That was on the list of suggested readings on manufacturing technologies for some ET L3 exams 25 years ago.
I read it again. Tears as Scott said, thanks!
It’s all about deciding on which specs are relevant to the task, choosing the lowest accepted levels, settling on relevant standards and adhering to them through strict manufacturing quality control .
The adopted -or allowed- method of quality control and the number of control points affect the cost of a product a lot.
Count the inspection stamps on the certificate that accompanies a spool of wire for aerospace use (or of any component for aerospace use), understand what lies behind each stamp and you will understand that it’s astronomical price is justified.
There are a few critical technical sectors that demanding though.
I do not imply that audio is one of them.
George.
I agree 100%.
Strange though that you dismiss ears only testing with 1 variable. Do you really believe this statement?
1 I would like to see those measurements.
2 Audibility is the only thing that matters. Where are those results? I haven't seen them, but if I see credible results from ears only 1 variable tests, I will shout it to the world.
Directivity of cables ought to show up as assymetric distortion of AC signals, so it shouldn't be too difficult to prove it exists, if it would, but it doesn't with the equipment presently available.
In other words, untill the state of the art of equipment connected by cables improves to the point where we can see this distortion, I for one will be chill with what we have.
In other words, untill the state of the art of equipment connected by cables improves to the point where we can see this distortion, I for one will be chill with what we have.
Actually, Scott, I did read Bob Cordell's book on audio amplifiers. I've said so before and I repeat, I find that book to be an excellent effort well worth the time and trouble and amust for anyone wanting to do it.
The fact that Bob Cordell has his views which may differ from mine is of no consequence to me. The fact that Bob may not agree with Otala's findings from 1973 is again of no consequence to me.
What really bothers me is the way opposition is presented, not the fact that it exists. We seem to completely overlook the fact that Otala's findings came way before almost everyone who seems hell bent to prove him wrong.
I do not understand why is it so improtant to some that Otala be wrong.
I do not understand how they don't see, or rather don't want to see, that many years have passed in between, and that we have learnt quite a lot over that time, so it's only natural that as we know more, we re-evaluate what we thought we knew before. To me, that's natural evolution of any line of thought.
I do not understand why people like yourself, who as you said were concerned with things like slew rates 5 or 6 ears before Otala ever uttered a word about it and I have a feeling now in retrospect feel hurt that he discovered something they knew about but said nothing.
I do not understand why, if the knowledge or awareness if you like was there, NOBODY made an amp like Otala and Lohstroh did and demonstrated that knowledge in practice. And that was a tremendous leap, believe me, I made it in 1975 and foolishly sold it off in 1980. At the time, I know of nothing that could better it, however, there were some merobale models from that age, and believe it or not, most emplyed some of his principles, albeit in modified form.
I do not understand why people talk in absolutes. Otala was wrong, or at best not quite right, period. It's NOT reasonable to expect someone starting up a new line of thought to get it all right in just one go, for all time. Rather, it's to be expected that his theories will be examined, evolved and modified, his work was not the end, but only the beginning.
I understand that part of the blame for this unholy state of affairs also lies with the equally blind followers of Otala/Lohtroh. I remember only too well the fedayeen who preached that we have the problem licked and thaat was all we would ever need, an approach so foolish it doesn't really merit a serious answer. No single achievement is so complete, so encompassing that it will stand forever, excpet of course for the underlying basic principles, like Ohm's Law.
Division breeds strife, unity may breed true progress. Instead of proving anyone wrong, it would be better to offer constructive critcism. In his book, Bob Cordell has, in fact, embraced quite a e few of Otala's principles, such as wide bandwidth, carful judgement of the Miller compensation, and so forth.
My own rationale for embracing Otala's basic principles is twofold. On the one hand, I see companies like Harman/Kardon who adopted them, but didn't stop there, instead the went on to further develop them. And they must be doing something rigth, because they keep growing and their models tend to get better over time. I should know, I own their products spanning a period of some 10 years or so, and cover the ground from the very much standard fare to their best commercial efforts of the day.
As a matter of fact, their 6550 integrated amp is the best nominally 50WRMS amp I have ever heard from anyobody so far, after just one little modification, their junk quality volume pot was replaced by an ALPS Blue. Obviously, I haven't heard all there is out there to hear, so I stress - which I've ever heard. On the other hand, locally, that's the most popular class of integrated amps ever, so I did hear a hell of a lot.
The second reason is my own limited experience. Obviously, I don't design a new amp every week, over the years I have managed a total of just 3 "models" (for my own use, not commercial). I also embraced Otala's general principles as noted in his 1973 IEEE text, but not taken blindly, rather every now unit had modifications done to it which were intended to make it better still. The point being, that no matter how they turned out overall in the end, they always did a better job of playing music than similarily made commercial units of comparable power output. And they always made me feel that I could have done better.
