[Uncle Erik]

Goraman, people have a strange way of overlooking power supplies. They're usually engineered to remove line noise and provide clean DC to a circuit. If something needs special ferrite or whatever, then whoever engineered the power supply did a lousy job. If anyone thinks their power supply is poor, they'd do well to contact the manufacturer and let them know the power supply is inadequate. Any response from the manufacturer would be very interesting.

 

[goraman]

 Both ,I live in a condo each  building has 4 units.
Line noise at night NO PROBLEM,line noise during the day in summer with all the fans and A/C units can tax even the best filtered power supplies,not a big deal with solid state but noise made louder through transformer hysteresis Even in my Audion and Manley amps.
I never expect tube gear to go dead black  at 12:00 gain. But line noise can be more in a largely populated area than a rural area and it helps to reduce it before it gets to the psu.BTW all transformers have some self created noise called hysteresis or so I have been told.

 

[Steve Eddy]

 
Quote:

 BTW all transformers have some self created noise called hysteresis or so I have been told.

Hysteresis isn't noise. It's ultimately a non-linear magnetization of the transformer's core material which results in harmonic distortion. But it's pretty irrelevant in a power transformer. The act of rectifying the AC voltage in order to get DC produces a HUGE amount of harmonics.
 
The only self-created noise in a transformer is the thermal noise of the windings and barkhausen noise. Neither of which are an issue for a power transformer.
 
se
 

 

[TheAttorney]

Quote:

The allegedly perfect blind test is one where the subject does not know anything about a change. I would have thought that giving someone the heads up that they are being tested would be more accurate.

 
I agree with this Prog Rock Man. It’s given me an idea of an analogy to show one of my concerns re DBT:
 
Test1. Sighted.
I’m watching TV with my wife (and lovely test assistant). The program is an outside broadcast, where the volume of both presenter and background noise is fluctuating. My digital AV amp’s volume control increment’s in 1db steps. In this situation, I can reliably tell the difference when I use the remote control to change the volume by 1db. It’s subtle, but completely obvious and repeatable time and time again. AFAIK, I can readily detect a 1db volume change – beyond reasonable doubt.   
 
Test2. Secret Swap.
Unbeknown to me, my assistant now has the remote and secretly occasionally changes the volume by 1db (never cumulative, always 1db either side of start point). I’d bet money that I wouldn’t be able to spot the secret change, but if I did manage to do so, it would confirm what I already knew. And if I didn’t, then I would conclude that, based on all previous honest observations, Test2 is less reliable than Test1 for this particular application. If you accept this as reasonable, then it’s not such a big leap to...
 
Test3. DBT-like.
My assistant is given a modified remote, with a single button that randomly changes the volume by 0,-1db,+1db (never cumulative, always 1db either side of start point, and 0 is important in this test). It’s got an LED to let me know when a potential change is happening. I would probably not be able to repeatedly spot the difference in this test, although I may not bet as much money as I would for Test2.
 
Now, if the test moderator told me that had I failed Tests 2 and 3, and so the conclusion is that I can’t detect a 1db volume change, and also I must be deluding myself on Test1, then I would not accept that conclusion. Even though Test1 has it’s own flaws, I can reasonably reason (!) that Tests 2 and 3 have greater flaws for this particular application. For different applications, my conclusions may change. For example, if the TV was to output a continuous tone.            

 

[Prog Rock Man]

 
Quote:

Originally Posted by Gu Sensei /img/forum/go_quote.gif

...........
 
Let's take the case of two sets of cables that are constructed to exactly the same measurable specifications except one uses wire made of copper and the other made of silver. If a person perceives sonic differences when the cables are changed, then there are two possibilities; one, the nature of the cables' material influences the electrical signal somehow, or two, the sonic difference is a trick of the mind. Of course, it can never be proved beyond all possibility that it is one or the other. But, the idea that the cable material has properties that can account for described changes is no less unlikely than the proposition that those disks are actually moving. If you deny this point, then you do not really grasp the physical principles under question, foolishly ignore them or have some sort of agenda. Furthermore, the mind is no less capable of producing the experiences described by every single person who has reported hearing differences between silver and copper than it is of spinning those disks when they are in fact stationary. Again, if you cannot accept this, you simply are unaware of what is well known, foolish to dismiss it, or have an agenda.
 
 

You are right, but it provides a plausible alternative explanation. Actually, the only plausible explanation.
 
The sophistry going on in this debate is the shifting of attention from what is well-known, ordinary, and easily demonstrable to the philosophical. Science can't 'prove' anything. So what? Fortunately, we do not need it to. It is quite useful even with that imperfection. Personal experience is unnecessary (and potentially misleading). All you need to do is read with an open mind to settle this 'debate.' The evidence is already out there.
 
 
 
 
 
 
 
 
 

Regarding the highlighted part. Blind tests, so far show that there is no actual difference in the sound. Even if there are slight differences in the cables which can be measured, they cannot be heard. But more importantly, sighted tests which result in a perceived change in the sound can only be due to the mind. That is why we need more blind tests, particularly from the pro-cable side as such will result in absolute proof beyond all reasonable doubt.
 

