I'd like to offer my thanks and congratulations on one of the more interesting and entertaining cable threads I can remember. Not since the time of JD (Jade) have I felt as interested in cable.
The analysis reminds me a lot of the outstanding AudioQuest advertising copy from the 1980s. After going through all of their arguments, the choice seemed so apparent. It wasn't until I lived with AQ Midnight for a bit did I realize that despite all of the logic, the cable sounded surprisingly mediocre. Along with Carver amplifiers and Legacy speakers, AQ taught me the lesson of the dangers of drinking by the label when it comes to this hobby.
In the end, while I appreciate (more than you're going to believe) everything you've laid out, again I'm left disappointed as I read you wound up with Nordost. In my opinion, one of the most amusical and wrong sounding cables I've come across. Ah, high-end audio cabling... |
Trelja, you should have gotten the Audioquest Truth cables (ICs and digital cable, air dielectric). Absolutely fantastic in every way!
Cheers |
I like Jneutron's statement earlier that it is design that matters, not cost. A good mantra for any decision making process involving technology! |
It seems that this thread is going 300 or more directions!,thanks, jneutron,, regarless of the science here with audio cables,as I said,as an audiophile I buy what my ears tell me that sounds good!,LOL,this thread reminds me of a comedy on t.v. called the big bang theory! |
Jneutron
...First however, one clarification on a comment you made earlier, that a vacuum dielectric would have no capacitance. Totally wrong. Capacitance is proportional to epsilon free space times epsilon relative. For a vacuum, epsilon relative is 1, and epsilon free space is 8.854 times 10e-12 farads/meter. I DO NOT UNDERSTAND HOW AN ENGINEER COULD MAKE THIS MISTAKE....
Good, this is correct. Sometimes my head is in a vacuum...sometime not. That number is much higher than I would have expected, too.
...""I've stated that as well If you wish a general feel, the Belden website illustrates this for a general 75 ohm cable. For audio use, I recommend a value 2 to 6 times the hf value""..
I'd rather know what they are at audio, but they are of little use in a speaker cable circuit load which do not act like true transmission lines in the manner we use them. On one hand we want precision, and the other we don’t, it seems. I do agree this can get really hard to characterize, and sooner or later it is indeed precise enough.
...You need better sites. Just because it's on the internet doesn't mean it is correct...
Yes, the methods commonly used are correct, and verified in three places. But, you feel at lower frequencies, like impedance, differing assumptions are made. So there may be different methods, but the object is to determine exactly why, and to what degree the various methods are limiting performance. If the equations overlap, and there is no ideal wire small enough to be "perfect", than knowing approximately where to be on wire size is OK. Since we can’t make a perfect skin effect wire, at what point is one “good enough”? You comments, please.
""If this question is intended for me, you are barking up the wrong tree. What I speak of here is a very small subset of what I do for a living.""
Nope, I need not speak of people, I speak of principals only...so I did not intend the statement to be derogatory to anyone so much as getting the right information. Some feel God like in their presentations, some don't. Your posts aren't really about information they seem to be about you. I’ve said this before, the “push” (fill in your awesome ness) then “tell” (your story or throw your arrows) is not a sign of maturity or constructive advancement of the subject matter. I’m here for the subject matter and advancing the understanding for all involved. I haven’t figure out your purpose yet.
...Be nice, get nice. Be arrogant, get same...
Yes, I agree with that. But, I think some of this deservedly stuck to me with a little bouncing off me and sticking to you. True class keeps its class at all times. Yea, it's tough, I know. We do our best. Me, I'm fine with good information, being corrected and moving on. I don't use my knowledge to go hunting for those that don't without any real regards for the actual topic, just the hunt. Grow some civility with your posts and more will follow. You seem to be aware of this, so why not change it? Witness...
“…ps. are all posts on this site moderator approved, or is this a trial period for bad eggs like me?…
No, we love having you. What you say is good enough. We’ll make good use of your input and being respected for that should be a better feather in your cap than simply using the push tell prose (you guys stop me when I do it to…yes, you too Mapman!)to mash people.
