[PD] why do [bp~] and [vcf~] sound different?

[Ichabod]

(posted this on the Pd forum, but it was suggested that I e-mail the list as
well, so here I am out of lurk mode)

I was working on some patches with bandpass filters that were initially
[vcf~], but I ended up deciding not to vary the center frequency, so I
replaced them with [bp~].  Now I find that [bp~] sounds different; e.g., a
[phasor~ 100] going through a [bp~ 440 3] sounds different from one going
out the left outlet of a [vcf~ 3] with [sig~ 440] going into its center
inlet.  I couldn't find anything in the help files indicating that they're
different other than using control vs. signal for the center frequency, so
what's the deal?  How do I replace a non-varying [vcf~] with a [bp~] that
sounds the same?

--Stefán
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