Re: [fluid-dev] Gain distortion with many soundfonts

[Josh Green]

Glad you figured out what was causing your distortion issues.  Internal
sound card distortion is indeed a good thing to look out for and I think
it would be a really good FAQ item.  I think I'll leave the ticket open,
since there may be other causes as well.  Your findings were not an
annoyance at all, and will likely help others who might be having
similar issues.  Thanks for your investigation!

Cheers.
        Josh

On Wed, 2008-04-09 at 23:47 +0200, Bernat Arlandis i Mañó wrote:
> Thank you for your reply. I've finally found the problem and it was much 
> easier than I thought. It seems it's a pretty common HW problem. I've 
> explained it in the ticket to better document my case.
> 
> Several users on internet claimed that gain levels around 10-20 were 
> necessary to avoid distortion. Finally, I've managed having a good 
> output level from fluidsynth avoiding speaker output distortion. :)
> 
> Sorry for the annoyance, the info on internet pointed me in the wrong 
> direction and I failed to go back on track.
> 
> Cheers.
> 
> 
> Josh Green escrigué:
> > Hello Bernat,
> >
> > Sorry it took me so long to answer your question.  Unfortunately I'm not
> > sure currently what exactly causes this issue and I haven't yet really
> > put any time into figuring it out yet either.  As you mentioned though,
> > it does indeed seem like its a distortion that occurs even though the
> > sound card output is not maxed, which would indicate internal distortion
> > of some sort.  I suspect it might have to do with reverb or chorus (try
> > turning them off) or perhaps with the volume attenuation of samples and
> > how they are mixed.
> >
> > I've added a ticket for this issue here:
> > http://fluidsynth.resonance.org/trac/ticket/13
> >
> > I'm currently working on getting Swami 2.0 released after which I'll be
> > putting some more time into FluidSynth.
> >
> > Thanks for reporting this issue and your other findings.
> >
> >     Josh
> >
> >
> > On Mon, 2008-03-17 at 02:03 +0100, Bernat Arlandis i Mañó wrote:
> >   
> >> I've done some more investigation. Connecting Fluidsynth output to
> >> Rezound I've saved the waveforms with lower gain (no distortion) and
> >> higher gain (with distortion). I've always avoided clipping that occurs
> >> at very high gain levels. I've used piano soundfonts, mainly the
> >> "Microfont piano collection (6MB)" soundfont.
> >>
> >> I've compared the same sound with distortion and without distortion and
> >> I've discovered that the distortion is caused by the gain changes alone,
> >> but I don't know why some samples don't get distorted. For example, the
> >> "triangle simple" preset in Vintage Dreams soundfont can be maxed with
> >> gain 140 without any distortion before it starts clipping.
> >>
> >> I'm not an audio expert and I certainly missing something. I've tried to
> >> ensure soundcard and speakers are not the problem. I can supply the wave
> >> files tested. Please, could someone throw some light?
> >>
> >> Thank you.
> >>
> >>     
> >
> >   
> 
>