Sorry for not making myself clear. My intention was to recommend the
Butterworth filter for removal or attenuation of subsonic frequencies.
It is true that DC does not always act like an AC signal with a
frequency of 0 Hz. FYI, for the Windows platform, Cool Edit 96
(http://www.syntrillium.com), can remove DC offsets. I don't believe
that program is available for Mac, however.

-dB

> -----Original Message-----
> From:	Jean Piche [SMTP:pichej@ERE.UMontreal.CA]
> Sent:	April 20, 1998 16:49
> To:	tolve; csound
> Subject:	Re: Protecting speakers [Long]
> 
> tolve,
> 
> Also be aware that while the butterworth filter solution works well in
> most
> cases (Cecilia has a DC remover module), it will not work in all cases
> (in my
> experience). We are considering building an opcode to do just that.
> MixViews has
> a *very* efficient DC-remover.
> 
> ________________________________________________________
> Jean Piche
> Universite de Montreal
> http://mistral.ere.umontreal.ca/~pichej
> http://www.musique.umontreal.ca/electro/CEC/