ahhh - never mind (except the "best practices" part - i'm still totally interested in that ;)
i had a bad understanding of "q" (confusing "q" with bandwidth). i was set straight by this excellent guide: http://www.tonmeister.ca/main/textbook/electroacoustics/01.html
An inherent problem in this type of filter is commonly known of as "ringing." This is "the tendency of a filter to resonate at its natural frequency when excited by a sine wave pulse at that frequency." This effect is present to some extent in all equalizers but is of a low enough level to be masked by the remainder of the signal. It does, however, become excessive with filters with a high Q. At Q=0.5 the circuit does not ring and is said to be critically damped. Higher values of Q, however, will result in ringing for more cycles as the bandwidth becomes narrower.
On Wed, 2004-04-21 at 15:59, Star Morin wrote:
howdy -
i'm working on a 6 band eq, and was wondering if folks have any recommendations on a problem i'm having with it.
i use noise~ as the sound source, through 6 bp~'s (with frequency ranging from 60hz to 12k) through 6 *~'s w/ a range of 0-2. all of the "Q"s set to 20.
my problem is that 2 of my middle(ish) frequency bp~'s (800hz and 1k) are creating a distinctly noted sound... why is this? what would be considered "best practices" in creating a multi-band equalizer (q and frequency ranges, etc) in pd?
thanks!
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