OK, enough of that lets do something.
Your comment here Jneutron, …cable impedance changes at all frequencies based on the amount of real to imaginary components in the complex impedance. The RF return loss will vary significantly with each frequency point. The higher the imaginary component, the higher the reflection signal and the worse the signal transfer to the resistive load. The cable can be 75-ohms at all frequencies even (not likely!), but have differing reflection coefficients. Throw that into a speaker resistive load, and it gets messy for sure. Low frequency signal is a whole different world.
As low as the resistance is in 10 AWG speaker cable, arriving at an eight ohm load requires a good amount of "something" imaginary (most cables end up most capacitive) to create a complex impedance that high relative to the cable's very low resistive component. I don't see realistically consistently matching the speaker cable to the load by adding capacitance. True, some cable can be made to a specific length to “add” capacitance. Has anyone played with this? Not that it would be easy to do (cut up expensive cables) and or buy various lengths of cable).
With such LONG wavelengths, it seems odd to suggest reflections are from true wavelength load reflections. Yes, I hear you on measuring the reflections, but the load has to be taken into account, too. RF uses a resistor equal to the characteristic impedance. I’m still not convinced of how reflections allows us to convey this as a transmission line.
For power transfer, the speakers get mighty hot, the cables not so much. I’m not clear on exactly where you suggest all the energy is dissipated any why. Resistors absorb power, and the cable is not a good resistor. Audio is still a pretty slow AC signal not too far removed from DC. We want power on the load.
When the waves begins to approach the length of the cable used it is plausible to consider "reflections" as a transmission line. We aren't really close to that in audio. The cable isn’t alone in all this, the back EMF from the speaker is a hell of a circuit in itself.
When you “freeze” the circuit, it’s a static situation. The current and voltage can be examined in turn. AC voltage signals in a transmission line are “pulsing” in the line so to speak, at each frequency if the ideal transmission line acts like it should. But a speaker cable with LONG wavelengths into a speaker with low output impedance from an amplifier?
Trelja
No, I have one NORDOST cable as a reference. Trust me, it was much better than the alternatives. And, to "end up with" is a certainty no matter what we use, you included. Are you to be a poorer judge of cables if one is deemed better than yours is by someone? Many feel differently about NORDOST speaker cables (I don't have those). But enough on that, you'll have Jneutron on your case in no time. Tough love, but he is knowledgable.
Mapman
"I like Jneutron's statement earlier that it is design that matters, not cost. A good mantra for any decision making process involving technology"
No, that was I, go to the top of the thread..."DESIGN is first...." This was the purpose of the thread, to put design ahead of myth that is paid for.
And, my point was, and still is, to get audio cable out of the closet. Many are simply afraid of conflict, as that seems to be the general direction that "knowledge" tends to be going all of a sudden, and NOT to the real subject matter. WHAT are the major issues with audio cable design that can indeed be characterized by known principals?
I stated what is somewhat relevant, but the issue is to drill that down to a finer level so we can all better examine cable constructions for neutrality and possible performance.
I'd rather have half the knowledge and work towards a solution than all the knowledge and sit there with it. Jneutron, where are "our solutions" as you see them? What attributes do you look for?
This group should use each member’s input to help move the topics forward, not throw arrows or use indefensible arguments that can’t be analyzed when this thread is about just that. Believing is fine, but this is for the other half.
|
Rower30 wrote,
"This group should use each member’s input to help move the topics forward, not throw arrows or use indefensible arguments that can’t be analyzed when this thread is about just that. Believing is fine, but this is for the other half."
Ok, fair enough, but I'm getting a bad feeling this discussion is being limited to those who have trouble trusting their ears and rely on textbooks and Über Measurement Specialists to tell them what they should listen to. I was under the distinct impression advanced audiophiles had jettisoned such old fashioned notions back in the '80s. "Believing is fine." Yeah, right, as if audiophiles are religious heretics. As they say on The Shark Tank, I'm out.
