A good A/B test for a boutique power cable? (not a joke)

[Mbira]

Please see this thread:

http://www.groupdiy.com/index.php?topic=11122

My teacher has offered to let me borrow one of his high-doller boutique power cables to do an A/B test against a regular old cheapie. I don't believe I'll find a difference, but in the spirit of open-mindedness, I am certainly willing to do some tests. So I have access to most types of test equipment here at the EE dept. Can we come up with a good consensus test (or several tests) to see the facts on these cables? I figure a ripple test using a common power-supply is an obvious first test. Any others?

Joel

 

[tk@halmi]

The shear strength test. The one requiring more lb/inch force to severe is the better one. I know you said it isn't joke, but I couldn't keep it straight...
Btw, leave this test for last.

 

[Mbira]

Considering this is like a $600 power cable, I won't be performing that one...

 

[Crusty2]

What specifically does the manufacturer (or your "teacher") claim this cable does/improves upon?

Knowing that, you can design your test criteria to test these claims.

 

[soundguy]

I personally would put it on a power amp and see if you can hear a difference. I dont think it needs to be particularly scientific, just plug it into different things and see if you can hear it in and out. May be it makes no difference or at least no difference which is relevant on your system which is basically the same thing.

dave

 

[VacuumVoodoo]

Try powering a spectrum analyser with different power cables and SEE if you get different measurement results with same input signal. This should eliminate the "wishful hearing" effect.

 

[chrissugar]

There is a misunderstanding about the "audiophile" power cables. People say what difference can you have with an "audiophile" power cable if you have kilometers of cheap wire from the power plant to your house. This interpretation is totaly wrong because those "audiophile" power cables are not made to plug your equipment into the wall.
The idea is that the power line is contaminated with lots of interferences from radiostations, CB radio, computers, motors and other sources. The idea is to use a power conditioner that will filter/isolate out all the garbage and produce clean power. You should use those "audiophile" power cables between the power conditioner and your audio equipment.
Those "audiophile" power cables are shielded, have large diameter wires, have hospital grade connectors and ferrite rings at both ends of the cable.
All these will help to filter out any kind of RF and other noises. A good power conditioner design will not only filter the garbage from the power side but also will filter for example noise produced by the CD player into the other elements of your system.

Next question is, it is justified to spend 600$ for a power cable. In my opinion it is completely absurd as long as you know how to make a quality power cable. You need a pair of hospital grade connectors, large diameter shielded power cable, a pair of ferrite rings and some heat retracting tubes to fix the ferrites to the cable. Even if you use the best quality components you are below 100$.

Do they work? Before I answer I have to say that I am totally against audiofool bulshit so I always try to find the logical answers for these problems.
I am lucky enough to have access to some absolutely high end systems, one of them is made of Wilson Watt/Puppy speakers, Spectral power amp (designed by Bcarso's friend, the recording and design genius Keith Johnson), Boulder preamp and DAC, Clearaudio turntable, Siltek cables, all the system is vibration isolated with air, no mechanical contact with vibrating elements. The other system is an even more refined one.
We regulary make tests to see how things influence the sound of the system.

The difference between an ordinary power cable and a shielded quality cable is significant. It is not about placebo, the difference is big enough to take it seriously. Probably all the noises that enter into the system are responsible for the loss of stability in audio circuits (they have to work not only in audio but also in the RF zone), loss of detail and distortion.
I am against paying stupid prices for cables but I am for making similar quality cable with much, much less money. They work.
Audio cables and speaker cables have to be designed taking in consideration the same things. Large diameter conductor, low capacitance, quality dielectric, good shielding, ferrite rings, quality connectors. They also have a significant influence.

chrissugar

 

[Gus]

From what I am reading here it sounds like a good filter at the powered device should do the same thing.


Thick wire is easy just buy it, connectors and outlets just buy good ones that make good contact. outlets do seem to wear out with use and if you remove the plug and use another or the same one you will clean the contact.

