Because the moon is made of cheese.
Isn't some of these signals DC?
Marty |
I've wondered a bit about this myself. The only logical conclusion I can come up with is that the dielectric does change with electrical flow. If this is true (I have no conclusive evidence that it is), then cable break in (which changes the dielectric) should be performed in the same direction that the cable is to be used. Could you go either way and get the same result? In other words use the cable in the reverse direction, as long as you were consistent? I would think so. I have heard (or read) from Synergistic somewhere that they determine the direction by listening to the cable. There are some theories about eddie currents in cables, but I know little about this and would really like to hear from a cable manufacturer. Is the arrow absolute, or just a way to continue to use the cable in a consistent manner? In other words, are we dealing the dielectric effect or the actual wire? |
I posted this some time back. If you search the archives you'll find many spirited answers. (I'm an old EE and don't understand it either.)
Marty: There should be no DC on any of your cables. Music is only ac.
One person said it was because only one end of the shield is connected and that should be the source end. |
The cable will have two inner conductors and the shield isn't terminated to the ground connector at the source side of the cable. I've seen this illustrated in some pro audio books when going from ballance (xlr/trs) to unballance (rca/ts) terminals. Hope that helps. Rich |
Rich, A lot of cables are terminated with both ends of the shield connected. I have a couple of pairs of Tara Labs that are and have seen others. Recently, I have seen where manufacturers are advertising in their white pages that the shield is connected at one end only. I know with a lot of equipment, the shield is ultimately tied to ground of the unit which in turn is tied to the home grounding scheme. To me, this cable thing seems like an episode of the X-Files. |
Having developed interconnects I think that directionality is of minimal importance when the cables are made, the shielding grounding point is a good one and it is supported by the physics professor that aided me in developing the Argento interconnect. I do not use a grounded shield, I actually use a floating shield because I am aprehensive about using a grounded shield due to the increase in capacitance and inductance that a grounded shield will introduce. Our floating shield extends over the RCA connectors but is separated by heat shrink.
When it comes to the belief that something changes I also disagree but do so respectfully. Static electricity is what changes. The static charge that is held by the dielectrics is what the "break in" is all about. My cables just like all others take time to break in because they need to dissapate their static electricity. Flexing and bending and shipping them do build up static electricty. Leaving them be once connected is the quickest way to break them in. Thankfully the Argento is a flexible but shape maintaining cable, meaning you bend it but it stays in that shape so it takes less time to break in because it doesnt wiggle around like worms near vinegar every time you listen to music.
The belief that the silver or copper "changes" is crap too, how does a metal change when you are only putting a few volts through it. Please explain that to me with some proof. What I really like is the so called Cable cooker that I have seen for sale on the net. It supposedly breaks in cables. Right but when you disconnect your cables they need breaking in again. Intelligent very intelligent, thats like washing your car in the middle of a S#1% storm. It is a good idea, but it just doesnt work in reality. |
The arrows are there to satisfy audiophiles who think directionality matters. Of course, it's AC, so the signal is constantly going in both directions. |
The shield is typically connected at source end in pro applications. Allegedly helps keep interference away in long cabling situations.
If we coin a word, "directionality", to mean which way does the cable sound better to our ears, then we can do away with manufacturers' marketing hype. However, WHY should a cable sound slightly different depending upon which way it's connected? Unless the shielding on one end counts (electrically)... |
Orbeck, Tara Labs is using this design with their isolated floating ground shield(ISM). However, this is not the same shield that runs with the cable that is connected to the outer portion of the RCA jack. Tara uses a separate shield that is suppose to lower RFI and EMI interference. It is the one connected to the floating ground station. I checked it with a meter and you will not get a reading from the shield to the outer portion of the RCA plug. Tara runs two RSC conductors through the cable. One as the signal carrier and the other as the ground(or shield.) It is connected at both ends as verified with a VOM. If you look at all the equipment, without fail, the outside of the RCA connector is tied to the units common ground. I know there is a lot of potential for noise here. However, back to the original question, what difference does pointing the direction if the signal is alternating back and forth. Since no signal potential should be on the shield, where does it fit in(as in break in.) I can understand the dialectric issue but what would direction have to do with that? Man, lots of questions here. |
In general, the reason that the shield of a twinaxial cable is grounded at the source is because this is where the signal is being driven. The most accurate ground reference for a driver will be at the driver, not at the destination component. If there is noise developed across the signal return, then this will not be induced on the shield as it will if you ground the shield at the destination end. The felling is that the ground will be noisier with respect to the signal at the destination end compared to the source end. |
I'm glad to hear the vast word from Audioengr!
