Subwoofer Setup

Bob Katz

To whom it may concern,

I read the very informative article regarding setting up subwoofers but I just wanted to ask a few questions as I’m a little confused by the terminology used.

When setting the crossover frequency it mentions using “filtered pink noise”, is this the same as pink noise that has been band-pass filtered e.g. if I wanted to set my crossover to 120hz I could use pink noise that has been band-pass filtered to 120hz?

My other question is what is meant in the article by the raise in filtered pink noise “pitch”, what am I listening out for? The only difference I can hear is loudness as I adjust my crossover frequency higher and higher. When I listen out for the pitch change from the subwoofer do I turn off the satelite speakers?

I hope my questions aren’t too confusing, any help or advice would be greatly appreciated. Thank you.

Kind regards,

My answer:

Ultimately, the best tool for adjusting a subwoofer properly is to use an FFT analyzer and test microphone. But in the absence of those tools you can do a pretty good job as I described. 

Yes, filtered pink noise means pink noise that has been band-pass filtered. The cool thing about it is when you are setting levels of the sub and the mains and the crossover frequency, you can hear the pitch shift upward or downward if the amplitudes of the sub and the mains are not matched. So if you can filter pink noise to a narrow bandwidth you can use it as a tool to manually adjust subwoofer level, polarity, phase, etc. I used to have that filtered pink noise available as a test CD but nowadays it’s not easy to get that onto CD so I have to turn that into individual WAV files for download. Sorry, I haven’t gotten to that yet! I’ll try to get to it before the end of the year and put it up.

I repeat, that sets the amplitude perfectly at the crossover frequency but does not tell you as much about the linearity of the system as an FFT analysis would accomplish. The same deal with the Rebekka Pidgeon music test I describe in that article. It’s great for a subjective evaluation and help you set your subwoofer level if you have good acoustics and don’t need to run parametric EQ on the sub. 

Hope this helps,