Nikkidanjo wrote:
"Basically, I don’t by the filter part unless some form of RF filter was deliberately added."
Agree 100%, power cords should not be filters, particularly on power amps.
The best analogy is that the pressure in the outlet of the pipe is the indicator of performance. If the pipe is 2" diameter for 25 feet and the last 6 feet are 6" in diameter, this will yield a much higher pressure at the outlet than if the pipe were 2" diameter the whole length. This is what happens when you add a low-inductance 6 foot cord to a 25 foot high-inductance wire in the wall. It really does work. |
Bwhite wrote:
"Here are quotes from Audioengr's "Technical Papers" - seems he is contradicting himself in claiming that resonance is for the most part not audible"
No contradiction. If you take the time to read the paper, you will see that I am talking about ELECTRICAL resonance, not mechanical resonance. I have extensive measurement and simulation data on this effect proving that it is real.
Mechanical resonance is a second-order effect at best. Electrical resonance is more of a first-order effect.
As for your metal outlet covers, I beleive that you are experiencing the placebo effect. There is no scientific explanation as to why this should make any difference whatsoever. Resonance requires a high-Q system, which this is not. Even if the outlet cover resonated, what electrical effect could this possibly have? |
"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."
Sorry, but this is technically nonsense. Ask an engineer friend whether this makes any sense. You are mixing shielding from EM fields and mechanical resonances. Shielding eliminates susceptability to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.
"It may be a long wait before technology is developed that "proves" how some power cords work in our systems. Having heard significant improvements with several power cables, I don't intend to wait for a piece of paper telling me what I already know is true."
What is wrong with the analysis I just did above? It proves conclusively that lower inductance power cables reduce impedance to current flow by 22% or more in a typical home scenerio. Do you not understand the analysis? |
"I intend to purchase a couple of plates next time I visit Home Depot. Worse case I return them a few weeks later."
I cannot believe that you guys are inventing your own "snake-oil". Best of luck.
I have tried my best to actually do the science to prove which effects are significant with all types of cables. This is significantly more than 99% of the cable manufacturers do. I even publish the experiments and the results. Evidently the public is hard-pressed to read this and understand the significance. |
Audioengr - One thing I have learned in Audio is that measurements aren't necessarily worth the paper they're printed on. What measures good usually - in most cases -doesn't sound good. Measurements don't tell the whole story. I trust my ears and not fancy-schmancy SPICE simulations. Here is an Audioengr blooper: Audioengr wrote:Shielding eliminates susceptability to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance. Duh! Anytime you increase the mass of an object you potentially change the frequencies at which the object resonantes. Adding shielding to a cable will change the mechanical resonance of everything it touches. Read a thread in Audiogon's Tech Talk Forum Entitled: Tweaks & How My System Disappeared by Jadem6 - a well respected Audiogon member who has been very diligent in tweaking his system. Most of the changes he's made have been in regard to the Mechanical Resonance of his system. But I am sure that's placebo too right? Regarding Audioengr's comments on Audiogon vs. what is stated on his website as it pertains to his discounting of the effects of Mechanical Resonance in this thread, Audioengr wrote: No contradiction. If you take the time to read the paper, you will see that I am talking about ELECTRICAL resonance, not mechanical resonance. Hmmm.. well given that the second sentence in your "FAQ on resonance" reads: Resonance can be excited by many phenomena. If you pluck a guitar string or strike a bell, they will ring at their natural resonant frequency and then decay over time due to losses in the systems. This doesn't imply that you are speaking of electrical resonance. Unless you have an electric bell. So I read further. ANYHOW get this!! I cut and pasted the text from his Resonance FAQ into a text editor, did a search and find on the text - and bingo! It doesn't even have the word *Electrical* contained in that FAQ. It doesn't say electric, electronic, or even electricity. Whatever Audioengr! What are you hiding? Audioengr wrote:
As for your metal outlet covers, I beleive that you are experiencing the placebo effect. There is no scientific explanation as to why this should make any difference whatsoever. Resonance requires a high-Q system, which this is not. Even if the outlet cover resonated, what electrical effect could this possibly have? Guess it depends on what science you subscribe to. So get this, DUDE!!! there is no electrical effect. This is what I keep saying to you. When you plug in your power cord and it snugly presses against the metal outlet cover, the mechanical properties of your power cord (and system) change. Maybe you will understand this: plastic plate + powercord + system = X metal plate + powercord + system = Y X sounds different than Y Nice math huh? When power flows through the power cord pressed against a plastic cover plate they resonate together. When power flows through the power cord with a metal cover - they resonate together (but differently). The cover plate has an effect on the power-cord and hence the rest of the system. Plastic is a bit dull sounding and metal is a bright sounding. The thicker the metal the less bright.. wood is odd sounding and not what *I* hoped it would be... the best is to just remove the plate all together. |
Audioengr, since you singled out the following quote that I gave credit as POSSIBLY being part of the explanation of why cables sound different.