I might add that conductors inside the cables have a certain % of impurities that have mostly semi-conductive structure; there are some dielectrical micro-structures as well. All these components might play the role while the cables burn-in but not on directionality.
Orbeck, the metal does change but with larger signal levels when the electric break-in of impurities occurs. With line level signals this is nearly-impossible. |
And another cable question to Orbeck:
How long it's needed to take off the statics from the dielectric if it's all we need to break-in the cable?
I would estimate it to tenths fractions of the second or even less... |
Geeze, Here we go with the signal return, etc. The signal returns on the same line it went down in the first place. It is AC, therefore, it alternates according to frequency. What has the ground got to do with the signal wire other than it helps isolate the signal from the effects of interference. That is like saying that the AC line in your house alternates on the ground wire. I have taken bare wire (wonderwire to be exact) and plug one end into a CD player and the other into the amp. You know what---it worked fine (other than the radio station I picked up a few times.) |
I'm glad we have a cable designer here--welcome Orbeck. As a physicist I like hearing the scientific explainations, when I can only surmise the bits I know about cables. It's certainly refreshing to the hocus pocus. |
BigTee,
Please don't confuse voltage with current. In order to drive your amplifiers to drive your speakers current must flow. The same thing happens in your AC line analogy. The cable shield issue that you are raising is real. Current will flow through the shield if the circuit driver and receiver are at a different reference potential.
Regards,
John |
OK so interconnect shielding is grounded at one end only, hence the cable is "directional".
But I have seen "directional" speaker cable, and I cannot think of any possible explanation for this. Can anyone offer a plausible explanation? |
John, But what if the shield is only connected at one end as some other folks are saying? Now, how does flow occur? I agree with the "Possibility" of potential on the ground circuit but I also know that electricity takes the path of least resistance (both voltage and amps---since volts do push amps.) You can see a ground wire (white wire---not the copper ground) spark at the breaker panel when it is connected to a load such as a motor but it has NO potential. Ground faults help with large, potentially dangerous shorts to ground as through your body. You are always going to have a difference in ground potential between a large amp drawing component and something less. You certainly cannot have voltage potential(and flow) without some sort of current, ever how small. No current, no flow.
So, I guess my question remains, since we are dealing with AC, how can wire be directional? |
BigTee, you are confusing a "shield" with a "ground". They can be two different things. In some cables a "shield" is connected only at one end. There are still two other conductors to carry the signal. There is no mystery here to anyone who has ever worked in a calibration lab! |
Sorry, but I can't help but be somewhat amused by this thread (and ones like it). I know next to nothing about electricity and circuits, so all I can do is humbly take note of the fact that no one yet in this discussion has claimed to have either heard the supposed difference flipping their cables around, or to have tried it and failed to hear a difference. Well, neither can I - I guess I just don't care enough to have bothered (and I'm quite willing to entertain notions of marketing-driven audiophilic excess here). But what I can say with certainty is that I haven't been able to learn anything for sure from all the confusion and contradiction above. Can it be that the engineering side of this hobby contains even less clarity and consensus than the listening side? |
Zaikesman ... I'm an electronics engineer. We engineers are always being bashed on this board for being closed minded to what audiophiles have "heard with their own ears".
For once I am inviting explanation for something I am extremely skeptical of (directional AC carrying cables) and now you accuse us of lacking clarity.
It would have been much easier to state that cable directionality is utter bullshit for an AC signal. For a pure cable I think this is certainly the case. However in the case of interconnects I had previously overlooked the grounding issue. I'm wondering if I have similarly overlooked something in speaker cable design.
