non-trivial field of science. I have taken courses from industry "experts" in this field. |
Honestly, when I was done braiding the wire and all the mess, the DIY were going to be better...No matter what :).
I had not a/b the cables, until just before this reply. "more noise" between the two- nope. Seems to be the same. I had meant this for another post, how much noise is too much? The old crank the volume and stick your ear up to the tweeter, I do here a little noise. Not heard from the listing position, but can hear with my ear on the tweeter. Not sure really how to put this into words. The tuner will bleed into the next/nearest analog input. $6000 bucks for bleeding inputs, huh.
On the flip side the "dynamics" seemed improved with the shielded DIY's. The highs seem higher and the lows seem fuller. Interesting...
The amp circuit to the wall is unshielded, all runs in the room are shielded. The source circuit is actually shielded all the way to the breaker panel. I use balanced ic where possible, from the processor to the amp. With HT, one seems to have a few more devices, which seem to add more possible problems.
No, the existing ROMEX are not shielded. That's the reason a normal person would buy the live lead finder pen(I gotta find out this thing is really called), to find these lines. My equipment is also not placed directly up against a wall, next to these lines.
Please explain what "unwanted capacitance" means. Is this the ability of the wire to store a charge.
Also the power conditioners in the system are a ps ultimate outlet ran into a Richard Gray 400. Really weird part with out the power conditioners, the buzz is 75% louder, plain as day. What I would call very bad. With the ps, same. With the "noisy" RGPS, very quiet. Funny, exactly the opposite of what I would have thought.
I hope I am not describing a long winded minor ground loop hum. This was not the purpose of the thread. This background noise is very minor.
Learning something new every day,
Thanks all
Marty
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Audioengr: Sorry to step on your toes, but thanks for proving my point. Your line of questioning to Marty just goes to show that even those that i consider to be "worthy" and design / manufacture PC's think of them as nothing more than "an extension cord" ( hypothetically speaking ).
While you have a point about what happens upstream from the PC, you also have to take into account several other factors:
1) One can piss anywhere along the river that they want. So long as the contents of the river are highly filtered prior to delivery to the water fountain, i don't care what takes place. In effect, one could use unshielded wire for a few million miles. This would in no way reduce the effectiveness of a well designed filter at the end of the wire.
2) Why is it that most engineers / designers / manufacturers have such a hard time thinking of a power cord as being anything more than a "conduit for power delivery" ? Aren't the internals of a PLC made up of capacitors, inductors ( which is nothing more than wire or wire on a former), resistors, diodes, impedance altering devices, etc.. ??? What would stop someone from applying filter technology and the associated componentry to a power cord design ?
3) The fields generated by the in-wall wiring are not anywhere near as close to the low level signal carrying cables and components as the power cords are. Therefore, EMI and radiation from the in-wall wiring is far less critical.
4) Stop thinking of a power cord as an extension cord and start thinking of it as a part of the power supply.
Sonic Genius: Your comments apply only to designs that are made by those "thinking within the box". If you were to step outside of the "box", you might begin to see how those factors could be reduced or even put to use as a positive aspect of the design. Certain design attributes are only "negative" when you can't control them or they are not taken into account for. When it comes to AC, signal manipulation is the name of the game. Sean
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On the flip side the "dynamics" seemed improved with the shielded DIY's. The highs seem higher and the lows seem fuller. Interesting... This may be true, but it is difficult to attribute this to the shielding. The new cables were likely lower capacitance or lower inductance as well. Please explain what "unwanted capacitance" means. Is this the ability of the wire to store a charge? Yes, but it also contributes to a low-pass filtering effect when installed in the system. Creates an impedance to high-frequency currents. I hope I am not describing a long winded minor ground loop hum. This was not the purpose of the thread. This background noise is very minor. It seems to quack and look like a duck.... |
Sean - No offense taken. Why is it that most engineers / designers / manufacturers have such a hard time thinking of a power cord as being anything more than a "conduit for power delivery" I can only speak for myself. A power cord is just one segment of a longer power transmission circuit, which can be described as series resistance and inductance and parallel capacitance. However, the catch is whether this is described as a lumped parasitic or a distributed set of parasitics, like a transmission-line. The former is used at low frequency and the latter at high-frequency. The debate goes on ... Aren't the internals of a PLC made up of capacitors, inductors (which is nothing more than wire or wire on a former), resistors, diodes, impedance altering devices, etc.. ??? What would stop someone from applying filter technology and the associated componentry to a power cord design ? Nothing. You can get filtering effects from different power cord constructions or just add filtering elements to the cord, such as inductors, ferrites, resistors and caps.. I do not happen to believe in filtering in PC's myself, except for the ground wire. This can be useful to minimize noise from ground-loops. Stop thinking of a power cord as an extension cord and start thinking of it as a part of the power supply. I agree. Certainly is a part of the power system. As is the transformer on the pole and the transmission lines that deliver to that. However, the further that you get from the component, the effects of the component load on the system become smaller and smaller because the impedance of the source gets increasingly lower. At some point, you ignore the effects because they are second-order. I have chosen this point to the be power panel in the house. This causes a small error in any calculations of power delivery. |
Radiated power drops rapidly with distance. No need to shield Romex in wall. It's too far away from the system.
