Is this 20khz or is it only close?

[Artemis]

I've used the 20-20khz frequency test and I get very slight, almost unnoticeable static when it's close to the end. I want to know if this is 20khz, or if it only comes close:

[Artemis]

Bumping for an answer.

[Shawn]

Well, I don't know about your test volume, but I have got a much higher amplitude at the whole frequency range.

[swisston]

Mine looks like this when listening to a normal sub:

[Leo1990]

how do i test?