"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."
YOUR RESPONSE WAS:
Sorry, but this is technically nonsense. Ask an engineer friend whether this makes any sense. You are mixing shielding from EM fields and mechanical resonances. Shielding eliminates susceptibility to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.
MY EXPERIENCE IS:
I have Soundlab Ultimate One speakers, and the brands of AC cables connected to them and to my ( home theatre use only ) sub woofers make a huge difference in sound. Crazier still, disconnect the sub woofers from the wall and the performance of the Soundlab is improved.
The amplifier and resulting magnetic field of the sub woofer ARE interacting with my Soundlab. This may also be proven by placing a large shield between the sub woofer and the power supply of the Soundlab. I had Purist Audio build such a shield and among a group of six listeners the change of inserting and removing was obvious to every member, every time.
I still contend that there are many things going on in an audio system all at the same time. Any number of changes in equipment and cables can effect RF, magnetic and electrical interference. I've tested TI shield, Purist's shields, Audio Prisms wall filters, dozens of audio grade power cables and ferrite blocks purchased from Ferishield in New York.
Bottom line is they all change the sound. Some can reduce one problem while messing up something else. Ferrite for instance, is not to my liking even though it can reduce or eliminate some radio signals.
As for the wall plate that Bwhite is discussing, I never said that it was effective, only that I am open minded enough to experiment.
I don't know if you are familiar with Marigo dots. They are varying size stick on dots that are manufactured from lead and other materials.
Placing a single dot the size of a pencil eraser on the end of an electrical plug DOES change the sound. The dots work on interconnect cables, equipment faceplates and even on amps beside the speaker posts.
Since these cannot possible have any electrical properties, they are effecting the mechanical properties of the component, regardless if electrical or mechanical in nature.
Seems logical then that electrical plates could contribute to the systems performance.
Anyway, the cost of such a test is miniscule. I have many failed experiments in attempt to improve my music system, but I have also found a number of things that helped.
I think it's important to keep an open mind and experiment with a eye toward learning. Closed minds seldom learn anything new. |
In my own experiments, the introduction of 2 feet of stranded 16/3 extention cord onto the end of my preamp, turntable or power amp was enough to influence the sound negatively. Keep in mind, the typical 18 awg cord supplied on equipment, has a up to 7 amp capacity. Resistance played no part in the additional 2 feet. If your speakers have at least the resolving power of an LS3/5A, anyone with an open mind should be able to hear the effects.
A simple tool called an Elfix, can eaisily demonstrate the incredible amount of stray currents surrounding A/C wire.
Shielding almost always results in degredation. The ultimate dielectric is AIR, followed by glass. Since these are all near impossible to achieve in a wire, we are stuck with compromises like teflon.
As usual, everything Albert states is true. I tend to agree with BWhite as well. My guess is the wallplates will most definitely hurt the sound if they are metal.......Frank |
Audioengr,
To defend my honor I must clarify my statement about shielding,
"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."
I'm not talking about mechanical resonance, I'm talking about EMI from equipment feeding back into the system through the power cord. This sort of phenomena would happen if you placed unshielded interconnects right next to your speaker wire. The output signal would then be fed back into the amp in some form.
That being said, I do not make any claim how this could affect the system. I'm simply offering way that I think things could happen. I did say I know just enough to be dangerous :) |
The reason is simple: They sound better. Have you listened to a better power cord yet? |
Albertporter wrote: "I have Soundlab Ultimate One speakers, and the brands of AC cables connected to them and to my (home theatre use only ) sub woofers make a huge difference in sound. Crazier still, disconnect the sub woofers from the wall and the performance of the Soundlab is improved. The amplifier and resulting magnetic field of the sub woofer ARE interacting with my Soundlab."
This is certainly possible. Sounds like you have a combination of magnetic field coupling and mechanical coupling from the sub. Subs put out a lot of energy that can certainly resonate the shutters and probably some component chassis. Power cords make a difference for reasons other than mechanical resonance or magnetic coupling. However, if the subs are on the same circuit as your other components, they may be causing droops in the AC line that the other components are reacting to. Sounds like a complicated problem at best. There is no way it can be diagnosed over the internet.