What do you audiophiles want from us engineers ? Clarity, or open-mindedness ? Please make up your minds because it's getting awfully confusing.
For the record I have tried it, but failed to hear any difference. |
Bigtree - Here is why your single-wire scenerio worked: The return current for the signal was running through the ground of the power cords of the two components. This is simply batteries and bilbs. The current flowing in the signal wire must return on another wire. The optimum scenerio is that the wire is identical in length and type and running alongside the signal wire. This will minimize noise in the signal. If you dont run a current-return wire, you risk inducing a lot of noise, like your radio station for instance, or 60 Hz hum. As for shields that are unconnected, this is only possible in cases where there is already a signal and return wire present. There is no current running in the shield because it is only connected at one end and this provides a partial "faraday cage" that will prevent EMI from being picked-up by the internal two conductors. |
seandtaylor99 - I have also tried it and found no difference in my particular system. I believe that the results are very system-dependent. In systems with poor grounding, it could make a big difference in theory.
BTW - I am also an EE with 26 years experience, and a cable company to boot! |
I have direction all speaker cables, and I have tried. I didn't hear anything, but i wouldn't be surprised if on some systems, it turns the sound South. |
Audioengr, So, lets take a 60HZ signal and run it down the "Signal carrying" wire. Since this would be the same as a 60hz sine wave, are you trying to say that the positive half cycle goes down one wire and the negative half cycle comes back on the ground? We are talking about AC here. Hate to disagree, but I don't think so. Also, we cannot have current without voltage since volts push amps. In less than 120 volt applications, we have one line of potential(as in house wiring)and according to your described theory the ground(neutral) would also have be a hot wire since each half cycle would need to be equal with respect to volts and amps on each conductor. It must return on another wire according to this theory and that would be the neutral. In 35 years of being around electricity in various forms, I've never had the need to measure the ground except when we had an electrical "Short" popping people. However, I am a ME and design air conditioning systems. I will present your theory to my EE friends. If they agree, I will humbly apologize to you in this forum and will consider myself enlightened! |
Seandtaylor99, no accusations were made or intended (and I don't think that clarity and open-mindedness are necessarily mutually exclusive qualities). I'm just observing an analogy between the debates on sonics that pervade these forums, and the apparent capacity for trained engineers to take each other to task over their explanations. I will readily admit to having a certain degree of automatic respect for all the engineers who contribute on A'gon, and do not engage in "bashing" them as a group (if that indeed exists here at all). Anybody can suffer from an inability to hear, not just engineers! :-)
P.S. - As for "what we want" from you guys, it appears in actuality to be beautiful sound at any price, but personally, I'd settle for realistic sound at a price that's likewise...heh, heh... |
Zaikesman---Amen brother! |
Cable directionality is one of those things that is very easy to hear and very difficult to measure to the Hard Line Objectivists (HLO) satisfaction as the differences are buried in the noise and couldn't matter anyway....Ben Duncan heard the differences in wire directionality and developed a test for this that has been severly criticized by HLOs who say it was measurement error or it was far down as not to make any difference anyway....I use my ears and my cables all are set up for a proper stage and venue information which is in the diode effects in wire and likely 120dB down in the mix....It matters to me and is the reason I can pull more information out of cables that aren't much different than any on the market....Nothing mystical here, just care in putting together wires for the best presentation....It is a pain to listen to each spool of wire and document which end goes to source and which to load as respects each leg, but that is necessary for a proper presentation without hot spots in the stage, normally at the speakers, and proper image height....
Bob Crump
TG Audio/CTC Builders/DDR Mfg |
Bigtee .. I think Audioengr was saying that your signal ground (where the current is sunk and sourced) was your power cord ground lead. I think this is correct. If course AC current doesn't go part down one wire and part down another ... rather it pushes current into ground, and then pulls the current back from ground. |
"Audioengr, So, lets take a 60HZ signal and run it down the "Signal carrying" wire. Since this would be the same as a 60hz sine wave, are you trying to say that the positive half cycle goes down one wire and the negative half cycle comes back on the ground?"
