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

Tim Goetze tim at quitte.de
Mon Oct 28 14:01:00 UTC 2002


Steve Harris wrote:

>That is a side effect of class B amps IIRC. I would have though that
>preamps would be class A, but maybe not.

they are, afaik. you're right, it's a property of class B. 
still my amp's preamp stage shapes the lower half differently
(less) than the top.
 
>> i'm still trying to model the hard-driven valve in the time
>> domain. the more i look at it, the more i think the 'building of
>> potentials' i've tried to describe comes near it. though it would
>> be nice to base it on hard facts about valve amp behaviour, too.
>
>'building of potentials'? Are you refering to your sinc summation idea?
>Its a nice idea, especially as you get anitaliasing for free, but I think
>it will be hard to turn a hardish clipping shape into a sum of sincs.

no, this is the other idea that would try to model a simple
wave shaper (pushing energies and so on). the sinc idea is
reserved for dire emergency situations, it's not really gentle
on the cpu and tough to get right.

>> interestingly, the sine, shaped by the hard-driven amp, looks
>> a lot like the plots of 'ion conductivity' and 'Aktionspotential' 
>> from human heart analysis.
>
>Woooosh. [that was the sound of that going way over my head ;) ]

if you could see those plots, you'd know exactly what i mean. in
fact they look almost exactly like one half of a sine cycle
after it's been mistreated by a 12ay7 valve at high gain
(quitte.de/wave.ps.gz).

tim




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