This is the schematics of Schaffner FN2030-4 line filter. Current rated up to 4A.
Did you bother reading their site with respect to impedance used to measure transfer function? I assume not despite the fact that I pointed that out to you. Here is their white paper on "50" ohm test per CISPR 17:
https://www.schaffner.com/fileadmin...note/Schaffner_AN_CISPR17_Measurements_E8.pdf
They go no to say:
So no wonder the "industry" likes to use 50 ohm, damn the reality of it.
It was disingenuous of
@KSTR for not mentioning this and instead saying,
"It's not immediately clear if Amir's insertion loss measurement used the industry standard input and output termination impedance of 50Ohms? If not, it is not really useful. "
Not really useful? Following an industry practice that uses fictitious impedances is useful instead?
Even if we cared to follow the industry to sell such products, these measurements are not aimed at audio frequencies. The lowest range specified in the standard is 9 kHz. Again from the same doc:
See how the lowest frequency is 10 kHz (often written as 0.01 Megahertz) and goes up to 1 MHz? They do that because the intent is to get rid of emissions that cause you fail regulatory certification and interfere with radio operation. Not because they are trying to examine efficacy for filtering noise in audio band. If I had followed the "standard" you would not see anything below 9 kHz which would make such measurements useless.
And it is not like you are given any such measurements from the companies whose products I am testing. Where do you find a single graph showing the transfer function? If they had such, sure, we would try to match their test conditions to verify. But in absence of that, using any test means is fine as long as we are consistent and are using it as a first order approximation of whether they device is doing any filtering and if so, by what order magnetite.
So stop following someone else's futile attempt to justify these boxes without understand what it means. You are filling all these review threads with nonsense of no value....