"It's what I choose to believe." Dr. Elizabeth Shaw in the movie, Prometheus |
Go here;
http://www.audioholics.com/education/cables/debunking-the-myth-of-speaker-cable-resonance
In reality cables DO NOT resonate at all! The model represented here is single RLC lumped circuit for simplicity and is only accurate at audio frequencies for circuit analysis. A speaker cable is actually a distributed element and should be represented as infinite number of lumped RLC models. As an infinite number of lumped RLC circuits are modeled becoming its true distributed form factor, we see the resonance frequency go to infinity.
In addition, once we approach much higher frequencies such as in the RF region we must re-evaluate the cable as a transmission line. In that respect the characteristic impedance becomes the SQRT (L/C) =SQRT(8.8*10^-6/700*10^-12) = 112 ohms. So if our source and load terminations at transmission line frequencies (1/6th the wavelength) do not match, we see reflections in the line, which can appear like a resonance behavior, but in reality are simply reflections or power loss down the line.
Also note that when an exotic cable vendor claims Inductance, Capacitance and Resistance dramatically varies within the audio band, that this is more total and utter nonsense as can be seen in the following real world measurements...
As always, we welcome any cable vendor to furnish us proof of their claims, and cable samples for us to conduct our own testing for verification purposes. I agree, the FTC should be involved in this business, as it is a consumer product based on engineering truths that must not be ignored. - edited to remove vendors.
END
I don't know you everyone.
We look at 20KHz signal (lower than this is even more far fetched) that are far, far too long to properly conduct as a transmission line, add-in the fact that the load is not matched to the cable, and varies with frequency as does the cable too and you have a line model that is closer to your 110-volt wall outlet than your CATV outlet.
END
http://sound.westhost.com/cable-z.htm
In order to obtain a low characteristic impedance, it is necessary to have very low inductance and relatively high capacitance, and the high capacitance may impose serious constraints on the amplifier. Indeed, many amplifiers will become unstable if there is sufficient capacitance connected directly to the output, causing oscillation which may damage the amplifier. As described above, regardless of anything else, the cable does not act as a true transmission line at audio frequencies, and claims to the contrary are fallacious.
Matched impedances ensure maximum power transfer from source to load, and this is obviously very important for RF transmitters and telephony applications. It is completely irrelevant for a solid state audio power amplifier however, since the drive principle (known as voltage drive, or constant voltage) does not rely on maximum power transfer, but relies instead on the amplifier maintaining a low output impedance with respect to the load.
Even though most power amplifiers are limited to at most a few hundred kHz or so, there can still be some energy at higher frequencies - typically noise. What often happens is that an amp can be quite stable with a capacitive load and no signal, but as soon as it is driven it "excites" the whole system, and it then bursts into sustained oscillation.
At audio frequencies, speaker cables are not transmission lines. They are merely cables, with inductance, capacitance and resistance. Despite popular belief, they are bereft of any magical properties, only physics.
It is worth noting that a cable will never act as a true transmission line with a defined (and maintained) Zo unless its source and load impedances are equal to the line impedance. This means that no audio cable will ever be a transmission line, (almost) regardless of length, unless the amplifier output impedance, cable impedance and load impedance are all equal at all frequencies within the desired range. No known amplifier or loudspeaker system can meet these criteria. Alternatively, the cable may be infinitely long, however this is usually impractical in a domestic environment.
END
The above is pretty much what I've said all along. And will continue to say. Keep capacitance lower is better, and the cable is NOT a transmission line.
I do not agree that wire is wire to the extent that audioholics goes to. Make a cable with two large stranded conductors and one with multiple solid AWG strands of the same AWG (or just a different design) and the differences are definitely there.
I'd would indeed like to visit audioholics with the two types of cable and set-down and measure the cables and have them formulate the impact of the design on the sound through measurements. I haven't seen this done, so you can't deny that it could not be done. This would be tremendously informative.
I'm not going to hide behind "my" hearing and say XYZ exists (transmission-line effects) or any other "invisible" attribute. This is to properly define a good audio cable with realistic attributes everyone can enjoy.
The wealth of evidence is not in the favor of audio as a transmission line. |
You cite audioholics as a source???
That explains a lot.
