Subject: Re: [linux-audio-dev] [ann] unmatched - a LADSPA amp tone
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Thu Oct 24 2002 - 16:02:06 EEST
On Thu, Oct 24, 2002 at 01:19:20 +0200, Tim Goetze wrote:
> >I'm 90% sure its from the crossover between the two halves of the class B
> >amp (thats the power amp IIRC).
>
> drat. i wish i was better at understanding electronics.
> the amp guy pointed in this direction too.
Did he give the impression that he though it was an important part of the
sound? I'm not clear on this.
> the aliasing is not that strong, you're right. maybe i'm
> over-sensitive.
No, no. Aliasing really ruins analogue effects IMHO. On Friday and/or over
the weekend I'm dig out my bass and try it.
> what i gather from the scope shots and the analog distortion
> guy's pages is that we want a range of clipping from none to
> square. if we're going implement 'square' clipping -- which
Yes, that sounds about right.
> we'll need for the real rough tone -- we'll have to come up
> with a bandlimited solution. the current valve clipping is
> real soft compared to those scope shots, isn't it? if we
> stack the valve to get to hard clipping, the net result will
> carry the sum of all aliasing i'm afraid.
Yes, it will compund it. I can't think how to apply oscillator
antialiasing to wavewhaping though. Maybe it can be done.
> my feeling is that oversampling alone will not do, although
> you're probably right in that it will get rid of most of
> the aliasing.
Its how most people tackle to problem. I think I can get the valve cheap
enough that it will be practical.
> i'm thinking about how to apply the technique to produce
> square clipping, or better a [0 .. 1] range of clipping,
> but the integration approach is awkward.
I doubt that the electronics ever produces hard square clips.
- Steve
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