Ralf11 Posted November 22, 2016 Share Posted November 22, 2016 I see a lot of posts about noise on here, but has anyone ever measured their line noise (AC noise)? Also, it seems Aussie-land has a lot of line noise problems. If so, why? Link to comment Share on other sites More sharing options...
Cebolla Posted November 22, 2016 Share Posted November 22, 2016 Also, it seems Aussie-land has a lot of line noise problems. If so, why?Interference from all that chatter, perhaps? - Pommy bashing, moaning about the current state of the Baggy Greens, general mouthing off, ... We will win because our NHS is the beating heart of this country. It is the best of this country. It is unconquerable. It is powered by love. -- Boris Johnson We are far more united and have far more in common with each other than things that divide us. -- Jo Cox Link to comment Share on other sites More sharing options...
mansr Posted November 22, 2016 Share Posted November 22, 2016 Also, it seems Aussie-land has a lot of line noise problems. If so, why? I don't know about noise, but they have a lot more sandyk. Link to comment Share on other sites More sharing options...
Speedskater Posted November 22, 2016 Share Posted November 22, 2016 One has to know what they are doing to measure AC power line noise without damaging the test equipment or having the test equipment become part of the noise problem. But the real measurement should be how does the noise affect the audio output of the hi-fi system. For that a battery powered RMS DMM and/or a battery powered O-scope at the amp's speaker terminals is the best test. Well designed hi-fi equipment should be able to deal with a dirty AC power line. Link to comment Share on other sites More sharing options...
Ralf11 Posted November 22, 2016 Author Share Posted November 22, 2016 Yes, "Well designed hi-fi equipment should be able to deal with a dirty AC power line." That's why I am curious about all the posts on this issue. I do have a Tek scope too.... Link to comment Share on other sites More sharing options...
One and a half Posted November 23, 2016 Share Posted November 23, 2016 Here's a couple of shots showing noise. Worthwhile to remove. This is the FFT at the speaker terminals of a JC1 amplifier with a stock power cord. It's full of harmonics and shite. This is a screen shot of my speaker's terminal voltage FFT. Just the fundamental exists. AS Profile Equipment List Say NO to MQA Link to comment Share on other sites More sharing options...
mansr Posted November 23, 2016 Share Posted November 23, 2016 Here's a couple of shots showing noise. Worthwhile to remove. [ATTACH=CONFIG]30993[/ATTACH] This is the FFT at the speaker terminals of a JC1 amplifier with a stock power cord. It's full of harmonics and shite. That's an 8-bit scope. You won't get a cleaner reading than that. [ATTACH=CONFIG]30994[/ATTACH] This is a screen shot of my speaker's terminal voltage FFT. Just the fundamental exists. What measurement device is that? What is the measurement supposed to prove? These images show the presence of a 60 Hz tone. If this is power line hum making it to the amp output, it only proves that your amp has a problem, nothing about the quality of the mains power. Link to comment Share on other sites More sharing options...
Speedskater Posted November 23, 2016 Share Posted November 23, 2016 I'm not at sure as to just what we are seeing in those two screen shots. Don't know how a power amp with a linear power supply could pass that much 60Hz and no harmonics. Link to comment Share on other sites More sharing options...
One and a half Posted November 23, 2016 Share Posted November 23, 2016 Ok. The TEK scope picture is from the Polk Audio site posted by Raif Smith to determine which AC power cord works best at attenuating 60Hz and harmonics. Measurements were made at the speaker terminals. If you google : Studies On Residential Power Line Noise Part 1-Statement SC Power Cord you can also find more references. The article refers also to Parts1, 2, & 3 however these links are now gone from the Pol audio site. If anyone wants the full set, I have the posts, all 8 parts, PM, and I might upload to Dropbox. The other screen shot is from a Fluke 195C scope which shows a 250Hz signal fed into an amp measured at the speaker terminals. Unlike Raif Smith's TEK scope photos, there's no harmonics, just the 250Hz fed by Jriver. The 60Hz crud could be conducted leakage currents at mains frequencies by a device that loves to make them. At this power I can only think of a power amp/pre amp perhaps. Diode/cap load a possibility that can create harmonics like this. AS Profile Equipment List Say NO to MQA Link to comment Share on other sites More sharing options...
mansr Posted November 24, 2016 Share Posted November 24, 2016 Ok. The TEK scope picture is from the Polk Audio site posted by Raif Smith to determine which AC power cord works best at attenuating 60Hz and harmonics. A power cord that attenuates 60 Hz is thoroughly flawed. Link to comment Share on other sites More sharing options...
jabbr Posted November 24, 2016 Share Posted November 24, 2016 I think when we discuss various types of transformers to isolate/balance AC power we are on solid ground. Beyond a well constructed AC cord I have a hard time figuring out why I don't want to do all the filtering in my power supplies themselves. Sent from my iPhone using Computer Audiophile Custom room treatments for headphone users. Link to comment Share on other sites More sharing options...
One and a half Posted November 24, 2016 Share Posted November 24, 2016 A power cord that attenuates 60 Hz is thoroughly flawed. If I withdrew "60Hz and" from the sentence , would that be acceptable? AS Profile Equipment List Say NO to MQA Link to comment Share on other sites More sharing options...
Speedskater Posted November 24, 2016 Share Posted November 24, 2016 The charts are from Raife F. Smith II the 'DarqueKnight" ? OK that explains everything. It is best to ignore everything that he writes. Link to comment Share on other sites More sharing options...
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