John Dunlavy On "Cable Nonsense"

Waveform measurments are made all the time and no differences are foundusing the test as I suggested above. Your results are flawed because it is near impossible to gather accurate acoustic measuments in a standard reflective rool with a time averaged meter as the RS. You will have better measurments to use a dvm at the speaker terminals so all of the sound bouncing off the walls do not enter into your measurments. Good luck though!

leme

Well, I think we might be setting out to prove different propositions. I am not trying to measure exactly how much difference exists. I am trying to show that a somewhat reasonable and impartial model of the human ear can detect and measure differences in the exact same environment humans listen in. I am not trying to demonstrate the exact amount rather that differences do exist and are easily measurable. The closeness of a SPL meter to the human ear is topic for another thread to debate.

The question of reflection of sound waves strikes me as a red herring unless you are suggesting that human beings also listen in a reflection free environment. Since I listen in exactly the environment I measured, I am reasonably sure that there's a match there :-). I am not trying to prove what causes the difference either. I am pretty uncaring about the reasons unless they can lead me in a direction which leads to improvement. Conjectures such as little green men following each speaker cable around and pushing a little harder in some spots than others is fine with me as long as it is repeatable and reproducible and directly related to the usage of the cable in the system.

The SPL meter was mounted on a tripod one meter away from the woofer and was never moved during the testing. The gain on the preamp and power amps was never changed. The speakers never moved. The input source material was exactly the same and for exactly the same time. Three trials of each cable were performed. The only part of the system which changed during the measurements was the speaker cable and each time it changed, the same results were obtained, except for a half dB on one measurement of one trial of the non-Monster cable.

So bottom line, I don't really see how measurable and repeatable differences in the target environment can be ignored, since that is exactly what I am trying to show, and exactly what a human would hear, but whatever. I would really rather see what some other peoples results under the same conditions and with different cables are. Those results says a lot more to me than any testing I myself perform. Could be I had a defective or unusual cable in there and no one else in the entire world can reproduce the results with any brand of cables, ever. Only one way to tell...

My suggestion is just to confirm your measurements. If there are differences with the RS acoustic meter you will also see differences with a voltage meter. A 2dB bass hump due to cabling is unexplainable and unreasonable. Are you using music as a source? You state the measuments we taken at the same time during each trial. I hope you can try with a test cd with tones.

thanks for the help

leme

I was using the Stereophile Test CD 3 bass decade 1/3 octave warble tones track. I agree the 2 dB hump really threw me also, since I had always believed that wire was wire and once you got a big enough one it didn't matter anymore. I was using the digital meter so under just the right circumstances it could have been a 1.1 dB difference.

There was a difference in the length of the cables, the Monster was 12 foot while the other brand was 8 foot, but I have never seen a calculated result showing that this should have made the difference in the SPL I measured. Even if it did make a difference, I would have expected this to have been consistent across the board, not varying by frequency.

Lets pretend (cause it probably will not happen in real life) that your speaker has a strong impedance dip and drops from a nominal 8 ohms to say .25 ohms. If both cables were of simular guage then the longer ones could have a little more resistance in them and not deliver the exact same current to the speaker that the shorter one did at the frequency of the impedance dip. This type of situation is where the difference could be frequency selective.

I am impressed with your testing method. Three identical measurements with test signals would imply valid results. I for one feel that the differences are very large and would like to have others see if they can find results of this magnitude. Was the test conducted while only one speaker was playing? That would help to remove some reflection problems and the effects of the other speaker. Chris