SY and rdf,for information purposes,the Carbon resistance is 36ohm/m,while a coaxial's from same maker can vary depending on model,and lies between 3.8 and 38.7 ohm/100m.My preamp's output impedance is around 50k and power amp's input impedance is 47k.If input impedance of power amp was 47036 ohm would it make any difference?
Panicos K said:
It depends on the severity of the changes. Obviously if I swap out a pair of B&W book shelf speakers for some Wilson Maxx's I would be quite confident that I could tell the difference. Even with double blinding, and even with there being a significant delay between hearing one speaker and the other.
However, if you were to swap the power amps between say a Bryston and a Krell, then I would probably say "I don't know which is which".
I might even "think" I heard a difference, but I wouldn't believe it until I was able to identify which amp was which 100% of the time in a blind test. Until then I would most likely chalk it up to a level mismatch between amps, and/or channels.
That's because I'm familiar with the concept that not everything I see or hear is necessarily what it immediately appears to be.
This isn't to be confused with the fact that if I was able to afford to spend large amounts of money on stereo, that I would probably buy fancy gear for reasons such as: I like the design, and philosophy behind it and it makes a great sounding system. I might even use quite subjective data from friends and forums like this one to help me choose. But I certainly wouldn't try to defend my purchases with some kind of pseudoscientific mumbo jumbo, or claims that I can hear things I probably can't.....
macgyver10,agreed to many of your comments,but still I think that if you wanted to base any purchase of yours purely on your hearing evaluation,I'm sure you would make the best choise for your taste.Please don't make me feel bad for the cost of my system.Most components wewe bought secondhand and repaired,don't think I have money to throw here and there.
Panicos K said:
I would, and have made most of my decisions about audio equipment from personal preference. I don't think that the pursuit of a "perfectly accurate" system is something that can be attained. I also don't think most people would even want it, if they found it.
Stereo is a flawed concept from the get go, but a very enjoyable experience non the less. So I choose what "sounds best" to me. I suspect that's what all serious listeners do.
However, that's not what this forum thread is about, and I've tried my best to stay on the topic of "do speaker cables make a difference?"
Assuming that the point of the question is to get a definitive answer as to whether or not (using current technology and recordings) speaker cables make an audible difference, you can't rely on the same methods that one would use to buy a new piece of stereo gear.
The answer to the question has become fractured amongst many different ideologies so far.
There are those who say all proposed testing procedures are flawed, and therefore invalidate any results. Others claim that human hearing is too complex and misunderstood, and until we better understand it's intricacies we can't know how to test for the influence that speaker cables have. There are other opnions as well, but in short most seem to be contending that no matter what you do, you can't test whether or not humans can hear a difference if you swap speaker cables.
However, there are plenty of people who claim this is not only possible, but the effect of different speaker cables is obvious and easily identified.
It's these latter folks that I have been focussing on. I suggest that if they are positive that they can tell the difference between cable A and cable B when fully aware of what cable they are listening to, then we should be able to easily set up a double blind test to verify that claim. Using the same equipment, source material...even listening space that they used to make the claim. The only difference is that they won't know what cable they are listening to.
In fact, we could even let the claimant have the test comparison apparatus (level matching and switching equipment) in their system for a period of time, so that they can see if they can tell the difference with it inline. Without the double blinding. If they still claim they can, then proceed to the double blind test.
soongsc,it is exactly the way that we must choose,that I think will allow more people to detect more easily some/some more differences in cable ''sounds''.I don't know which this more widely acceptable way is,but till one is found,you are right,each has his own.Perhaps this could be a nice new thread,consentrating on new possible ways of evaluating cables.
soongsc said:
The trouble with simply detecting the change, is that you can be "tipped off" that a change occured, if the switch isn't perfect.
This is where true randomization of the switching needs to happen. Truly random "coin toss" methods will often result in long series of the same "side" in a row, so guessing would be somewhat controlled by this technique.
I'm not a statistician, though, but I have a feeling this would require a very large number of trials to result in significant results.
macgyver10 said:
If you actually do the "unplugging, put down, pick up, plug on" operation regardless whether you use the same cable or not, then I don't know what other "tip offs" could occur unintentionally, especially if the person doing the switch does not want you to guess the right one.
soongsc said:
That method is useless for testing. By the time you have unplugged a cable, and reconnected another, your auditory memory has been lost. The switch has to be instantaneous, or there's no point to the exercise.
You might think you can "remember what the other one sounded like", but it's been shown that that's not how it typically works:
http://en.wikipedia.org/wiki/Sensory_memory
This is part of the whole point of the test, which is to eliminate illusionary aspects of listening such as this.
The tip off is simply knowing that the switch has occurred. If levels have been matched perfectly, and you can switch in the other cables seamlessly, then you wouldn't necessarily know that a switch has, or hasn't occured, until you were cued to make a judgement.
macgyver10 said:
Of course if you can do a seamlessly, that would be ideal. But now we have to deal with how much the switching device itself effects the sound. If the listener agrees that he/she can still hear the same magnitude of difference, then it might be a good idea.
Just from my recent experience with interconnects, I did not think the switching time was a problem even when they had to be unplugged and replugged with shutting the amp down and turning it back on. Rather it was the time listening to each switch caused more impact.
During the second listening session described in my previous post, The first 5 identifications were very quick, but gradually con slower and I would request playing certain tracks again. This is when the errors started to show up. In both sessions, my correct identifications occured in the first 6 identifications.
soongsc said:
I still don't quite understand the issue of "how much the switching device itself affects the sound" argument.
Since the switching device is constant to both cable paths, it really would have nothing to do with obscuring the DIFFERENCE between the cables.
Another approach, perhaps, would be to set up the test using a mono source, with one speaker, and two amplifiers. Switching could be done at line level to the amp inputs, and gain matched at the speaker inputs.
As long as no signal is present at the input of the amp, there should be no signal at the output.
However, I've never considered this arrangement before, so I'm not sure what effect this would have on the output stages of the amps, and there's bound to be some problems with essentially having two amps running one speaker in parallel but with a line level signal only sent to one?
rdf would more than likely have an answer for that one.
macgyver10 said:
Differences in cables sometime are so small that adding anything in series to the cable will effect the sound, and could hide whatever difference was originally audible.
If two amps are used, then amp differences might also effect the differences. If the amp difference is enough, then that alone would dominate the difference. Probably the best bet would be proper selection of cables that widen the difference. Also each having it's own hype or explanation why it is the best cable. I think if the JREF organization starts picking and restricting specific commercial cables, then it only proves ackowlegement that cables to make an audible difference, thus no need for the challenge. That will probably make Randi keep quiet for a while.
Hey, if someone does win 1M out of this discussion, how about inviting all of us from around the world to celebrate.
soongsc said:
Personally, if I were to do a test like this, I would make sure all "measureable" differences were matched, since the claim is most often that it's heard, but impossible to measure.
So I think that voltage at the speaker terminals, phasing, and basic frequency response of the cable would all have to match. None of these MIT "impedance network" cables would qualify. Essentially it would have to be wire (copper or silver or whatever you like) end to end.
Restrictions of this nature would not be "proof" of anything.
I think the $1 million is quite safe, but not because Randi or the JREF will attempt to "rig" the test.
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