Gene D's a nice guy. Some of the articles are pretty straitforward, even though I don't care for the style. I didn't even mind that he quotes some of my technical explanations in some of his articles. On occasion he'll ask me to write a technical article or two for him, but we've not gotten together on that. What I prefer to write is a tad over his target audience with respect to E/M theory, and he would rather have the debunking style.
But to use his site to debunk of what I'm discussing is funny. The last person to do that was trying to teach me skin effect from AH, and he was quoting me in an attempt to teach me my quotes....incorrectly btw. Hmm, you appear to be the second one..
You never answered my question. Are you an engineer, or did you learn skin effect on the web? I asked that seriously, because you had no clue as to what I was speaking of with respect to skin effect and Bessels. You still do not know that the exponential equation is based on normal e/m waves at a conductive boundary, and it is inadequate for audio frequencies and audio size wires.
Rod Elliot's also a nice guy. But he's still not an E/M guru, nor does he have a good handle on EMC theory.
As I said, you need better resources. I mentioned a few, but you could just ask. Do you really believe that websites like that are sources for E/M theory??
As to your belief that cables cannot be transmission lines. Silly and inaccurate. Get a reflection bridge and see for yourself. Cyril Bateman did..
You have a lot to learn.
jn
|
Some have asked about ZOBEL networks as we've moved along. Here is a good analysis of what they can do for you;
http://sound.westhost.com/cable-z.htm
Granted, we don't have a true transmission line with a speaker cable since output, cable and load impedances aren't ever matched and the line is too short, but as Jneutron pointed out, there are termination reflections based on cable length. A Zobel network can remove them WHEN you know the "impedance" of your speaker cable. The article doesn't state the frequency of the cable impedance calculation, which is varying with frequency pretty badly. The objective is more for amplifier stability than cable "sound" per say. Still, some amps may benefit from Zobel networks. Those that want to try one, here is a good place to start.
You need to use the right quality / type parts, and depending on your amplifier, you could get tertiary benefits. Long cable low cap or short higher cap cables are more likely to see enhanced your amplifiers performance with a speaker end Zobel network.
Jneutron, where should user's of Zobel networks calculate the impedance? What do you use when you suggest cable "impedance"? |
Rower,
A simple followup.
Your first post to me included your words.."""information is power. get some.""
You are arrogant without foundation to be so.
I provided actual engineering on skin and cables, most taken directly from UNDERGRADUATE engineering E/M texts.
You "counter" with non peer reviewed content from audio hobbyist websites.
Your technical discussion attempts appear to be cut and pastes from online sources, mainly the same audio hobbyist websites, and how you meld them together tends to be both inconsistent and inaccurate, as though you do not have a real understanding of the topic..
Your attempt at diverting the discussion into one of ego has been seen before.
Like this gem...
Stated by rower::
But, I think some of this deservedly stuck to me with a little bouncing off me and sticking to you. True class keeps its class at all times. Yea, it's tough, I know. We do our best. Me, I'm fine with good information, being corrected and moving on. I don't use my knowledge to go hunting for those that don't without any real regards for the actual topic, just the hunt. Grow some civility with your posts and more will follow. You seem to be aware of this, so why not change it? Witness...
end of quote..
How old are you??? Bounce off me stick to you??? Stick to topic and please post more like an adult.
Enough of the unpleasantries, perhaps that chapter can be left behind? Your call.
1. Skin effect within a wire is NOT correctly calculated via the exponentional equation in the audio bandwidth. Skin effect is not as pronounced as the exponential equation describes. That is because the exponential equation assumes the energy is an E/M wave impinging on hte conductive material, NOT being generated by internal currents. You clearly have a problem understanding this. Do us all a favor, E-mail the owners of the sources you are quoting from , Rod Elliot the owner of sound.westhost, or Gene Delasalle, owner of Audioholics...give them verbatim everything I've stated on skin effect, ask them if I am correct. Both will either agree with what I've stated, or they will go to their trusted sources to ask what the story is. In which case, I might get some e-mails. I haven't been in contact with Rod in years, last time we discussed techniques for measuring doppler distortion in speakers, maybe 8 years ago... Gene, I discussed some article possibilities a few months ago.
