Jump to content


Photo

Audiophiles...


  • Please log in to reply
150 replies to this topic

#126 POV

POV

    AV Forum Member

  • Member
  • PipPipPipPipPipPip
  • 2,426 posts

Posted 17 January 2012 - 12:24 PM

An interesting Shunyata Research visit and interview. I actually found the read quite fascinating and learned quite a bit. I suggest approaching the article with an open mind.

Shunyata Research visit & interview - TheAudioBeat.

Thanks to my Brother Simon for the heads up on this one.

Blade

Edit - This link was from Off-Topic apparently (JohnA).


Fascinatinvg read. Good to see the development of new measurement equipment/techniques regardless of how one feels about a particular subject.

I suspect though that there will be tose that will simply poo-poo the machine based on where it has come from, and thus the circle will continue.

#127 Drizt

Drizt

    AV Forum Member

  • Senior Member
  • 5,930 posts

Posted 17 January 2012 - 12:33 PM

I still haven't read it.... will do tonight..

It would be interesting to see if they could objectively measure an audible difference or even a measurable difference at the output of the device the power cord is connected to. For me that is what really needs to be answered.

#128 JohnA

JohnA

    AV Forum Member

  • Senior Member
  • 3,342 posts

Posted 17 January 2012 - 12:36 PM

An interesting Shunyata Research visit and interview. I actually found the read quite fascinating and learned quite a bit. I suggest approaching the article with an open mind.

Shunyata Research visit & interview - TheAudioBeat.

Thanks to my Brother Simon for the heads up on this one.

Blade

Edit - This link was from Off-Topic apparently (JohnA).


i posted this one earlier today in the power cables thread which was moved to off topic

ps, tried to send you a PM ealrier blade but couldnt do so

#129 JohnA

JohnA

    AV Forum Member

  • Senior Member
  • 3,342 posts

Posted 17 January 2012 - 12:38 PM

Fascinatinvg read. Good to see the development of new measurement equipment/techniques regardless of how one feels about a particular subject.

I suspect though that there will be tose that will simply poo-poo the machine based on where it has come from, and thus the circle will continue.


the machine will eventualy become available to manufacturers, testers and maybe to public. Then at least some independant testers could get hold of it and try it.

as for poo pooing it, thats a given. People are quick to do that these days

#130 dJOS

dJOS

    AV Forum Member

  • Senior Member
  • 8,298 posts

Posted 17 January 2012 - 12:40 PM

An interesting Shunyata Research visit and interview. I actually found the read quite fascinating and learned quite a bit. I suggest approaching the article with an open mind.

Shunyata Research visit & interview - TheAudioBeat.

Thanks to my Brother Simon for the heads up on this one.

Blade

Edit - This link was from Off-Topic apparently (JohnA).


Good read, it's nice to see that the high end market does have a real technical innovator in it and not just a bunch of snake oil salesmen!

#131 myrantz

myrantz

    AV Forum Member

  • Member
  • PipPipPipPipPipPipPipPip
  • 16,181 posts

Posted 17 January 2012 - 12:53 PM

as for poo pooing it, thats a given. People are quick to do that these days

:poke: Want to know how quick? MLXXX already did it last Oct.... :hyper: :lol:

#132 JohnA

JohnA

    AV Forum Member

  • Senior Member
  • 3,342 posts

Posted 17 January 2012 - 01:01 PM

:poke: Want to know how quick? MLXXX already did it last Oct.... :hyper: :lol:


NOOOOO, i find that so hard to believe

#133 POV

POV

    AV Forum Member

  • Member
  • PipPipPipPipPipPip
  • 2,426 posts

Posted 17 January 2012 - 01:21 PM

:poke: Want to know how quick? MLXXX already did it last Oct.... :hyper: :lol:


ah...of course. I suppose he said it was not a bit persuasive :poke:

#134 BladeRnR

BladeRnR

    AV Forum Member

  • Senior Member
  • 3,817 posts

Posted 17 January 2012 - 02:53 PM

the machine will eventualy become available to manufacturers, testers and maybe to public. Then at least some independant testers could get hold of it and try it.

as for poo pooing it, thats a given. People are quick to do that these days


No problem John I did modify my post after my Brother told me it was your post that motivated him to show me :)

Cheers

Blade

#135 JohnA

JohnA

    AV Forum Member

  • Senior Member
  • 3,342 posts

Posted 17 January 2012 - 03:05 PM

No problem John I did modify my post after my Brother told me it was your post that motivated him to show me :)

Cheers

Blade


no probs there mate, just wanted to ask you a question via pm, but i think maybe your inbox is full

#136 BladeRnR

BladeRnR

    AV Forum Member

  • Senior Member
  • 3,817 posts

Posted 17 January 2012 - 03:06 PM

I still haven't read it.... will do tonight..

