[Les Cargill[_4_]]

William Sommerwerck wrote:
"Les wrote in message
...
William Sommerwerck wrote:

His essential point -- ultrasonics are a liability -- remains quite true.

That assumes amps and speakers suddenly misbehave badly above the upper
limits of human hearing. That's unlikely.



Fair enough.

"Sampling does not affect frequency response."

Not quite true. The sampling function itself has an "amplitude envelope"
that varies as (sin x) / x. The wider the sampling function, the greater
the
ampliftude variation introduced.

Cite, please?

Any book with a thorough discussion of sampling.

Yeah, that's the sinc function/kernel but it does not mean that there's
any nonlinearity or response change over the published passband
of a properly ... sampled system.

There has to be some, because you can't have an infinitely narrow sampling
function.

of course not.

Please note the phrase "over the published passband." Or did I
miss your meaning?

In practice, it's not of any major importance. But there /is/ an
effect on frequency response, however small.



If I am confused... so you are saying with a narrower, more
perfectly-approximating-a-Dirac-Delta ... impulse response
( I am not 100% sure *that* is even correct ) that we would get a
wider bandwidth... which is probably assumption #1 of his whole
thing ( and a widely used assumption which he defends pretty well ).

because otherwise I think you're up against the Shannon
Theorem and its "completely reconstructs."

I read him to ( reasonably well ) state that the 20-20KHz limit
is a working assumption, with lots of empirical support.

--
Les Cargill