No, what I am saying is that when there is a positive current flowing in the signal wire of an interconnect, there is an equal and opposite current in the "ground" or "return" wire.
We are talking about AC here. Hate to disagree, but I don't think so. Also, we cannot have current without voltage since volts push amps. In less than 120 volt applications, we have one line of potential(as in house wiring)and according to your described theory the ground(neutral) would also have be a hot wire since each half cycle would need to be equal with respect to volts and amps on each conductor.
No, the Neutral in house wiring is not ground (earth ground). Hot is equivalent to signal wire and Neutral is equivalent to return (which can be ground) in an interconnect. Current flows in both Hot and Neutral, but not in the earth ground. Since the ground for interconnects is also used as a return path, there will be current running in this one.
"In 35 years of being around electricity in various forms, I've never had the need to measure the ground except when we had an electrical "Short" popping people."
In audio systems, it is important to measure earth ground as the system usually comprises several components plugged into several outlets, which may be on different circuits. The result is that the various grounds can be at different potentials, which can result in hum due to current flowing in the power-cable ground wires. The fact that there are ground connections between components through the grounded power cords and also in the interconnects creates ground-loops by definition. This is unavoidable in "single-ended" systems.
Balanced signalling eliminates this problem becase there is an earth ground with no current flowing in it and two signal wires with equal and opposite currents. So, you see, the balanced interconnect is actually more similar to household AC wiring with Hot, Neutral and Earth Ground being similar to +, - and Ground.
BTW - I have 26 years experience as an degreed Electrical Engineer. |
Audioengr--- well, I didn't get to talk to the EE's here at work today, duty called. However, I will. I still don't understand this so I will get one of my troopers to explain it up close and personal. With house wiring, the neutrals are connected straight to the buss bar in the breaker panel and and connected to earth ground. I still don't understand your previous analogy of the battery and bulb since DC does flow in one direction period. And you do have positive and negative on DC. There is no such thing as positive and negative on AC which it would have to be. The return would be negative. As I said before, you have the positive half cycle and then the negative half cycle that "Flows" the opposite direction on the same wire. In an Air Conditioning unit you have a step down transformer usually 120/230 to 24 volts. On the output of the secondary, one side is tied directly to earth ground and also serves as the common for the wiring activating all the small 24VAC coils on relays. The other runs to the other side of the coils. I still can't believe that you will have an opposite polarity running through the unit chassis. I know I can't measure it because I have tried. Why would it go back when the path of least resistance is to earth and not through the resistance in the wire? AC is AC is AC. It doesn't matter if its in a house, an Air Conditioner or a signal carrying cable. I suppose coaxial cable, with a single conductor, alternates with the shield and with the shield connected to earth ground and there is no second wire.
By the way, I don't need to be convinced that you are an EE with whatever experience. To me, this is research and I will find a definitive answer that satisfies my curosity. Call me hard headed. And I defer back to my final statement in the last post. Anyway, this post was about cables being directional and not a dialog in electrical theory. They may never let me post again! Anyway, I am convinced that cables being directional is BS and ALL the EE's I work with are in agreement with that. |
Audioengr---Well, I just had one of the EE's stop by and we had a nice little chat. It convinced me of basically what you are saying and actually created a few more questions. As stated previously in my post, I will officially acknowledge that you were essentially correct. I think terminology got in the way a little but I have to say this has been a very enlightning experience and I do appreciate your patience with a ME. He also talked about DC coinciding with AC in a cable which I will have to research now. Bleed I believe was the term he used. He left me a book to read (which I will do) and a bag of terms about lifting ground, floating above ground, etc. He also blew right over my head talking of using DC on signal cables to make the AC behave itself. This will require more research. |
Bigtee wrote: "As I said before, you have the positive half cycle and then the negative half cycle that "Flows" the opposite direction on the same wire."
Correct, the current alternately flows in what I like to call the "forward" wire, but the inverse of that current also flows simultaneously in the second wire, which I call the "return" wire. In most AC power systems, this is NOT the ground wire, because this would violate electrical code, regardless of whether the circuit is single-phase or three phase.