Contacts are funny things. I just got done looking at a friends solid state bass amp combo it was acting weird. It turned out the vibration at one of the board mounted fuse holders cause the connection to increase to about 300ohms between the fuse and holder ends, the holder had good pressure on the fuse ends. Vibration and current caused the end of the fuse to turn a darker color I am guessing it was form mini sparks.


It might be that the power cable is made with high cap between conductors that acts like a simple filter.

One can use premade power filters There are ones made that will work an the power rating of a power amp I believe.

 

[Viitalahde]

I mostly install filtered IEC sockets to my equipment.

I had some problems with incoming disturbances in power line. Snaps & pops. So I bought a 30A inline filter and put it in a box before my voltage distribution. That took care of most of it.

 

[chrissugar]

[quote author="Viitalahde"]I mostly install filtered IEC sockets to my equipment.
[/quote]
From our tests it looks like it is not enough. They are good but not eficient enough to solve all the problems.


Related to contacts I also find it stupid to use gold plated connectors on the cable if the connector on the device is nikel or something else. Good practice is to use similar metals on both (male/female) connectors. If you have nikel in the IEC, use nikel on the cable, if you want gold on the cable, change the IEC with gold plated. It is no rocket science.

chrissugar

 

[Viitalahde]

I have trouble understanding this.

RF & other crap contaminating the power line? I'd bet that this stuff gets eaten in the mains transformer (if not, they have a better HF response than my Lundahls!) or at least in the filtering caps.

When an obviously sane man starts speaking this, I get interested. Could there be something in it..?
:shock:

 

[Gus]

Anyone old enought to remember HO or slot cars and how much rf crap they make when running.

A food mixer with brushes in the motor or a drill etc.

turn the input down and fader up and record with a drill on and off etc in the room maybe even in the same wall outlet. That should make enought RF, AF noise to get in via the power cord I would think.

Then run a FFT etc on the recording

 

[Viitalahde]

Never thought it that way, I was just thinking of the radio/TV signals and such. My working environment has always been good with RF, so that's probably why I don't really give much thought to it.

 

[kiira]

[quote author="soundguy"]I personally would put it on a power amp and see if you can hear a difference. I dont think it needs to be particularly scientific, just plug it into different things and see if you can hear it in and out. May be it makes no difference or at least no difference which is relevant on your system which is basically the same thing.[/quote]

yeah that's what me an a friend did. I closed my eyes while he switched cables and then I listened. Aside from hearing increased air around the acordian and a certain glassiness to the harmonium, oh and hearing for the first time someone screaming in the background "Johnny get yer ass in this house wait til your father comes home you little brat!" there was no diffference in cables.

Kiira

 

[owel]

"Hospital-grade" marketing hype is a crock.

I've worked in an Electrical Engineering company and we do labs and hospitals. I asked the factory rep what's the technical difference between their Hospital-grade outlet and the regular outlet besides the EXPENSIVE price (and color).

He said "None. The high cost of "hospital grade" outlets/connectors/etc... is to cover settlement and lawyer fees in case somebody dies if our outlet failed while powering a life-support equipment."

 

[chrissugar]

Owel

When I say hospital grade connectors I mean Wattgate, Hubbell and similar high quality products. It don't have to be the expensive one. www.wattgate.com


Kiira, you can make fun, but you can be sure that one cable will not make a difference, and also not on a low resolution system, and you will not hear significany difference if the test material is not a proper one.

The whole system should be connected to a quality power conditioner, the system should have at least a decent resolution and the test recording should be something that will reveal the differences. Multi mike, multitrack, mixed modern music (rock. pop. electro) has no proper resolution/distortion/phase information. In my opinion the only suitable test materials are the ones recorded with two mikes with real acoustic like the ones made by Chesky, Reference Recording, Naim, and others.
For example my Dynaudio BM6A is in my opinion the lowest acceptable quality speakers (although they don't sound bad) that will allow you to have some info about detail, phase, dynamics, soundstage. But compared to some really serious systems they look like toys.

chrissugar

P.S. I didn't lost my mind, I'm involved for more than 15 years in both the proaudio side and in the audiophile side and I try to remain sane and not accept the audiofool bulshit. You can be sure that I will never pay stupid money for cables but there are things that work and produce better sound quality so I will try to understand how things work.

