Re: Help requested on blind cable test

[EMAIL PROTECTED] (Svante) wrote:

>I have performed blind tests with music, and I could hear a first
>order 47 kHz lowpass filter. Yes, I had a random generator connecting
>the filter for me, and seven correct responses out of seven tries,
>giving me 99% confidence. Need I say that the difference was not
>large? 

Most likely you heard changes due to phase shift which start to get
noticable at 1/10 of the frequency of your filter, in this case at
about 5 kHz. You may repeat the test but use pink noise rather than
music and you should no longer be able to detect the presence of the
filter.

>Note that this does not not mean that i hear frequencies at 47
>kHz, sadly the limit is somewhere around 15kHz nowadays, but a 47 kHz
>first order lowpass filter has a drop of about 0.42 dB at 15 kHz and I
>am pretty convinced that this is what I heard.

So I think that you didn't hear the 0.42 dB drop at 15 kHz but the
phase shift. OTOH, at 7.5 kHz the drop ist 0.2 dB which may not be
audible as loss of trebble but as a slight veil on the music.

Norbert