It would be interesting to see if they could objectively measure an audible difference or even a measurable difference at the output of the device the power cord is connected to. For me that is what really needs to be answered.


I agree.

No matter how complete/accurate the measuring device used it still does not invalidate blind testing IMHO. The article did suggest at the end of the day the User will either hear a difference or not. Personally, if one wants to ensure proper scientific process is followed and a more complete result achieved, a formal electrical measurement should be followed by blind testing (Human trials if you will) to paint a braoder picture. The caveat (again) is that some will hear a difference and some will not (For all the reasons already discussed). Having read a great deal about Acoustics & Psychoacoustics in the last 8 months I can say hand on heart that if there is an "answer" it is not as clearly defined or definitive as you may think.

Summary - Try a Power Cord / Power Conditioner and see what you think. If you do hear a difference in your system follow it up with blind testing to see if you're fooling yourself. At the very least you have had a bit of fun and added to your store of knowledge. I will also say there is no onus on you to prove to somebody else you heard the difference or not. Choice. It's a luxury to be cherished.

Blade

#137 BladeRnR

BladeRnR

    AV Forum Member

  • Senior Member
  • 3,817 posts

Posted 17 January 2012 - 03:10 PM

no probs there mate, just wanted to ask you a question via pm, but i think maybe your inbox is full


Thanks for the heads up mate. Inbox was indeed 100% full. Should be ok now.

Cheers

Blade

#138 Chicken Man

Chicken Man

    AV Forum Member

  • Senior Member
  • 6,313 posts

Posted 17 January 2012 - 04:00 PM

Well, I read it to the point where he got on to power connectors.

What he is initially doing is using a square wave to illustrate differences between pieces of cable, well that's no revelation in itself.There will naturally be detectable differences with such an arduous test. This is hardly a proper investigation of differences between power cables that work at Mains frequencies.

The time base is set at 5 uS/division or 1/200,000 of a second/division that is equivalent to measuring differences at 20,000 c/s not at 50 or 60 c/s.

If you measure cables with different resistance then naturally you'll get different results in current flow and voltage drop.

He does not care to mention whether both cables are of the same length, they are obviously of different resistance values and different gauge.
The point here is that this test highlights nothing at all. Such transient differences over such a short time of a 1/20,000th of a second on a 1/20th of a second timebase ( 50c/s Mains) is ridiculous, particularly when this would only happen when you initially turned on the amplifier when the storage capacitors charge.Once that happens there is no great influx of current into the power supply thereafter, there is only some topping up as needed.

So an ordinary power cord supplied by the manufacturer is more than adequate for the purpose.

To Quote

CG: Right. Remember this is a transient burst of current because power supplies pull current in pulses. They are not like fans or lights, where power is drawn continuously across the full waveform of a power cycle.

Power supplies pull current in pulses. If you don’t understand that, I’ll show you very simply when we sit down basically how a power supply works. But for now, let's look and see how this standard power cord reacts to pulsed current delivery.


I don't see anything different between the two power cords ( their respective curves) except the effect of D.C resistance marginally limiting the initial current surge that would flow into the storage capacitors......and that is a good thing. Remember the power transformer that would be connected to the power cord will have substantially higher winding resistance than the very worst power cord one could buy. So this test is completely irrelevant as any difference in power cord conductivity is annulled, that is, once the primary winding of the transformer transfers electrical energy into the secondary winding and then rectified the storage capacitors are then charged, any differences between the two power cords is negated.

But now he considers 'pulsed current delivery' and its influence on the power cord in use.

So once the amplifier has been turned on and the initial charging of the storage capacitors has taken place any initial charging current transient has passed. The capacitors will be charged to almost the peak voltage of the secondary winding ( i.e minus the bridge diode loss when current flows), there is very little 'ripple' on the HT + and - rails of the amplifier when no signal is being amplified. Of course, once a reasonable output signal is developed across a connected load (loudspeaker) a 100c/s rectification 'ripple' does appear on the + and - rails due to the current demands on the power supply.

Now with the storage capacitors fully charged to the peak secondary winding voltage, the bridge rectifiers become reversed biased so there is no conduction at all through them,there is also no 'ripple', but once the amplifier begins to produce output current through the load 'ripple' again appears on the bus rails and the rectifiers begin to conduct again in accord with the difference in voltage between the secondary winding and the storage capacitors.

But this 'ripple', regardless of its voltage value, only has a rise time equal to a 50c/s Mains frequency (it is not a square wave) thus any 'effects' made on the primary winding side of the transformer by the connected power cord will only be that due to 50c/s Mains current,not by any other cause.These 'pulses' he refers to is the 100 hertz 'ripple' and are not real transients but pulses with very slow rise times, much like sloping hills, and do not impose undue demands on the transformer or its power connection to the Mains.