 

[Samuel Groner]

RFI pick-up trough the PSU can be a problem--I have to work with a PA amp that turns into a noise-generator if you run anything switching (i.e. dimmer) on the same line.

However, I believe that with good design practice there is no danger. Usually I use custom torroids with magnetic and static shielding and an additional RFI-filter, and I never noticed any problem.

"Hospital grade" has, at least here in Switzerland, a real meaning--don't remember what it was, something with the fuse(s) or the X/Y caps... And they are not seriously expensive, just different.

Samuel

 

[chrissugar]

Just to ad more fuel to this thread I have some more.
We did some tests about microphonics.
As I said one of the systems is floating (mecanical isolated from the stands) and you can do realtime changes like make the devices to float or to make direct mechanical contact. The difference is also significant.

One explanation is that for example when capacitors vibrate, they produce some small voltage changes.
I read at mister Borbely's (a very respected designer) page something related to microphonics about PCBs:
"The FR-4 works very well in most audio applications. However, it is a very hard material and has a tendency to vibrate. This might cause tiny current changes in the components on the board, which, especially in very low level circuits like MC phono preamps and microphone preamps can cause unwanted ?sounds?. Teflon base-material, which has been developed for HF circuits, is much less prone to vibration. Consequently it is very much preferred for low-level circuits."

chrissugar

 

[Emperor-TK]

Chrissugar makes a good point, but it is still in line with what Soundguy was getting at, which is "does it matter for your system or applications?". There are two ways to test the cable, one being the way that most of us work (multi-mic, multitrack, etc.) and the other way being the purist route. Dave, if we are going to do the test that Chrissugar suggests, I might know the place. This is my friend's mastering studio in NYC. I would guess he might like to fart around for and hour or two with a $600 cable to see if it can help his chain too:

http://www.jigsawsound.com/

Professionally tuned room, good monitors, good signal path...no excuses not to hear any differences.

-Chris

 

[Mbira]

Thanks for the info so far. Chris, very good explinations. You're the first person that is making me think the darn cable will actuall work. I will be getting the cable next Thursday, so I want to come up with some good tests that we can all agree on by then. So far for tests we have:

[quote author="dave"]I personally would put it on a power amp and see if you can hear a difference.[/quote]

This is a test that I will certainly do, though I'd like to also do a less subjective test.


[quote author="VacuumVoodoo"]Try powering a spectrum analyser with different power cables and SEE if you get different measurement results with same input signal. [/quote]
Nice. I only have a software spectrum analyser. I could record the AB test and then view the results on the anayser. I could also post the results then (in a really high-quality mp3 :green: ) The best pres I have are a G9 and a Green. The green would probably be the best for an "uncolored" test. Unfortunately, the best mic I have to record with is an AKG 414, but if I use the same mic on both cables, maybe I'll see the difference?

[quote author="gus"]turn the input down and fader up and record with a drill on and off etc in the room maybe even in the same wall outlet. That should make enought RF, AF noise to get in via the power cord I would think.
Then run a FFT etc on the recording.
[/quote]
This seems like a good test!

[quote author="chrissugar"]my Dynaudio BM6A is in my opinion the lowest acceptable quality speakers (although they don't sound bad) that will allow you to have some info about detail, phase, dynamics, soundstage. But compared to some really serious systems they look like toys.
[/quote]
Therin lies my biggest deficiency. I do not have an audiophile system. Therefore, I would like to do these tests on actual measurable results (in my studio). I totally understand that that will result in a very small piece of the pie of knowlege about this, but that's probably the best I can offer to 'real' results.

Keep it coming!!!