2. Cables as t-lines at audio frequencies. Here, I guarantee both of your audio hobbyist website "sources" WILL have to contact higher level technical resources. There are only two sources on this planet I am aware of that understand this and have MEASURED, modelled, and quantified it cleanly. Cyril Bateman, and myself. (there may be more, I am not aware of them). Cyril wrote a really nice but unfortunatly extremely technical article which goes over the heads of most people. I am using this understanding to better a work project. Repeat, actual hardware.
I shudder at making this post so long, but the delays are incomprehensible to me...
Rower Quote/question:
I'd rather have half the knowledge and work towards a solution than all the knowledge and sit there with it. Jneutron, where are "our solutions" as you see them? What attributes do you look for?
End of quote.
Another slap upside the head. And you wonder why you have problems with someone of higher technical proficiency??
I stated that rather clearly before, go back and read. Human ITD discernment is 1.5 uSec interchannel max. Any effect which is in excess of that threshold cannot be discounted as inaudible. When the line/load mismatch is such that current group delay exceeds that threshold in the mid audio band where our undithered loclaization capability is strongest, method to reduce that delay are required.
Rower quote/question::
Jneutron, where should user's of Zobel networks calculate the impedance? What do you use when you suggest cable "impedance"?
End of quote..
I already stated that, you either missed it or did not understand it.
When a t-line is terminated by a load which matches the line, the amplifier DOES NOT SEE A CAPACITANCE. It sees a resistance. That is INDEPENDENT of the characteristic impedance of the cable. If you run a 5.77 ohm cable with 300 pf per foot and 10 nH per foot, into a 5.77 ohm load, the amplifier sees NO CAPACITANCE. NONE. You need to understand this.
When the load becomes higher impedance at higher frequencies, THEN the amplifier will see capacitance. It is a consequence of the line to load mismatch, NOT a consequence of the cable per foot capacitance in isolation.
When the load "unloads" at higher frequencies which are BELOW the amplifier's open loop unity gain bandwidth, the phase margin lowers and the system will be marginally or entirely unstable. A zobel is used to load the line at frequencies the speaker will unload at.
At audio frequencies, if you wish to know what the amplifier "sees" given the line impedance and the load impedance, just calculate the energy stored in the cable.
When line equals load, the inductive and capacitive energy storage will be equal, and it will be a minima. The amplifier will see a resistor.
When the line is much higher than the load, inductive energy storage will dominate.
When the line is much lower than the load, capacitive energy storage will dominate.
And, regardless of the ratio, all energy that is stored in the inductance and capacitance will make it to the load. I know full well where you get this dissipation schtick wit respect to capacitance and inductance, I've seen that site. AND IT"S WRONG. Both storage mechanisms introduce phase lag, not dissipation.
My post consists of technical theory and practice within the disciplines of E/M physics, amplifier design, and human localization. You would be better served asking questions on entities you either lack understanding of, or have a different opinion. Using audio hobbyist website content as technical argument material has it's limits.
Needless to say, you spouting t-line approximations which were taught for the RF guys is a waste of time. You do understand that it is taught that way so that we can use smith charts, right?
Geoff, you crack me up. btw, you never answered my question..how have you been? I hope all is well with you.
jn |
Jneutron
You seem to be a little too easy to get upset about some things so it's going to be hard to please you. I'll do my best.
Zero capacitance? Sure, my perfect conductor example was just that. You can't do anything in that cables example let alone the capacitance. Not sure why you got so excited about it. Yes, a dielectric constant of 1.0 is a give away to the fact that capacitance can't be zero in THIS world, but I wasn't limiting the perfection to the real world but the "perfect" world where things do go infinitely fast, have no resistance, ETC. I see no sense in making a "perfect" wire half-in one world and then the other. So, I put it all in ONE world.
And yes, you're right, I do not have a source for very low frequency skin effect. Nor does it seem anyone else! As long as the numbers are "close" and you use a wire size that is smaller than the calculation, and use the number of wire to meet DCR things should get into the reasonable range.
