Originally the title of this thread was
Speaker Wire - What is correct or accurate?
Read-only archive
I found this site and thought it was interesting enough to pass along. I still think you get what you pay for and that a sucker is born every minute 
http://home.earthlink.net/~rogerr7/wire.htm
JZ
http://home.earthlink.net/~rogerr7/wire.htm
JZ
This is true for zip cord. Zip cord is not speaker wire.
Speaker wire should be a coaxial product designed for 8 or 4 ohms. Zip cord is anywhere from 150-300 ohms.
Richard
Speaker wire should be a coaxial product designed for 8 or 4 ohms. Zip cord is anywhere from 150-300 ohms.
Richard
Richard - what is your rationale? Coaxial construction and characteristic impedance pertain to unbalanced systems operating at frequencies where transmission line effects occur. Audio frequencies are too low to take advantage of the self-shielding properties of coax, and its controlled impedance. If anything, a shielded twisted-pair cable would be more appropriate for a speaker cable. But speaker impedance is so low, and levels are so high, there's no advantage to having the shield. Two conductor cable like zip cord is just fine.
Are we getting into another 'power conditioner' thread?
emc guy
Are we getting into another 'power conditioner' thread?
emc guy
EMC Guy's got the coaxial requirement for speaker cable pretty well covered. I'll ask about the other half.
Zip Cord is a pretty generic term and the product comes in a variety of configurations.
http://www.therfc.com/zipcord.htm provides examples
Excluding the fiber optic stuff, most of what we are (IMHO) talking about here is twin conductor copper cable from maybe #8 down to maybe #18 AWG.
Richard, when you say:
Under what conditions would this be true? Last time I measured a piece of copper wire, the resistance was pretty low. Without some kind of statement about frequency or length, the statement is meaningless.
Are you just checking to see if we're reading this stuff?
Toddk
Zip Cord is a pretty generic term and the product comes in a variety of configurations.
http://www.therfc.com/zipcord.htm provides examples
Excluding the fiber optic stuff, most of what we are (IMHO) talking about here is twin conductor copper cable from maybe #8 down to maybe #18 AWG.
Richard, when you say:
Zip cord is anywhere from 150-300 ohms.
Under what conditions would this be true? Last time I measured a piece of copper wire, the resistance was pretty low. Without some kind of statement about frequency or length, the statement is meaningless.
Are you just checking to see if we're reading this stuff?
Toddk
I don't know how deep I want to get into this because I will discuss standards when none exist. It will be difficult to apply the knowledge. If we are to have any kind of a serious discussion then much of it will be theory since there are very few products in the world that actually follow any kind of real world engineering standards. As an example there is not an industry standard for input and output impedances of line level signals nor the cables and connectors for those impedances. The same goes for the amp/speaker interface. There is a true 8/4 ohm coaxial speaker cable out there from Sumiko called Ocos, very pricey but accurate in this regard.
Do you transmit power to anything that is sensitive to small variations in response using zip cord? We are not driving a fan motor here folks. Think of how an audio amplifier works and the fact that regardless of roll off the active components themselves are typically in the 1-10 Mhz range. Has it ever occured to anybody that hanging a wire completely open to RF connected to a speaker completely open to RF is just like connecting an antenna to your amplifier which is monitoring the output by the way for VERY small differences between the output and input. Regardless of the lower frequency response it still matters and we need to move ahead beyond the science of the 50's.
Under what conditions would this be true? Last time I measured a piece of copper wire, the resistance was pretty low. Without some kind of statement about frequency or length, the statement is meaningless.
That is AC impedance using audio frequencies.
Richard
Do you transmit power to anything that is sensitive to small variations in response using zip cord? We are not driving a fan motor here folks. Think of how an audio amplifier works and the fact that regardless of roll off the active components themselves are typically in the 1-10 Mhz range. Has it ever occured to anybody that hanging a wire completely open to RF connected to a speaker completely open to RF is just like connecting an antenna to your amplifier which is monitoring the output by the way for VERY small differences between the output and input. Regardless of the lower frequency response it still matters and we need to move ahead beyond the science of the 50's.
Zip cord is anywhere from 150-300 ohms.
Under what conditions would this be true? Last time I measured a piece of copper wire, the resistance was pretty low. Without some kind of statement about frequency or length, the statement is meaningless.
That is AC impedance using audio frequencies.
Richard
That is AC impedance using audio frequencies
OK Richard, you believe speaker cables should be considered transmission lines, correct? You are bringing to attention 'AC impedance' which I assume you mean the same as 'characteristic impedance'.