The power cord, which is the last 6' of the power delivery system, seems to be an ideal place to put a tuned filter. Filtering out everything but the pure 60Hz using a power conditioner and a tuned power cord would seem to be optimal.
It seems that shielding on a power cable would keep it from radiating noise to the high impedance lines, such as the IC's. If the power has high frequency noise, it may radiate this too. Shielding is a difficult design process, however. No doubt many manufacturers just use trial and error.
Just my 2 cents (or maybe 3). |
Sean - as usual, right on the money! I especially like what you said about thinking outside the box.
Those of us who have built AC power cords realize that it is quite difficult to make sonic improvements beyond a certain level - which isn't all that fantastic in the grand scheme of available audiophile AC cords. Cables which carry low level signals are easier to improve upon.
Why do we suppose this is? Come on guys, think outside the box!!!
AC cable manufacturers like Electraglide, Elrod, and Shunyata for instance, have thought outside the box. It is doubtful that any of these cables measure well from an "inside the box" mentality yet the results these cables bring to a system is dramatic - far exceeding anything *I* have ever used from an "inside the box" kinda manufacturer or DIY enthusiast - at any price.
Regarding 'electronic add ons' to power cords. I seem to remember Bob Crump post that he fiddled with making a power cord for years without the ability to make any real improvement in sound from a stock cord....until he finally decided to add some circuitry to the design and hence make the improvements he was after.
Now... If Bob Crump cannot make a significant sonic difference with "inside the box" thinking it is doubtful that anyone can and I don't care who they are!
So those of you who believe in measurement and inside the box thinking as it applies to audio (especially you Audioengr). I dare you to find a Power cord that measures well and lets put it up against an Elrod Signature cord, Electraglide FatMan K, or Shunyata Anaconda Vx. I'm sure all three of these cords measure differently and all worse than an "ideal" cord... yet, I guarantee they will absolutely blow the doors off anything which measures good. |
Bwhite wrote: I dare you to find a Power cord that measures well and lets put it up against an Elrod Signature cord, Electraglide FatMan K, or Shunyata Anaconda Vx. I'm sure all three of these cords measure differently and all worse than an "ideal" cord... yet, I guarantee they will absolutely blow the doors off anything which measures good. Be careful what you ask for, you might get it. I have a very good cord, the Magnum2, which measures and sounds good (reviewed in BFS issue #140). However, my new reference cord, the "Grand Slam" will measure and sound even better. I believe it's going to be the one to beat. If other manufacturers would publish measurements on their cords, at least a comparison could be made. However, it seems that none of them do. I don't believe there is another manufacturer that has a plausible theory of why one power cord sounds better than another. At least I have this. |
Audioengr that's outstanding! I am excited to learn that you've come out with a cable like that. I certainly wish you the greatest success with it. If when your cable comes out, you would like to put it against one of Dave Elrod's Signature cables, that would be fantastic! If your cable sounds better - I'll eat my hat (so to speak) and buy a few of 'em from ya. Hey... you know? Sean mentioned that you have really high grade measurement equipment. Maybe you could do us all a favor and buy a few used high end cables on Audiogon - measure them and then resell. You would not loose any money other than maybe shipping - which you could write off as a business expense. Then.... YOU can publish the measurements on your website. Hey! That's a great idea!!! Then there would be no mystery, no pouting and wishing that other cable manufacturers published their own measurements. The truth be told!! Audioengr...you have the power! But if you do this, wont it be amazing to find out how poorly these things measure and at the same time how fantastic they sound? Audioengr wrote: If other manufacturers would publish measurements on their cords, at least a comparison could be made. Come on.. you're pouting. Buy the cables and make the measurements yourself. Audioengr wrote: I don't believe there is another manufacturer that has a plausible theory of why one power cord sounds better than another. At least I have this. Dude... if you had an amazing recipe for Chocolate Chip Cookies would YOU publish the theory on how they were made and why they taste good? Its the same set of ingredients everyone else uses isn't it? If you're smart you wouldn't share that information and likewise, I am sure that cable manufacturers have plausable theory's - that's how they maintain a "signature sound" (or flavor if you will) They just don't publish the info so that every Joe Blow DIY guy can duplicate their efforts. If making a cable sound good was as SIMPLE as making it measure good, every single manufacturer out there would be publishing their measurements and people would buy the cable that measured best. It would be a simple world. Unfortunately that is not the world we live in. Its tough... we actually have to listen for ourselves and decide what's best instead of just looking at SPICE simulations. Darn! I hate listening!!! |
