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

Bravo, an extremely interesting article and one that dares tell the truth.

This is true for zip cord. Zip cord is not speaker wire.

Just remember that the article is about SPEAKER wire and not audio and video cables.

Speaker wire should be a coaxial product designed for 8 or 4 ohms. Zip cord is anywhere from 150-300 ohms.

Richard, you are wrong. Just because you are some kind of technician does not mean that you know everything. Standard zip cord makes excellent speaker wire. I have never heard of using coaxial cable for speaker wire and can't imagine that it is even desirable!!!

> Speaker wire should be a coaxial product designed for 8 or 4 ohms. Zip cord is anywhere from 150-300 ohms.

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'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:
>> 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

Everyone is entitled to one mistake.

Hugh

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.

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

>> 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.

Tell it Like it Is.....

Richard, zip cord has been used for speaker wire for more than 50 years. It is very doubtful that you know more about speaker cable than all the professfionals that have come before you.

per Richard "we need to move ahead beyond the science of the 50's".

Richard, raw speaker design has not changed one bit since the 1950's. You still have basic cones, horns and electrostatic speakers. The cabinets those speakers have been placed in have changed but not the raw speakers themselves. There is no new radical speaker design that provides significant improvement to the raw speaker designs mentioned above that I am aware of. (Electrostatic = Martin Logan, Magnepan and others, Horns = Klipsch and others, basic cone design = just about all manufacturers)

Ralph,


Not trying to nit pick, but Magneplanars are not electrostatic speakers. Their only similarity with Martin Logans is that they are a Planar design.

Mark

>>Richard, zip cord has been used for speaker wire for more than 50 years. It is very doubtful that you know more about speaker cable than all the professfionals that have come before you.

Zip cord and professional. Hmm... Modern studios DO NOT use zip cord.

>>Richard, raw speaker design has not changed one bit since the 1950's.

Yes, we still use the same extremely cheap low power ferrite material for magnets - so much to be proud of. The late Harvey Rosenberg had much too say about this issue. We miss you Harvey! As for not changing one bit what about ribbon drivers such as Infinity, Magnepan and Carver. The uni drivers from KEF.


Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

> 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.

Richard, ribbon drivers are nothing new and are very similar to electrostatic speakers. Magnepan has been around for a long, long time. Electrostatic and ribbon speakers are both flat pannel speakers. Neither are at all new. You could have very easily purchased either type 30 years ago.

I should not have used the word 'theory'. These are well known engineering principles and not something like the 'Big Bang theory' or 'Darwin's theory'.

Richard EM Man has it totally together and is 100% correct. I don't know where you went to school but I would ask for my money back.

Ralph,

With all due respect, similar shape does not make for a similar product. Yes Maggies have been around for quite some time (I have a pair in a closet that is at least 25 years old). Ribbon Drivers are a fairly recent part of the Maggie product line. KLH Model 9's are quite old now too. But I can assure you that they don't have much in common other than the fact that bot are flat, planar speakers.

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

From what I've seen, I would say that this is not a neutral party. Also too many incorrect answers that have no basis in fact.

“There is a true 8/4 ohm coaxial speaker cable out there from Sumiko called Ocos, very pricey but accurate in this regard.”

Why stop there? That product is only $355 for 10’.
For only $1,000, you can get 4’ of Passion V3 speaker cable (more $ for 10') (http://www.zcable.com/Speaker-Cables.asp) This fine product is “...voiced with copper and copper alloy conductors for the perfect tonal balance.” (there’s a new electrical characteristic) It also includes “…proprietary ZCable Optimization treatment for that special ZCable openness and transparency.” (mustn’t forget the “magic dust.”) The result is that “…your audio system becomes dramatically more musical.” Truly, this product must be more accurate than that cheap, unprofessional Ocos stuff.

While you’re at it, check out the selection at: http://www.fatwyre.com/speaker_b9_02.html. The Siltech Emperor Signature G5 at $25,500 for 10’ must be the most accurate of all. I personally prefer the appropriately named Acoustic Zen Hologram II at $1,248. You can see them, but they’re not really there and if you can’t hear the difference, it doesn’t matter. (It only proves you’re not an audiophile.)
a.

>>You could have very easily purchased either type 30 years ago.

Yes, but not 50 years ago.
_______________________________________________________________________

>>From what I've seen, I would say that this is not a neutral party. Also too many incorrect answers that have no basis in fact.

What makes me not neutral? Do you own a TDR or know anybody with a TDR? What is your basis in fact?

________________________________________________________________________

>>Why stop there? That product is only $355 for 10’.

Pure sarcasm.

_______________________________________________________________________

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.

________________________________________________________________________

As for me,

I leave this thread. Flame away!

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

Thank you JZ for the extremely informative website. I would also like to thank ER Man for the excellent information also.

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.

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, going back to your earlier statement

>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?

Hi Mark, actually I was really not really arguing about speaker types or designs as much as the fact that they have been around for a long while. I hopped over to the Magenapan sight and came up with the following: In 1969, Jim Winey invented the Magneplanar, a thin-film magnetic equivalent to the electrostat.

Nothing here for me to argue, Magnepan is a highly respected speaker in the audiophile world.

I had also auditioned a pair of "Carver Amazing Loudspeakers" a while back. It seems like it might have been close to 10 years ago, I can't say for sure. They also sounded excellent.

Thing is though, in the electronic world even 10 years is a long time. If there is a newer design of speakers out that operate on totally different principles, I simply am not aware of it.

