[linux-audio-user] abusive audio, will it blow up the PA?

[Paul Winkler]

On Fri, Jan 12, 2007 at 01:25:08PM +0000, James Stone wrote:
> On 1/12/07, Georg Holzmann <georg.holzmann at student.kug.ac.at> wrote:
> >
> >Hallo!
> >
> >>> As the others already said you should at least use a highpass to
> >>> remove the DC ...
> >>
> >> At least? Other things I should run it through?
> >
> >Well, you could also a limiter+etc. - but I think the biggest problem is
> >the DC offset ...
> >Because if you have no DC-offset you will here when it is too loud and
> >can decrease the volume ...
> 
> 
> I think there is a DC-offset remover ladspa plugin...

FWIW, I've been experimenting with a pair of Harrison Labs FMOD
passive highpass filters.  They're very portable, being built into a
small brass female -> male RCA adapter.  They're also pretty cheap,
about $25 US for a package of two.

I haven't used mine much yet but they seem to work as advertised.  I
got the 30Hz model. That's the -3 dB point, and they're all 12 dB /
octave.

I'm wondering if I should have got the 50 Hz model, since the vast
majority of output from typical PA subwoofers is in the 50 Hz - 200 Hz
range anyway.  (The fundamental of a low E on a bass guitar is about
40 Hz, but most of the energy of that note is in the first few
overtones.)

Supposedly you can daisy-chain two filters with an attenuator plug in
the middle to make a 24 dB/octave filter with the crossover point cut
in half. I haven't tried that.

The website is unfortunately pretty bad, and hard to find exactly what
you're looking for...
http://www.hlabs.com/technical/crossovers/
List of color-coded FMOD models:
http://www.hlabs.com/technical/crossovers/page2.html


-- 

Paul Winkler
http://www.slinkp.com