For instance, one needs a 300VA power transformer to deliver 200w RMS via circuitry to a load, so the transformer will only draw 1.25 Amps from the 240 v Mains to provide that output, but could easily draw 30 to 40 A at the initial charging of very large storage capacitors in an amplifier. This would only be for about 5-20 milliseconds, depending on the time-constant involved, thus if fuses were resistive they would vaporize instantly and would hardly make a marketable product.

But if you want to spend your money on expensive power cables that really offer no benefit at all but are only a fanciful means of connection then by all means, but that's all you get for your money.

Sorry about the techno waffle but as this article's claims are founded on techno baffle, it needs such a reponse no matter how badly put together by me.

C.M

Edited by Chicken Man, 18 January 2012 - 10:05 AM.


#139 MLXXX

MLXXX

    AV Forum Member

  • Senior Member
  • 5,415 posts

Posted 18 January 2012 - 11:30 AM

:poke: Want to know how quick? MLXXX already did it last Oct.... :hyper: :lol:

Yes, in the infamous Advice on Power Cords thread. Here is what I said:

... Í now see there's a "white paper". It includes this:

The DTCD Analyzer is designed to test a single current pulse through the DUT (device under test). Since the primary purpose of DTCD Analysis is to measure devices that inherently have very low impedance, it becomes challenging to create test equipment that can accurately measure the differences between what amounts to differing wire types and sizes or different switch designs.Further, it is important that the differences (if they can be measured) have some relevance to the task that they are intended to be used for. With that in mind, the DTCD Analyzer needed to simulate the AC electrical power grid, with its characteristics as a constant voltage source. The DTCD Analyzer's voltage source consists of a capacitive array whose characteristics include ultra-low impedance, resistance and ESR (measured at 0.0016 ohms) with the ability to provide peak currents of several hundreds of amps with minimal voltage drop. (From http://www.shunyata....whitepaper.html , red font added.)


The "relevance" of 0.0016 ohms is very moot unless you have perhaps theoretically climbed up your street power pole in the dead of night to connect your AVR directly to the thick distribution cables; and preferably very near the secondary windings of a distribution transformer! In real life, an AVR in a house is connected via a power cord to a portable power board which then connects via a metre or so of cord to a power plug, which is inserted into a wall power point. The power point is connected via perhaps 10 to 30 metres or so of cable to a switchboard, which is then connected by a further 10 to 20 metres or so of cable to a power pole. Typically if you turn on a household electric oven, lights in the house will dim slightly. Having the last metre of the wiring use very thick cable cannot undo the resistance of the many meters of cable preceding the special cable. At my place tonight I measured the mains voltage at a double power point in the kitchen with an electric toaster connected to the power point turned on or off. Readings were as follows: No load: 235V Toaster on: 230V The toaster is rated for 1650W at 230V, which corresponds to just over 7 amps. A 5 volt drop at 7 amps corresponds to a resistance of about 0.7 ohms. There is not all that much relevance in testing a power cord with a device with a source impedance of 0.0016 ohms if a household power point has over 100 times that impedance. The house wiring at my place is modern, and the kitchen is about 20 metres from the switchboard. The graphs in the white paper do show clear differences between power cords, but only when connected to an unrealistically low impedance voltage source. Place a 0.7 ohm resistor between the high performance source and the power cords under test and the graphs would become hard to tell apart. However, such realistic graphs would not be favoured by a marketing department...



#140 dJOS

dJOS

    AV Forum Member

  • Senior Member
  • 8,298 posts

Posted 18 January 2012 - 12:12 PM

Good points MLXXX, Here in SA we seem to have quite high grid voltages which typically vary between 247v and 256v - I measure it from my Solar inverter and it's surprisingly variable (purple line on graph):

http://pvoutput.org/...00&vmax=300&m=0

#141 MLXXX

MLXXX

    AV Forum Member

  • Senior Member
  • 5,415 posts

Posted 18 January 2012 - 01:09 PM

Here in SA we seem to have quite high grid voltages which typically vary between 247v and 256v - I measure it from my Solar inverter and it's surprisingly variable (purple line on graph):

http://pvoutput.org/...00&vmax=300&m=0


Fascinating graphs. You have long days in summer at your latitude. The photovoltaic panels contribute a lot. Conversely in your cold winters, you would have rather limited hours of sunshine.

For the power authority to manage changing loads, and changing contributions from domestic solar electricity installations, would be a challenge. As you point out, the domestic supply voltage varies considerably in the course of a day.