I used to love going to the high-end stereo stores and listening to the Magnaplanars hooked up to massive Tube amps, haha.

I have Vandersteen speakers and a Yamaha receiver in my system. I initally used 10' 16 guage "consumer quality" monster cables in my system. About a year ago I purchased my ws65909 and had to go on a cable buying spree (non of my AV component cables would reach the inputs on my 65" TV). After 100.00 in new cables I figured 100.00 more for my speakers might be worth it, so decided to see if the higher quality wires in my system would make any difference. I purchased Monster Mseries cables and have been very happy. The sound did not signifigantly improve, but seemed to be warmer.

Can this be proved scientifically, maybe... Does it really matter, probably not. I heard an improvment in my system and felt I got what I paid for.

The selection and purchase of speakers is a very personal one, no matter how many reviews saying that this or that is better, worse, or no difference will not tell you how the speaker will sound in your home to your ears. I believe that high quality speaker wires fall into the same category. Purchase what you can afford, listen in your home, return them if you don't feel they are worth the cost. For my personal tastes the use of lamp cords in a $11,000.00 entertainment system just seems wrong.

Augeas, it looks like the advertising industry has you just where they want you. Enjoy the overpriced cables!

>> Pure sarcasm.
Good catch, quite perceptive. Note that the products, prices and “claims” are real world examples. No measurable, verifiable claims, just fluff. What did someone say above?- "warmer?" Some prefer "bright." Does that mean the cables are introducing an undesirable characteristic? OK, #16 lamp cord is a little "light," but the next level doesn't have to be $1,000 Passion V3's. With so many examples of over-priced products (and apparently, willing buyers), it is very easy to make fun of the effete snobbery of the “philes.”

>> 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…

Pure arrogance – the Master Technician will now instruct the engineer. EMC guy is too polite here -- he just simply corrects the "Master's" (wrong) assumption about equipment availability and knowledge.


a

Anon,

It seems all you want to do is to create friction and validate your own preconceptions or wallet. Your first response is to find even more expensive wire to make me seem foolish. You claim I am arrogant and then EMC Guy is too polite when it seems what we have is two professionals trading information with both seeking the same goal which is to understand what is going on here yet you try to make me seem like an ass and EMC Guy foolish. You pick on another guy for his choice in wire and seek to make him foolish.

I respect anybody who states they tried such and such wire and heard a difference. That is the easy part. Defining and categorizing that difference is extremely difficult and a lack of standards make it nearly impossible. Those of us who have heard it now stand around wondering which wire is more accurate.

You have stated your opinion on how foolish you think this thread is so now please go listen to your inexpensive zip cord and leave this thread alone!

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

You're right about the maggie web page...the point I think they were trying to make though is that Jim was trying to make a similar product to a stat speaker without the use of transformers that are necessary in stats.

As far as the Carver Speaker goes...a buddy of mine is a friend of Bob Carver's, he owned both a regular production set and a pre-production set. Nice speakers, I'm thinking it was around 15 years ago but I might be wrong.

I currently own (along with an old pair of Maggies) a pair of ribbon hybrid speakers. Love the planar sound, but they require a good bit of juice.

Mark

Richard,

Actually, my wallet’s more than fine and I don’t use inexpensive zip cord. (Talk about preconceptions!) I’m actually a big fan of some expensive “toys” and don’t mind paying for real performance improvements. Heck, my BMW costs two or three times as much as a lot of decent cars but the performance improvement is (to me) worth the delta. When I bought my HDTV, it must have been 5 or 6 times the cost of a “regular” TV, but again (and I clearly don’t have to convince you of this) it was worth the increased cost. But in these admittedly simple examples, I both perceive a difference in performance and the performance difference is measurable. (Resolution, lap times, whatever.)

Where differences in actual results are established, I would never set a price or price multiplier to establish value for others. For some (and even me) small performance increments can command large price differences. There is also no way for me to judge for others the value of quality construction, user feel, form factor, color, art, or even “cool.” Each of us makes our own decisions in these matters and cannot be “wrong.”

Lord Kelvin was quoted: “When you can measure something and express it in numbers, then you know something about it.” I’m a big fan of that quote. Engineers and scientists seem to share that philosophy. I must also agree, somewhat reluctantly, that we have not yet learned to measure everything. In those cases, the accepted scientific method is double blind comparison testing. That’s the problem with most of the testimonials; the user knew which (insert magic product name here) they were “testing” and as some time typically elapses between “tests” that’s not a true A/B. Add in that many have stated that they expected better results and you have an invalid test.

Look at the way these things are “sold.” If a product had better “numbers,” either by measurement or scientifically valid test results, you can bet you’d see it in the literature. If others want to buy them because they look cool, are the right color or they wish to brag about how much they spent on the product, that’s their right. Performance claims are different. The non-data presented for these products is the big red-flag of snake oil. You said it yourself above – “Yes, they were right, science means little.”

There was no intent to “pick on” Augeas – if “warmer” is better and he/she is a happy customer, then I’m happy for him/her. You’re the guy who (correctly) sells “accuracy.” I most certainly don’t think EMC Guy is foolish, and I don’t see how calling him polite could be construed as such. Frankly, he frequently presents the most analytical, technically knowledgeable and fact based discussions and arguments on this forum. I did note that there are speaker cables out there that are priced in excess of $1,000 per foot. If that fact and/or the marketing “fluffery” of the industry make you feel foolish or seem like an ass as you defend high priced cables, well, that’s on you.

