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Math + Logic + Science = something completely mad...

So, I've done a metric fuckton of research, notwithstanding the clear bias the man who designed and built my Belles has against esoteric cabling.  And here's the conclusion to which I arrived. 

My monoblocks are sitting on top of the speakers.  The distance from the amp to the speaker is barely a foot, which is exactly how long a run of wire I intend to use.  Goal is to minimize the effect the wire has on the sound.  

According to the calculations I've seen and done, the skin effect depth on copper wire at 20Khz is 461 micrometers.  Meaning a 19-gauge copper wire (911 mics diameter) would reduce skin effect to zero.  As in no impact whatsoever on the signal. 
 
Of course, it's actually very difficult to find 19-gauge wire.  18-gauge (1024 mics) is much easier, and the skin effect is near zero, but not quite zero.  Seems to be an acceptable compromise. Could go down to 20-gauge and eliminate skin effect entirely.  If I could find insulated aluminum wire, 18-gauge would eliminate skin effect entirely, because skin effect depth on aluminum at 20khz is 580 mics.  

12 inches of 18-gauge wire produces 0.006 ohms of additional resistance.  20-gauge = 0.01 ohms.  

Frankly, I don't see the value in spending big bucks on esoteric, heavy-gauge wire for this application.  I'd rather make the bigger investment in the 2m runs from the preamp to the blocks, because that's where the wire's going to have a hell of a lot more of an effect on the sound.  

Stepping back to allow you all the opportunity to punch holes in my thought process here. 
jerkface
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jerkface OP
73 posts
 
I still like mogami for RCA though they are on the expensive side I think they're constructed very well and sweetwater is great to do business with.

We're on the same page regarding Sweetwater.  Just bought a 7-string multiscale axe from them a few weeks ago, been doing business with them for years.  

kijanki's avatar
kijanki
4,428 posts
 
Those amplifiers had lots of feedback, but very poor gain bandwidth product. That was why they had bad distortion products, and why they had poor output impedance at high frequencies.
They had excellent THD and IMD.   Designers were sure they have to sound great.  In 1969 I almost bought inexpensive 100W amplifier modules with incredibly low THD and IMD.  NFB increases bandwidth and reduces output impedance.  40dB of negative feedback will reduce output impedance 100 times.

Even when RF gets in, short of causing oscillation it may not even do anything.
You don't even need nonlinear element, like diode, to demodulate.  It is enough if amplifier's slew rate for positive and negative signal is different to demodulate, for instance, AM radio.  It is called "rectification phenomena" and is very common to opamps.  

Yes, high impedance nodes are sensitive, but output of an amp, in spite of lower impedance (many ohms at high frequencies), is an input to the amplifier with 100x higher gain (for 40dB NFB) than amplifier's normal input.  We want to reduce phase delay (improper summing of harmonics) at high frequencies caused by limited bandwidth.  For that we increase bandwidth to more than 100kHz  (my AHB2 has 200kHz@-3dB)  getting very close to AM radio stations, not to mention switching frequencies of SMPS present everywhere (computers, TV) and even LED bulbs.

kijanki's avatar
kijanki
4,428 posts
 
I am wrong about 100x higher gain, since only fraction is fed back to the summing junction, but it is in the same level as nominal amplifier’s input. It won’t be as sensitive because of lower impedance, but will still inject noise picked up by long unshielded speaker cable.
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