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

[Frank van de Pol]

On Mon, Oct 28, 2002 at 10:37:18PM +0100, Tim Goetze wrote:
> i'm sure frequency responses and Vin/Vout mappings for common
> amp tubes (EL34 comes to mind, too) would be very helpful, but 
> can i ask you to take a look at
> http://quitte.de/driven.gif 
> first?
> 
> it shows my badly-driven fender amp's line output (top) vs. the sine
> wave it was fed at the same time. i'm wondering how come the output 
> overshoots every time the input crosses zero. trying to model this 
> behaviour into a waveshaper, but i'm a bit lost on the physical laws
> that rule here.
> 

looking at the distorted signal it look to me like an amp that is clipping,
but it's power supply can't maintain the voltage (eg. relatively high
impendance on the powersupply/series resistance). While +ve or -ve side of
the output pair is used it drains the capacitor from the power supply, hence
the exponential slope from 'spike' till drop. 

Frank.


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| Frank van de Pol                  -o)    A-L-S-A
| FvdPol at home.nl                    /\\  Sounds good!
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