OK, you asked me politely to leave. I just had to say ‘bye.

a

Is this a Jekyl Hyde thing or what?

I have looked through your previous comments and they do appear to be flippant, sarcastic and snide. If this is just me I do apologize.

This last post appears to follow the spirit of my goal in this thread and it appears we actually agree about many things.

Were you just playing devils advocate?

Anon, you presented fact, not theory or BS. Maybe, just maybe a few folks out there with open minds may have learned something. After all, I thought that was one of the key reasons for this forum to exist.

Other than quoting a few retail prices, which I assume are correct, what facts did Anon present. I looked through this thread pretty closely, all I saw were a few personal attacks.

Mark

I have some fat guage zip cord I'm using on one of my speakers, and it seems to work fine. I plan on replacing it someday, but its the right color to blend into my carpet, and that let me esthetically put the speaker about 6 inches farther out, improving the soundstage.

Try the pink zip cord, I understand it's the best! :)

Mark

"are you wasting your money on those cables?" Well, chuckle chuckle, yes I am !!! If you are happy using the piece of string cables that come with "mass market" products then that is fine...but I prefer quality...and it appears that you do not...

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.

I wonder if there would be a market for zero resistance liquid nitrogen cooled superconducting cables?

Liquid nitrogen is cheaper then milk and a standard superconducting material isn't that hard to make. Condensation on the cables would be the main problem.

Better yet would be speaker coils wound with superconducting wire. Imagine those subs really cranking without any losses. But unfortunately room-temp superconducting wire not available from your local Radio Shack yet.

Room temp superconductors aren't available yet, but "high temp" ones could be used if LN2 was circulated around the wire.

>>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 “synergy” in this biz which means since there are no standards so you will have to experiment with products and wires to obtain the correct signature. It doesn’t have to be that way which I proved by modifying or building components in my system to meet common engineering standards. Also, as pointed out, 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 really wish you had called or e-mailed me. The scenario you describe would be an improper application of the wire, defeats the main purpose - impedance matching, and as pointed out could easily cause a lot of problems. For your reference single ended amplification and bipolar transistors are the norm. I don’t really know how one would apply this wire with a balanced or bridged amplifier except that this type of amp sees half of the load or impedance so you would need 4/2 ohm coax. The fact that I do not have all the answers is not surprising since I did not come up with this wire nor did I do the research to determine its accuracy. The engineer who did figure this out did it with test equipment - now that is science. In your scenario the effects are obviously negative even if the listener liked the “synergy” created by it. If you have the knowledge then the only conclusion to be drawn is something else is wrong with the system and while the wire is counteracting that error it is obviously wrong and could cause other problems.

The proper use of this wire requires a single ended amplifier where the negative speaker terminal is actually ground and the output swings positive and negative. The speaker terminates the cable and a series resistor and capacitor must be attached in parallel at the speaker terminals. The resistor equals the impedance of the cable and the capacitor is a 103. Per the engineer this is to fine tune the cable for audio frequencies and prevent ringing. The cable he made used your basic 50 ohm coax requiring about 6 cables in parallel for an 8 ohm impedance. This was obviously a mother to work with but it proved his hypothesis. Per the engineer similar results are obtained using just a single run since 50 ohms is a lot closer to 8 than the typical 150-300 he experienced and in this case the resistor of the terminating circuit is changed to 50 ohms. Sumiko is not the only one to have made an 8 ohm coax for this application and interestingly enough they do not warrant the application of the wire unless you purchase their black box to terminate it and I assume that black box is nothing more than the series resistor cap as described for the same reasons. Per the engineer there was another company during the late 80's early 90's that made this 8 ohm cable at an affordable price but as noted science is a difficult sell and the company went under. Until a few years ago Sumiko was providing a 30 ohm version because it was easier to work with.

The RF shielding ended up being a side benefit. What it does is prevent RF noise from appearing on the output of the amplifier which the feedback loop will see as an error when compared to the input signal and will attempt to correct leaving you with a feedback loop compensating for errors that the amp did not create. When using the cable you will find the amp has a more open sound. The most common remedy over the last decade for this “sonic signature” has been to significantly reduce the feedback. As you said “those who claim it changes the sound could be drawing their conclusions on the wrong reasons also”. Per the engineer these folks are simply trading the sonic signature of an overworked feedback loop for the sonic signature of increased distortion with out really solving the root cause of the error.

Since you are matching impedance the amp sees a direct unfettered path to the load. Some amps will react to this and go into oscillation with just the right combo of amp, this cable and a speakers crossover. Per the engineer this is caused by faulty amp design and not the cable which is doing exactly what it is supposed to do. Using the typical speaker wire in the 150-300 ohm range prevents this event from occuring.

My initial experience with this wire was both positive and negative yet after getting everything in my system corrected I found it to be quite accurate as expressed by the engineer.

If readers want to try this you do so at your own risk. Low fi and mid fi equipment seem to be OK with it. Hi-end audio designs are most susceptible to melt down since many play with the circuit to attain a specific “sonic signature”.

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

I didn't mean to cause such a stir, but I found it very interesting.
So does anyone have a bottom line opinion here? It seems all the data points in the direction of saving your money on speaker wire. Has anyone done an independent study to see if this websites statments are accurate?
JZ
PS: HOw about that All Star game :)

>>I didn't mean to cause such a stir, but I found it very interesting.

