[LAU] LADSPA Plugins from ALSA,would like some help, please !

[Chris Caudle]

On Wed, September 7, 2016 11:06 am, bricolodu wrote:
> By the way according to the box my 2" speaker is in, without any settings,
> I can go down to less than 60 Hz ! But then, the size of the box is too
big,
> around 5L and I want 0.5L !

60 Hz is not so bad, so maybe two different settings for the 5l box and
the 0.5l box.

> /I think that trick works best when the speaker system can get down to
> within one octave of full bass response, so down to below 80Hz for sure, /
> It is the case with the 5L box, I can even listen to 30 Hz although
> attenuated !

What you are trying should work OK with the 5l box.  I'm not sure about
the 0.5 l box, that will depend on the low frequency cutoff for that
system, which

> /You may also need something like a speaker crossover, where
> only frequencies below the bass cutoff of the speaker system are sent to
> the distortion circuit,/
> This is what I'm doing, a low pass that cuts everything above 200 Hz
> first.

Too high, if the box can output to 60Hz, then the cutoff should probably
be around 60Hz to 80Hz (see what sounds best).  The idea is to fool the
ear into hearing what is not produced, with the low pass at 200Hz then you
would add extra harmonics to frequencies which are being produced by the
speaker already, that will likely make the sound "muddy" or "thick," maybe
you would use some other word to describe, but probably will not be the
sound you want.

> /then the output of that goes through a high pass to get rid of the low
> frequencies which cannot be reproduced by the speaker, / Why ? To lower
> distortion ?

Yes, my assumption is that if the speaker cannot make audible output at
those low frequencies, if you send the low frequencies anyway it will add
distortion.  Since that is what you are trying to do with the plugin,
obviously the speaker does not add distortion in a way that you find
sounds good, so best to avoid it.

> What cut-off Frequency ?

The lowest frequency where the speaker has full output.    I think by the
way you described the 5l box that would probably be around 50Hz or 60Hz
(since  you said 30Hz is very attenuated definitely above that).

> It will be very limited if I use the
> 0.5L box, the natural cutoff frequency of the box is around 150 Hz.

That is probably around the limit where this technique could work.  Even
150Hz is a bit high, 100Hz or 80Hz would be better.

> /and the harmonics added back in to the original source to create the
> illusion.  /
> This is what I'm doing.

OK, you may be in the right direction, just off in the settings.  Try
lowering the high pass to 100Hz or lower, let the speaker play what it can
play naturally, and only add in harmonics for frequencies the speaker
cannot play naturally.  The speaker can play 100Hz to 200Hz no problem, so
don't make changes there.

I do not know the answer to which plugin would work best to generate the
harmonics.  Perhaps someone can suggest a plugin more suitable, but you
can start by experimenting with the changes to the filter frequencies.

-- 
Chris Caudle