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

[Steve Harris]

On Wed, Oct 23, 2002 at 02:37:17 +0200, Tim Goetze wrote:
> still i'm not convinced that a sine should only be compressed
> if < 0 by valve_1209.so.

Well, the valve plugin is an aproximation of a single valve, a guitar amp
has several if I understand correctly.

To make distortion I generally use a softish valve followed by some stuff,
followed by an inverter (to make the DC offset smaller), followed by some
stuff, followed by a harder valve. That will give something roughly like
the scope shot Paul posted after this.

Stacking the valve plugins is the key to making them sound interesting.
As I have said before, if someone comes up with a chain of effects that
sounds even vaguely like a guitar amp I will combine it into one plugin.
That should be easier to use and faster.

I dont think the sign of the signal will effect the sound of the output,
just the appearance. Remember the DC offset and the phase shift. The
valve plugin has none, I would expect a real valve to have a fair bit. It
shouldn't noticably effect the sound though.

> i've copied (950 + 50 silent) samples of each into
> http://quitte.de/fender-sine.wave -- the quitte.de quota is 

Cheers. Just looked at it. It was what I was expecting from your
description.

> >Infact, this should just happen, if you use the crossover plugin and
> >put the output through your speaker cone IIR you should see a similar
 
> yup, it definitely looks more like it on the scope. but the 
> aliasing the crossover introduces is simply unbearable. i think 
> i'll go for a ride and show some waves to the guy who fixed my 
> fender amp recently, he knows a lot about the circuitry.

The crossover plugin was a shot in the dark, based on a vague description
of the effect by someone who understood the electronics. Now I have seen
your recording, and have applied some brain power to it it's obvious what
I did wrong, and how to fix it.

- Steve