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. yuck!

Unless you're a gourmet cook (like myself) you cannot even begin to appreciate the subtle, yet marked improvement of the flavor of microwave popcorn cooked in an oven connected to high-end power cables.

Even chicken pot pies in my electric oven benefited tremendously once I connected the oven via these cables.

I have a limited quantity for those with a ton of cash and proof they are food-a-philes.

It has been proven by many differnt studies, that the human ear can not tell the difference. In fact, test equipment can hardly tell either. Any 12-14 gauge wire connected to consumer electonics will produce the same sound as "monster"

Sorry about the microwave popcorn sarcasm, but I do find it interesting that as a professional musician and recording artist for the past 20 years, I've realized that the only folks chasing high-end cables are the END USERS.

You'd think if cabling was so OMNI-IMPORTANT, that it would be MOST critical at the recording/capture environment.

Look at all the pro recording mags and you'd discover scant recommendations for spending big bucks on cables. It's electricity, man. If there was a difference, I'd be plugging in a more expensive cable into my 1976 Tobacco Sunburst Les Paul Deluxe that has appeared on countless recordings and commercials.

The reason is simple: Audio professionals - who are PAID to write, record and PRODUCE the source materials are too shrewd and "ear-educated" to fall into the trap layed for regular consumers - some who have enough money to spend poorly.

The same holds true in the film/video industry.

Check out any top post house or production facillity. If high-end cables were needed, wouldn't the artists/producers be demanding the ultimate for their studios? Afterall, they have the money to spend yet almost every production suite I've booked uses standard wire and connections.

INCLUDING 12 gauge zip-cord attached to the Yamaha NS 10's which has been used to reference nearly every recording produced in the last 20 years.

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 -

> 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 ...

Michael's comments certainly contain some interesting points. I'd like to see how Richard, and others, would respond. Keep it coming, guys; this is one of the most interesting threads going here.

>>Look at all the pro recording mags and you'd discover scant recommendations for spending big bucks on cables.

While this is true at least you have XLR connectors and balanced lines using a 600 ohm impedance for low level signals - you do have standards.

>>It's electricity, man. If there was a difference, I'd be plugging in a more expensive cable into my 1976 Tobacco Sunburst Les Paul Deluxe that has appeared on countless recordings and commercials.

Have you ever talked to Eric Johnson?


>>The reason is simple: Audio professionals - who are PAID to write, record and PRODUCE the source materials are too shrewd and "ear-educated" to fall into the trap layed for regular consumers - some who have enough money to spend poorly.

There is much truth here but lets not throw out the whole concept. Not all of it is BS.


>>Check out any top post house or production facillity. If high-end cables were needed, wouldn't the artists/producers be demanding the ultimate for their studios? Afterall, they have the money to spend yet almost every production suite I've booked uses standard wire and connections.

Yes, they use fairly inexpensive wire and connectors from within their industry. They are not using the garbage that comes with consumer products.


>>INCLUDING 12 gauge zip-cord attached to the Yamaha NS 10's which has been used to reference nearly every recording produced in the last 20 years.

Just a listing of studios in MIX Magazine kind of refutes this statement. While the speaker is indeed popular stating it’s use a reference for nearly every recording is a bit much. More often then not the engineer is using headphones, far more accurate, while the rest are listening to the monitors. Your statement also bypassed the initial stage of laying down the tracks and creating the initial and final mixes which in most studios is done with headphones. Naturally all mastering is checked via normal speakers to make sure the mass consuming public will get “their” sound and there was a time when they would mix the stuff so it would sound great on 6X9 car speakers. I have worked in the recording end a little bit myself, am a musician and also have my own studio.


Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

>>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’s.

>>If you are trying to do impedance matching of speakers, you've opened a can of worms.

Yes you will. That doesn’t mean that we can’t improve the situation. In fact one step closer is to get the amp within less than a foot of the speaker and then all you need is the right guage of your favorite flavor since there is not enough wire to have an effect. The final step is powered speakers where an electronic crossover is used to feed separate amps for each driver. Better to have long low level signal lines than power lines any day!

>>Were you looking at the transient voltage response at the speaker terminals? Just interested in how you know that what you did was good, besides going by what it sounded like.

All I have are my ears and the limited test equipment and budget I have to work with. I am fully dependent on the engineer I have been working with. I can only say that once I followed all the rules the sonic signature fell into place and I have not looked back since. This is NOT expensive to accomplish and all that is required is some TLC and attention to detail by a major manufacturer. The japanese could be spitting this accurate stuff out just like they do current consumer audio.

>>It is the current in the voice coil which should be optimized for transient and frequency response.

Yes but that task is for the crossover accomplish. The cables purpose is to get the power to the crossover correctly and of course deal with the return current created by the drivers and the crossover. Correct crossover design is yet another facet of the system.

>>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.

We both agree on that. Man, do we agree on that!

>>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.

Absolutely!

>>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.

Absolutely!

>>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 ...

I have stuck my neck out to accomplish this and am very grateful to have connected with an engineer who also feels the exact same way and is willing to assist me in understanding and explaining all this stuff. I thank him every time we talk for reinventing the wheel for me. What is sad is that most of this has been for my benefit only. Maybe this is the beginning of getting this out to the public but for real change we need a lot of PO’d folks out there demanding the BS be stopped. Real standards, that is all I/we want. Unfortunately there are many who will fight it since they will have some difficulty getting their products to work correctly with these standards and it will eliminate much of the snake oil and false claims.


Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

>>It has been proven by many differnt studies, that the human ear can not tell the difference.

Yes I know. That is the claim. I would love to be tested on my system with my material.


>>In fact, test equipment can hardly tell either.

How about CAN'T tell it either and if it can the skeptics will claim the readings are too insignificant to matter.


>>Any 12-14 gauge wire connected to consumer electonics will produce the same sound as "monster"

I certainly wouldn't go racing with a Toyota Tercel so you are correct in this qualified statement - any 12-14 guage wire connected to most consumer electronics in most consumer setups will produce the same sound as "monster". It is possible to detect some subtle differences with this stuff if you have the speakers setup correctly and use acoustic treatments in the room.


Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

Some of the best racing is in small cars: they are incredibly agile and light. Why do you think low powered sportscars are so popular, like the Miata and the MIni?

Ok, maybe not a Tercel, since its suspension is sub-par, but a little Mazda 323 or a Volkswagen Golf, or a Honda Civic will give you the thrill of a lifetime bruddah!

While fun corner hugging sports cars for sure they don't compare to Stealth, Mits 3000, 300Z (91 on up), Ford Mustang or if your pockets are really deep how about Corvette, Acura NSX, Viper, Ferrari, Porsche, ect.

The point is simply this:

Companies are marketing ultra high-end cables to end-consumers because they are finding some success in it. Their margins on a set of $100 cables is astronomical.

You're not going to find "Monster" anything in a modern production suite. Studios that create the A/V source material buy quality cables yet at a relative low price.

It boils down to this. While a producer might spend $5,000 on a microphone, chances are he's connecting it to $3,000 pre-amp with a $30 XLR cable. Even if consumer interconnects were balanced XLR (which they should be) companies would be successful in finding consumers willing to spend hundreds and thousands of dollars on wiz-bang magic cables.

The moral of the story is: Spend your money like a pro not a sap. You want better sound? Spend your extra cash on speakers - they're only responsible for 99.9999999999999999% of what you hear.

Maybe Richard could come over and calibrate my Klipsh Cornwalls while they're being driven hard with my pair of Crown DC300's playing King Crimson's Lark's Tongue in Aspic part III.

For what it's worth, musicians as well as those involved in the recording process are notorious for not owning/buying high quality audio gear. I can not tell you how many interviews I have read over the years in better Audio publications that shed light on this fact.

You're right about the Yamaha NS-10's in that they have been in use a long time, actually longer than you give them credit for. But to suggest that they were used on virtually every recording released in the last twenty years is ridiculous. I know of many recording studios that primarily use JBL and B&W monitors.

As far as inviting Richard over to listen to your Cornwalls, Why would he want to? That products (in it's time) main claim to fame was that it was efficient, not accurate.

Mark

I didn't mean to imply that NS 10's were the exclusive monitors utilized, only that they were popular. The point was that whatever speakers are used they are not typically connected with exotic cabling. Good 'ole 12 gauge stranded copper is standard.

As for the Cornwalls and similar products, they are efficient yes, and they accurately replicate a live performance - which is the goal here, right?

It's silly to observe folks like my friend Brad who pays thousands on Martin Logans, et al and claims "But they're soooooo accurate." They're weak if you ask me.

Again, compare what you buy with what the pro industry buys. When was the last time you attended a concert who's sound reinforcement utilized Martin Logans? Chances are they used TurboSound - big, juicy and efficient and moving enough air (another goal here) to remind you that you're alive.

Michael,

You got me...I've never been to a concert where ML speakers were used for sound reinforcement. But we both must remember (I too primarily listen to Rock and I commend you on your listening taste by the way) that many listeners aren't trying to reproduce electronically enhanced music. There are many listeners that find the transparency, and speed of ML products to be just what they are looking for. I've shyed away from Stats over the years (even though I like planar speakers) because I prefer a bit more bass.

The point I made about audio gear earlier though amazes me. I guess many musicians don't want to take the office home with them, so they don't invest much time or money in HiFi gear. And I agree that lamp cord is probably the best choice in most applications. But I also think that if you have a good ear, and revealing equipment, and good source material, you can often hear an improvement when you switch interconnects or speaker wires. Granted, the difference in most cases is very subtle, and as the end user you do have to look at the cost difference to determine if it is worth it.

As a musician, I think you might appreciate this example. Take two amps-both rated at 100 wpc .5% THD,
same damping factor, etc...but one is solid state, and the other is tube based. Most would argue that they sound the same, but to a sophisticated listener, the tube amp might sound better. Like Richard stated earlier, it might be due to synergy. I've never listened to Mark Levinson's Red Rose equipment, but I have heard from many that it is a prime example (along with his prior Cello Equipment) that synergy does in fact exist.

Anyway that's my rant...whether you do it with zip cords or MIT cables...keeep making and listening to music.

Mark

Richard, are you going to tell us next to replace our car's jumper cables with coax also? I've yet to see a set of coax jumper cables, but I'm sure you're working on it! Driving speakers is more like jumping your car than sending a HDTV signal to your TV.

It's all about resistance, and underground garden lighting wire works just as well as exotic speaker wire with the same resistance and distance.

Actually, jumper cables work very well for speaker wire (and you can get them as large as 4 gauge). I dare you to tell the difference between any exotic cable, no matter the price, and the 6 gauge jumper cables that I've had in the trunk of my car for the last 10 years.