As far as transmission line effects well, the source impedance sure is small at less than 0.05-ohms on average of an amplifier's output stage. The cable impedance is small (looking at the real component of the cable) compared to the speaker's varying input impedance so it is hard to imagine the speaker cable as a classic transmission line (matched source, line and load impedance’s). Not to mention the wavelength are WAY long to even begin to couple between the source and the load. A reflection bridge certainly can show reflections but to say this is a transmission line?
If I shove my amplifier up to the speaker terminals where is all the power dissipation going? the speaker. If I stick a cable in there, the power is still going almost all into the speaker and not the cable. The L and C energy eventually goes into the load but is lagging one way or the other. Probably not a good thing.
True, the "impedance" of the cable can be complex in nature and a higher vector magnitude per low frequency equations (mostly capacitive, as the resistive load value is so small in the cable). But at such a low frequency it's really hard to see this as a transmission line, or impedance values near the speakers input impedance.
How do we negate the effects of the LONG wavelengths relative to the line length at audio? Even worse, go lower than 20KHz.
I'm all ears on your low frequency transmission line model (pun intended)and impedance matching. The Z=SQRT(L/C) is only good above 1 MHz.
The ability to design to metrics that are repeatable would be a great benefit to designers who want to use the best of what's really capable in design without "faith" based engineering. But, I'd rather try to do the right thing with a few bumps in the road than do the wrong thing perfectly. Too little risk can limit the outcome as bad as anything else. Yes, we lose a few that insist on only what they perceive and hear. That's fine, but for right now I want to concentrate on the "knowns" (yes, even the one's I don't know!) to look for in a nice, and reasonable, cable. Design elements that are always beneficial to sound.
Bridges go up and fall down, space shuttles go up and explode... all these things have "experts" at the wheel and still failed. People may be experts, but the ones that do their jobs can overreach even their understanding(s).
So, as far as being the second one, I sure didn't know I was competing with the first. Sorry about that. If I only stick with what I know today, what benefits do I achieve tomorrow?
Looking at cable, you can't see a common design thread across the lot of them that indicates forward thinking to a known set of conditions. I can even see a few, not hundreds, of designs for a specific set of amp (SS or VALVE)/speaker (dynamic or electrostatic) combinations.
I listen to cable with the same R, L and C and am amazed at how different they sound. I am not even close to shutting down my ears. That’s what got me in this mess! How do you recognize correctly made audio speaker cables.
I did look back at some of your post so as NOT to pester you, and yes, the main things my ears hear is much improved openness, imaging stability, precise location of the image and debth in good speaker cords.
I can't say I grasp speaker cable impedance at such low frequencies as they "rise" as the frequency drops, making consistent low impedances at audio seem implausible, at least to my way of thinking about the measurements. My guess is if you look at the cable like a T-line, the impedance is the same at any cable length. Of course, the low pass nature of the cable changes too.
With your respone Jneutron, I close comments in this post. I've bugged you all enough. |
Jneutron, oops, did not mean to blow off your question, I have been assembling a new headphone system. For insurance I had the ICs and power cords broken in on the latest AudioDharma Cable Cooker and also sent them off to the cryo lab, figuring better safe than sorry. :-). I'm using small 1" tempered steel springs and heavy masses for isolation of modded Oppo 103 and hybrid tube headphone amp. |
Rower,
You said:
You seem to be a little too easy to get upset about some things so it's going to be hard to please you. I'll do my best.
My response:
Nothing could be further from the truth. Your statement is a diversionary tactic being used in an attempt to push blame on others rather than admit to your own arrogance. It is a common enough tactic, many people use it.
You said:
Zero capacitance? Sure, my perfect conductor example was just that.
My response:
NO, you stated that when the insulation is a vacuum, there is no capacitance.
Here, I'll refresh your memory...you said this exact thing on 3/15/2013:
4.0 The dielectric would be a vacuum so we have ZERO capacitance and velocity would be 100%.
My response to that was No, a vacuum dielectric does not have zero capacitance.
