The original thread having been closed (see http://www.diyaudio.com/forums/showthread.php?s=&threadid=23440 ), I'm starting this thread for the discussion of the followup measurements intended to address the concern that John and Bruno hadn't measured the same cables.
To that end, I made up two sets of identical cables. Each set included an old Radio Shack Gold interconnect that I had laying around here which was well used but hadn't been used for at least a couple years. A brand new, unused Radio Shack Gold interconnect. A bog standard giveaway cable which were included with my DishNetwork boxes. And finally, just to add some interest, a cable made up using Manhattan/CDT M4214 which is an RG 174/U type.
The reason I threw this last cable into the mix is because its center conductor (7/34 stranded) is made of copper clad steel.
I figured that if the distortion John is measuring is indeed being produced by the conductors themselves, then using a ferromagnetic conductor such as steel should result in distortion significantly greater than even the most bog standard copper or silver conductors.
Interestingly, of the four cables I sent John, the cable with which he measured the LEAST distortion, was the copper clad steel core RG 174/U.
Here's John's response from the other forum:
Been there, got the cables, measured them.
RS cables are slightly the worst, but not too bad, el cheapo cable came in slightly better, custom 174 came out best. No cable was quite as good as the reference, but not bad.
Signifcantly worse were some cables here already.
The old Radio Shack Gold and the giveaway cable are on their way to Bruno (they were sent the same day that I sent John's cables). The new Radio Shack Gold and the RG 174/U are ready to send to Bruno on Monday.
se
To that end, I made up two sets of identical cables. Each set included an old Radio Shack Gold interconnect that I had laying around here which was well used but hadn't been used for at least a couple years. A brand new, unused Radio Shack Gold interconnect. A bog standard giveaway cable which were included with my DishNetwork boxes. And finally, just to add some interest, a cable made up using Manhattan/CDT M4214 which is an RG 174/U type.
The reason I threw this last cable into the mix is because its center conductor (7/34 stranded) is made of copper clad steel.
I figured that if the distortion John is measuring is indeed being produced by the conductors themselves, then using a ferromagnetic conductor such as steel should result in distortion significantly greater than even the most bog standard copper or silver conductors.
Interestingly, of the four cables I sent John, the cable with which he measured the LEAST distortion, was the copper clad steel core RG 174/U.
Here's John's response from the other forum:
Been there, got the cables, measured them.
RS cables are slightly the worst, but not too bad, el cheapo cable came in slightly better, custom 174 came out best. No cable was quite as good as the reference, but not bad.
Signifcantly worse were some cables here already.
The old Radio Shack Gold and the giveaway cable are on their way to Bruno (they were sent the same day that I sent John's cables). The new Radio Shack Gold and the RG 174/U are ready to send to Bruno on Monday.
se
My test frequency is 5KHz and my level is 70mV with a 600ohm source and 2Kparalleled with 50K load.
Let's see first if Bruno can find ANY distortion at all.
Sy, I don't need to be second guessed by Steve Eddy. If you have a question, please ask me.
I have found an expensive VDH video cable terminated with VDH connectors works very well. I have also found that a JPS cable works at least as well, but it is less flexible, so it is more difficult to use on a regular basis. Both cables are shielded 75 ohm types, and both have a distortion residual at about -120dB or better.
Steves cables measure worse than this, by 5 to 10dB typically.
Let's see first if Bruno can find ANY distortion at all.
Sy, I don't need to be second guessed by Steve Eddy. If you have a question, please ask me.
I have found an expensive VDH video cable terminated with VDH connectors works very well. I have also found that a JPS cable works at least as well, but it is less flexible, so it is more difficult to use on a regular basis. Both cables are shielded 75 ohm types, and both have a distortion residual at about -120dB or better.
Steves cables measure worse than this, by 5 to 10dB typically.
john curl said:
Thanks. I'll pass that on to Bruno.
Is 600 ohms the lowest you can go with regard to your source impedance? It would be interesting to measure the RG 174/U cable with as much current as you can manage and at a much lower frequency which would maximize the nonlinearities due to the steel core. What's the maximum level of your 1700B's oscillator?
If the cables I sent are in fact producing distortion at -115 to -120 dB relative to the fundamental as you say, then they should stick out like a sore thumb seeing as the System Two Cascade's generator's thrid harmonic residual is at -130 dB and clearly visible on the previous measurements that Bruno made.
se
fdegrove said:
Well, unless you expect them to have sufficient distortion that it'll show up on the System Two Cascade, I don't see much point.
So far none of the cables Bruno has measured on the System Two Cascade have shown any signs of distortion. That's why I decided to send the steel cored RG 174/U cable in hopes that SOMETHING might be sufficiently nonlinear that it'd be within the System Two Cascade's reach. Can't think of anything worse than copper clad steel that would stand much chance of being used at all for audio cables.
If the RG 174/U doesn't do it, I'll go over to Mills and get some nichrome wire and try that.
se
Steve Eddy said:
So, it's nickel that is "bad"? Just wondering because the Vishay bulk metal foil resistors are nichrome. Steve when I wrote about these before, you mentioned "ruthenium oxide", not having the details that these particular resistors are constructed with nichrome. They are "non-inductive" but I guess they could be magnetic.
