A pricey power cord

[k4kyv]

http://en.wikipedia.org/wiki/Oxygen-free_copper

I like the tubes in my radios to be of the oxygen free type. They normally work much better.  

 

Yeh, and that 1% increase in conductivity is going to have an "astounding" effect on sound quality when used in audio cables.

Conductivity is generally specified relative to the 1913 International Annealed Copper Standard of 58 MS/m. Advances in the refining process now yield OF and ETP copper that can meet or exceed 101% of this standard. (Ultra-pure copper has a conductivity of 58.65 MS/m, 102.75% IACS.) Note that OF and ETP coppers have identical conductivity requirements

[WA1GFZ]

When you have been throught a couple MIL-STD-704 power tests, A couple MIL-STD-461 EMI Tests and a few DO160 lightning qual tests.
Then you can appreciate how stupid most of this audio fool stuff sounds in the world of real science.

[WA2TTP Steve]

I wonder if cryogenically cooled audio circuits have been used by those with deep pockets?

I worked for Comteck Labs for a few years back in the early 70's working on cryogenically cooled parametric amplifier systems for satellite down link receivers. They were used on the commercial and military bands plus we made a few custom systems for radio telescope use at Ku band. It was always neat to watch the system noise level just fade away as it cooled down towards absolute zero, it got down to about 11-12 deg k and we ended up with noise figures of 13-14k deg with gains of about 40 db in three stages. At these temps electrical loses were nil and circuit noise was minimal.

The system used helium as a refrigerant and modified freon compressors. There was also a slow moving piston pump right up in the cold station where the amps were mounted. The cold station and amps were in thick stainless steel vacuum chamber about 15" high and 8" around.

These systems were used all over the world and were usually mounted at the feedpoint of dishes that were up to 300' in diameter.


Steve

[k4kyv]

I wonder if cryogenically cooled audio circuits have been used by those with deep pockets?

https://www.tubeworld.com/kuhltube.htm#

[WBear2GCR]

Fwiw cryo treatment of tubes has been around for some time now. Bill Pearl out on the west coast was one of the first to do it.

I have never tried cryo tubes myself so have no idea if it has any discernable effect at all - or how you would know if it did since tubes are all over the map in terms of noise and microphonics and curves.

Fwiw.

And all that...


                      _-_-bear

[W1RKW]

Thermal stress. Freeze the crap out of a tube then heat it up under normal service. Go from one extreme to the other.  That's good for the elements and seals.  Can you say 'premature crap out'.

[WA2TTP Steve]

I was thinking more along the lines of actually running the amp at cyro temps, at least the low level solid state stages, to reduce noise. I wouldn't want power bill for the compressor which runs full time in cyro apps.

Steve

[WBear2GCR]

One can get rather low noise in the front end of things like mic preamps and phono preamps, close the noise limit of a resistor by using low noise JFETs or bipolar transistors. I think it was the LM394(?) that was a massively paralleled set of transistors on a chip, very low noise.

So, thus far it hasn't seemed to be necessary to dunk ur components full time in a cryro tank.

But I could see the cold condensate and vapors sliding off this frozen mass of pipes down the end of some millionaire's listening room...

I could retire on that sale... any cryo experts here?

                    _-_-bear

[k4kyv]

That would open up new possibilities if room-temperature superconductivity is ever achieved. I believe some scientists have done serious research and even reported some positive results. Imagine zero resistance in cables and transformer windings!

As far as power cords go, the way I would test them out if I suspected a power cord was degrading the operation of a piece of equipment, having eliminated all other likely possibilities, would be to use a precision a.c. voltmeter and oscilloscope.  I would measure the voltage and look at the waveform of the mains voltage at the outlet, or preferably, at the entrance panel, and then take the same measurements at the terminals of the primary winding of the power transformer, then compare the two sets of readings with the device drawing maximum current, idling, and with the power switch turned off. Ideally, there should be no difference in any of the sets of readings, but most likely there will be some voltage drop in the house wiring between the panel and outlet, especially if other appliances are connected to the same line.  There should be no difference in readings at the outlet plug and transformer terminals.  The scope would reveal any noise on the line or irregularity in the a.c. sine wave. Maybe take another set of readings at the output of the power supply, using a good DVM set to DC voltage, and use a scope to check for ripple and noise.

