Actually it's a resonation.
They are happening in every piece of operating electronics on the planet, at more and lesser degrees.
The questions are which to address, and which to live with over others. Generally we deal with the over obvious ones that blow up capacitors. However there are others that should be dealt with, if you're goal is as best as possible instead of adequate (Audiophile).
Did not saved it since I used my Tektronix 2225. I need to open soon my last-made filter box in order to rewire some things inside, then I'll take screen pictures of measurements.
In general, my house power is not very clean (it is because I live in very close distance to Micron Technology manufacture Fab) and in addition I have about 1.7 VDC RMS between N and GND.
All true, even RIFA X-caps explode after more than 10 years. All the other X-caps I "build" myself with 0.1uF+100R boutique highend components still working after 20 years.
Did you ever tried to clean up the mess in an expensive component, not to speak of the devilishly stubborn smell...yuck
No thanks, Philips, RIFA, WIMA = nevermore!
I use ones that look like this, price determines in part which I use. Vishay, Kemet, EPCOS, it varies a bit. But I haven't used any PHE426 like stuff from Kemet (formally Rifa line). I don't use Wima unless it's a very specific shape I need.
An externally hosted image should be here but it was not working when we last tested it.
The only ones I trust from the bunch of non-highend caps are the over 1kV caps from WIMA. They are robust.
I came across an interesting paper that used vibration testing to identify when a transformer was experiencing DC bias that caused onset of half-wave saturation.
http://www.uni-stuttgart.de/ieh/forschung/veroeffentlichungen/2012_Usability_of_Vibration_Measurement_for_Power_Transformer_Beltle.pdf
The concept is that normal vibration is at twice mains frequency, and that can be discerned by an accelerometer attached to the transformer. Adding a level of DC bias that causes on set of saturation then causes additional vibration forces at just the mains frequency. A spectrum of the accelerometer signal shows that up.
Of course, you could also try and use a microphone, or your ears!
Perhaps one means to test that your blocker is working (if the DC bias is somewhat continuous and not dynamic in nature).
http://www.uni-stuttgart.de/ieh/forschung/veroeffentlichungen/2012_Usability_of_Vibration_Measurement_for_Power_Transformer_Beltle.pdf
The concept is that normal vibration is at twice mains frequency, and that can be discerned by an accelerometer attached to the transformer. Adding a level of DC bias that causes on set of saturation then causes additional vibration forces at just the mains frequency. A spectrum of the accelerometer signal shows that up.
Of course, you could also try and use a microphone, or your ears!
Perhaps one means to test that your blocker is working (if the DC bias is somewhat continuous and not dynamic in nature).
Unfortunately I have found that the DC effect is very variable and over a short time scale.
I can hear it on the bench rising in volume and falling back, over a 2 to 4second duration. Yet often I don't hear anything at all.
Andrew, it is question mainly for you....
I installed DC blocker (rectifier and 2 10kuF caps) into my headphone single MOSFET amp and sound became very bright. Mid-highs and heights are dominated. Removed it and everything got normal. Why such shift? Since Ele caps are doing most of work there, may be my caps are bad? I tested them and see no spec violation for capacitance and ESR. Please share with your opinion.
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I installed DC blocker (rectifier and 2 10kuF caps) into my headphone single MOSFET amp and sound became very bright. Mid-highs and heights are dominated. Removed it and everything got normal. Why such shift? Since Ele caps are doing most of work there, may be my caps are bad? I tested them and see no spec violation for capacitance and ESR. Please share with your opinion.
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That's is impossible its your imagination !
The blocker is just balancing the mains and that should have no effect on sound or at least an absolutely minimal effect.
First of all, you're absolutely right and I do have very reach imagination. But... it works towards certain aspect of our live which I can't discuss here on our forum. Amdin will kick me off right away.
In serious note, and if you remember my previous posts, I also claimed that such device might stop mechanically originated noise on toroids by removing little DC "component" from main AC. Guys replied back that DC might and usually do some sort of saturation on toroid's core. It probably might and for sure it is depend on how much DC is exist in your AC line. In my case, it is going up and down, but I have about 1.8VDC as Max value and also question if I measure it in a correct way. I tried to use my simple blocker in order to see if I have any changes and believe me, I trust what I hear (I hope I do not have a schizophrenia with the imaginary voices).
In serious note, and if you remember my previous posts, I also claimed that such device might stop mechanically originated noise on toroids by removing little DC "component" from main AC. Guys replied back that DC might and usually do some sort of saturation on toroid's core. It probably might and for sure it is depend on how much DC is exist in your AC line. In my case, it is going up and down, but I have about 1.8VDC as Max value and also question if I measure it in a correct way. I tried to use my simple blocker in order to see if I have any changes and believe me, I trust what I hear (I hope I do not have a schizophrenia with the imaginary voices).
1.8V is quite a high amount of DC. toroids would not like that at all. I think your caps sound too small.
My lovely house is about 2 miles far from Micron Technology Inc R&D and Manufacture fab in Boise. So, my AC is very contaminated by all that powerful semiconductor manufacture equipment (RF and plasma generators, vacuum and pressure pumps, deep UV lasers impulse generators and ext..). So, no surprise for me that I see 1.8 VDC sometimes in my relatively new house receptacles. BTW, it is constructed in 2006 with all contemporary electrical codes and USA NW construction standards. No errors with N and GND in house.