John
I put my caveat in for good reason ...
The way I thought about it was to think what I would do to design one. I
would need a reactive component somewhere, to do it easily, and then I would
cancel out that component's phase shift with an all-pass. I am fairly
certain that can't be done perfectly (though for the moment I can't quite
think why not for a first order original. I suppose because it has to add,
so you can never get a perfect time delay.)
But are you sure that radiation resistances are only real? I'm fairly
certain that acoustic radiation impedances aren't naturally real and that
it's only because drivers are mass controlled that they appear so. (I
suspect that means masses in the f = ma sense rather than an equivalent C.)
Christian
On 15 September 2011 20:32, John Woodgate <jmw@...> wrote:
**
In message
<CANj54jwDGEMhNQA5E=DD=cMmYJTwDN=mMCrX2FaMfB4YgiLxuw@...>,
dated Thu, 15 Sep 2011, Christian Thomas <ct.waveform@...>
writes:
In which case the answer needed is "No, you can't. Or at least you
can't have a full solution. (I think that must be right).
I'm not sure. We have real resistances that change with frequency -
radiation resistances for example, There are definitely resistances - at
any fixed frequency they are consistent with Ohm's and Joule's Laws.
So why can't I define a resistor R(f), such that R(f) = kf, or K*F(f)? k
and K have dimensions, of course, but that doesn't seem to be a problem.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star
will
be more interesting.
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