Talk:Band-pass filter

message: The rippling in the frequency response of a filter has ABSOLUTELY nothing to do with the Gibbs phenomenon (the so-called "overshoot" response in the time domain to a filtered step function).  The "ripples" in the frequency domain for some filters (e.g. Chebyshev filters) are a design choice, unlike the "Gibbs phenomenon" which is unavoidable mathematically.... Aargh.
90.17.171.36 14:41, 15 June 2007 (UTC)
thread_title:  Discard "Gibbs phenomenon" reference 

message: What order of filter is the example in the article? -- ∞Wirelain 03:56, 10 July 2006 (UTC)
replies: text: True, and the word "bell" is nowhere in the article.  But I agree the example figure is misleading and atypical, and the caption is complete nonsense. Dicklyon 01:16, 8 April 2007 (UTC)

text: I don't see any indication that it should be a Bode plot.  But as I said, it's misleading and atypical, and therefore really NOT "more than adequate". It's particularly inadequate if it gives wrong impressions. Dicklyon 21:22, 25 April 2007 (UTC)

text: The plot has been replaced with one that is less bell shaped and more bandpass shaped.  It is not a Bode plot.  The ordinate is linear, and the abscissa is unspecified. Dicklyon 07:17, 28 June 2007 (UTC)

text: Square shaped bandpass can be obtained by using crystal filters  —Preceding unsigned comment added by 193.71.218.226 (talk) 11:21, 9 April 2010 (UTC)
replies: text: No filter class can produce square filtering - only close approximations to it. SpinningSpark 11:51, 9 April 2010 (UTC)
thread_title:  The example; 

message: Since Wah pedals are probably the most famous implementation of a Bandpass filter; shouldn't they be mentioned?  —Preceding unsigned comment added by 143.239.7.1 (talk) 15:48, 27 October 2007 (UTC)
replies: text: Sure they should; but not without a source. Dicklyon 17:05, 27 October 2007 (UTC)
replies: text: The wah-wah pedal is a bandpass filter with that is also tunable. "Most famous" is nonsense except among a few electric guitarists and must not be claimed in the article. Cuddlyable3 (talk) 09:28, 2 August 2011 (UTC)
thread_title:  Wah Wah 

message: I see that other filter pages have formulas.  Why doesn't this one.
I was looking to see if the formula for the center frequency uses the one I discovered in the early 80's.  I have not seen it anywhere, yet.  The formula is Fo=√FlFh (sorry, new to wiki don't know how to make sqrt look correct). ClydeCoulter (talk) 05:58, 1 October 2009 (UTC)
replies: text: \textstyle \sqrt {f_1 f_2}  is the formula for the geometric mean of the two end frequencies.  Center frequency more usually means the arithmetic mean \textstyle \frac{f_1 + f_2}{2}. Both of these, in general, will be different from the resonant frequency of the resonators which depend on filter design. SpinningSpark 06:42, 1 October 2009 (UTC)
replies: text: \textstyle \sqrt {f_1 f_2}  is the logorithmic center which does apply to a simple bandpass filter.  The older usage of calculating the center frequency using \textstyle \frac{f_1 + f_2}{2} is way off in the audio range of frequencies.  This could be discussed on the bandpass page with examples. (thanks for the example of markup for these formulas) ClydeCoulter (talk) 11:04, 1 October 2009 (UTC)
replies: text: It depends on your application.  FM for instance, is usually aiming for a linear deviation of the carrier, arithmetic mean is the most applicable concept.  In audio you are probably looking for the centre-frequency which has an equal number of octaves either side; that would be the geometric mean.  There are many other possibilities for mean. SpinningSpark 20:43, 3 April 2010 (UTC)

text: Yes, someone, I guess me, ought to put up the formula in terms of the convolution with the sinc function. It is used in textbooks like all the time.200.55.128.88 (talk) 18:22, 5 November 2014 (UTC)
thread_title:  Bandpass Formulas 

message: Hey all, as can be seen on the RLC circuit page, http://en.wikipedia.org/wiki/RLC_circuit, Kilroy is actually a band-STOP filter. Is Pynchon wrong, or was this added to the wrong page by mistake?  I'm removing the Kilroy reference until it can be decided, as it could lead to confusion w.r.t the circuit.
:Yes, it looks like Pynchon was in error, unless that circuit fragment was used in a shunt leg.  But check the ref to V; it's on the right page.  We can still use it, as long as we attribute what he said, rather than repeating the error as fact.  So I fixed it.  Dicklyon (talk) 06:18, 29 May 2010 (UTC)
replies: text: Perhaps he meant to say "Kilroy stopped here". SpinningSpark 11:49, 29 May 2010 (UTC)
thread_title:  Erroneous use of Kilroy