[linux-audio-dev] Diode wave shaper (LADSPA plugin)?

Erik de Castro Lopo erikd-lad at mega-nerd.com
Mon Aug 16 06:45:49 EDT 2004


On Mon, 16 Aug 2004 12:13:51 +0200
Alfons Adriaensen <fons.adriaensen at alcatel.be> wrote:

> This is a bit too simple. The diode circuit does not perform hard
> clipping when driven at moderate levels.
> 
> Something like 
> 
>   out = tanh (in)       (or tanhf() if available)
> 
> or
> 
>   out = in / sqrt (1 + in * in) 

Both of those would probably sound better than what I posted,
but the original circuit had a 12k source impedance. As soon
as the the input overcomes the forward voltage drop of the
diodes the impedance of the diodes drops to the low hundreds 
of ohms.

If you Spice the given circuit I think you'll find that the
output looks a lot more like what I posted than either of
the above.

Erik
-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam at mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"Lumping configuration data, security data, kernel tuning parameters,
etc. into one monstrous fragile binary data structure is really dumb."
- David F. Skoll


More information about the linux-audio-dev mailing list