JF
johnferrier said:
Well it's that nickel is ferromagnetic and saturable if the field's strong enough so if you want something that can produce nonlinearities, nickel and nickel alloys should work. Steel would be the poorer choice between the two since it saturates at much higher flux densities.
Not sure what you mean about the Vishays and ruthenium oxide. I don't recall saying the Vishay bulk metal foils were made with ruthenium oxide. I do recall mentioning a while back that ruthenium oxide was typically used for thick film resistors.
se
johnferrier said:
I looked up the post. Here it is:
http://www.diyaudio.com/forums/showthread.php?postid=282096#post282096
My mention of ruthenium oxide was in response to a link you'd given to an article about why Vishsay bulk metal foils were superior to carbon comp and thick film resistors and you'd made note of the bit in the article as to why carbon comps and thick films were noisier than the bulk metal foils and thought perhaps that could explain the "microdiode" theory.
I was pointing out that the situation with carbon comps and thick film resistors wasn't the same as you'd have with copper wire. In fact the reason the situation wouldn't be the same with copper is the same reason the bulk metal foils aren't as noisy.
No problem.
se
Frank, please quit putting your foot into this.
First, we have to see if we are measuring anything at all.
Steve implicitly trusts Bruno, because Bruno is getting null results.
I don't get nulls as often, so my test system is suspect.
Up to this point, I believe in my testing, but I am not interested in further measurements for people on this website, in general.
Furthermore, I don't care what Steve Eddy wants. He is no friend or even competitor of mine. My competitors and I treat each other with dignity, and we even help each other, on occasion.
He, and he alone, brings this subject of wire distortion, continually. If he can 'trash me' he will do so, big time.
I did my tests because I thought they showed something interesting about cables. I even invested in better test equipment, after being ridiculed at first, for my 'Mac the Scope' printouts. I cannot justify a $30,000 rig, just to please Steve Eddy, or any of the rest of you. Get your own test equipment, or leave it be.
First, we have to see if we are measuring anything at all.
Steve implicitly trusts Bruno, because Bruno is getting null results.
I don't get nulls as often, so my test system is suspect.
Up to this point, I believe in my testing, but I am not interested in further measurements for people on this website, in general.
Furthermore, I don't care what Steve Eddy wants. He is no friend or even competitor of mine. My competitors and I treat each other with dignity, and we even help each other, on occasion.
He, and he alone, brings this subject of wire distortion, continually. If he can 'trash me' he will do so, big time.
I did my tests because I thought they showed something interesting about cables. I even invested in better test equipment, after being ridiculed at first, for my 'Mac the Scope' printouts. I cannot justify a $30,000 rig, just to please Steve Eddy, or any of the rest of you. Get your own test equipment, or leave it be.
Well, I'm interested in Bruno's measurements, too, because he's doing it on a system with better resolution than yours and enormously better than mine. And he seems to understand the need for documenting the gauge R&R capabilities of the system.
I'm also not a competitor, nor in the hifi business in any capacity, but having a pretty strong background in the physics of conductive materials, I'd sure like to see some interesting new phenomena to study. But they have to be REAL phenomena, not measurement artifacts- I learned well my lesson from Stan Pons.
If I were going to add one more thing to the list of test candidates, it would be some coathanger wire with the ends scraped free of insulation. That seems to be the favorite whipping boy of the magic cable set ("No more wire hangers! No more wire hangers!" "Owwww! No! Mommy!").
I'm also not a competitor, nor in the hifi business in any capacity, but having a pretty strong background in the physics of conductive materials, I'd sure like to see some interesting new phenomena to study. But they have to be REAL phenomena, not measurement artifacts- I learned well my lesson from Stan Pons.
If I were going to add one more thing to the list of test candidates, it would be some coathanger wire with the ends scraped free of insulation. That seems to be the favorite whipping boy of the magic cable set ("No more wire hangers! No more wire hangers!" "Owwww! No! Mommy!").
john curl said:
Yes. Which is why I've so far spent over $50 of my own money on cables and postage so that you and Bruno can have the same cables to measure.
I implicitly trust no one and have always kept open the possibility that Bruno is being dishonest.
However I am more inclinded to trust the measurements made on a modern, reference standard measurement system known to be capable of measuring well below the levels you claim to be measuring.
Your test system is suspect because if simple wires were as grossly nonlinear as your measurements indicate, not only is it difficult to believe that this behavior would have completely escaped the notice of the materials science research community, but it would render wire absolutely useless in applications where it's been working just fine for many decades.
se
About test equipment, can I use a simple THD analyzer like the HP 332A to null out the fundamentals and put this signal into a soundcard like the DAL CardDeLuxe togetherwith a good FFT software, is this a good measurement device?.
What I think is, it may be very simple to make a reference measurement that will go for all comming measurements or?
Just measure the nulling device with a good soundcard Card DeLuxe then you have a very good an cheap instrument.
If not! where is the fault, and can I do it with even cheaper nulling device and soundcards.
What I think is, it may be very simple to make a reference measurement that will go for all comming measurements or?
Just measure the nulling device with a good soundcard Card DeLuxe then you have a very good an cheap instrument.
If not! where is the fault, and can I do it with even cheaper nulling device and soundcards.
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