Well, let's look at the wavelengths of some audio frequencies. 1000 Hz is 300 km. 1 MHz (well above audio) is 300 m. Most speaker wire lengths around the home are what, maybe 5 m - 10 m max? (up to about 30 feet).
Your transmission line theory simply does not apply. At these frequencies the cable simply looks like lumped elements - capacitors, inductors, resistors. That's all. And it turns out that resistance is the predominant factor. Capacitance and inductance are insigificant compared to the load (speaker) and source (amplifier) impedances.
Now to shielding to RF. Speakers and amps are way too low impedance and have too high signal levels to be susceptible to RF. Speakers and amps don't have shielded RF connectors and internal wiring anyway to make a shielded cable effective. Also, coax does not work to provide shielding at audio frequencies as with RF. Think of it this way: If you put a load on the end of a coax and run DC through it, all the current on the center conductor returns on the shield. However, if you provide an external ground return path outside the cable, the current will return on that also. Same is true at audio frequencies. But at 'RF' frequencies, almost all the current will return on the shield regardless of the external path. And the fields cancel outside the coax. A coax does not work at audio like at RF, for preventing radiation off the cable or protecting it from outside radiation. They do use shielded wiring for low-level, high-impedance audio circuits. But his is not coax. And you have to be careful how you terminate the shields to prevent 'ground loops'.
This is not the science of the 50's. It's the science of today and it's basic electromagnetic theory. There are some good books on the subject and I can suggest a few, perhaps you should read up on it.
emc guy
EMC Guy,
Go get a TDR, a real amplifier and I will tell you how to make some cheap 8 ohm cables and a couple of dummy speaker loads using caps, inductors and resistors and then you can see it all for yourself.
Richard
Go get a TDR, a real amplifier and I will tell you how to make some cheap 8 ohm cables and a couple of dummy speaker loads using caps, inductors and resistors and then you can see it all for yourself.
Richard
I've got a TDR and use it once in a while. It puts out some nice picosecond risetime pulses. Great for checking characteristic impedance, load matching, and cable faults (discontinuities). Not used for audio but mainly for RF and digital with fast rise/fall times. LCR lumped element circuits are often used for computer modeling of cables up to several MHz. Meters that measure RLC directly are better than TDRs for low freq work.
If you had 8 ohm cables, something I doubt could be made because the impedance is way too low, they would be highly capacitive. Do you want your amp pumping all that current into that capacitive load? Really, all you need are for the cable's resistance, inductance, and capacitance to be no more than about one-tenth of that of the speaker. Most zip cord or inexpensive speaker wire will do that. Go back to the top of this thread - that link tells the real story.
emc guy
If you had 8 ohm cables, something I doubt could be made because the impedance is way too low, they would be highly capacitive. Do you want your amp pumping all that current into that capacitive load? Really, all you need are for the cable's resistance, inductance, and capacitance to be no more than about one-tenth of that of the speaker. Most zip cord or inexpensive speaker wire will do that. Go back to the top of this thread - that link tells the real story.
emc guy
Since you have the most expensive part of what's necessary then why not give it a try. You do not login and therefore I cannot e-mail you. If you are serious send me a private note.
The purpose of my response is the same as everyone elses - common sense and logic. I could write a novel of the trials and tribulations of my audio journey through "nobody seems to KNOW just what the hell they are doing" to end up with "and nobody really cares to KNOW what the hell they are doing" and "who ever said this has anything to do with science". I nearly started manufacturing and was stopped stone cold when it became obvious that my sales would end up being directly related to how much money I made you spend on the cosmetics. Yes, they were right, science means little.
Here we have this Hi-End Audio community that seeks to resolve the most miniscule of differences and improvement yet THERE ARE NO STANDARDS!?!? Go and find a book telling you what the standards are for an audio circuit and you will be greeted with 1950's mentallity. Research it further and you will find everybody does what ever they want as long as it passes sinewaves at a reasonable distortion level and doesn't blow up with some of the wierd combos out there. This is one of the reasons Mark Levinson did Red Rose Music - all his equipment is designed to work together properly and he can replicate his sonic signature anywhere in the world. Yes, it is expensive.
So what about the wire? The engineer who researched this with equipment and his ears had a eureka moment 18 years ago and used a common industry coax to create an 8 ohm wire. He gave this wire to the lead engineer and owner who played with it for months delighted with the results. They turned on a couple of dealers to the wire and they tried it on some other equipment. What they found out was that their products loved it but some other hi-end products blew up - poor design. I have tested it on a number of mid-fi products succesfully with out any implosions. It is difficult to recommend because it is one part of the chain and the end results were not always positive. Correcting one thing can lead to negative results until you correct the other stuff. Another way to say this is the wire is accurate on an accurate system in terms of engineering from the CD player output through all your stuff to the speaker terminals.
