Subject: Re: [linux-audio-dev] [ann] unmatched - a LADSPA amp tone
From: Tim Goetze (tim_AT_quitte.de)
Date: Wed Oct 30 2002 - 23:30:48 EET
Steve Harris wrote:
>> http://quitte.de/sine-spectrum.gif
>> http://quitte.de/straight-spectrum.gif
>
>The sine spectrum looks pretty close to me, except that some of the low
>harmonics are too high, probasbly cutting back some of the parameters to
>the valve would fix this.
i've been mucking around a little but it seems real hard to
make the harmonics fit, especially with such a wide range of
possible mixes being aimed at.
>I was planning to vary the generated harmonics with incoming
>amplitude, but it doesn't look like this is the right appraoch, there are
>allready plenty of strong harmonics, a cheby would just make it muddier.
i can't say i really like the idea of dynamic parameters,
sounds a bit messy to me. to make it work smoothly, there'd
be some discontinuity every time parameters change, or one'd
have to overlap blocks, and how would one go about choosing
their size to begin with ...
>The strong presence of low harmonics is probably the cause of the
>softness.
it seems hard to come up with a wave shaper that favours higher
harmonics, i've tried some in the past few days. most of the
shapers that compress the waveform favour even harmonics, while
shapers based on even powers of the input sample generate only
odd harmonics. they're hard to distribute though. afaict, the
mechanism is refined in the chebyshev (even powers = odd harm.
and vice versa).
tim
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