The thing I want to point out is that it is easy to get sidetracked from root-causing the real problem, particularly if the physics is not well understood. I have seen posters change interconnect cables over and over to solve a ground-loop problem, when the real problem is the AC power grounding. |
Frap - I believe that resistance played a part in the added 2 feet, and inductance as well. The 16 gauge cable 2 feet long can have the resistance of 20 feet or more of 14 AWG ROMEX. It has the inductance of about 12 feet of ROMEX. So this was like adding 20 more feet of ROMEX to the circuit.
I agree with you on the air dielectric being the best, however the goal with a power cord is low inductance and resistance. This means large conductors or lots of smaller conductors that are tightly magnetically coupled. Some cords do not do this coupling well and the result is excessive stray magnetic fields. Power cords do not "pick-up" stray fields, but they do create them. If you have unshielded interconnects running side-by-side with a power cord to an amp, you might pick-up some magnetic crosstalk in the interconnect. Incidently, shielding a power cord is a bad idea, IMO, because it adds unnecessary capacitance. Typical shielding also will not stop the stray magnetic fields for the most part. You need MU metal shielding to do this. |
Nikkidanjo wrote: I'm not talking about mechanical resonance, I'm talking about EMI from equipment feeding back into the system through the power cord. This sort of phenomena would happen if you placed unshielded interconnects right next to your speaker wire. The output signal would then be fed back into the amp in some form. I got what you are talking about. This is a common misconception. It can happen from power cords or speaker cables to unshielded IC's. However, power cords are part of a very low impedance circuit, which as a result of being low-impedance,is not susceptable to pick-up of RFI or stray magnetic fields. This is also the case with speaker cables. Even if they did pick-up some high-frequency noise, this would be immediately filtered by the AC transformer in the component. Power cords radiate fields, but do not pick-up much because they are low-impedance. The ferrites that are on computers, for instance are there to prevent RFI that is generated inside the box from using the ground of the power cord as an antenna. This way they pass FCC regulations. The ferrite is not there to prevent noise from entering the computer chassis. Some AC filters for PC's are useful for "surge" protection and lightning strike protection, which can damage a PC power supply. I know about this because I have been a EE for 26 years and have worked in PC design, including for Intel for 16 years. On the other hand, if there are ground-loops created by several power cords being plugged into one or more circuits, this is an entirely different story. This ground loop makes a very nice antenna for RF or AC pick-up. Shielding these cords will have no effect whatsoever on the ground-loop unless it lowers the ground-wire resistance a bit. The only real fix is to break the ground-loop or go to balanced interconnects. |
Audioengr said: This is certainly possible. Sounds like you have a combination of magnetic field coupling and mechanical coupling from the sub. Subs put out a lot of energy that can certainly resonate the shutters and probably some component chassis. Power cords make a difference for reasons other than mechanical resonance or magnetic coupling. However, if the subs are on the same circuit as your other components, they may be causing droops in the AC line that the other components are reacting to. Sounds like a complicated problem at best. There is no way it can be diagnosed over the internet. My comments were not a cry for help, my system is pretty much full out. Please see the thread: http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1022712214&viewI have a dedicated line for every component, including all six boxes that make up my preamp. My comments were meant to bring to light the fact that mechanical, electrical and magnetic interference all produce changes in a high end system. The sub woofer affects the Soundlabs when there is NO signal going to it and it is sitting idle, two feet from each Soundlab. The fact that the internal amp is on creates enough problems to hear during two channel playback. Hope that explains my point more clearly. For what it is worth, each position in my system has been tested with a dozen or more better known products. I liked several of these, but ultimately the Purist Dominus was first choice for two channel and Proteus and Venustus for the HT system. |
Albertporter wrote: My comments were meant to bring to light the fact that mechanical, electrical and magnetic interference all produce changes in a high end system. I certainly agree with this. Particular systems can have effects from all of these. What I do not agree with is that mechanical resonances are one of the most important factors in a typical system. What might be happening with your powered subwoofer is that it might be using a class-D amplifier or a switching power supply. These can create large switching noise on the power line and create fields that can get picked-up as well. If this is the case, I would recommend using a ferrite on the power cord to each subwoofer. Have you tried this? Unless the other cables are draped on top of the subs, It is hard to believe that they are picking-up noise this way. |
My sub woofers can present a problem for the main system in that they affect resolution and distortion levels of my Soundlab U-1.
That being said, this is a two channel issue and since the subs are a deterrent to stereo sound quality, they are not supplied with signal.
However, power even being AVAILABLE to the subs in an inoperative mode damages the reproduction quality of the Soundlabs.
I have my own opinions as to the cause, but since the HT system is used three hours a week, and this is not a problem with Dolby 5.1, the solution is to save electricity and unplug the offending product.