Richard
The purpose of my response is the same as everyone elses - common sense and logic. I could write a novel of the trials and tribulations of my audio journey through "nobody seems to KNOW just what the hell they are doing" to end up with "and nobody really cares to KNOW what the hell they are doing" and "who ever said this has anything to do with science". I nearly started manufacturing and was stopped stone cold when it became obvious that my sales would end up being directly related to how much money I made you spend on the cosmetics. Yes, they were right, science means little.
Here we have this Hi-End Audio community that seeks to resolve the most miniscule of differences and improvement yet THERE ARE NO STANDARDS!?!? Go and find a book telling you what the standards are for an audio circuit and you will be greeted with 1950's mentallity. Research it further and you will find everybody does what ever they want as long as it passes sinewaves at a reasonable distortion level and doesn't blow up with some of the wierd combos out there. This is one of the reasons Mark Levinson did Red Rose Music - all his equipment is designed to work together properly and he can replicate his sonic signature anywhere in the world. Yes, it is expensive.
So what about the wire? The engineer who researched this with equipment and his ears had a eureka moment 18 years ago and used a common industry coax to create an 8 ohm wire. He gave this wire to the lead engineer and owner who played with it for months delighted with the results. They turned on a couple of dealers to the wire and they tried it on some other equipment. What they found out was that their products loved it but some other hi-end products blew up - poor design. I have tested it on a number of mid-fi products succesfully with out any implosions. It is difficult to recommend because it is one part of the chain and the end results were not always positive. Correcting one thing can lead to negative results until you correct the other stuff. Another way to say this is the wire is accurate on an accurate system in terms of engineering from the CD player output through all your stuff to the speaker terminals.
Richard
Richard, going back to your earlier statement
Yes, I guess there probably isn't. Connectors are probably driven by cost and what's easiest to hook wire up to. Some are better than others, but good conductivity and reliability are the most important. Doesn't really matter how you do it. For output impedance, lower is better. For max. power transfer it should match the load. But what's the load? Depends on the speaker design and quality. Just a hard thing to standardize, and if you did I bet you'd still have differences in apparent sound quality because of other reasons.
I'll have to email you for info on your 8 ohm cable. Interesting that some equipment blew up. Too much load capacitance (high peak currents) for the output transistors to drive perhaps?
As an example there is not an industry standard for input and output impedances of line level signals nor the cables and connectors for those impedances.
Yes, I guess there probably isn't. Connectors are probably driven by cost and what's easiest to hook wire up to. Some are better than others, but good conductivity and reliability are the most important. Doesn't really matter how you do it. For output impedance, lower is better. For max. power transfer it should match the load. But what's the load? Depends on the speaker design and quality. Just a hard thing to standardize, and if you did I bet you'd still have differences in apparent sound quality because of other reasons.
I'll have to email you for info on your 8 ohm cable. Interesting that some equipment blew up. Too much load capacitance (high peak currents) for the output transistors to drive perhaps?
I've been thinking about speaker cables and wires today and I've got some ideas for all you to think about. I have come to the conclusion that speaker wires actually can make a difference in the sound, specifically shielded cables or using coax. The engineer's immediate assumption is that it shouldn't make any difference, but some people, including Richard, claim it does. The engineers may be wrong, but also, those who claim it changes the sound could be drawing their conclusions on the wrong reasons also.
Here's what I think is going on, based on some very similar past experiences with amplifiers. Audio power amps are essentially differential amplifiers. They put out a balanced signal and are intended to drive a balanced load. Usually they use P or N-channel power MOSFETs in the final output stage. When the audio signal causes one side to go positive, it sources current through the speaker to the other side of the driver, which has gone negative and is sinking the current. Neither output is referenced directly to ground, and if you did, you'd probably blow the output driver or it just wouldn't work right. Follow me so far?
Now, those FET output transistors have what's called a gain-bandwidth product typically several MHz or 10s of MHz. In other words, you could probably make a low freq. RF amp out of them if you wanted to. In audio circuits, they could drive much higher frequencies if there weren't audio filter circuits to limit the bandwidth. Now days, everything is made faster, and you can't really find a transistor that will only work for audio frequencies.
So, what happens when you put a nice piece of coax cable on each speaker output? Say you cut a couple 20' pieces of RG-6. You want to have a sheild, so you pull off the shields into a pigtail and ground it to the back of your amp someplace. At the speaker end, you connect the center conductors to the terminals.