That's all there is to it. So long as following Otala and Lohstroh's design cues I get a better sound, I will follow them.
Interesting that we've moved into cable thrashing territory,. I have only a tiny interest in such matters, and that is only in the sense that aspects of the construction and positioning can be an influence - I can easily go from totally obnoxious quality, to fully convincing reproduction without worrying about any of this, so it's well down on my list of "worries" ...
Its not cable thrashing, all electrical systems require cabling of some sort, be it a plane, train, or automobile (or a LDC, a server room the list is endless). Its the esoteric beliefs and magic that is attached to cables that is being questioned...not thrashed.
Metal grain structure and its effects are studied, not just in cables but for PCBs, especially now designs will often have areas working into the GHz range.
here are a couple of links there are many more, including research into signal propagation, current carrying ability etc. not a lot on directivity though!
http://web.mst.edu/~marinak/files/My_publications/Papers/S_Hinaga-IPC2009_Formatted.pdf
http://www.hkpca.org/uploadfileMgnt/0_2013418103354.pdf
Exactly. Cables exist and we need them, period.
What we don't need are hordes of voodoo priests, shamans and other junkies polluting our space with tales of mystery and imagination.
regarding cable directivity in relation to signals...the only place I have ever heard of it is on Audio based sites and cable manufacturers marketing...never heard it discussed (apart from with scorn) anywhere else, one wonders why this is, is audio so cutting edge
Whilst not supporting the directionality debate I think it is not a selling feature of cables. In fact some say not being directional is the quality good cables have. A suggestion I read that might make sense is that the way cables are pulled through dies and the way that abuts the dielectric might be the cause ( electrostatic I presume ). A Harwell scientist told me new cables have charges which take forever to discharge. He was criticized by the semi scientific accountants at Harwell for buying expensive cables ( not audio ). He said he was pulling his hair out to say the standard cables affects measurements at 10 -6 ampere and the effects he wanted at 10 - 9.
The cable I gave a link to I always have the writing from source to receive. That's nothing to do with anything except my hyper symmetry obsession. When I make some for friends I always say try it that way to reassure them. To reassure you all I never checked it myself. One friend said on the whole he agreed with my way. He ended up the opposite way as it sounds less bright!!!! You know there is a 1% chance he is right and what did it cost? I will add this to the mix. I suspect it is 1% right and I suspect I can hear it. More to the point for reasons I don't pretend to know cables do improve with use. Maybe Dr Smiths residual charges? Knowing how almost nothing will discharge a LP record I don't doubt that wire at speed in a processing plant could cause a charge. Nordost say gasses also build up. Some might be other than inert? I have to say most audio friends will be very unhappy not to have this direction pointed out. It is interesting to observe that those who pay the piper get the greatest criticism by implication of who demands this ( the customer is as guilty as the Piper in what is said and bought). The cable industry is male jewelry and not a lot to do with anything else. My cables I described yesterday will eat most for breakfast due to how well made they are and how they solder. I bet almost anything no one builds any?
What I liked most about my cables is they brake the dielectric rule in using PVC. I suspect if it can exist they do sound good. Sweet , open and neutral. That quality DAC's never quite manage. Now logically a cable should out perform a DAC. Some give me doubts. Many op amps are no worse when buffers. I have a very daft theory as to why. Small and the neoprene outer is very well damped. A joy to work with.
One last point. Most audiophiles cable do have a sound. Many have a bad sound. My reasoning is the further from 1950's RCA in construction you get the more bloated the sound. It's not a marked effect. Marked enough that mine are better. I have been wrong about this many times so each make on it's merit. For what it is worth tubular RCA are my favourite. The dreadful looking ones are not far from perfect. SME ones are the posh version.
One thing I do on cheap CD players is use the Rean RCA sockets. Looks good and allows a good fit with the connectors. If wired with very cheap cable inside I usually leave it alone as my DAC observation is the king pin.
One thing to add. If an RCA is made up in Belden form with the twisted pair inner and shield to one end that cable should be directional ( Mission 774 arm was where I first saw it ). This type of cable was highly recommended when this debate kicked off. The direction is one earthing point will be better . That is amp chassis or CD player chassis. Amp one presumes? Douglas Self says how a capacitor might be added at one end to give better RF anchorage ( 10 nF ? ) .
If anyone here said blandly that directionality is false this might be the example of when that advice would be very poor. Who is to say that many are not Belden? Not all companies say.
If anyone here said blandly that directionality is false this might be the example of when that advice would be very poor. Who is to say that many are not Belden? Not all companies say.
A cable more than any other part of a system should have NO effect on the signal, they are not filters, they are not active devices, they are a means of getting a signal from a to b with absolutely minimum effect on that signal.