In addition, I provided the free space permittivity number, 8.854 times 10 to the MINUS 12 farads/meter.
You then stated :
That number is much higher than I would have expected, too.
My response...
Your kidding, right? I provide a physical constant, free space permittivity, and you say it's higher than you expected??? This physical constant is taught to ALL physicists and engineers, as well as in every AP physics course in high school I've become familiar with. It is needed to calculate capacitance. You've never seen it before, have you.
It is also "odd" that someone would thing that the number .000000000008854 is "larger than expected"..
This statement of yours is a very clear indication:
3.0 Carries energy in BOTH directions at the exact same time. Umm...this is a short circuit in reality.
My response:
WHAT???? A SHORT CIRCUIT????
YOU ARE ABSOLUTELY CLUELESS WHEN IT COMES TO TRANSMISSION LINE THEORY, FREE SPACE WAVE PROPAGATION, AND EVEN SIGNALS TRAVELLING THROUGH INDIVIDUAL CONDUCTORS.
Pay attention.
There are many websites out there which explain transmission lines and signal propagation. Find them and learn from them.
You stated:
I can't say I grasp speaker cable impedance at such low frequencies as they "rise" as the frequency drops, making consistent low impedances at audio seem implausible, at least to my way of thinking about the measurements. My guess is if you look at the cable like a T-line, the impedance is the same at any cable length. Of course, the low pass nature of the cable changes too.
My response:
I CAN say I grasp cable impedance. I can say I understand real skin effect. I can say I understand transmission line theory. The reason:
I am an EE. I do this for a living. I've done so for 35 years now. And I do it at a level which unfortunately, makes my resume incomprehensible to almost all EE's at the ScB level, most at the masters.
I am more than happy to share my understandings on the web so that others may learn.
I am not so happy when wannabe "engineers" attempt to use arrogance, belittlement, hobbyist website content, and rambling incoherent prose disguised as "technical speak" to badger others. Your type of "engineering" is one of the primary reasons cables and cable discussions are stuck in a quagmire.
I have provided valid reasons why cables can sound different, speakers, IC's, as well as power cords. Not that they all do, but rather, the physics processes which do impact the electrical function at some level.
That stated, if you wish to discuss actual technical things and how they can alter sound, fine. I've no problem with that. But you have to drop the shtick, it's old, it's worn, and you can't support the technical arguments.
jn |
2 gurus -> 2 directions.
A limited sample no doubt but extrapolate anyway and why there might be 300 becomes clear.
And that only includes people who might actually know something about this being in scope.
Just stick some flying saucers on the windows and be done with it. :^) |
Jimmy/Rower, can either of you explain to me why the fairly unique minimalist designed DNM Reson analog stereo phono plug ICs that I use and like in so many ways sound as clean coherent and lively as they do? They essentially look like old style 300 ohm antenna wires but use a small gauge single strand wire. The simplicity of the design attracted me initially and I have been very impressed ever since.
Do think this is a sound design approach?
Thanks. |
Mapman,
Yah, they do look like the old style antenna wires...
That configuration will increase inductance and lower capacitance. Low C is always liked by the audio guys.
This also increases the characteristic impedance of the cables as well. Phono ins are 45K give or take, amp ins run 10k give or take. That style certainly is closer to the load impedance than normal coax (50-75) or twisted pairs (100-150).
There are a few ways to skin the cat so to speak.
Shielding as per coax protects the higher impedance inputs from stray E fields, that cable doesn't.
Twisted pairs is not as good for E field, but is better for magfield protection.
Parallel such as that is worst case for both in terms of shielding.
You've traded off noise and hum protection to gain in capacitance and impedance.
But honestly, if you have no noise or hum issues, that is great..Tain't broken, don't fix it.
All IC's can suffer loop induced hum and noise incursion from external magfields, but you seem very happy.
Is it a sound design approach? Yes, it certainly is. If you had noise or hum issues, it would not be the best design approach for your system.
ps. AS a general rule, if a circuit is lower than 377 ohms impedance, it is sensitive to inductance and time varying magnetic fields. If the circuit is over 377 ohms, it is more sensitive to capacitance and time varying electric fields.