What you have done is connected a 20' open-ended transmission line to each amp output. So what you say? Well, RG-6 has about 16 pF/ft capacitance and 91 nH/ft inductance. The amplifier still has it's normal differential load of 8 ohms (or 4 or whatever) due to the speaker. However, each output now also has a single-ended load to ground which looks like a series L-C circuit. It will look like you have a 324 pF cap in series with a 1.8 uH inductor on each output.
The bad thing about series L-C circuits is they have resonances. At the first resonant frequency, the impedance goes to nearly zero. For a 20' length this will happen at about 6.5 MHz. Open-ended transmission lines have pretty high Q, which means the losses are low and the resonance is quite sharp.
If you put a reactive circuit like this on a transistor output, various things can happen. The worst thing is you turn your output stage into something resembling a feedback amplifier. If the transistor still has some gain, and since the phase goes from capacitive to inductive reactance at resonance, you can get instability or oscillation in your output. Lead and circuit board trace inductance around the transistors also plays a big role. If it is oscillating at RF you probably won't hear it, you may not hear any audio, and you might blow out the output stage.
Even if it does not become unstable, you are introducing a reactive circuit which may have some effect in the frequency response of the amplifier at lower frequencies. This is where I think people hear a difference. Perhaps it's either rolling-off the high end response, or maybe even peaking it. Whatever, I could see someone thinking they have changed the sound and it has to be better, because you have just shielded your cables!
Sorry for this being so long. I'm sure I'll get some argument with this. But I have seen differential amplifiers do screwy things when they had too much transmission line hung on their outputs.
emc guy
Here's what I think is going on, based on some very similar past experiences with amplifiers. Audio power amps are essentially differential amplifiers. They put out a balanced signal and are intended to drive a balanced load. Usually they use P or N-channel power MOSFETs in the final output stage. When the audio signal causes one side to go positive, it sources current through the speaker to the other side of the driver, which has gone negative and is sinking the current. Neither output is referenced directly to ground, and if you did, you'd probably blow the output driver or it just wouldn't work right. Follow me so far?
Now, those FET output transistors have what's called a gain-bandwidth product typically several MHz or 10s of MHz. In other words, you could probably make a low freq. RF amp out of them if you wanted to. In audio circuits, they could drive much higher frequencies if there weren't audio filter circuits to limit the bandwidth. Now days, everything is made faster, and you can't really find a transistor that will only work for audio frequencies.
So, what happens when you put a nice piece of coax cable on each speaker output? Say you cut a couple 20' pieces of RG-6. You want to have a sheild, so you pull off the shields into a pigtail and ground it to the back of your amp someplace. At the speaker end, you connect the center conductors to the terminals.
What you have done is connected a 20' open-ended transmission line to each amp output. So what you say? Well, RG-6 has about 16 pF/ft capacitance and 91 nH/ft inductance. The amplifier still has it's normal differential load of 8 ohms (or 4 or whatever) due to the speaker. However, each output now also has a single-ended load to ground which looks like a series L-C circuit. It will look like you have a 324 pF cap in series with a 1.8 uH inductor on each output.
The bad thing about series L-C circuits is they have resonances. At the first resonant frequency, the impedance goes to nearly zero. For a 20' length this will happen at about 6.5 MHz. Open-ended transmission lines have pretty high Q, which means the losses are low and the resonance is quite sharp.
If you put a reactive circuit like this on a transistor output, various things can happen. The worst thing is you turn your output stage into something resembling a feedback amplifier. If the transistor still has some gain, and since the phase goes from capacitive to inductive reactance at resonance, you can get instability or oscillation in your output. Lead and circuit board trace inductance around the transistors also plays a big role. If it is oscillating at RF you probably won't hear it, you may not hear any audio, and you might blow out the output stage.
Even if it does not become unstable, you are introducing a reactive circuit which may have some effect in the frequency response of the amplifier at lower frequencies. This is where I think people hear a difference. Perhaps it's either rolling-off the high end response, or maybe even peaking it. Whatever, I could see someone thinking they have changed the sound and it has to be better, because you have just shielded your cables!
Sorry for this being so long. I'm sure I'll get some argument with this. But I have seen differential amplifiers do screwy things when they had too much transmission line hung on their outputs.
emc guy
The engineer's immediate assumption is that it shouldn't make any difference, but some people, including Richard, claim it does. The engineers may be wrong, but also, those who claim it changes the sound could be drawing their conclusions on the wrong reasons also.
That is a great point and a trap that every designer and subjective listener must be aware of and one of the reasons I have the PS Audio AC synthesizer. If you take a neutral/accurate CD player and drop it in your system and are unhappy with the sonic signature then what you are unhappy with is your system and not the player. There is
Richard, I've got a better understanding of what you were trying to do with the coax. What I described earlier would not necessarily apply to a single-ended amp design.