I do the same thing with my DSS receiver, DVD player, and Dolby 5.1 processor. Disconnecting them from the wall mains is a small but audible improvement for two channel analog reproduction.
As for details of my system's wire and cable dressing, a visit by way of my provided link makes it apparent that it is not an issue in this discussion.
As for mechanical resonances, if a system is pushed to a high enough level, solving miniscule problems can be a significant improvement.
I think this dead horse has been beaten enough.
I am confident my Purist interconnect and power cables are not an issue, and wish you success in marketing your products. |
Do power cables make a sizeable difference? I'm no technical expert, but I'd like to share my experience.
Until a month ago, despite having a high end system (comprising Capitole MKII, KR8000 monos etc.) I was a total disbeliever in power cords. All power cords in my system were stock cords. Soundwise, I was satisfied.
For quite a while I had been wanting to try quality power cords, but there are no dealers in my country, Mauritius, which is close to South Africa is very far away from the US and Europe and dealers whom I contacted for a trial often limited the money back policy to one month. Since postage & customs formalities would take about two weeks for the products to reach me, there would hardly be any time left to audition and return the cables within the specified limit. The risk was too much.
A few weeks ago, I decided to make my own power cords with some Audio Note AN-D speaker cables (retails for about $10/metre). I made 3 cords; those on the power amps were grounded while the one on the CD player was not.
Result: well, after two days, I could not believe my ears. A huge amelioration in musicality, smoothness, detail and soundstage. Almost creamy and gently massaging my ears.
To be honest, my experience tells me that the addition of power cords had a better impact in my system than my Audio Aero Capitole MKII replacing my Micromega Stage 6.
I don't know whether that would apply to every system, but my advice is, one audition is better than 100 debates, as already mentioned ealier in this thread.
Since I am curious to know how far the performance of my system can extend, I am still willing to try megabucks power cords but can't find any dealer willing to send me 3 so-called high end PCs for a 2 months trial period, everything paid in advance, but fully refundable. I am even willing to pay a fee of $100 for the trial if I don't end up buying any of the three cords sent to me. Anybody (including fellow audiogoners) willing to help? thnks.
Dr Jawa Lallchand
Mauritius |
Albertporter - something just occurred to me form waht you said. I do not mean to kick a dead-horse, but since you say that the 2-channel system is affected when the subs are plugged-in, but not turned-on, I suspect a ground-loop may be at fault. Usually these cause hum, but not always. One way you can test this hypothesis is to leave the subs on and plugged-in , but disconnect the IC's to both subs. If this has the same improvement effect as unplugging power to them, then it is definitely a ground-loop at fault.
If this is the case, the cleanest solution to this is either to unground both subs with AC cheater plugs or run isolation transformers to one or both subs. |
I think it's clear from the entirety of this discussion that each system requires its own unique treatments in terms of electrical and mechanical conditions. However, I do agree that there are some activities which will transcend the individuality of the system, and be virtually universal in their behavior.
#1 - Make sure your power is clean, and constant, regardless of the methods used to achieve that.
#2 - Reduce stray hum, RFI, and EMI fields surrounding your equipment, and block, or otherwise deter these fields from affecting your equipment, including cables.
#3 - Consider your equipment and cables to be "vibration antennas" and attempt to reduce, or control, the mechanical resonances that may be induced by external sources. Attempts to control inherent, natural resonant frequencies can be counterproductive.
#4 - Remember that all signal carrying wires have an inductive field around them that is actually a part of the signal. Attempts to suppress this will affect the quality of the signal in the wire. Allowing these unsuppressed fields to interact with other unsuppressed signal carrying wires could be detrimental to sound.
#5 - Place transformers and other large magnetic field generating devices far enough away from sensitive items which may be influenced by the fields.
#6 - Just because it may be difficult/expensive to do something behind the wall does not mean that you may not reap improvements from these efforts. It is a known fact the the Romex moves enough from its own movement inside the wall, that it can cause a connection to sever from metal fatique, and this is why the Romex is to be stapled within several inches of the rough-in box. We haven't even discussed whether the conductive staples on the Romex could be a factor, when these are plentiful, and in direct contact with the Romex sheath, and even pinching the wire in some cases. Maybe non-conductive staples may play a part. Maybe distance between staples may have some electrical or mechanical effect.
#7 - Make good, clean connections wherever any connection is to be made, and periodically clean them. Including in the outlet boxes, and breakers.
#8 - Use good grounding tecniques.
#9 - If power conditioning is required in your area, due to grungy power from the street at varying times of day, use it.
#10 - Use your ears to decide the value of the modification. |