I can see this challenge looking like a Ginsu (sp?) knife commercial. I jumpstart my car, then use the same cables to play classical music with amazing clarity. Kinda like cutting a nail and then slicing a tomato.

I'll stop now...

Tim

Micheal,

>> and they accurately replicate a live performance - which is the goal here, right?

Is it? Did it sound like a live performance in the studio coming off the master? Will a CD ever give you that “studio” sound? Now that we have DVD-Audio and SACD that problem is solved. Vinyl doesn’t count because of all the variables involved to get the right needle and cartridge in the right tone arm on the right platter with the right drive with the right preamp - consistency is not its forte. Now that we can deliver the same sonic signature that was in the studio what is the final frontier? The microphone. Microphones are still incapable of reproducing live sound and may very well never do it. No matter what I do it will always sound like your performance going through a microphone. Bottom line is in an accurate reproduction system the best we can possibly hope for is accurate reproduction of the bit stream coming of the disc so we get the same sonic signature the engineer had in the studio using headphones. Headphones!? Yes, headphones because unless you have the same speakers, amplifier and wire setup the same way in the same acoustic environment as the studio you will NEVER do that (could throw AC power into that recipe also). It is much easier for me to reproduce the mixing sound stage for film or video than for the music only industry since these guys do have standards right down to where the speakers are suppose be. Headphones are the reference for music. If you can get your speakers in your room to equal or exceed the clarity you get with good headphones then you are obtaining accurate reproduction.

There are few consumers striving for this kind of reproduction. Most are trying to do the same thing you are which is to get it to sound like a live performance but this can be separated even further into close, middle and far field reproduction of an acoustical environment. When you start going down this road you are moving away from accuracy to sonic illusion and your only choice is the pursuit of synergy. In this case you might actually want to experiment with some of these wacky cables because they will change the sonic signature. Tube products are well renowned for this kind of reproduction goal.

I would be happy to hear your Cornwalls and I bet they are killer.

>>When was the last time you attended a concert who's sound reinforcement utilized Martin Logans? Chances are they used TurboSound - big, juicy and efficient and moving enough air (another goal here) to remind you that you're alive.

Sound reinforcement has absolutely nothing what so ever to do with accurate reproduction. The main goal here is to get good sound at extremely high SPL to the audience - be careful of the front rows.

__________________________________________________________________________

Mark,

The goal of Red Rose Music is accurate reproduction using common engineering standards and their stuff is not designed to work accurately with other products since there are no standards. Synergy is what you get when you do not have any standards and literally have to guess and figure out what sounds good with what and then the final sonic signature will be in the ear of the person who put it together.

Let’s face it synergy is what makes this a hobby. Synergy is what many enjoy about 2 channel audio. Synergy is what drives sales of equipment and product.

_________________________________________________________________________

Tim,

More amusement and sarcasm from the audience directed towards me when I recommended nothing.

In this thread I have yet to suggest or recommend anything for speaker wire including the coax that has been heavily discussed. My point is a link was posted with supposedly scientific results but zip cord is not speaker wire and I then addresses what correct speaker wire is. While many have been fuming over snake oil and high prices not one person has researched the cost of using any form of coax. The wire I suggest is not snake oil, it is fairly accurate and VERY inexpensive. If you want the 8 ohm version of this concept Sumiko has it for $10 a foot which comes with the side benefit of “look how expensive my wire is” bragging rights. Again, I have not recommended my wire since there are no standards and I cannot guarantee performance in you system and have already given my conclusion to this thread:

“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. yuck!”

That statement includes zip cord.





Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

Well you got me on the Cornwalls. Never have heard of them. I did use to think that Bozak was the best in speakers......back in the 70's. I'm talking about the largest enclosure they made with four woofers, etc. No need for subs with those things. And I know a very wealthy guy who still has a pair and only used a pair of 200 W amps to drive them. He finally got some more amps and tri-amped them. Still sounds pretty good.

Hugh

THE HEART OF THE MATTER
Cabling Basics



by Peter H. Putman, CTS

It's a fact of life: The active components in any professional AV installation get most of the attention, while wiring is often taken for granted. Check out the booths at trade shows - the "buzz" is typically focused on the latest projector/monitor technology, computer/video interface, and control interfaces. Things are comparatively sleepy around the cable and wire company booths.

Maybe that's not a bad thing. After all, we've had access to high-quality cables for a lot longer than we've had high-quality video images and interfaces. Advances in imaging technology are measured in quantum leaps from year to year, while refinements in cable design and construction move in much smaller increments.

That is, unless you believe all of the hype generated by resellers of cable for the home theater and consumer electronics industry. Over the past years, we've seen Teflon-dielectric cables for both video and audio, speaker cables with directional arrows, and even audio cable with a water jacket - ostensibly for cooling. Claims of superior performance, reduced signal loss and constant energy flow abound as the unwitting hand over hundreds of dollars for what amounts to snake oil.

Do these "wonder cables" belong in your installation? Will they hold up over time, or require constant attention? (High performance and high maintenance usually go hand-in-hand - ask any professional race car driver.) Or, are you better off going with a simpler but tried-and-true product that you can install and not lose any sleep over it?

Last May, I wrote about baluns and the part they play in the transmission and matching of AC signals. Subsequent to that piece (and following a trip to this year's NAB convention in Las Vegas), it became apparent that there is a great lack of understanding when it comes to cable - specifically, cables for carrying video signals from one point to another. This was made all too clear as I thumbed through the latest copy of a major home theater magazine - several advertisements and much of the editorial material revealed a basic lack of cable "smarts".

