Subject: Re: [linux-audio-dev] [ann] unmatched - a LADSPA amp tone
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Thu Oct 24 2002 - 19:36:52 EEST
On Thu, Oct 24, 2002 at 05:32:22 +0200, Tim Goetze wrote:
> >I suspect this dip is some kind of reflection from the limit, but I can't
> >tell without trying one.
>
> you mean you intend to change valve to have adjustable
> slope where it compresses? sounds good, if that is what
> you mean.
Nope, that would be hard ;) I was thinking of having a second, hard
clipping alg. and bringing that in for high ampltudes.
> i did some testing with a simple
>
> in -> valve -> invert -> valve -> convolver -> out
>
> setup and it's beginning to sound like fairly good
> distortion when the input signal is strong enough.
> aliasing is very, very faint, with both valves set
> for maximum saturation (and "character" = 1.). could
> use some more saturation/clipping though.
Yes. Its not really meant to be distortion at that level, more of a
saturation thing. I usually put something hard in the middle (near the
inverter, a cliper or sinus wavewrapper, something like that. Probably
wont make a good guitar sound though.
> two things: 'in' should probably be HP-filtered, because
> the low frequencies become too dominant. and the valve
Yes. Aparently they do this in the hardware too.
> clipping is too strong at low input levels. it seems to
> adapt the clipping level to the input level. i think that
It doesn't. there are no time domain effects, and it doesn't adapt to
amplitude - just a static trasfer function. It could be an interrelation
with the two valves, but I dont think so...
> it should rather have a certain threshold beyond which
> saturation becomes more noticeable. 'weak' input sines
> are flattened almost completely, at very low amplitudes,
> rendering a sound resembling that of a torn speaker.
Try turning down some of the parameters. You wont get good, hard
distortion out of the valves, more of a natural warmth.
- Steve
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