I was under the impression that coax was being used in some fashion as a replacement for speaker wire. I saw another thread about someone doing this. I was trying to point out that this can cause an RF short circuit to appear at the amplifier output at certain frequencies, and this could be very bad for the equipment. I was assuming that most people are using amplifiers that have floating balanced outputs meant to have the load across the +/- outputs. Most home and auto equipment I've seen is like this. I didn't think bipolars were used much anymore. Perhaps there's some nostalgia for bipolars just like for tubes.
If you are trying to do impedance matching of speakers, you've opened a can of worms. You've got a passive compensation network with the cable, and R-C at the speaker terminals. Were you looking at the transient voltage response at the speaker terminals? If so it might be that what you have done isn't necessarily a good thing. It is the current in the voice coil which should be optimized for transient and frequency response. Just interested in how you know that what you did was good, besides going by what it sounded like.
To add to one of your other comments -
I think the prejudice comes from hearing the reasons given as 'fact' for when something, like expensive speaker wire or power conditioners, are touted as an amazing miracle for improved audio (or video) quality. What I'm learning here is:
1. There may be perceptible changes in audio/video quality but there are often other scientific explanations for those changes. And understanding what actually happened may offer an alternative which is far less expensive or easier to do. This unravels the black magic and snake oil claims behind a lot of this stuff.
2. Engineers should be open-minded about claims of improved or changed performance, but that does not mean accepting the given reasons behind those claims. Especially if those claims are from the equipment manufacturer. They are in the business to make money.
3. It really takes someone with good engineering background and an active interest is audio/video/home theater to figure it all out. That's what's needed to sort out the truth from the BS. So how many people out there do we have like that? Probably not too many ...
emc guy
I was under the impression that coax was being used in some fashion as a replacement for speaker wire. I saw another thread about someone doing this. I was trying to point out that this can cause an RF short circuit to appear at the amplifier output at certain frequencies, and this could be very bad for the equipment. I was assuming that most people are using amplifiers that have floating balanced outputs meant to have the load across the +/- outputs. Most home and auto equipment I've seen is like this. I didn't think bipolars were used much anymore. Perhaps there's some nostalgia for bipolars just like for tubes.
If you are trying to do impedance matching of speakers, you've opened a can of worms. You've got a passive compensation network with the cable, and R-C at the speaker terminals. Were you looking at the transient voltage response at the speaker terminals? If so it might be that what you have done isn't necessarily a good thing. It is the current in the voice coil which should be optimized for transient and frequency response. Just interested in how you know that what you did was good, besides going by what it sounded like.
To add to one of your other comments -
the engineers knowledge can be a double edged sword. It can help you reason out an event but if you are not careful it can also prejudice one against an event with out actually testing the hypothesis of that event in a real world setting.
I think the prejudice comes from hearing the reasons given as 'fact' for when something, like expensive speaker wire or power conditioners, are touted as an amazing miracle for improved audio (or video) quality. What I'm learning here is:
1. There may be perceptible changes in audio/video quality but there are often other scientific explanations for those changes. And understanding what actually happened may offer an alternative which is far less expensive or easier to do. This unravels the black magic and snake oil claims behind a lot of this stuff.
2. Engineers should be open-minded about claims of improved or changed performance, but that does not mean accepting the given reasons behind those claims. Especially if those claims are from the equipment manufacturer. They are in the business to make money.
3. It really takes someone with good engineering background and an active interest is audio/video/home theater to figure it all out. That's what's needed to sort out the truth from the BS. So how many people out there do we have like that? Probably not too many ...
emc guy
I didn't think bipolars were used much anymore. Perhaps there's some nostalgia for bipolars just like for tubes.
Not at all. Bi-polars are still common as dirt. Typically only hi-end gear has used FET
I didn't mean to cause such a stir, but I found it very interesting.
JZ
JZ
Don't give it a second thought. Your post was well received. The testing of different zip cord was well done. Unfortunately zip cord is not real speaker wire.
The conclusion will end up being that nothing has changed and each individual will have to select the product that provides optimum results for the stuff in their system because there are no standards in audio - just synergy.
Richard
The conclusion will end up being that nothing has changed and each individual will have to select the product that provides optimum results for the stuff in their system because there are no standards in audio - just synergy.
Richard
SPEAKER CABLES: Science or Snake Oil
http://www.hdtvmagazine.com/forum/viewtopic.php?p=19668
http://www.hdtvmagazine.com/forum/viewtopic.php?p=19668