 

[K.I. Unlimited]

Even for pro- or anti-cable people, there are also extents of their stand. I am personally more pro-cable because I can tell some differences (read: not for better or worse, just differences), but not to the extent I will part with more than $200 local currency for a 1-2m RCA cable.

 

[Uncle Erik]

Quote:

 
I agree with this Prog Rock Man. It’s given me an idea of an analogy to show one of my concerns re DBT:
 
Test1. Sighted.
I’m watching TV with my wife (and lovely test assistant). The program is an outside broadcast, where the volume of both presenter and background noise is fluctuating. My digital AV amp’s volume control increment’s in 1db steps. In this situation, I can reliably tell the difference when I use the remote control to change the volume by 1db. It’s subtle, but completely obvious and repeatable time and time again. AFAIK, I can readily detect a 1db volume change – beyond reasonable doubt.   
 
Test2. Secret Swap.
Unbeknown to me, my assistant now has the remote and secretly occasionally changes the volume by 1db (never cumulative, always 1db either side of start point). I’d bet money that I wouldn’t be able to spot the secret change, but if I did manage to do so, it would confirm what I already knew. And if I didn’t, then I would conclude that, based on all previous honest observations, Test2 is less reliable than Test1 for this particular application. If you accept this as reasonable, then it’s not such a big leap to...
 
Test3. DBT-like.
My assistant is given a modified remote, with a single button that randomly changes the volume by 0,-1db,+1db (never cumulative, always 1db either side of start point, and 0 is important in this test). It’s got an LED to let me know when a potential change is happening. I would probably not be able to repeatedly spot the difference in this test, although I may not bet as much money as I would for Test2.
 
Now, if the test moderator told me that had I failed Tests 2 and 3, and so the conclusion is that I can’t detect a 1db volume change, and also I must be deluding myself on Test1, then I would not accept that conclusion. Even though Test1 has it’s own flaws, I can reasonably reason (!) that Tests 2 and 3 have greater flaws for this particular application. For different applications, my conclusions may change. For example, if the TV was to output a continuous tone.            

This could also mean that you're hearing a difference because you're expecting to hear a difference in Test 1.  If you hit the button and expect a change, you'll notice it.  Seems to be explained by Expectation Confirmation Theory.
 
Don't discount Apophenia, either, where people find patterns where none exist.  Most people search for patterns and meaning and occasionally find something in nothing.

 

[TheAttorney]

Quote:

This could also mean that you're hearing a difference because you're expecting to hear a difference in Test 1.  If you hit the button and expect a change, you'll notice it.  Seems to be explained by Expectation Confirmation Theory.
 
Don't discount Apophenia, either, where people find patterns where none exist.  Most people search for patterns and meaning and occasionally find something in nothing.

 
Yes, these are the flaws of sighted tests - they always will be. Actually, I'm not sure Apophenia applies only to sighted tests, but never mind.
 
But that wasn't my point. I used a real world example, with an application that all sides can agree on - i.e. that humans are capable of detecting differences in volume and that this difference is also readily measurable. And then I gave a real world example whereby it was reasonable of me to deduce that, despite it's undeniable flaws, the sighted test could be more reliable than an unsighted one. It's an example that doesn't require a belief in voodoo to appreciate.
 
This alone won't prove anything, but I'm just trying to directly respond to the OP. It is one reason why I won't "blindly" accept DBT results in certain applications.

 

[Prog Rock Man]

I have regularly said (to some annoyance, sorry!) that i accept that cables can result in differences to volume and theorised that that is a cause of some, mistaken claims cables sound different.
 
Blind tests should have the volume equalised to avoid that.

 

[TheAttorney]

Looks like people are completely misunderstanding the point of my analogy. Never mind. Probably didn't write it very clearly - I'll go away quietly... 

 

[goraman]

This may have been posted before, if so sorry for the repeate but it dose make some good points.
http://sound.westhost.com/cables-p3.htm#interconnects
 

 

[grokit]

 
Quote:

I have regularly said (to some annoyance, sorry!) that i accept that cables can result in differences to volume and theorised that that is a cause of some, mistaken claims cables sound different.
 
Blind tests should have the volume equalised to avoid that.

I think that it would be reasonable to infer that if the volume is changing due to the cable being used, that there could likely be other sonic properties undergoing change as well. Whether or not these other changes are detectable audibly or measurably is another matter entirely. It is not outside of possibility that these changes could be perceptable to some but not all individuals, and that they are not measurable.

 

[Prog Rock Man]

I do not agree with that as all is needed is to match the volume between two cables and that one difference disappears.
 
There is a correlation between volume and sound quality in that too quiet and there is a lack of detail and dynamics, too high and distortion sets in. It is easy to hear that and show it repeatedly, so it is provable. Other claims are not, well yet anyway.

 

[Uncle Erik]

If the volume is changing, that's likely due to resistance.  Potentiometers are resistors, after all.  Well, most of them are.
 
But if there's enough resistance to change the volume, there's enough resistance to measure.  Likewise, if the output level changes enough to be heard, that can also be measured.  Even a $5 DMM from Harbor Freight should have no trouble with that.

 

[grokit]

Digital Molecular Matter?