For those of you who already understand how AC signals (power, audio, video, RF) move over transmission lines, my apologies for covering old ground. For those who don't, it's time for another session of Cable 101.

BACK TO BASICS

Forget everything you've read about Teflon dielectrics, polarized cables, gold-plated RCA connectors and multiple shield strands. Most of these gee-gaws are the result of marketing hype, not any scientific testing in a lab. For most installations, there are garden-variety cables that will work just as well, and they don't cost an arm and a leg, either.

There are several types of coaxial cables available from manufacturers such as Alpha and Belden. For our industry, we're primarily interested in the 75-ohm types, a number we inherited from the CATV and broadcast industries. (Readers of my May feature will recall the characteristic impedance of open-wire transmission line for TV antennas is 300 ohms, and a 4:1 balun transformation results in a 75-ohm connection.)

How the heck does a manufacturer determine what makes a 75-ohm cable? Simple. The characteristic impedance of a cable (Zo) is determined by the formula 138 log b/a, where b represents the inside diameter of the outer conductor (read: shield or braid), and a represents the outside diameter of the inner conductor. Any unit of measure can be used (millimeters, inches, microns, etc.) as long as it is the same for both terms in the equation.

Coaxial cable companies have had over 50 years to determine what combination of wire sizes and diameters make up 50-ohm, 52-ohm, 72-ohm, 75-ohm, and even 92-ohm coaxial cable. Because the impedance is strictly dependent on this ratio - and NOT on the dielectric, outer jacket, or composition of wire used - it's a pretty simple matter to manufacture coaxial cables in sizes ranging from 1/8" in diameter (RG-176/U) up to 2" waveguide.

Because AC signals travel at slower speeds through wire than they propagate through air, coaxial cables also carry a velocity factor specification. The velocity factor is useful to know when working with RF energy; it's essential for the design and construction of antennas and coaxial baluns. For the AV installation business, velocity factor is generally not a specification we need to be concerned with, unless we are matching and transforming RF energy - say, splitting a signal from a satellite dish, or constructing power dividers for distributing cable TV signals.

The dielectric of a coaxial cable serves but one purpose - to maintain physical support and a constant spacing between the inner conductor and the outer shield. In terms of efficiency, there is no better dielectric material than air. However, air doesn't offer us any structural integrity, so cable companies use a variety of hydrocarbon-based materials such as polystyrene, polypropylenes, polyolefins and other synthetics.

As AC signals increase in frequency, they have a tendency to be absorbed by, rather than pass through, insulating materials. Teflon, a synthetic plastic that was invented over 40 years ago, is often used as a dielectric material in RF applications above 200 MHz. Microwave transmission lines and connectors make extensive use of Teflon (when they aren't using air dielectrics), as it is also an excellent high-voltage insulator.

Flip open a consumer electronics magazine, and you'll see ads for "boutique" speaker cables and coaxial cables with Teflon dielectrics and (in some cases) Teflon outer jackets. Don't waste your money - the improvement in performance is negligible at these frequencies, often measuring less than tenths of 1 dB. That kind of improvement is hardly worth hundreds of dollars, particularly when there are industrial-grade cables available that are economical and adequately suited to the job.

These "traveling medicine show" ads play off fears of signal attenuation, and often attempt to convince would-be purchasers by boasting of '99% shield coverage' and 'multiple interwoven strands for greater shield coverage'. The truth is, attenuation has absolutely NOTHING to do with shield coverage - it's strictly a function of the electrical resistance of the center conductor and the efficiencies of the dielectric material.

When AC signals propagate through wire, some of the energy is lost as heat. (Remember Ohm's Law?) This effect can be over come by using larger-diameter wire, which is the reason we specify RG-59/U for cable interconnects and RG-6/U /RG-11/U for longer cable runs. There will also be some absorption by the dielectric material, resulting in energy being dissipated as heat. Certain organic plastics (polyolefins, polypropylene, and polyethylene) exhibit less absorption than others and are consequently better-suited for carrying AC signals.

At VHF radio frequencies and higher, certain cables are sold with a combination of air and solid dielectrics. Special pressure fittings allow the user to fill the line with nitrogen, which prevents moisture build-up. Water should NEVER be used as a dielectric or insulator in any cable! The nitrogen approach is appropriate for cable installations in harsh environments, such as cellular phone repeaters, microwave towers and broadcast stations.

You may be surprised to learn that open-wire line has considerably less attenuation that coaxial cable. RG-59/U coaxial cable with a foam dielectric has a loss specification of 2.4 dB per 100 feet @ 50MHz, while RG-11/U (O" 75-ohm coax) clocks in at just over 1 dB at that same frequency. Generic 300-ohm TV antenna wire? How about .27 dB per 100 feet - almost ten times better than RG-59/U!

Shielding is another aspect of cables that is widely misunderstood. When AC signals travel in a balanced transmission line (which is where AC signals propagate most efficiently), there is little or no radiation of the signal. Assuming the source and load impedance transformations are optimized, all of the energy goes where it's supposed to - a speaker, a monitor, or an antenna.

Coaxial cables exists because we can't run open-wire line near metallic objects (such as ducting) or bury it. We trade signal loss for convenience and flexibility. Unfortunately, we also complicate matters when making transitions between balanced and unbalanced wiring - if we don't have a perfect match (and we rarely do), there will be a certain amount of energy reflected back down the cable as standing waves.