If I found the power cord to have any detectable effect such as voltage sag and maybe noise caused by imperfect electrical contact, I would go to larger size conductors and better male and female outlet connectors, until I resolved the cause of the difference.  In any case, there is no reason to use any larger wire size in the power cord than what is used in the house wiring up to the mains outlet (usually #12 to a 115v residential outlet). If noise pick-up appears on the scope, check to see if it is coming in off the power lines, or from some other appliance in use in your house.  If the a.c. voltage checks OK but there is noise or hum on the DC output from the power supply, that is probably due to a deficiency in the equipment itself.  Any one of those problems can be resolved with a little research and effort, with the possible exception of rubbish coming in off the a.c. power grid. In that case, the power company may or may not be willing to cooperate in eliminating the problem, and a shielded isolation transformer might be in order.

All these issues can be resolved with standard electrical troubleshooting techniques. After all, we are working with a  simple 60~ sine wave, not a complex audio waveform with all its subtleties, and there is no magic involved. Bubba the electrician (brother-in-law to Joe the Plumber) could do the job if he has any professional skills at all, using ordinary off-the-shelf tools and hardware available from the local electrical parts store. Power cords with conductors made of special copper alloys serve no purpose other than enriching unscrupulous vendors, and a good power cord will work exactly the same the first day it is plugged in as it does the 5th year of every-day use, assuming nothing is broken and the connectors haven't worn down or otherwise deteriorated.  Those 1.25m (4' 1.2")  long power cords costing £8,795.00 ($14,093.99) and their ilk are pure rip-off and anyone gullible enough to fall for such crap has to either be totally ignorant of electricity or else a damned fool (probably both), to spend that kind of money on a simple a.c. power cord to a piece of audio equipment.

[W7TFO]

The question of the RF changing is rather irrelevant. It may well change. But it doesn't matter. A red herring.

            _-_-bear

A crimson fish?  It has just as much bearing on the subject outcome.  

If indeed the "power purity" is the issue, an amp, be it RF or audio, would behave the same and give listenable results.

An overbuilt audio amp running on clean & real 3-phase would sound better by design in this case.  Especially if that power came via Ag plated OFC, suspended in virgin whatever.

73DG

[k4kyv]

Hey, that could be the next phase (pun intended?) of audiophoolery : three phase power. Only problem, it is very difficult if not impossible to get the power co. to deliver 3-phase to a residence.  But if one has the money to casually afford a $14,000 power cord, I'm positive exceptions could be arranged.

[WQ9E]

To add to Don's post from 1:59 P.M., I agree with his methodology.  To make it easier to see any distortion of the AC wave, use an operational amplifier configured for differentiation which will then emphasize any divergence.  Tektronix had 1 and 7000 series scope plug-ins designed specifically for this type of task.

Now, what about that nasty little line fuse???  If it isn't oxygen (and resonance) free it might undo all of the wonders wrought by the fancy line cord

[Sam KS2AM]

To add to Don's post from 1:59 P.M., I agree with his methodology.  To make it easier to see any distortion of the AC wave, use an operational amplifier configured for differentiation which will then emphasize any divergence.  Tektronix had 1 and 7000 series scope plug-ins designed specifically for this type of task.

Now, what about that nasty little line fuse???  If it isn't oxygen (and resonance) free it might undo all of the wonders wrought by the fancy line cord

Well obviously you would only use an audiophile line fuse!   

These ones "reduce distortion and grunge while tightening up imaging and improving the sense of placement"!

http://www.positive-feedback.com/Issue22/isoclean.htm

Be careful when you get them though, "Each fuse is marked with an arrow, indicating the direction the current should flow. Take care to not reverse these, as it harms the sound."   


Sam

[N8UH]

 

That takes it... You sir, have won the prize. I thought a power cable was bad...

But what about the fuse socket? Gold-plated, directional, adjustable tension, oxygen-free, cryogenically treated and broken-in?

Hmmmm. Perhaps I'm in the wrong business... 

[WBear2GCR]

TFO - RF and AM are rather not low noise or low distortion means of information transmission, this makes higher order differences rather meaningless and impossible to discern. It's not a reasonable comparison.

The rest of youze guyz, I hope ur having fun flogging this mule.

Don, your idea is reasonable, worth trying.
The problem is that the relationships between measured differences and audible differences shows little or no correlation. Well, there are differences that correlate but they tend to be the more gross ones... You would likely be able to see the effect of different line cords, but figuring out how what you saw was related to what you heard would be tough, impossible. And, nothing you said or did would effect whatever RF was impinging upon the AC cord.

As far as NOT using wiring that is heavier gauge than the wall wiring, that is questionable on several levels. First any voltage drop is not desirable. Secondly, bigger conductors have more self inductance, which may be a benefit.