If a cable 'has a sound' ie is altering the signal so that it is noticeable it is defective.
If a cable 'has a sound' ie is altering the signal so that it is noticeable it is defective.
Marce. My last statement can not support that. Many audio problems are as Robin at Naim Audio said to me. " We have no idea where 0 volts is on the Naim concept. We think it is a few feet up one of the cables ". Doubtless you will say that's them getting it wrong. It is a wrongness that was more right than most. Robin was just being honest and a touch mysterious. I knew exactly what he meant having tried to find 0 volt null points. Naim was a single ended PSU for preamp's so not quite the modern norm. Douglas Self gives sage advice on this and says induction more complex than many guess. I must say one never gets to what Douglas suggests. He gives examples of how ideal earthing solved distortion problems due to slightly wrong choices. If only it were that simple. My Dead Bug preference and using an oscilloscope is to be recommended if any of this is pricking the imagination. Hence I build very low distortion amps with almost no parts in them. I then spend weeks bending wires and trying new earth points. Usually 90% is a waste of time . 10 % is often excellent. On Tube Cad he describes bootstrapping the anode to the cathode in an SE amp to null some ripple. That's what I call engineering. I am sorry to say I was too stupid to see that one. And 99% of others also.
It should be obvious to everyone that a cable made up asymmetrically (e.g. with the shield grounded at one end only) may show 'directionality'. It ought to be equally obvious to everyone that a symmetric cable cannot show directionality. If there is a change in characteristics along the cable (e.g. conductor size, insulator permittivity) then the lack of symmetry may show some effect at a sufficiently high frequency that the cable length is significant with respect to the wavelength i.e. RF, not audio. Note that unless deliberate such a cable should be regarded as faulty. Same for a cable which includes a diode - but that would not be directional for AC, merely distorting.
Therefore any reports of cable directionality at audio frequencies are either false, or based on some accidental or deliberate asymmetry (almost certainly in the connectors, not the bare cable).
What would you need to make a genuine 'directional' audio cable? You would need to use materials (conductors and/or insulators) whose properties are affected by both (very small) electric and magnetic fields. Only in this way could you sense the direction of the signal, which is a prerequisite to directionality. As far as I am aware nobody makes audio cables like this. However, I suppose it is possible that some esoteric materials used in some 'audiophile' cables may be sufficiently inappropriate for the task that directionality could be accidentally introduced. This must be regarded as a fault in design or manufacture.
Therefore any reports of cable directionality at audio frequencies are either false, or based on some accidental or deliberate asymmetry (almost certainly in the connectors, not the bare cable).
What would you need to make a genuine 'directional' audio cable? You would need to use materials (conductors and/or insulators) whose properties are affected by both (very small) electric and magnetic fields. Only in this way could you sense the direction of the signal, which is a prerequisite to directionality. As far as I am aware nobody makes audio cables like this. However, I suppose it is possible that some esoteric materials used in some 'audiophile' cables may be sufficiently inappropriate for the task that directionality could be accidentally introduced. This must be regarded as a fault in design or manufacture.
I am talking specifically about a piece of wire used to join two components together, not internal wiring, just a plain old interconnect, in every industry (bar audio it seems) this is a wire to get signal from a to b with the maximum signal integrity and the minimum EMC problems, nothing else, if it changes the signal so much that it is noticeable then it is incorrectly engineered for its role, or the equipment it connects has some design issue.
That is the sole function of a cable....
That is the sole function of a cable....
I think to say it might matter is good enough. I have just been signing off some new choke designs today. It has been agony as they will cost £10 000 for a very marginal DCR improvement to make a batch ( overall cost is good ). Creapage distances my big problem. By asking very nicely I have some bespoke cores to my preference. We will get 20% better inductance and 80% DCR . The overall cost rising 7%. Talking about my boss Graham said he as a scientist couldn't agree with what my boss said. He and I get on OK as we only ever talk standard stuff. I said this " if you took my boss and measured his sincerity against all the religious people of the world he would be in gold medal position". Graham agreed with that. I said he is an alchemist and the wine industry has them also. It was a chance remark to my boss about this which set the ball in motion. I said DCR and if you like the bells at Las Vagus went off. Years ago I taught him about this and now it is the alchemists creed ( quite right too).