Bigtee wrote: "On the output of the secondary, one side is tied directly to earth ground and also serves as the common for the wiring activating all the small 24VAC coils on relays. The other runs to the other side of the coils."
If this is the case, then for these internal circuits, the ground is used as a return path for the current. It would be difficult to measure any voltage drop across a grounded chassis, because the impedance is so low.
I actually worked as an industrial electrician apprentice while I was going to college 27 years ago, so I have some experience with electrical code, 3-phase, contactors and transformers etc.. |
Audioengr-
I appreciate your information and trust me, I will get a handle on the "Why." I think we have been engineers for about the same length of time. I graduated a ME in 1975. I didn't learn much about electricity in school and have been in industrial design for a long time. We have electrical guys in our group that handle the biggest portion of the electrical work, naturally. I do design air conditioning control systems working closely with general contractors. I have always understood the codes and the wiring requirements but never researched the "Why." I guess now is a good time to start. I have been playing with audio equipment since I was about 12. Never had any electronic training but understand how it works somewhat. I have built some really decent sounding interconnects but don't have a clue to why they turn out as they do. I have played around with the metals and the shield schemes. I have found, keep them as short as possible and for whatever reason, I find solid wire better than stranded. I have never been able to detect any direction inconsistancies in the wire. |
Here are some more tips for you, since I design wires for my company:
1) interconnects should be low capacitance - this means spiraled pairs of small gauge wire that are spaced-away form each other. Use Teflon or air-filled dielectrics to separate and insulate them.
2) Speaker cables should be low inductance and low resistance. To get low inductance, you need coupling, so make many twisted-pairs of 20-24 gauge wire and then connect then at the ends to for a single circuit. |
I had a breakthough, The arrows (directionality notation)are so you can see which way the signal goes when you are wading through your orgy of interconnects behind your AV rack without having to trace each one back to where it comes from or goes to.
-Phil |
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Audioengr, if I may sidebar and ask a few general questions about things electrical:
1. I current have a 115 volt 20 amp dedicated circuit to my amplifier and the ground has been lifted. I have the schematic and instructions on how to convert my amp to 230 volts. If I install the proper 20 amp duel circuit at the service panel and connect my rewired 230 volt amplifier by simply running two leads (using my currently installed 10/2 romex and obviously from opposing sides at at the service panel), would I need a ground? I know I should always have a ground but I am not using one right now. But all's I need for 230 volts is two 115v lines from opposing phases?
2. If your answer to number one is yes, then why does a 20 amp or 30 amp cooktop or oven have two leads, 1 neutral, in addition to the ground? What's with the second lead in these appliances? Or is it the neutral I should be asking about?
3. You say that the neutral contains the return current as I've heard this many times. But why is it that I can touch my neutral bus in the service panel and not feel a thing? What is different about 'return current'?
-Sparky |
Stehno wrote: would I need a ground? I know I should always have a ground but I am not using one right now. But all's I need for 230 volts is two 115v lines from opposing phases? No, the ground is strictly for safety. It is not needed in the circuit, however it is well-advised to leave it attached. If you have ground-loops, it is safer to float low-power components to eliminate them, or use an isolation transformer. why does a 20 amp or 30 amp cooktop or oven have two leads, 1 neutral, in addition to the ground? What's with the second lead in these appliances? Or is it the neutral I should be asking about? I believe that some appliances use more than two legs from the transformer, or they have internally relays or motors etc. that need 117V with neutral. Not that familiar with appliances. You say that the neutral contains the return current as I've heard this many times. But why is it that I can touch my neutral bus in the service panel and not feel a thing? What is different about 'return current'? There is no potential on the neutral bus in the panel because it is referenced to ground there. All neutrals that return to the panel are referenced at a single point. There is a voltage drop in the wire from the component back to the panel, but since the neutral at the panel is tied to the ground at the panel there is no potential on the neutral at the panel. However, if you measure the AC voltage on the neutral at an outlet where there is a load attached, you will measure a small voltage. This is the voltage that is generated across the resistance of the neutral wire from the outlet back to the panel. This voltage on neutral at the outlet will exist only when current is flowing in the circuit. This voltage must be measured with respect to ground. |
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