Three phase power to an audio amp is not a bad idea, but not practical commercially. The big amp that I built, the Symphony No.1, was set up with two transformers so that it could be run off 240vac. I think it was noticeably better off the 240vac, even though the source for both the 120vac and the 240vac came off the same iso transformer. The 240vac was stiffer... but if you have not looked, the amp uses ~500,000ufd of filter caps, >4kva of power iron and large copper buss bars with stud mounted rectifiers... so how could that matter given that the amp per channel rating is ONLY ~180wrms?? How?

Fuses are non-linear devices. Good to avoid in audio if possible.

Directional fuse holders? Nonsense.

I'll say it if I wasn't clear on my viewpoint - anyone who spends more than a few hundred dollars on something like an AC line cord with an IEC on one end is foolish, to understate. In the thousands? That's like people who buy gold plated toilet hardware... or maybe a watch that costs 10 grand - does it tell time better than a $19 Timex?

                       _-_-bear

PS. for sure almost anyone on here can make their own line cord using "good" parts - but figure out the actual cost of materials, premium materials including the aesthetic finishing stuff, add it up report back and then multiply that by 5, that is your retail price. It won't be as low as you think. Thus, a few hundred today is reasonable.

[Jim KF2SY]

Errr, speaking of flogging mules.  Don't forget to "Fall back" and set your clocks back 1 hour this weekend....


 

[W2PFY]

Hey, that could be the next phase (pun intended?) of audiophoolery : three phase power. Only problem, it is very difficult if not impossible to get the power co. to deliver 3-phase to a residence.

I know of two places that are residential and have 3 phase power. Both were used to power three phase motors for theater pipe organs installed in their homes. The man with a 30 HP blower had a demand meter on his. He said cost about 50 cents to start the motor and it ran all evening for a few dollars. The other case was a ten HP blower and no demand meter was required. They were in NYS and NJ respectably. Both said they had no problems getting  three phase.

[W2DU]

Bear, I quote from your post above:
"Secondly, bigger conductors have more self inductance, which may be a benefit."

Are you sure this is true? It's been my understanding that the smaller the wire diameter the greater the inductance. Which is correct?

Walt

[WBear2GCR]

Good question Walt!

I have been told and read that larger conductors have more self inductance.

I think that is one of the reason that litz wire is used? (individually insulated strands)

Otoh, I am frequently wrong, and am always willing to adjust to the facts and realities.

                      _-_-bear

[Steve - K4HX]

The self inductance of a straight wire is inversely proportional to the diameter of the wire.

L = 2l (2.303log(4l/d) – 1 + u/4 + (d/2l))

 Where L is the inductance in nH, l is the length (cm), d is the diameter of the wire (cm) and u is the permeability of the material


Same for parallel wires

L =  l/pi (ln (d/a) +Y)

Where, a is wire radius, d is distance and d ≥ 2a, and l is length of the pair, Y varies with the amount of skin effect (relative to freq)


More tricky when d is reduced (wires are in close proximty).

[WBear2GCR]

Here's an online calculator with the equation(s) shown:

http://www.consultrsr.com/resources/eis/induct5.htm

Steve, seems you are correct. I am not. Walt too. Not me. Nope.

However this presents a problem, as I recall a study on the effects of gauge and other geometries upon the frequency response of speaker cables. A rather extensive test. I seem to recall that they decided that 12ga. was about optimum for moderate and typical runs of speaker cable. Larger gauge wire was not as good, and I seem to think that they said that there was more HF droop (fractions of a dB mind you) because of increased self inductance. However this appears to be impossible.

Now to find the original publication. I seem to think it was by Ben Duncan, from Great Brittan...

...I find this somewhat distressing, in that it doesn't add up in my head at the moment!

                         _-_-bear

[W7TFO]

TFO - RF and AM are rather not low noise or low distortion means of information transmission, this makes higher order differences rather meaningless and impossible to discern. It's not a reasonable comparison.

Well, RF + detection + audio, no?  If better is better, why can't you hear that?

73DG

[The Slab Bacon]

Be careful when you get them though, "Each fuse is marked with an arrow, indicating the direction the current should flow. Take care to not reverse these, as it harms the sound."   
Sam

OK-FINE! ! ! ! !  Now, with the fuse fusing the incoming AC mains. If they are current flow "direction sensitive" which way do you point the arrow for AC ? ? ?

Or do you keep flipping the fuse back and forth at 60 flips per second? ?     

[The Slab Bacon]

Errr, speaking of flogging mules.  Don't forget to "Fall back" and set your clocks back 1 hour this weekend....
 

this ought to get Don fired up again..........    

[W1ATR]

I thought I heard the west coasters talking about having the tube shoot this weekend also.