My boss paid for a Japanese company to restart the POCC production. They had been very difficult and wanted plenty of money to think about it. I had no idea this was being done. Having used the product myself it is delightful to solder. As said before the better copper solders so well. That is even when the OK copper has been cleaned. The POCC as far as I know will outperform silver. It is such a minefield . As I said before my 20 cents cable is almost perfect. I need the truly perfect around to have that opinion. For some daft reason the cheap one is truly what it claims. It is even UK produced!!! I no more than anyone worry about this too much. What I will say is perfection can be had for peanuts if you know what perfection is. I suspect 90 % of OFC isn't. It doesn't solder well. How are we to know? It could be it gets contaminate by lubricating oils or whatever. What I object to is dogmatic rejection of a no cost solution. I note dogmatic people in history are usually wrong. Most don't live long enough to find out. What I like is someone saying" as best as we know". Is it a lack of confidence which makes people need to appear confident ? Myself I am open minded until my life depends on it. I then side with dogma as I also lack confidence.
I never have to go outside of well understood principles of mostly 1850 to make a new product. My boss will not think that way. I guess if we talk the scientist at Chateau Rothschild I am he. The boss will speak of the nose and whatever. The scientist the complex chemistry. I bet you anything the scientist is the make or brake person these days?
As to being dogmatic. I notice evolution , Big bang and the forming of the Earth is always taught as fact. None of these are facts. They are best hypothesis. " and the Earth and Moon were formed when a large planet hit Earth". My goodness that's extreme. As best we know.
I was told all the bones that say how Humans evolved from Apes would fill a large dinner table. That is a span of 2 million years. I was asked if it was good science? I said not in my book. It is interesting and must have a high degree of truth in it.
My boss paid for a Japanese company to restart the POCC production. They had been very difficult and wanted plenty of money to think about it. I had no idea this was being done. Having used the product myself it is delightful to solder. As said before the better copper solders so well. That is even when the OK copper has been cleaned. The POCC as far as I know will outperform silver. It is such a minefield . As I said before my 20 cents cable is almost perfect. I need the truly perfect around to have that opinion. For some daft reason the cheap one is truly what it claims. It is even UK produced!!! I no more than anyone worry about this too much. What I will say is perfection can be had for peanuts if you know what perfection is. I suspect 90 % of OFC isn't. It doesn't solder well. How are we to know? It could be it gets contaminate by lubricating oils or whatever. What I object to is dogmatic rejection of a no cost solution. I note dogmatic people in history are usually wrong. Most don't live long enough to find out. What I like is someone saying" as best as we know". Is it a lack of confidence which makes people need to appear confident ? Myself I am open minded until my life depends on it. I then side with dogma as I also lack confidence.
I never have to go outside of well understood principles of mostly 1850 to make a new product. My boss will not think that way. I guess if we talk the scientist at Chateau Rothschild I am he. The boss will speak of the nose and whatever. The scientist the complex chemistry. I bet you anything the scientist is the make or brake person these days?
As to being dogmatic. I notice evolution , Big bang and the forming of the Earth is always taught as fact. None of these are facts. They are best hypothesis. " and the Earth and Moon were formed when a large planet hit Earth". My goodness that's extreme. As best we know.
I was told all the bones that say how Humans evolved from Apes would fill a large dinner table. That is a span of 2 million years. I was asked if it was good science? I said not in my book. It is interesting and must have a high degree of truth in it.
I wasn't even thinking about asymmetrical cables. Good to point that out as many seem to use such a configuration.
That sounds interesting - the sort of results I get at times could suggest some mechanism like that.
Frank . Dr Smith and I met when he said " do you have any interest in the Quad 405 ". He gave me the measurements of a perfectly balanced 405. Ron said Quad seemed to have used the 405 as a cheaper way to make an amp not any better than usual. The graphs showed about 20 to 30 dB improvement . This was using the Harwell gear I suspect? I asked the obvious " did it sound better " ? Big grin for Dr S " Oh yes ". I think he said the tolerance of the critical parts was no better than 1% and it needed to be 0.1%. I believe the tolerance was wider than he thought in the inductor.
Apparently the telling off over wire was very strongly put.
Apparently the telling off over wire was very strongly put.
That's right and is often differential rollers. When automated to the highest degree plastics are added as soon as possible to avoid contamination.
It is argued that the smaller gauges have been OFC since the 1930's . This is to allow the speed without snapping. True OFC is a slightly different animal and seems to have come from the aircraft industry. Along with going better through machinery OFC resists work hardening. The question to ask is this. A material that work hardens or less obviously is different. It implies a connection. To the extent it matters for production it might matter to us. The surface of drawn metals is said to have a herringbone patterned surface. The suggestion is the dielectric molds with the herringbone.
It is argued that the smaller gauges have been OFC since the 1930's . This is to allow the speed without snapping. True OFC is a slightly different animal and seems to have come from the aircraft industry. Along with going better through machinery OFC resists work hardening. The question to ask is this. A material that work hardens or less obviously is different. It implies a connection. To the extent it matters for production it might matter to us. The surface of drawn metals is said to have a herringbone patterned surface. The suggestion is the dielectric molds with the herringbone.
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