Bwhite: I'm trying to do something similar to what you want Audioengr to do. That is, test various cords and collect the results. I do not have some of the equipment that Audioengr does, but then again, i have some equipment that he doesn't have either. Maybe we should move closer to each other : ) Sean
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Then.... YOU can publish the measurements on your website. Hey! That's a great idea!!! Then there would be no mystery, no pouting and wishing that other cable manufacturers published their own measurements. I wish it were that easy. Besides the possible legal issues with naming other manufacturers on my website, there are actually laws in other caountries against this. Best not to do it. If making a cable sound good was as SIMPLE as making it measure good, every single manufacturer out there would be publishing their measurements and people would buy the cable that measured best. It would be a simple world. True. However, even if I prove that inductance or some other parameter accounts for most of the performance of a cord, there will always be second-order effects that are less audible that can be optimized with good recipes, such as dielectric absorption, magnetic distortion etc..... These are much more difficult to measure and there are no standards for measuring these either. |
Sean - do you want to be in the cable business??
Here are the requirements:
1) be independently wealthy, because you will not make any money
2) be neurotic about audio and audio components
3) some engineering background
4) really good ears.... |
Audiognr: I think i've got 3 of the 4 covered, at least part of the way. Try and figure out which part of the equation i fall short on... : )
One can be in the cable business and make money at it. It might not be a lot of money to start off with, but it could be very profitable if you know how to market other people's products. After all, isn't that most wire & cable "manufacturers" do ??? : ) |
What? Not make money in the cable business... HA HA! People who have made good cables (and some not so good) have done rather well. Ya it takes marketing but take a look at Dave Elrod's business. He does ZERO marketing - he doesn't post to audio boards all day and night to market his stuff...his products just sound good and his products high demand! The products speak for themselves and people who use them...speak for the products. Audioengr wrote: you want to be in the cable business?? Here are the requirements: 1)be independently wealthy, because you will not make any money Ya.. Poor George Cardas. I hear he has to eat Top Ramen 4 times a week. And Caelin Gabriel, he is just suffering! Noel Lee - Now.. I know he's hurting for cash - I hear he's trying to expand his audio business into other areas. Ray Kimber? Who's he? Scotty Hall and Walter Fields broke! Kondo-San is down to his last yen!!! I hear the owner of JPS labs is working on a contract with Alcoa's recycling division to pick up all the salvage Aluminum cans in California for it's 2003 product line-up. I don't think Jena Crock is broke. Who's the Nordost Dude? Synergistic dude? Audioquest dude? Straightwire dude? Transparent? MIT? Wireworld? Tara Labs? Robert Lee might be hanging in there by a thread and his HT buddy Jim Wang cannot turn a profit. Serguei at Stealth? Purist are they going chapter 11? Rick Shultz is busy... Brian at BMI is quite the marketing guy and brings in a few bucks a month. Who owns Siltech? How about Max at Silver Audio? I think Bob Crump is independently wealthy...at least with his sense of humor he SHOULD be! King's TMC's seem to be selling well... The Frat Guys over at ZuCable are making a few bucks. Hell!! Even Tekunda is doing well selling cables!! So Audioengr? Who isn't making money in the cable business? |
Bob Crump told me the amount of money that he made on his "best" year of selling cables. Believe me, nobody here would want to try and live on that amount of money on an annual basis. If Bob did not have other money coming in from previous employment and having planned for his future, he would be in the "lower middle-class" income bracket. I made the amount of money that he mentioned when i was 18 years old working in the mail room of an engineering firm. TG is strictly something that keeps him busy and allows him to to make money off what would otherwise be a thankless hobby.
Obviously, not "everyone" is getting rich off of cables. As mentioned though, the potential to make what most of us would consider "a good living" is definitely there if you know what you are doing and / or know how to market your product. Sean
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