John Dunlavy On "Cable Nonsense"

You can invert the polarity of one channel and measure accross the positive leeds at the speaker, with a mono source you will then be measutring the difference between channels. Then with different cables on each channel, you will be measuring only the difference caused by the cable and since the differences will be very low you can add amplification to bring the signal above the noise floor of your sound card. An intersting variation of this descrived by Hafler allows you to listen to the difference signal directly.

Sqjudge,
Can you suggest any components for doing this measuring and testing.
Only 96db sensitivity?
What about taking an A/D converter from someone like dcs which is really high quality and take the digital out of that and do the measurements?

Is there a PC interface for TOSLINK or ST link????

Trappist: The quick answer ... No I do not have any recomendations for equipment. The resolution om a 16 bit system mathamaticaly is around 86 db. It would be higher for a higher bit a/d converter but that is not the problem with making high accuracy measurements. Yhe problem is the noise floor of the analog front end of the converter. Therman noise and resistor noise (thermally related btw) would limit the actual resolution of the system. It would require cooling (like liquid nitrogen) to get the thermal noise low enough to get 110 db range accuratly. I do not believe a computer can be effeciently used in a near absolute zero enviroment. Chris

Thanks Chris. Clearly you're knowledgeable! Seems though that digital source equipment can't produce quality up to what we can hear, so we can probably measure at a similar quality level and get some meaningful results.

The dcs 904 will sample at 192 khz 24 bits.

But then of course, the cables could have such subtle effects that these measurements won't be meaningful. The differences I have heard with interconnects though lead me to think that they could be measured fairly easily. l liked lemme's idea of inverting channel polarity and comparing that way with different cables on each. Very clever.

Trappist.

I have to say I would agree with those who hear differences in speaker cable. These differences are measurable with a SPL meter.

Here are some measurements of speaker cables I have taken with a Radio Shack meter. This was comparing Monster MC1 (I think that was the type) versus another cable. The differences in the cables were actually greater in the mid ranges and treble end (to my ear), but I took these measurements because I was trying to diagnose and tame some bass problems I was having with the speakers. I did alternating tests Monster - Other Cable - Monster - Other Cable - Monster - Other Cable, and the results were consistent. The source for these measurements was the Stereophile Test CD 3 bass decade 1/3 octave warble tones.

Freq. Monster Inexpensive Delta
200 83 84 +1
160 83 84-85 +1.5
125 81-82 83-84 +2
100 86 87 +1
80 92 92 +0
63 85 85 +0
50 82 82 +0
40 81 81-82 +0.5
31.5 74 74-75 +0.5
25 73 73 +0
20 66 67 +1
As you can see there are some very definate differences on this most basic of all tests, which is able to be conducted by anyone with $50.00 and enough gumption to do them. Forget measurements we can't make yet or don't know to make yet, while I think there are some out there, but let's stick to what we can measure now.

How about some people actually measure some cable out there instead of just making unsubstantiated claims that all cable sounds the same or vice vesa?