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    SubjectRe: NEWSFLASH! Linux ported to Commodore VIC-20!!
    On Mon, Sep 21, 1998 at 09:00:18PM +1000, Nathan Hand wrote:
    > It's a lot easier than this. Yes, pulse width modulation creates
    > a Fourier series with highr order harmonics. The inductor in the
    > speaker coil simply cancels these frequencies out (an inductance
    > resists a dramatic change in current) thru integration.

    Well, this (low-pass) model works quite well in the limit of low
    volumes, when the pulse width is much less than L/R time constant
    of spkr. But it is dangerous to push this explanation very far
    beyond that.

    I actually spent a lot of time a few years back trying to improve
    on the pcspeaker performance based on this model, and was eventually
    forced to admit that it either does not tell whole story or simply
    has poor predictive powers.

    Was only after taking another look this weekend with benefit of
    hindsight that I find a trivial calculation which explains
    why. This is why I was quick to post: it would be a shame for
    anyone else to waste similar time chasing down a blind alley.

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