Re: [linux-audio-dev] [ann] guitar preamp plugin, v2

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Subject: Re: [linux-audio-dev] [ann] guitar preamp plugin, v2
From: Tim Goetze (tim_AT_quitte.de)
Date: Mon Nov 03 2003 - 19:21:45 EET


Steve Harris wrote:

>On Sun, Nov 02, 2003 at 10:49:17PM +0100, Tim Goetze wrote:
>> the frequency response is mostly due to the oversampling filters;
>> unfortunately i am at a loss for good realtime-compatible design
>> methods for those. it would well be possible to recalculate them
>> (chebyshev prototypes) but that would take quite a few cycles, and
>> knowledge about how to move the ripple/s in a chebyshev design
>> (anyone?).
>
>Have you tried polyphase filters? I've never used them but I've heard they
>are good for oversampling.

i don't have any precise cycle-consumption figures (a good reason to
try the polyphase filters one day) but i seem to remember having
figured that they come at equal or bigger cost for comparable stopband
attenuation.

then, their peak at 2 - 3 kHz made me go with the current filters
because it is a characteristic of the circuitry i investigated, and it
comes for free. just seemed to fit so nicely, and i could use the
tools i know best.

though one day i'll try the polyphase design for some exact figures.

>Nice plugin BTW, I've noot been able to play it myself (my guitars ill),
>but the sample recording sounds great.

thanks, it's lovely to hear that from 'Mr LADSPA'. :))

tim


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