Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics.

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Hi Mudcat

Posted by jneutron on February 16, 2005 at 12:01:43

In Reply to: It's not going to be in the cables either ;-) posted by Mudcat on February 16, 2005 at 11:31:09:

MC: ""How the human brain perceives localization of soundstage is not going to be in the cables.""

I did not say "how the brain perceives localization is in the cables".

What I am referring to is the fact that a 5 uSec ITD (Interaural Time Delay) shift is interpreted by the brain as a sideways shift of the perceived location of the source, to the tune of 3 inches at 10 feet distance from a pair of speakers 10 feet apart.. If the speakers are 5 feet away, and 5 feet apart, the perceived side shift is 6 inches.

Current views on "what a cable can do"...do not even consider the possibility of:
1. 5 uSec temporal shifts as being audible. from 500 hz to in excess of 12 Khz.

2. They do not consider the possibility of that shift being frequency dependent.

3. They do not consider the fact that the speaker is a current fed device.

4. That the energy storage, both capacitive, and inductive, are both lagging mechanisms, and are minima only if the cable impedance matches the load.

5. Nor that the energy stored within a non impedance matched cable set can be on the order of 4 to 5% of the total energy delivered by a 10 Khz signal. That storage, is of course, lagging.

The model of hearing you are considering is only one of IID, Interaural Intensity Difference, which is the equivalent of a pan pot.

That model doesn't even consider the interaction of ITD and IID to provide us the illusion of depth...

But, aside from all those items I've listed as being neglected, your model is dead on....

Seriously, the current model of human hearing with respect to cables...does not include two ears, only one...and it's the two ears that makes the measurements so difficult..it's trivial to measure to 20Khz, but a bear measuring temporally accurately to 1 uSec, at 4 ohms, up to 20Khz..with two channels driven..

MC: ""Only if a massive phase shift is introduced between channnels would this be a function of the cables.""

You are incorrect in your assumption..the phase shift doesn't have to be "massive"..it can be 2 orders of magnitude below that which you are capable of accurately measuring, and still cause perceivable shift in image...that is why it is taking so long for me to develop my test loads, cvr's, and v-taps..getting down into the picohenry range is not an easy one...so far, 1.5 nH is best I've done...It's probably accurate enough for what I want, but my next load rev will be capable of at least 200 watts, vs the current 50 watts. I can't stress the amp at 50 watts, and I have melted the load solder..

Cheers, John

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