[linux-audio-dev] [ann] unmatched - a LADSPA amp tone

[Steve Harris]

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