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Snarfie

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#1
Found this recent interview on Stereophile. At minute 28:00 they addressed the RF distortion picking up by cables like speaker, AC other cables acting as an antenna causing a Amp sounding different because of RF distortion. Knowing this problem will be here for the unforeseeable future (think of powerfull wifi routers signals etc) they suggest you have to develop gear such it has a minimal influence on the measurements an eventually sound. They even suggest that because of this RF phenomenon amp's for instance could sound different not because where cables made from (silver OFC copper etc ) but because of RF interference which could explain the cable snake oil phenomenon. Found it a quite interesting interview.


Does my cable tray qualify for a RF antenna :facepalm:

 
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Cbdb2

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#2
RF interference is not new. Electronics have dealt with it for 100 years. Why havent these guys done the measurements they talk about? As easy as a scope on the speaker leads of the amp with no music playing and the amp turned on. Why hasnt any of the cable companies done this? Because it shows no problem.
 
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Snarfie

Snarfie

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Thread Starter #3
RF interference is not new. Electronics have dealt with it for 100 years. Why havent these guys done the measurements they talk about? As easy as a scope on the speaker leads of the amp with no music playing and the amp turned on. Why hasnt any of the cable companies done this? Because it shows no problem.
They argu if the low impedeance of the amp is at the same level as the RF it's ok if not it could cause problems an probably a change in sound. So i see it more as an open question.
 

Cbdb2

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#4
That first sentance isnt clear. A question thats easily answered with a couple of measurements. Measure the RF at the amp output and at the negative feedback point ( thats what matters since RF at the output needs to get to the input to cause changes). Look at any power amp and look at all the caps and resistors the RF at the output has to go thru to get to the feedback. How much of that 2 uV ( a speaker cable is a terrible antenae) is actualy getting there. And all you need to do is put a small bypass cap at the output if theres a problem. Which nobody does, because you dont need to fix a made up problem.
 
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#5
Most amplifiers made today already have an output inductor and a zorbel network which work pretty well to attenuate RF. If you lived next to a radio transmitter, adding a secondary zorbel network would likely fix any such problem. Not an issue with most locations and equipment.
 
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