Even with a very good match, there is always some signal radiating from coaxial cable. Hence, the outer conductor also functions as a shield to reduce coupling of the signal into adjacent wiring. More shield coverage means less radiation of energy, but it does NOT mean less attenuation! A Teflon-insulated cable that is improperly matched to a load will radiate more signal than a generic Radio Shack coaxial cable that is properly matched.

Many of our cable "difficulties" were foisted on us by manufacturers of consumer video equipment. For one reason or another (usually simplicity), manufacturers started to make specialty cables that were convenient to use, but exhibit poor performance. You need look no further than the ubiquitous S-Video cable, typically two strands of very small 75-ohm coax terminated at either end with a connector that is anything but constant impedance.

Typical S-video cables are very lossy. And why not - their counterpart would be RG-176/U, a miniature 75-ohm coax that swallows up 2.5 dB of signal for every 100' at 4 MHz. Even Belden's 1807A and 1808A S-video dual-coax cables are rated at 1.5 dB attenuation per 100 feet @ 5MHz. Again, we pay a price in signal strength for convenience - both of these cables are very small and easy to bundle.

A better approach would be to use BNC connectors on either end of standard 75-ohm coax for moving S-video (and, for that matter, YUV component or YPbPr decoded analog HDTV) from point to point. As long as all cables are made from the same type of coax, phasing and delay problems shouldn't arise unless there are huge differences in the cut cable lengths. (That's where velocity factors and consistency in manufacturing come into play.)

So - before you buy any cable, why not get a copy of a reputable cable manufacturer's catalog (Belden's can be had by calling 1-800-BELDEN-1) and use it as your bible. Be careful of claims that can't be substantiated, such as improved performance from unusual outer jacket construction, crazy weaving patterns in shields and braids, combinations of copper and other metals in the center conductor, and excessive use of Teflon for dielectrics and connectors.

Look instead for specifications on attenuation, temperature ratings, voltage and current capacity, and the type of outer jacket used. Many cables come in both contaminating (can't be buried) or non-contaminating (go ahead and bury it) versions. Some can even be submerged in water without serious problems - something to think about when specifying cable for a humid environment.

Copyright ©1999 Peter H. Putman/Primedia Intertec
This article appears in the July 1999 issue of Sound & Video Contractor

Jack,

Not too old. Only a little off topic for a speaker cable thread (although the thread did move to coaxials. On the point about "exotics."

Why not just post a link and a summary or comment?

a

Why not just post a link and a summary or comment?

I didn't realize I had to get prior permission on format of replies. Sorry.

I wouldn't pay any attention to someone who doesn't have a name. And it is good info. You do not have to get permission to post.

Hugh

Jack,

Gee, don't be so touchy. I liked what the article said and called it "on the point." You certainly don't need my permission to cut and paste a large copyrighted article in full and not add any content or comments of your own. It'd get you seriously flamed elsewhere on the net. I just asked nice.

a

Hughscot,

I do use a consistent identifier --it's "anon" and I log in under a user name that was available. I guess if I just made up a "real" sounding name, that would satisfy you.

You continue to harp on this name thing and use it as a personal attack. Is that the best discussion you can initiate? As noted before, it's just lousy policy to put personnaly identifiable information on the internet. We have a difference of opinion.

a

This Forum appreciates a consistent login name for users. It keeps things straight and also prevents duplicate names and identity theft. By all means make it up if you wish to do so. We certainly understand why certain individuals would wish to remain anonymous.

"originalanon" meets the needs of the Forum and no other name or reference is required.

In the future version of this Forum a user login will be required for posting.

Thanks

Richard F. Fisher
Mastertech Repair Corporation, Lawrenceville, GA
770-513-3987 E-Mail - help@mastertechtv.com
Have you been calibrated? ISF and HAA Certified
Factory Authorized
Mitsubishi, Hitachi, Toshiba, Harman Kardon, Infinity, JBL, NAD

Normally I would have made comments but since most of us had already posted our thoughts when I ran accross this I thought it addressed clearly what most had already posted.

Rest assured I would not want to do anything to piss you off again, so I will just post links.

Jack,

I'm in total agreement with Mr Putman's position that we should "Look instead for specifications..." and made that pretty clear in earlier posts.

No need to worry about hurting my feelings. Owners of copyrighted material may take a different position but that's between you and them. It's a bit old fashioned, but large pastes of publicly available material have historicly been criticized as wasting "bandwidth," especially when that's the total content of the post. Probably doesn't mean much for text files in these days of cheap storage. I'm not at all pissed and I don't know why a simple question about posting philosophy would make you think so. Been flamed for it before?

a

Hey anon

> You continue to harp on this name thing and use it as a personal attack

You better be careful or Hugh will call you a 'Stereotypical Internet Shame' like he did me. :)

EMC Guy,

I’ll freely admit to a bit (or more) of flippancy in my earlier posts to this thread. I hope I clarified my position later on. In the interest of simplicity, I hesitate to couch every statement in softness (and, I’m not alone). Some seem to take any questions of, disagreements with, or comments on their positions as personal attacks, no matter how they’re phrased. Seems to me, if you post a statement to a public forum you can expect others to disagree or comment. Not all comments will be “me to.” That’s healthy. Name-calling, such as you describe, should be afforded the appropriate level of respect.

I certainly hope that our moderator’s response will put the “name” issue to bed.

a