It is also important to consider the level of the signals in the circuits as well. Speaker runs will be inductance sensitive to a point, but external magnetic fields can't really compete with 100 or 1000 watts of power.
jn |
Geoff,
You mentioned tempered springs. Do you get involved in the tempering at all? I ask because antique clock mainsprings tend to lose their strength over time, and I suspect that I may be able to re-temper them after opening them up again, perhaps oil or maybe water quench. I was wondering if you've had any experience in that.
And, you did indeed blow off the question again. I wasn't asking about your work....I was asking about you.
John |
"You've traded off noise and hum protection to gain in capacitance and impedance. "
Actually, I did have noise/hum issues from external EM fields with low level phono step up transformer device itself. I put that device (with DNM ICs running from it to phono input) inside a makeshift mu metal container to address that. I have not had need to use my alternate MIT ICs, which are shielded and have that advantage.
DNM resons are fantastic all around performers I have found in practice and my preferred ICs. Coherency and detail top to bottom are their best traits. The minimalist design seems to work well and keep things affordable to-boot. Your assessment would seem to be in accordance with what I have observed/heard FWIW. |
Jneutron wrote,
"Geoff, You mentioned tempered springs. Do you get involved in the tempering at all? I ask because antique clock mainsprings tend to lose their strength over time, and I suspect that I may be able to re-temper them after opening them up again, perhaps oil or maybe water quench. I was wondering if you've had any experience in that."
I have about 15 years of experience with cryo labs and used to cryo my springs six or seven years ago when I used larger springs, that were already hot oil tempered; these days my springs come heat tempered. The high carbon steel springs I use now don't loose their strength or stiffness over time. I have cryo'd all sorts of things over the years, most recently my interconnects and power cords plus CDs.
"And, you did indeed blow off the question again. I wasn't asking about your work....I was asking about you."
I have been doing pretty well, you know, considering the recession and everything. My last real job was in the FAA office of safety doing risk analysis for some big technical programs. Ocassionally i think maybe I'll go back to work but so far I have managed to avoid it.
Geoff |
@ jneutron,your post to mapman 3-26-13 was very informative and well said,I can see benefits of post such as that!,Hi mapman!,when you use the knowledge you have to help others,I am thumbs up!cheers! |
Just read this thread and love what I can glean off of it.
When it comes to cable design there hasn't been a better time I've had trying to follow but from what I understand, not all cables sound the same.
Gee....go figure?
All the best,
Nonoise |
Geoff,
You've made me laugh now. I've only been considering heat tempering/quenching for antique clock springs, and am preparing to purchase firebrick to be able to cherry red springs about 6 inches dia un-sprung for oil/water quench. Believe it or not, I never considered LN2 post processing. Go figure.
I'll have to do more research on the spring materials, as I don't know if they have a martensitic finish temperature, or where it is, or carbon content either (most do rust). The application really frowns on microscopic cracking as that is a typical failure mode, but you've now got me thinking. Still, it's gonna take some research specific to re-working spring steel that's more than a hundred years old.
Personally for me, the funding stream is scary stuff. Luckily, the big project I'm working on is through 2016, and the smaller more esoteric ones go past 2020. But hey, the angst never goes away.
The vibration stuff I mentioned to you years ago went well, we used all kinds of piezo's, geophones, lasers, and some active tables for measurement and cancellation. It's amazing seeing voices cause measureable vibrations as seen on a scope on a 15 ton granite table.
jn |
Jneutron, as you probably already know, cryo is used for many metal items like high performance pistons, engine blocks, golf clubs, razor blades, all manner of tools, etc. I used to cryo my brass rods for my sub-Hertz iso platform as well as all the metal fittings, figuring better safe than sorry. One of my fav isolation techniques are what LIGO uses in the search for gravity waves, which (at one time) included single crystal sapphire thread suspensions for optical elements, Multi-stage monsters than employ heavy masses on springs, not to mention active components.
Yes, I know what you mean about angst on the job, we used to call it the night of the long knives when the rumors about cuts started circulating. Lol |
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