Subject: Re: [linux-audio-dev] Re: Cheby amp code
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Mon Nov 04 2002 - 01:20:56 EET
On Sun, Nov 03, 2002 at 08:06:53 +0100, Tim Goetze wrote:
> >> i'm not up to understanding all implications of the fact that the
> >> incoming signal is not a pure sine; neither do i have a recipe for
> >> preparing the coefficient tables -- if we scale the individual
> >> coefficients by 1/sum their mix will not match what we want.
> >
> >I think we should probably abandon the cheby approach for now, this
> >combined with the freqency dependency problem probably makes it a looser
> >:(
>
> yep, it doesn't seem to be getting easier the more we look at it.
> the above approach could bring us close, but it does need xfading
> and two chebyshev shapers.
We'd also need to split up the incoming signal by frequency though, and
that would make it expensive to run.
> been thinking about how to do a hard clipper with sinc some more
> today, without real results though.
Yeah, I think thats difficult, and probably not neccesary, the "hard clip"
from a guitar amp doesn;t look very hard to me, so I recon you could just
apply the shaper, plus a bit of oversampling, a LP filter and it'd be
fine.
Remind me: what was the thing that put us off chains of models? Was it
just the messy bottom end? Or was there more? I'm pretty sure I can fix
the muddly low harmonics and it sounds like other people aren't modeling
the variation in harmonic amplitude with signal amplitude, so maybe it
isn't important.
- Steve
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