Remember the power transformer that would be connected to the power cord will have substantially higher winding resistance than the very worst power cord one could buy. So this test is completely irrelevant as any difference in power cord conductivity is annulled, that is, once the primary winding of the transformer transfers electrical energy into the secondary winding and then rectified the storage capacitors are then charged, any differences between the two power cords is negated.

Indeed. Not only is there relatively high source resistance at the power point end of the power cord, there is -- as you point out -- considerable resistance in the transformer windings, at the equipment end of the power cord. So in the overall analysis, the small resistance of the power cord itself is of no significance.

Edited by MLXXX, 18 January 2012 - 01:10 PM.


#142 Arg

Arg

    AV Forum Member

  • Member
  • 21 posts

Posted 28 January 2012 - 12:26 PM

I think some people are forgetting the word digital from the original post. It was said he thought the ultra high end amps were a waste on digital sources... Doesn't mean he doesn't rate them or see the value in them for a particular role in an analogue set up . It could also differ if he had drive particularly power hungry speakers too.


I agree. My reading of the OP's quoted retailer was suggesting a different approach to digital vs analog audio.

With digital, use your money wisely. Some aspects of the technology have surpassed human perception.

With analogue, it's different.

#143 MLXXX

MLXXX

    AV Forum Member

  • Senior Member
  • 5,415 posts

Posted 28 January 2012 - 12:41 PM

With analogue, it's different.

What analogue sources of recorded music exist these days?:

1. A conversion from digital to analogue created by a DAC decoding a digital stream from a CD transport? (Not really an analogue source.)

2. The output of a stylus tracking a 1970s vinyl disc? (A very old analogue source.)

#144 Arg

Arg

    AV Forum Member

  • Member
  • 21 posts

Posted 28 January 2012 - 01:34 PM

I meant the second one.

#145 Gutty

Gutty

    AV Forum Member

  • Senior Member
  • 4,083 posts

Posted 30 January 2012 - 05:27 AM

What analogue sources of recorded music exist these days?:

2. The output of a stylus tracking a 1970s vinyl disc? (A very old analogue source.)


Not that i want to get involved in the OP, but FWIW, lots of people still recording in analogue(tape) or even direct to vinyl and releasing on vinyl :winky:

I think it stopped airing before Christmas, but keep an eye out for a program on the ABC called "On Track". Takes a look at modern bands/musicians recording direct to vinyl, it's quite interesting... if you're into that sort of thing.

#146 MLXXX

MLXXX

    AV Forum Member

  • Senior Member
  • 5,415 posts

Posted 31 January 2012 - 03:07 AM

Takes a look at modern bands/musicians recording direct to vinyl, it's quite interesting... if you're into that sort of thing.

Would that be an unamplified acoustic "band", or one that included a digital keyboard...

The engineering challenges in using a stylus to track a spiral groove in a rotating vinyl disc, so as to extract analogue stereo audio over audible frequencies, are considerable. There is inevitably a disparity between the quality of the signal sent to the recording lathe, and the quality of the signal emerging from the magnetic or other cartidge.

Challenges with audio magnetic recording tape include significant non-linearity and hysteresis in the magnetic transfer characteristic.

I'm not into analogue recordings per se, though I am into unamplified instrumental and vocal performances.

#147 Gutty

Gutty

    AV Forum Member

  • Senior Member
  • 4,083 posts

Posted 31 January 2012 - 06:57 AM

Would that be an unamplified acoustic "band", or one that included a digital keyboard...


Fare point...

#148 myrantz

myrantz

    AV Forum Member

  • Member
  • PipPipPipPipPipPipPipPip
  • 16,181 posts

Posted 31 January 2012 - 12:54 PM

A friend of mine linked this on FaceBook...

What kind of reality do you live in? ;)

Ignore the words btw and just focus on the pics...

Case in point - there's a market for everybody... :)

#149 Gutty

Gutty

    AV Forum Member

  • Senior Member
  • 4,083 posts

Posted 01 February 2012 - 05:23 AM

A friend of mine linked this on FaceBook... What kind of reality do you live in? ;) Ignore the words btw and just focus on the pics... Case in point - there's a market for everybody... :)


Hahaha... funny, but true.

#150 bassett

bassett

    AV Forum Member

  • Member
  • PipPipPipPip
  • 812 posts

Posted 01 February 2012 - 11:34 AM

A friend of mine linked this on FaceBook...

What kind of reality do you live in? ;)

Ignore the words btw and just focus on the pics...

Case in point - there's a market for everybody... :)



That's hard to answer in a forum thread. That question would // could // should cover a hole internet forum all on it's own.

But lets remember folk's there's Drugs out there to control almost everything an anything.